JPH11271536A - Image display device, polarizated-light illumination device, polarized light separating element, diffraction optical element, hologram element, and manufacture of diffraction optical element and hologram element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the hologram element which can perform switching between the diffraction and straight travel of incident light and diffracts small an extraordinary light beam made obliquely incident in the straight travel by equalizing the refractive indexes of photocuring liquid crystal having set and nonpolymerizing liquid crystal to an ordinary light beam and an extraordinary light beam. SOLUTION: An area 503 which contains UV curing liquid crystal molecules 503a and an area 504 which contains nonpolymerizing liquid crystal molecules 504a are formed between two glass substrates 502 where conductive transparent electrodes (ITO) 501 are formed. While no voltage is applied between the ITOs 501, the area 503 (after setting) and area 504 are nearly equal in optical anisotropy. They function as a hologram element by applying a voltage between the ITOs 501 to diffract only a P-polarized light (extraordinary light beam) selectively and allow a S-polarized light (ordinary light beam) to travel straight. In the absence of the applied voltage, both the P- and S-polarized light beams travel straight and also securely travel straight even when made incident obliquely.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hologram element for converting a wavefront of an incident light beam, and an image display device using the hologram element.

[0002] The present invention also relates to a polarizing beam splitter for separating an incident light beam into different polarized light components, and a projection type image display device constituted by using the same and projecting and displaying an image.

Further, a polarized light illuminating device for obtaining uniform illuminating light having a uniform polarization direction using a polarized light separating element, and a projection type display for enlarging and displaying an image by modulating polarized light emitted from the polarized illuminating device by a light valve. It concerns the device.

Further, a monitor for displaying images, a display device for portable information terminals, a head-up display for in-vehicle use or personal use, an image display device used for road traffic signs or information display, etc. The present invention relates to a lighting device.

Also, an optical information processing apparatus including an optical head and an optical pickup for recording and reading information recorded on an optical storage medium such as an optical disk or a magneto-optical disk by using a laser beam, and an optical information processing apparatus used in the apparatus. The present invention relates to a diffractive optical element.

[0006]

2. Description of the Related Art First, a conventional hologram element will be described.

In recent years, a hologram element has been developed which forms an interference image by causing two coherent light beams to interfere with each other, records the interference image on a dichromated gelatin or a photopolymer, and reproduces the wavefront of the recorded light beam. Is thriving.

Examples of application fields of hologram elements include interference measurement, holographic optical elements, optical information processing such as pattern recognition, holographic displays, etc., as described in References, Toshihiro Kubota, “Introduction to Holography”. There is.

[0009] When the hologram element is applied to the field of image display, not only a three-dimensional image is displayed but also a hologram element is displayed.
Various applications are being considered.

In the following, examples used for (1) an optical switch and (2) a direct-view type liquid crystal panel will be described.

First, the optical switch will be described. For example, in Japanese Patent Application Laid-Open No. 5-173196 of the first conventional example, the interference script is illuminated with a mixture of a polymer material that cures with the wavelength of the light beam that forms the interference script and a liquid crystal that is uncured at the wavelength of the light beam. By the induced phase separation, a region made of a cured polymer material and a region made of a non-cured liquid crystal are formed, and the non-cured liquid crystal is controlled by an applied voltage, thereby controlling the diffraction / straight traveling of an incident light beam. A switch is disclosed.

A number of similar examples have been disclosed before, for example, Applied Physics Letter, No. 64.
Vol. 9, No. 107, pages 1074 to 1076, 1994 (hereinafter abbreviated as Conventional Example 2) discloses a hologram element capable of controlling diffraction efficiency.

In this example, as in the conventional example 1, a mixture of a polymer material that cures at a specific wavelength and a liquid crystal material that does not cure at this specific wavelength is illuminated with a two-beam interference document of that wavelength. Then, a polymer material is formed in a portion where the light intensity of the interference draft is high, and a region containing a large amount of the liquid crystal material is formed in a portion where the light intensity of the interference draft is low.

A hologram element which is not switchable but is formed by using light-induced phase separation by two-beam interference exposure is disclosed in Japanese Patent Application No. 8-162647 (hereinafter, referred to as Japanese Patent Application No. 8-162647).
Conventional example 3), Japanese Patent Application Laid-Open No. 9-324259 (hereinafter abbreviated as Conventional Example 4 in Japanese Patent Application No. 8-142533).
And many other examples are disclosed.

The hologram element manufactured by using such a light-induced phase separation phenomenon is not limited to two-beam interference exposure, but may be formed, for example, on pages 86 to 87 of the Liquid Crystal Symposium on Disclosure '97 (hereinafter referred to as Conventional Example 5). As described in US Pat. No. 6,064,045, a mixture of an ultraviolet curable resin and a liquid crystal material is mixed at an appropriate ratio, and then the mixture is injected into a cell formed using a glass substrate on which a conductive transparent electrode is formed. It may be manufactured by irradiating ultraviolet rays through a patterned photomask.

In each of the above examples, regions having different refractive indices are formed using light-induced phase separation. This technique is described in, for example, Sharp Technical Report, No. 63, pp. 14-17, December 1995. As disclosed in the Moon (hereinafter abbreviated as Conventional Example 6), this is a known technique that is also used to fabricate a microcell structure for widening the viewing angle of a liquid crystal panel.

In this example, a mixture of a photo-curable resin and a liquid crystal is illuminated with lattice-like light (wavelength is a wavelength for curing the photo-curable resin), and each pixel is caused by a photo-induced phase separation phenomenon. Is formed. As a result, the liquid crystal molecules are aligned in an axially symmetrical shape stabilized by the photo-curing reaction by the self-alignment force in the liquid crystal region, thereby realizing a wide viewing angle and a high contrast.

Next, the direct-view type liquid crystal panel 1 will be described.
About the example applied to 9 backlight units,
This will be described with reference to FIG. The direct-view type liquid crystal panel is classified into a transmission type and a reflection type, and hereinafter, the transmission type will be described as an example. For example, as disclosed in Japanese Patent Application Laid-Open No. Hei 9-178949 (hereinafter abbreviated as Conventional Example 7), the image display device of FIG. 1 includes a cold cathode tube (hereinafter abbreviated as CCFT) 23 as a light source. From the end face of the light guide 21 and output to the transmissive liquid crystal panel 19 by the hologram element 30 and the reflection mirror 23 formed on the back side of the light guide 21.
Reference numeral 0 denotes a reflection type hologram.

According to the above configuration, it is possible to reduce the number of parts, reduce the weight, and reduce the cost, and at the same time, it can be used as a backlight unit having high brightness uniformity, high efficiency, and directivity. This function is realized by using the hologram element 30 as an aggregate of minute holograms. That is, the mosaic-shaped micro hologram is manufactured so as to exhibit the maximum diffraction efficiency at different incident wavelengths and incident angles.

In a similar configuration, for example, Japanese Patent Application Laid-Open No. Hei 9-127894 (hereinafter abbreviated as Conventional Example 8)
Discloses an example in which the uniformity of brightness is further improved by increasing the area density of the reflection type hologram as the distance from the light source increases.

In addition, for example, Proceedings of International Display Workshops '97, pages 411 to 414 (hereinafter abbreviated as Conventional Example 9), or JP-A-9-1383.
As disclosed in Japanese Patent Application Publication No. 96 (hereinafter abbreviated as Conventional Example 10), it is used as a reflector of a reflection type liquid crystal panel, and selectively transmits an incident light beam in a direction substantially perpendicular to the liquid crystal substrate.
In addition, an application is considered in which light is substantially reflected (diffraction) within a specific solid angle, and a bright image is displayed although the viewing angle is narrow. This hologram element is a so-called reflection type volume hologram.

In the conventional examples 7 to 10, a general photopolymer is used as a material, and the hologram element always performs the above-mentioned reflection.

Next, the image display device will be described.

In recent years, since it is difficult to increase the size of the conventional direct-view television, development of a projection-type image display apparatus for enlarging and projecting an output image of an image display means for modulating an illumination light beam from a high-intensity lamp has been advanced. (For example, Oplusei, August 1993, pp. 58-101).

FIG. 67 shows a configuration of a conventional general projection type image display device, and shows a configuration example using a liquid crystal panel as an image display means. The output light 3 from the lamp 2 is reflected by the reflector 4, and the output light beam 5 is condensed and propagated by a condensing optical system (not shown), and is red, green, and blue by dichroic mirrors 12 and 13 for color separation. Separated into three primary colors, total reflection mirror 14, condenser lens 15
Through the liquid crystal panels 16-18. The output lights modulated by the liquid crystal panels 16 to 18 are combined by a dichroic prism (not shown) for color synthesis or by dichroic mirrors 19 and 20 and a total reflection mirror 14 and are projected by a projection lens 9 to a screen (not shown).
Enlarged projection above.

The liquid crystal panels 16 to 18 are mainly classified into a transmissive type and a reflective type, and each of the liquid crystal panels 16 to 18 converts a specific linearly polarized light incident through a polarizing plate or a polarizing beam splitter (hereinafter abbreviated as PBS). An image is displayed by modulating with a liquid crystal material.

The liquid crystal panels 16 to 18 generally use an active matrix system in which thin film transistors (hereinafter abbreviated as TFTs) are arranged in each pixel as switching elements for driving each pixel. It is generally formed of polysilicon.

As the lamp 2, a lamp having a high luminous efficiency, a small luminous body volume, a high luminance and a high color rendering property is required, and a metal halide lamp, a xenon lamp,
Ultra-high pressure mercury lamps and the like are used.

As the reflector 4, a parabolic mirror, an ellipsoidal mirror, a spherical mirror, or the like is used because the reflected light beam 5 can be effectively used effectively. Often located at the focal point or center. The current mainstream method is to use a parabolic mirror and install a light emitter of a lamp near the focal point to obtain a substantially parallel light flux.

In a recent projection-type image display device, when displaying an all-white signal, (1) the brightness of the central portion and the brightness of the peripheral portion of the projected image are made uniform, and (2) the entire projected image is displayed. Improving the projection efficiency (lumen / watt), which is defined as the value obtained by dividing the luminous flux (lumen) by the power consumption (watt) of the lamp, is a major issue for development. For (1), the introduction of an integrator For (2), a solution is attempted by combining a polarization conversion element in addition to combining an integrator with a high-intensity lamp having a small luminous body.

First, the integrator will be described. An integrator is described in, for example,
As disclosed in Japanese Patent Application Laid-Open No. 06-346557 and Japanese Patent Application Laid-Open No. 5-346557, two types of fly-eye lenses are formed by arranging micro lenses two-dimensionally. FIG. 7 shows a specific configuration example of the integrator. Reflector 4
And, by the first fly-eye lens 49, the image of the illuminator of the lamp 2 is formed on each lens of the second fly-eye lens 50 corresponding to each lens of the first fly-eye lens 49. You.
Each lens of the second fly-eye lens 50 is configured to form an image of the first fly-eye lens 49 on the image display means 7.

With the above arrangement, the second fly-eye lens 50
The image formed by each lens on the image display means 7 is obtained by finely dividing the output light having a large luminance distribution outputted from the reflector 4 by each lens of the first fly-eye lens 49, and then dividing them. 7 are superimposed. According to such a principle, it is possible to increase the brightness of the peripheral part with respect to the central part of the projected image to 70% or more.

Further, by introducing an integrator, the projection efficiency can be improved. Generally reflector 4
The light beam 5 reflected by the light source is substantially circular, but the image display means 7 is, for example, a 4: 3 rectangular shape. Therefore, when illuminating the image display means 7 in a circular shape, only the area ratio of the rectangle inscribed in the circle has been effectively used. This is called a rectangle conversion efficiency, and the image display means 7 has a 4: 3 rectangle as its outer shape.
, The rectangular conversion efficiency was about 61%. However, the opening shape of the lens used for the first fly-eye lens 49 of the integrator is disclosed in Japanese Patent Laid-Open No. 5-34655.
The arrangement of 4: 3 as disclosed in FIG. 2 of Japanese Patent Publication No. 7 can improve it to about 80%.

Next, the polarization conversion element will be described. The projection type image display device using the polarization display means such as the liquid crystal panel described above has a drawback that only the polarization component in a specific direction can be effectively used in the output light of the lamp, and the projection efficiency is low and the brightness is low. In order to obtain an image, there is a problem that a light source having a large output must be used.
Polarization conversion elements have been developed to solve these problems, and the polarization components or PB absorbed by the polarizing plate are
In S, the polarized light component not incident on the liquid crystal panel is effectively converted into a polarized light component having a plane of polarization substantially orthogonal to the polarized light component.

The polarization conversion element is described, for example, in Japanese Patent Laid-Open No. 5-107.
505, JP-A-6-20294, JP-A-7-20
Although many publications are disclosed, such as Japanese Patent Application Laid-Open Nos. 294906, 8-234205, and 9-105936, they basically consist of a combination of a polarization splitting element and a polarization plane rotating element.

FIG. 8 shows a configuration diagram of a general polarization conversion element 58. Non-polarized light (randomly polarized light flux) 62 is converted into polarization components orthogonal to each other by the polarization separation element 60, that is, P-polarized light (a light flux having a polarization direction parallel to the sheet of paper that is transmitted without being reflected by the polarization separation element) 63, The light is separated into s-polarized light (a light beam reflected by the polarization separation means and having a polarization direction perpendicular to the paper surface) 64, and only the s-polarized light 64 is used as the reflection means 60 '(generally, a film of the same type as the polarization separation means 60 is used. ) And is converted by the polarization plane rotation element 61 into P-polarized light 63 ′.

In recent years, in many cases, the configuration described above is combined with the lens array 66, and the contents described in the above five publications can also be used in combination with the lens array 66. The configuration is slightly different.

One method is a method in which the width of a light beam incident on the polarization conversion element 58 is made approximately half by the lens array 66, and the light beam is incident only on the polarization separation element 60 to perform polarization separation and polarization plane rotation ( (See FIG. 9). In this case, in many cases, the lens array 66 is configured as a fly-eye lens forming an integrator, thereby simultaneously ensuring the uniformity of the brightness of the projected image as described above. That is,
A configuration has been considered in which the lens array is used as a second fly-eye lens of the integrator.

On the other hand, as disclosed in JP-A-6-202094 and JP-A-8-234205,
An image is formed on the second fly-eye lens by installing a polarization splitting element on the lamp side of the first fly-eye lens and changing the exit angle of the light beam after the polarization separation by several degrees according to the polarization component. A method has been devised in which the position is changed for each polarization component, and only one of the polarization components rotates the plane of polarization. As an application of this method, a configuration in which a polarization splitting element is provided between the first fly-eye lens and the second fly-eye lens has been considered.

In a conventional polarization conversion element, a dielectric multilayer film formed by laminating a plurality of dielectric layers is mostly used as a polarization separation element. A hologram element having polarization selectivity as a polarization splitting element is conventionally known, but an example in which the hologram element is combined with an integrator to form a polarization conversion element and applied to an illumination optical system of a projection type image display device is disclosed. It has not been.

In the hologram element having polarization selectivity disclosed in Japanese Patent Application Laid-Open No. Hei 8-234143 and US Pat. No. 5,161,039, polarization selection is performed by using a liquid crystal polymer or a polysilane polymer material having a nonlinear light absorption effect. It has a function as a so-called volume hologram for each polarized light.

In using a projector, there is a high demand for a bright projected image that can be recognized even if the room is not too dark. Therefore, it is important to improve the light use efficiency of the liquid crystal light valve. As an optical system for improving the uniformity of the illumination area, Japanese Patent Application Laid-Open Nos. Hei 3-11180 and Hei 5-346557 disclose an integrator optical system using two lens plates.

This is basically the same as that used in the exposure machine. The parallel light beam from the light source is divided by a plurality of rectangular lenses, and the image of each rectangular lens is applied to each rectangular lens.
This is to superimpose an image on a liquid crystal light valve by a relay lens corresponding to one to one.

Japanese Patent Application Laid-Open No. 6-202094 proposes an illumination optical system in which a polarization conversion method is combined with an integrator illumination method. This schematic is shown in FIG. Light emitted from the light source 1101 enters a polarization splitting element using liquid crystal, and is split into a P-wave 1106 and an S-wave 1107. These lights are transmitted to the first lens group 11 constituting the integrator.
03 and the second lens group 1104, the second lens 110
4 are imaged at different positions of the phase plate 1105 arranged behind. In the phase plate 1105, a half-wave plate is periodically formed in approximately half the area of one lens forming the second lens group.

For this reason, for example, the P-wave 1106 imaged at the position of the half-wave plate is emitted as an S-wave with the polarization direction rotated by 90 °. The S wave 1107 is imaged in a region where the half-wave plate is not formed, and is transmitted as it is.
In other words, the light waves emitted from the phase plate 1105 have substantially the same polarization direction.

JP-A-7-294906 reports a polarization conversion element in which a lens plate and a prism are combined. This is shown schematically in FIG. This is because a light beam incident on a lens plate 1201 having an array of lenses formed thereon is focused on a light beam and is incident on a prism 1202. Where S
The wave 1204 passes through as it is, and the P wave 1205 is reflected by the prism, enters the adjacent prism, is reflected again, and
° Change the angle.

Then, the light passes through a half-wave plate placed in the optical path and is rotated as 90 degrees by the polarization direction and emitted as an S-wave. As described above, the lens plate 1201 and the prism 1202
The light wave emitted from the light beam becomes a light beam having a uniform polarization direction.

Here, the image display principle of the liquid crystal element will be described with reference to FIG. For example, light emitted from a light source 901 such as a fluorescent lamp or a metal halide lamp is composed of a P-wave 902 having a polarization direction parallel to the paper surface and an S-wave having a polarization direction perpendicular to the paper surface. This light beam enters the polarizer 904, where a specific polarization component is absorbed and the remaining components are transmitted. The polarizer 904 is configured to absorb an S-wave component and transmit a P-wave. Polarizer 904
Is transmitted to the liquid crystal element 905.

Here, as the liquid crystal element 905, a twisted nematic liquid crystal in which the directions of liquid crystal molecules are twisted by 90 ° between the entrance surface and the exit surface will be described as an example. A patterned transparent electrode is formed on the liquid crystal element 905, and an electric field can be applied to each pixel. The pixel (ON) to which an electric field enough to completely switch the liquid crystal is applied is in a state in which the liquid crystal molecule is untwisted and the liquid crystal molecule isotropically stands on the incident surface (homeotropic). Therefore, the P-wave incident on this pixel passes through the liquid crystal element while maintaining its polarization state without being modulated.

Next, a pixel (OF) to which no electric field is applied
In F), the liquid crystal molecules are in a state where the angle of the liquid crystal molecules is twisted by 90 ° in the thickness direction from the incident surface to the emission surface. For this reason, the P-wave component incident on the pixel rotates its polarization plane by 90 ° due to the twist nematic effect caused by the twist of the liquid crystal while passing from the entrance plane to the exit plane. Therefore, after passing through the OFF pixel, the previous light is S
It will be emitted as waves.

After passing through the liquid crystal element, the polarization direction of the light differs depending on the presence or absence of the electric field of the pixel corresponding to the passing position. Next, these lights are incident on the polarizer 906. Here, the polarizer 906 is set so that the axis direction passing the polarization component is inclined by 90 ° with respect to the polarizer 904 described above. That is, the polarizers 904 and 906 are arranged in crossed Nicols. Therefore, of the light that has passed through the liquid crystal element, the P-wave is absorbed by the polarizer 906, and the S-wave passes through the polarizer 906.

As described above, the light passing through each pixel of the liquid crystal element has its polarization direction modulated according to the electric field applied to the pixel, and as a result, the intensity of the light passing through the polarizer 906 differs. . The observer 907 gives the polarizer 90
Since the amount of light passing through 6 differs, an image as a light and dark pattern corresponding to each pixel is recognized.

Also, by controlling the amount of electric field applied to each pixel, the polarization direction of light passing through the liquid crystal can be set to an intermediate state between the P-wave and S-wave states. It becomes possible.

Next, the optical information processing apparatus will be described.

An optical information processing apparatus for recording and reading information stored in an optical storage medium such as an optical disk or a magneto-optical disk mainly includes a semiconductor laser as a light source and a light emitted from the semiconductor laser on an optical storage medium. And a hologram element as a diffractive optical element for guiding the laser light reflected on the optical storage medium to the light receiving element.

At one end, light emitted from the semiconductor laser passes through the hologram element and is focused on the surface of an optical disk as an optical storage medium by an imaging lens. The light that is reflected and spreads at the intensity according to the recorded information on the surface of the optical disk,
Once again converged by the lens, part returns to the semiconductor laser,
A part is divided in two directions by, for example, a hologram element divided into two regions, an image is formed on a light receiving element divided into several regions, and defocusing and tracking are performed using a technique such as a knife edge method. The detection of the displacement, the information signal, and the like are performed.

As described above, the light emitted from the laser passes through the hologram element as the diffractive optical element twice, on the outward path and the return path. If the light is strongly diffracted after passing through the hologram element on the outward path, the amount of light condensed on the surface of the optical disk will decrease, and sufficient light intensity will not be obtained on the disk, hindering accurate detection of signal information. May come. For this reason, usually, the hologram element is required to have a function in which the diffraction efficiency is different between the forward path and the return path.

Since a semiconductor laser as a light source has a polarization characteristic, selectivity of diffraction efficiency depending on a polarization direction is often used. More specifically, the light emitted from the semiconductor laser is transmitted as it is without diffracting the light in the direction of polarization, and thereafter, a quarter of the way in the optical path with the disk.
A phase plate such as a wave plate is arranged so that the direction of polarization is rotated by 90 ° compared to the initial stage when reflected by the disk and passed through the hologram again. At this time, the hologram element has a diffraction function, and the light passing through the hologram element is guided to a light receiving element for detecting an information signal or the like.

A hologram having such a polarization selectivity is produced using an optical medium having a refractive index anisotropy. For example, a mask is formed by photolithography or holographic exposure on a predetermined region of the surface of an optical medium having a refractive index anisotropy such as lithium niobate, and benzoic acid or the like is used on an exposed region of the surface. Perform ion exchange. Then, a refractive index distribution does not occur for a specific polarization direction, and the object can be handled as a uniform object.

However, for light in the polarization direction orthogonal to the above polarization direction, a refractive index distribution corresponding to the region formed by the mask is generated, and a diffraction phenomenon corresponding to this pattern is generated. An optical information processing apparatus is configured using a hologram element having such characteristics.

[0061]

All of the hologram elements disclosed in the above-mentioned conventional examples 1 to 6 are optically substantially isotropic light-curing type elements which do not always have refractive index anisotropy. And a liquid crystal material that does not cure at a wavelength that cures the photocurable polymer material (hereinafter abbreviated as non-polymerizable liquid crystal), which forms a fine region. Things. Therefore, for example, in the conventional example 1, even if a voltage is applied to the region of only the non-polymerizable liquid crystal so as not to cause diffraction, for example, a light beam obliquely incident acts as a hologram. There was a disadvantage. This situation will be described with reference to FIGS.

As shown in FIG. 2 (a), a conventional hologram element comprises a region 1 (having a refractive index of n1) made of a photocurable polymer material which is optically substantially isotropic, and a non-polymerizable liquid crystal. Region 2 (the liquid crystal molecules have refractive index anisotropy as shown in the figure, and the refractive indices for the ordinary ray and the extraordinary ray are no and n, respectively).
e).

Here, n1 and no are selected to be substantially equal. When a voltage is applied to the transparent conductive electrode 1 (hereinafter abbreviated as ITO) and the liquid crystal molecules in the region 2 are switched, the liquid crystal molecules are arranged substantially perpendicular to the glass substrate 2.

In this case, the vertically incident light flux 3 is optically isotropic (area) to the P-polarized light (polarized light component parallel to the paper) and the S-polarized light (polarized light perpendicular to the paper). 1,
Since both have a refractive index of approximately no), the light beam 3 goes straight without being diffracted.

When no voltage is applied to the region 2, FIG.
As shown in (b), the liquid crystal molecules are arranged substantially parallel to the glass substrate 2, and the region 2 has a refractive index anisotropy.

As a result, for example, the P-polarized light acts as a hologram element whose refractive index alternately changes to ne and n1, whereas for the S-polarized light, all regions have almost the same refractive index no. Acts as an isotropic medium. Therefore, the P-polarized light 4 is diffracted in the incident light beam 3, and the S-polarized light 5 goes straight.

However, as shown in FIG. 3 (a), even in the mode in which the voltage is applied to the light beam 3 'obliquely incident and the liquid crystal molecules are vertically aligned to make the incident light beam travel straight, 2 has a refractive index anisotropy. That is, it acts as an isotropic medium having a refractive index of no with respect to an ordinary ray (in this case, S-polarized light), so that it travels straight. (Θ), and the incident light is diffracted as a hologram. Therefore, for example, when it is used as an optical switch, there is a disadvantage that complete control cannot be performed except for vertical incidence.

Actually, even if the region 1 is formed using a photocurable polymer material which does not originally have a refractive index anisotropy, if it is formed between glasses having a narrow gap, the refractive index is slightly reduced due to stress or the like. Develop anisotropy. However, the difference is small and the above-mentioned phenomenon appears essentially.

The slight refractive index anisotropy may cause a problem. For example, in the case of Conventional Example 6, when displaying black, the grid portion becomes a discontinuous region, which is particularly conspicuous when displaying a high-contrast image, and has the disadvantage of impairing uniformity.

The problems described in detail above are problems that always occur in a system in which a mixture of an optically isotropic photocurable polymer material and a liquid crystal material is used as a material to exhibit phase separation. is there.

On the other hand, there has been reported an example in which a liquid crystal polymer composite retardation film is produced using a mixture of an ultraviolet curable liquid crystal, which has recently attracted particular attention as a photocurable liquid crystal, and several types of non-polymerizable liquid crystals. (Eg, '97 Liquid Crystal Symposium Proceedings, pp. 168-169, 1997). However, in the above example, the entire surface is simply and uniformly irradiated with UV light, and only the entire surface is uniformly cured.
No mention is made of the formation of interference fringes due to light-induced phase separation by two-beam interference exposure, and the effect that the configuration of the present invention does not produce diffraction even for oblique incident light, as will be described later.

In Japanese Patent Application Laid-Open Nos. 9-281330 and 9-288206, for example, a photocurable liquid crystal is injected into a cell in which a stripe-shaped ITO is formed, and a voltage is applied to align the liquid crystal molecules. The light-curing is performed in a state where is partially different to form a diffraction element.

However, in the above example, the liquid crystal material is formed using an essentially homogeneous liquid crystal material, and there is no disclosure regarding the use of a mixture with a non-polymerizable liquid crystal. Sex is equal, but not switchable and essentially different from the present invention.

In the case where the present invention is applied to a direct-view type liquid crystal panel disclosed in Conventional Examples 7 to 10, the hologram element always realizes the above-described functions. No example of changing the function is disclosed.

Further, in the conventional image display device, when the polarization splitting means is formed by using a dielectric multilayer film, since a plurality of thin film dielectric layers are laminated, it takes a long time to manufacture and has a disadvantage that the cost is high. there were.

Further, a plurality of prisms are laminated to each other, and a dielectric multilayer film is formed on a joint surface.
The polarizing beam splitters disclosed in Japanese Patent Application Laid-Open No. 294906 and Japanese Patent Application Laid-Open No. 9-105936 have problems such as difficulty in manufacturing, high cost, and heat resistance of the adhesive.

JP-A-5-107505, JP-A-8-107505
In JP-A-234205, a thick parallel flat plate or a rectangular prism is used, and it is difficult to make a compact configuration. Further, in JP-A-6-20294, it is difficult to manufacture a saw-tooth shape. As described above, the polarization separation element using the dielectric multilayer film has a disadvantage that the cost is high and the production is difficult.

The polarization splitting element using a hologram element having polarization selectivity disclosed in Japanese Patent Application Laid-Open No. Hei 8-234143 and US Pat. No. 5,161,039 employs an illumination optical system in a projection type image display apparatus as described above. As a system, no application example as a polarization conversion element combined with an integrator is disclosed. Assuming that the conventional hologram element is incorporated in the polarization conversion element as a polarization separation element,
Even if it is applied to a projection type image display device, it is difficult to realize high efficiency for the following reasons.

For example, consider a case where a polarization splitting element is provided in front of the first fly-eye lens of the integrator. What enters the polarization separation element is a substantially parallel light beam. These light beams are, of course, unpolarized light. In this case, the difference between the emission angles of the two polarized light beams output from the polarized light separating element after the polarized light separation and whose polarization directions are orthogonal to each other is preferably at most several degrees. This is because two images of the illuminator of the lamp are formed on each micro lens of the second fly-eye lens corresponding to each micro lens of the first fly-eye lens. If this angle difference is too large, the diameter of each lens of the second fly-eye lens must be increased.

That is, as the polarization splitting element, it is necessary to separate substantially parallel light beams into different polarization components and then output each of them with an angle difference of several degrees. This means that the difference between the incident angles of the reference light and the object light at the time of manufacturing the hologram element must be as small as several degrees at most. However, in general, in order to increase the efficiency of the volume hologram sufficiently high enough to be usable, the difference between the incident angles of the reference beam and the object beam is required to be at least 20 degrees or more. Efficiency is reduced. Therefore, the first type of polarization conversion element cannot be formed by using the conventional hologram element as the polarization separation element.

As a diffraction element, for example, Japanese Patent Application Laid-Open
As disclosed in Japanese Unexamined Patent Publication (Kokai) No. 173196, examples using a normal nematic liquid crystal, or Japanese,
Journal, Ob, Applied, Physics, No. 36
Vol. 1997, pages 589-590 using UV curable liquid crystals, or as disclosed in Chemical, Materials 1993, Vol. 5, pp. 1533-1538. Is also known, but the one disclosed in the above publication only discloses that it has a polarization separation function, and does not disclose any application as a polarization conversion element.

As described above, when a polarization conversion element combined with an integrator is formed using a polarization separation element formed of a conventional dielectric multilayer film and applied to a projection type image display device, (1) And (3) there are problems such as high cost, (2) difficulty in manufacturing, and (3) difficulty in compact configuration.

In general, the hologram element is used as a polarization splitting element of a projection type image display device in combination with (2) an integrator because (1) efficiency is low unless a difference between an incident angle and an output angle is increased. It was difficult.

Further, in the conventional diffractive element, 1) it merely discloses that it has a polarization splitting function, and 2) it does not disclose any combination with an integrator. It is not applicable to the device.

Further, a polarization splitting element using liquid crystal has a configuration in which liquid crystal is sandwiched between a glass substrate and a prism substrate having sawtooth grooves. Since liquid crystals exhibit refractive index anisotropy, the difference in the refractive index differs depending on the polarization direction, such as ordinary light or extraordinary light.

The light wave incident on the polarization splitting element generates a phase distribution corresponding to the sawtooth shape, and functions as a phase type diffraction grating. Further, the refractive index difference when passing through the liquid crystal layer differs depending on the polarization direction. For this reason, since the phase distribution differs depending on the polarization direction of the incident light wave, the ordinary light and the extraordinary light, that is, the directions diffracted by the P wave and the S wave are emitted differently.

In order to separate the P wave and the S wave in the second lens array, a diffraction angle that can be separated is required. For this reason, it is necessary to reduce the sawtooth pitch of the polarization separation element to about several tens of μm. At this time, it is necessary to uniformly and strictly design the sawtooth inclination. This is because the inclination of the sawtooth shape corresponds to the blaze angle of the diffraction element, and this shape and uniformity affect the efficiency of the diffracted wave. That is,
If the sawtooth-shaped groove deviates from the design, a problem arises in that the diffracted wave is dispersed and the degree of separation by the polarization separation element is reduced.

If the width of the gap between the sawtooth-shaped grooves is increased, the pitch of the sawtooth-shaped groove can be increased and the processing can be facilitated. In this case, if the separation angle is maintained and used to the same extent as the original case, it is necessary to increase the cell gap of the liquid crystal. However, it is difficult to uniformly align the liquid crystal in a thick cell gap, and a phenomenon such as white turbidity occurs, which causes a new problem that the transmittance of the polarization separation element is reduced and the light use efficiency is reduced.

In a polarization beam splitting element using a prism, a light beam is incident on a prism array at every other stop by a lens plate. Since the prism has the function of a polarizing beam splitter, for example, the S wave is transmitted and the P wave is reflected at a right angle, and further reflected at a right angle by an adjacent prism, so that the light propagates in the same direction as the preceding S wave. After this, one placed in the optical path
The polarization direction is rotated by 90 ° by a / 2 wavelength plate, and the light is emitted as a P wave.

Since the above-described operation is performed for each prism, it is possible to obtain a light beam having a uniform polarization direction from the light wave incident on the lens plate without largely changing the width of the light beam. The prism has a cube shape filled with liquid or solid for refractive index matching with the dielectric multilayer film. In order to increase the degree of polarization separation, it is necessary to form a multi-layer dielectric multilayer film, which increases the manufacturing cost. Also, since the separation film bends the light propagation direction by 90 °,
It is arranged at 5 °. For this reason, the size of the separation element in the thickness direction is fixed by the size of the separation film constituting one prism, and there is a problem that the element cannot be made thin and small.

The present invention solves the above-mentioned problems of the prior art,
To provide a polarization illuminator with high light use efficiency using a diffraction optical element having excellent polarization selection and high diffraction efficiency as a polarization splitting element, and to form a bright projection image by combining this polarization illuminator with a projection optical system. It is an object of the present invention to realize a projection display device that can perform the above-described operations.

In recent years, the use of monitors for car navigation and portable displays for personal viewing of video and image information has been increasing. It is positioned as a low power consumption type display for portable information terminals such as mobile phones. Common conditions required for such a display include small size, light weight, thin shape, and low power consumption. In the head-up display, there is also a need to switch between the display screen and the outside world, and it is desirable that the screen is transparent, that is, a see-through screen.

At present, a display using a liquid crystal element is considered as a display suitable for the above requirements.
A liquid crystal display has a smaller depth area and can be made thinner than a conventional display such as a CRT. In addition, higher definition has been achieved by downsizing the pixel size, increasing the capacity, introducing TFT elements, etc., and the image quality has been further improved.

However, in general, the principle of image display of a display using a liquid crystal element modulates the polarization direction of incident light depending on the magnitude of an electric field applied to the liquid crystal element. By combining polarizers arranged in crossed Nicols before and after the liquid crystal element, image information such as light and dark is displayed by utilizing the difference in the transmittance of the polarizer depending on the polarization state of incident light.

In such a method, the light transmittance is not so high because the polarizer is of the absorption type. Furthermore, since the polarizers are combined in crossed Nicols, the light transmittance is almost nil in the state of only the combination of the polarizers, and the state is black. Therefore, it is difficult to obtain external information through the liquid crystal panel together with the image display, and there is a problem that it cannot be used as a see-through type head-up display.

Since the polarizer is configured to transmit only a specific polarization component by absorbing light, the light absorbed by the polarizer is internally converted into heat. When the amount of incident light increases, the influence of heat generation inside the polarizer cannot be ignored, and problems such as a decrease in the light modulation function of the polarizer and deterioration of the element occur.

Since the liquid crystal display is not a self-luminous type device such as a CRT, a dedicated light source is required for displaying images. Of the power consumption of the liquid crystal display, the ratio of the power used for the light source accounts for about half of the whole, which is a barrier to lowering the power consumption. For this reason, a method of displaying an image without using a dedicated light source for illumination has been studied. As a method for this, there is a reflection type image display device in which a liquid crystal element and a reflection plate are combined using external light such as natural light or indoor illumination light as a light source. According to this configuration, a dedicated light source is not required,
Low power consumption can be achieved.

In the above method, the display state of an image changes depending on the state of external light used as illumination light. For example, it is difficult to view image information in a room where nighttime illumination is dark or where illumination light cannot be used. For this reason, it is desirable to adopt a configuration that switches between a backlight as an internal light source and external light in accordance with a place where the external light is used, environmental conditions, and the like, and has both low power consumption and convenience in viewing image information. .

However, in order to use external light, it is suitable to adopt a reflection type configuration in which one polarizer is placed on the entire surface of the liquid crystal element. It is suitable to adopt a transmissive configuration in which polarizers are arranged in crossed Nicols before and after. In order to satisfy both of these methods simultaneously, it is conceivable to adopt a configuration using two polarizers. However, when an absorption type polarizer is used, the transmittance is low, and the reflection type image by external light is used. In display, the brightness of the screen is significantly reduced and the image quality is degraded. Therefore, there is a problem that it is difficult to use the internal light source and the external light in combination.

The present invention has solved the above-mentioned problems of the prior art,
An image display device is constructed by combining a diffractive optical element with excellent polarization selectivity and high diffraction efficiency with a liquid crystal element, enabling see-through display, and a low-light that can be used in combination with an internal light source backlight and external light. It is an object to provide a power consumption type image display device. Furthermore, by using a diffractive optical element as a transmission type having a modulation in the refractive index distribution,
The aim is to increase the efficiency of light utilization and achieve versatile application as an illumination device for illumination light simultaneously with image display.

On the other hand, when detecting a signal from an optical storage medium using a hologram element having polarization selectivity manufactured by ion exchange or the like, the signal detection is greatly affected by the diffraction efficiency of the hologram element. Specifically, the light is reflected by an optical disk or the like, is changed by a phase plate so that the polarization direction is orthogonal to the initial direction, and is incident on the hologram element.

At this time, if the diffraction efficiency of the hologram element is low, the intensity of light reaching the light receiving element is weak and noise increases, making it difficult to detect a signal accurately. Furthermore, since the component transmitted without being diffracted is irradiated to the semiconductor laser, which is the light source, instability of laser oscillation occurs due to an increase in the amount of light returning to the semiconductor laser. Come up.

To solve this problem, it is necessary to improve the polarization selectivity and diffraction efficiency of the hologram element. At present, as a form that can be used as a hologram element having polarization selectivity, there is a two-dimensional diffractive optical element type. This has a refractive index distribution corresponding to a rectangular lattice shape, and causes a phase difference of 0 and π for each adjacent lattice with respect to the wavelength of incident light. Light passing therethrough is diffracted as a result of being intensified in a specific direction corresponding to the spacing of the rectangular grating.

In such a hologram element composed of a rectangular lattice, a diffracted wave is generated symmetrically due to a two-dimensional binary shape. Therefore, the diffraction intensity 1
Even with ideal diffraction efficiency focused in the next direction, 40%
There is a problem that it is limited to the extent. Further, when the grating shape deviates from the design value, the intensity ratio of the diffracted light to higher orders other than the first-order light intensity including the zero-order light intensity increases. Therefore, not only is the required primary light intensity reduced, but the higher-order diffracted light acts as return light to the semiconductor laser, causing noise to the laser oscillation as described above. Problems arise.

The present invention has solved the above-mentioned problems of the prior art,
It is an object of the present invention to provide a diffractive optical element used for an optical information processing device having excellent polarization selectivity and high diffraction efficiency, and a highly reliable manufacturing method of the element.

[0106]

According to the present invention, there is provided a photocurable liquid crystal having a plurality of regions having different compositions of materials, wherein the plurality of regions are cured by at least a specific wavelength and have a refractive index anisotropy. And a second region composed of a non-curable liquid crystal (hereinafter abbreviated as a non-polymerizable liquid crystal) according to the wavelength, and a refractive index of the photo-curable liquid crystal to ordinary light after curing. And the refractive index for the extraordinary ray is substantially equal to the refractive index for the ordinary ray and the extraordinary ray of the non-polymerizable liquid crystal.

The present invention comprises at least plate-shaped first and second hologram elements having polarization anisotropy with respect to an incident light beam and selectively diffracting substantially only a first polarization component. An angle θ0 formed between the incident light beam incident on the first hologram element and the optical axis, an angle θ1 formed between the incident light beam and a first output light beam diffracted by the first hologram element and the optical axis; The angle θ2 formed by the output light beam after being incident on the second hologram element and diffracted and output as the second light beam with the optical axis is | θ1−θ2 |> 20 | θ0−
θ2 | <15 is satisfied.

The first and second hologram elements are disposed substantially parallel to each other and selectively diffract predetermined polarization components substantially equal to each other.
And the diffracted light beam diffracted by the first and second hologram elements and emitted from the second hologram element, and the diffracted light flux incident on the first hologram element, The angle between the transmitted luminous flux transmitted from the second hologram element and the transmitted light flux emitted from the second hologram element is greater than 0 ° and less than 15 °, and is incident on the first hologram element. In the light beam diffracted by the first and second hologram elements, the angle formed by the light beam incident on each hologram element and the light beam diffracted by each hologram element exceeds 20 °.

[0109]

(Embodiment 1) An example of a hologram element which is a polarization-selective diffractive optical element having a different diffraction effect depending on the polarization direction of incident light will be described.

As shown in FIG. 10, this hologram element is provided between two glass substrates 502 on each of which a conductive transparent electrode (hereinafter, referred to as “ITO”) 501 is formed. A region 503 including molecules 503a and a region 504 including, for example, non-polymerizable liquid crystal molecules 504a are formed. The UV-curable liquid crystal is a photocurable liquid crystal having a refractive index anisotropy, which is cured by a light beam having a specific wavelength. On the other hand, a non-polymerizable liquid crystal is a liquid crystal material that does not cure with respect to a light beam having a wavelength that cures the UV-curable liquid crystal.

Here, the expression relating to “optical anisotropy” will be described. In general liquid crystal materials and optical materials having refractive index anisotropy as seen in uniaxial optical crystals, the refractive index for ordinary light and the refractive index for extraordinary light can be defined. The ordinary ray is polarized light whose refractive index does not depend on the incident angle of the ray, and the extraordinary ray is polarized light having a different refractive index depending on the incident angle.
The refractive index of the extraordinary ray according to its incident angle is shown in FIG.
The refractive index can be determined by a so-called refractive index ellipsoid shown in (b) (Reference: for example, Kudo and Uehara, “Basic Optics”, published by Hyundai Kogakusha, page 202). Therefore, "optical anisotropy of each region with respect to the incident light beam" is simply abbreviated as "optical anisotropy of each region" unless otherwise specified, and the meaning is "with respect to the incident light beam of each region. Anisotropy of the refractive index for ordinary light and extraordinary light. " Further, "the optical anisotropy of the region 503 and the region 504 is substantially equal" means that "the refractive index for the incident ordinary ray and the refractive index for the extraordinary ray are substantially equal to each other in both areas". Shall be. Similarly, “area 5
The expression "03 differs from the optical anisotropy of the region 504" means that "the refractive index for the incident ordinary ray is substantially equal in both regions, but the refractive index for the extraordinary ray is different in both regions". And The terms "optical anisotropy" and "refractive index anisotropy" are used in the same meaning.

In the state where no voltage is applied between the ITO 501, the hologram element has the liquid crystal molecules 50 in both the region 503 and the region 504 as shown in FIG.
3a and 504a are oriented in substantially the same direction (direction substantially parallel to the glass substrate 502), and the region 503 (after curing) and the region 5
04 have almost the same optical anisotropy. That is, the refractive indices for the ordinary ray are almost equal between the area 503 and the area 504 (the value is no), and the refractive indices for the extraordinary ray are almost equal (the value is n).
e). On the other hand, when a predetermined voltage is applied between the ITOs 501, as shown in FIG. 10B, only the liquid crystal molecules 504a in the region 504 are aligned (switched) in the direction of the lines of electric force, and the regions 503 and 504 are connected to each other. Have different optical anisotropy from each other.

The hologram element configured as described above functions as a hologram element for P-polarized light (extraordinary light) by applying a voltage between the ITOs 50, and changes the incident light flux to the pitch between the regions 503 and 504. And diffracted in a direction corresponding to the film thickness. That is, only the P-polarized light is selectively diffracted, and the S-polarized light (ordinary ray) goes straight (FIG. 10).
(B)). Thus, the selective diffraction of only P-polarized light is
The same applies to the case where the light beam enters the hologram element from an oblique direction. On the other hand, when no voltage is applied, both the P and S polarized lights go straight (FIG. 10A). Further, in the hologram element, when no voltage is applied, even when the light enters from an oblique direction, both the P and S polarized lights can be made to travel straight. That is, as shown in FIG. 11, when a light beam enters from an oblique direction, the refractive index for the ordinary ray is not equal to no in both the regions 503 and 504, and the refractive index for the extraordinary ray is also in the regions 503 and 50.
4 are equal in ne (θ), so that not only ordinary rays but also extraordinary rays can be made to travel straight without diffraction.

As described above, according to the above-mentioned hologram element, it is ensured that the ordinary light beam and the extraordinary ray can be made to go straight or the extraordinary ray alone can be selectively diffracted even with respect to the light beam incident from an oblique direction. Can be.

Next, a method of manufacturing the hologram element as described above will be described. This hologram element can be formed by so-called light-induced phase separation, for example, by irradiating an interference draft of two light beams.

(1) First, an alignment film (not shown) is applied to two glass substrates 502 on which ITO 501 has been formed, and an alignment process is performed.

(2) For example, beads of a predetermined diameter (not shown) are dispersed to secure a cell gap, and two glass substrates 502 are bonded together (instead of dispersing beads, use is made of silicon oxide or photopolymer). A column having a predetermined height may be formed.)

(3) For example, a liquid crystal material in which a non-polymerizable liquid crystal and a UV-curable liquid crystal are mixed at a weight ratio of, for example, 1: 1 is injected and sealed.

(4) By irradiating the interference draft with a desired pitch by two-beam interference exposure, the UV of the part where the light is strongly irradiated is irradiated.
The cured liquid crystal is cured, and most of the UV cured liquid crystal molecules in the mixed liquid crystal are gathered in the cured portion due to the photo-induced phase separation phenomenon, and good region separation is performed.

Here, in the above process (4),
If a two-beam interference exposure is performed with a voltage applied between the ITOs 501 and the liquid crystal molecules are oriented substantially perpendicular to the glass substrate 501, for example, as shown in FIG. The anisotropy is almost equal and both the P-polarized light and the S-polarized light in the incident light beam go straight, but when no voltage is applied, the optical anisotropy of each region becomes different, and only the P-polarized light is diffracted, A reverse mode hologram element in which polarized light travels straight can be manufactured.

As a method of driving the element, it is generally preferable to apply an AC voltage. However, when a non-polymerizable liquid crystal, for example, a ferroelectric liquid crystal is used, a pulse-like voltage is utilized by taking advantage of its memory property. May be applied.

Here, the difference between the hologram element of the present invention and the conventional hologram element will be described. For example, the above operation principle is basically the same as that of the conventional example 1. However, in the conventional example 1, only the photocurable polymer material is used for the region 503, and the refractive index anisotropy is not changed. Not disclosed. On the other hand, the hologram element of the present invention
It is characterized in that the photocurable liquid crystal has a refractive index anisotropy and the ne and no after curing are the same as the non-polymerizable liquid crystal in the region 504, and therefore, it is possible to improve the incident angle characteristics. it can. For example, consider a vertically incident light beam (see FIG. 2A).

In the conventional example 1, since the region 503 made of the photocurable polymer material does not have the refractive index anisotropy, the refractive index is always the value n1 substantially equal to the no of the liquid crystal. Conventional example 1
By controlling the liquid crystal molecules in the configuration shown in FIG. 8A, the incident light beam 3 can travel straight without being diffracted.

However, as shown in FIG. 9 (a), for the light beam 3 'obliquely incident, the ordinary ray (in this case, the S-polarized light 5) can go straight, but the extraordinary ray (in this case, the P-polarized light). The light 4) is diffracted because the refractive index of the region 503 remains ne (θ) while the refractive index of the region 503 remains no. As shown in FIG. 9B, the refractive index for an extraordinary ray can be obtained from a refractive index ellipsoid.

The above phenomenon is caused by, for example, Conventional Example 2 to Conventional Example 6
And the like, there is a problem common to all conventional devices in which the polymer material to be cured does not have essentially the refractive index anisotropy.

Although the conventional example 6 is not a hologram element, it does not disclose any refractive index between the photocurable polymer material and the non-polymerizable liquid crystal. In this case, the polymer material has a narrow gap. The problem is the slight anisotropy of the refractive index that occurs when formed inside.

(Embodiment 2-1) An example of a polarization splitting element constituted by using a hologram element will be described. This polarization separation element separates an incident light beam into, for example, S- and P-polarized light and emits them at slightly different emission angles.
For example, it is used for a polarization conversion element for obtaining a light beam having a uniform polarization direction.

As shown in FIG. 13, the polarization separation element 510 is formed by bonding a first hologram element 511 and a second hologram element 512 together. First
When a light flux α substantially parallel to the normal direction (Z-axis direction in the figure) of the hologram element 511 is incident, for example, an S-polarized component (a polarized component having a plane of polarization parallel to the X-axis shown in the figure) is diffracted. For example, the light is emitted at an emission angle of 45 ° (an angle between the Z axis and the traveling direction of the incident light with respect to the substrate normal, that is, the Z axis), and is incident on the second hologram element 512 at an incident angle of 45 °. It has become. On the other hand, a P-polarized light component (a polarized light component having a plane of polarization parallel to the Y-axis) is transmitted through the first hologram element 511 as it is.

The S-polarized light that has entered the second hologram element 512 at the incident angle of 45 ° is diffracted by the second hologram element 512 and is emitted at an emission angle of, for example, -7 °, while P The polarized light is applied to the first hologram element 5
As in the case of 11, the light is transmitted parallel to the Z axis.
That is, in the polarization separation element 510, the P-polarized light
The polarized light can be separated and output at a difference of 7 ° in the traveling direction.

As the hologram elements 511 and 512, for example, the hologram elements of the first embodiment can be used.
The above operation can be performed by applying a predetermined voltage to O. Also, a hologram element that performs the above-described diffraction without applying a voltage may be used. Such a hologram element can be manufactured, for example, as follows.

(1) A conductive transparent electrode (for example, ITO: not shown) is formed on a pair of glass substrates 25.

(2) An alignment film (not shown) is applied on each conductive transparent electrode, and a rubbing process is performed.

(3) Disperse spherical beads (not shown) having a desired diameter on the conductive transparent electrode.

(4) A sealing material (not shown) is applied to the periphery of the glass substrate 513.

(5) The glass substrates 513 and 514 are bonded together, and the sealing material is cured by heat treatment.

(6) For example, a UV curable liquid crystal 515 is injected as a hologram material from an injection port (not shown).

(7) The UV curable liquid crystal 515 is exposed to light by a two-beam interference optical system using a UV laser beam to form a predetermined interference image described later.

(8) UV light is again irradiated while applying a predetermined voltage between the conductive transparent electrodes.

A method for manufacturing such a cell is a well-known technique in the field of optics. The two-beam interference optical system also divides a coherent laser beam into two parts and irradiates the coherent laser light at a predetermined angle to irradiate the laser beam at a predetermined angle. This is a known technique for forming a direction and pitch interference draft.

Next, the principle of forming a hologram element having polarization selectivity by the above-described manufacturing method will be described. The UV-curable liquid crystal is a liquid crystal that is cured by irradiating UV light, for example, light having a wavelength near 360 nanometers. Due to the rubbing treatment of the above (2), in the state before the UV exposure after the injection of the (6) and (7), the molecules 515a of the liquid crystal are oriented in a direction substantially rubbed as schematically shown in FIG. ing.

In this state, when the interference light formed by the two-beam interference optical system is irradiated on the UV-curable liquid crystal 515 as described later, the UV-curable liquid crystal 515 is cured according to the light intensity of the interference light. Specifically, for example, as shown schematically in FIG. 15, when an interference fringe having a light intensity distribution in the Y-axis direction in FIG. 15 is formed, only the liquid crystal molecules 515 b in the strong portion are hardened.

Thereafter, when a voltage is applied between the conductive transparent electrodes, as shown in FIG. 16, only the liquid crystal molecules 515a in the portion of the interference image where the light intensity is weak are oriented (switched) in the direction of the lines of electric force. When the entire surface is irradiated with UV light again in this state, the hologram element maintains the alignment state of the liquid crystal molecules as shown in FIG. 16 even when the application of the voltage is stopped. That is, a region where the liquid crystal is switched and a region where the liquid crystal is not switched are formed at a minute pitch of the interference draft. Therefore, since the liquid crystal molecules have optically uniaxial refractive index anisotropy, in the example of FIG. 16, the liquid crystal molecules act as a phase type diffraction element with respect to the polarized light component oscillating in the X-axis direction. On the other hand, it functions as a diffractive element having polarization anisotropy that outputs a polarized component vibrating in the Y-axis direction without diffracting as an isotropic element.

In the present embodiment, specifically, each hologram element 511, 512 was manufactured with the following parameters.

The tilt angle of the interference draft of the first hologram element: 22.5 ° The pitch of the interference draft of the first hologram element: 0.757 μ
m Thickness of first hologram element: 9 μm Inclination angle of interference draft of second hologram element: 19 ° Pitch of interference draft of second hologram element: 0.651 μ
m Thickness of the second hologram element: 9 μm Average refractive index of liquid crystal: 1.593 Change in refractive index: 0.083 The diffraction efficiency of the polarization separation element 510 manufactured as described above with respect to S-polarized light is shown in FIG. Shown in The horizontal axis is the angle of incidence on the first hologram element 511. ± as shown
High polarization separation characteristics of 90% or more could be realized in the range of 2 °.

When a UV-curable liquid crystal that can be oriented by a magnetic field is used as the liquid crystal material, the glass substrate 513,
There is no need to form a conductive transparent electrode on the surface of 514,
In the process (8), a magnetic field may be applied instead of applying an electric field.

Alternatively, a hologram element may be manufactured by photo-induced phase separation using a mixture of a photopolymer and a liquid crystal polymer having sensitivity to a specific wavelength region as the hologram material 27.

In the present embodiment, the optical axis defined as the normal to the glass substrates 513 and 514 almost coincides with the incident light beam. However, it is not always necessary that they coincide.

As the hologram element used for the above-mentioned polarization splitting element, for example, the one shown in FIG. 18 can be used. The hologram element 521 is formed using an optical medium 522 having a refractive index anisotropy such as a liquid crystal and has a thickness of about 10 μm.
The refractive index distribution is periodically distributed also in the thickness direction. For this reason, the diffractive action differs depending on the polarization direction, and the diffractive action has a characteristic of exhibiting high diffraction efficiency in one direction.

Hereinafter, the hologram element 521 will be described in detail.

The inside of the element has a layer structure in which a layer inclined with respect to the thickness direction is periodically formed from the surface on which light enters. In the layers adjacent to each other, one is arranged so that the inclination of the optical axis of the optical medium 522 having the refractive index anisotropy is parallel to the surface of the hologram element 521, and the other is arranged in the direction perpendicular to the surface. doing.

Optical medium 522 having the above-mentioned refractive index anisotropy
Is incident on the optical medium 522, the polarization direction of the light is
When the light beam is parallel to the optical axis, the beam becomes an extraordinary ray, and the refractive index indicates the value of Ne. Further, the polarization direction is changed to the optical medium 522.
When the light is perpendicular to the optical axis, the ray becomes an ordinary ray, and shows a refractive index of No. Here, Ne> No.

Next, the hologram element 521 shown in FIG.
The behavior when these lights are incident on the hologram element 521 with light having a polarization direction perpendicular to the paper as an ordinary ray and light having a polarization direction parallel to the paper as an extraordinary ray will be described. .

First, when an ordinary ray is incident, its polarization direction is perpendicular to the optical axis of any optical medium 522 constituting each layer. For this reason, the refractive index of each layer is No, regardless of the direction of the optical axis between the layers. That is, since a medium having a uniform refractive index is equal to that of a medium having no refractive index, an ordinary ray incident on the medium is not affected by diffraction, and is transmitted as it is, as shown in FIG.

On the other hand, when an extraordinary ray is incident, in the layer where the optical axis of the optical medium 522 having the refractive index anisotropy is arranged parallel to the incident surface, the polarization direction of the incident light is aligned with the optical axis. Be parallel. This corresponds to the case where the light passes through a layer having a refractive index of Ne. Also, for a layer in which the optical axis of the optical medium 522 is perpendicular to the incident surface of the hologram element 521, this layer corresponds to the case where the polarization direction is perpendicular to the optical axis, and this layer has a refractive index of No. Works with things. Therefore, for an extraordinary ray, the hologram element 521
In the thickness direction, which is the traveling direction of the incident light, the light passes through a plurality of layers having different refractive indexes periodically. As a result, the incident light beam is subjected to a so-called Bragg diffraction effect in which the light is condensed in a specific direction corresponding to the inclination angle of the layer and the pitch of the period. Therefore, as shown in the figure, after passing through the hologram element 521, the extraordinary ray changes the optical path corresponding to the layer structure formed inside the element.

That is, by having a periodic structure in the thickness direction as described above, the Bragg diffraction condition is applied. This is because when light having a certain wavelength enters each layer forming the periodic structure, the light scattered in each layer causes a phenomenon in which the scattered component strengthens in a specific direction corresponding to the wavelength and the incident angle and the pitch between the layers. . This is called Bragg's diffraction condition, and such a condition is three times larger than that of a conventional two-dimensional diffractive optical element.
It has a dimensional configuration and has the effect of blazing (focusing light in one direction).

Therefore, the diffraction efficiency can be greatly improved as compared with the conventional diffractive optical element, and theoretically, an efficiency of 100% is possible. In practice, an efficiency of 90% or more can be expected even when taking into account the loss on the way. On the other hand, in a binary two-dimensional diffractive optical element, the diffracted wave is diffracted to the higher order symmetrically, including the 0th order, so that the diffraction efficiency in the primary order is at most about 40%. Which is a low value as a percentage of the total amount of light passing through the element.

FIG. 19 shows the calculation result of the theoretical diffraction efficiency of the hologram element 521 by "Bell System Technology".
Jay "(H. Kogelnik, (Bell Sys
t. Tech. J. , 48,1969, pp. 290
9-2947)). The diffraction efficiency is the ratio of the amount of light diffracted in the primary direction to the total amount of incident light. Table 1 summarizes various parameters of the diffractive optical element.

[Table 1]

In FIG. 19, (a) shows the change in the diffraction efficiency when the incident angle deviates from the Bragg angle, that is, the dependence of the diffraction efficiency on the incident angle, and (b) shows the case where the incident wavelength deviates from the design value. , Ie, the dependence of the diffraction efficiency on the incident wavelength.

The angle dependence in FIG. 19A corresponds to the efficiency when the light beam incident on the hologram element 521 deviates from the parallel light (when the incident angle deviates from a predetermined angle). The incident wavelength dependency of b) corresponds to the study of the efficiency at the time of illumination by a white light source. As shown in the figure, it is expected that a theoretical diffraction efficiency of 1, that is, a high diffraction efficiency of nearly 100% can be obtained by appropriately setting various parameters. According to the figure, the characteristic is flat with respect to the wavelength around ± 100 nm, and high efficiency can be expected for white light.

In FIG. 18, the hologram element 521
The optical axis of the optical medium 522 constituting
Although the case where the refractive index difference is the largest by tilting by 0 ° is shown, the refractive index difference can be changed from Ne to No by setting this angle arbitrarily.
Can also be set to an intermediate value. Further, it is also possible to adjust the diffraction efficiency by selecting a refractive index distribution using this.

It is also possible to divide the area of the hologram element 521 into several parts and shift the directions of diffraction respectively.

Further, R: red (0.6
G: green (0.55 μm), B: blue (0.45 μm)
μm), a layer having a different periodic structure, an angle, and the like is formed according to each of the center wavelengths, and these layers are laminated to form a hologram element 521, or a hologram element is formed by superposing these structures. By recording information in the area 521, a configuration in which the influence of chromatic dispersion or angle dependence is reduced is also possible.

Next, a method of manufacturing the hologram element 521 will be described.

First, for example, ITO is formed as a transparent conductive electrode on each of a pair of glass substrates.

Next, these substrates are washed to remove adhering dust, and then an alignment film made of a polymer, for example, a polyimide is applied by a spin coating method or the like, and the alignment is performed by performing a heat treatment or the like. A film is formed on a substrate.

Thereafter, the alignment film is subjected to a rubbing treatment in a specific direction using a roller or the like, and then a seal is printed around one substrate, and the other substrate is coated with a diameter of 5 μm to 20 μm.
Disperse beads of about μm. The two substrates are bonded together so that the rubbing directions are paired with each other to form an empty cell.

As the optical medium 522 having the refractive index anisotropy, for example, a liquid crystal having a positive dielectric anisotropy is injected into the empty cell. Note that a liquid crystal having a negative dielectric anisotropy can be used. More specifically, the liquid crystal contains, for example, a photopolymerizable liquid crystal monomer or a photocrosslinkable liquid crystal polymer. The liquid crystal is cured by irradiation with light having a wavelength in the ultraviolet region of about 360 nm, and the direction of the liquid crystal molecules is fixed. Use the one with the characteristics specified. The above-described implantation can be performed at room temperature in an air atmosphere, but may be performed at a high temperature of about 40 ° C. to 60 ° C. or in a vacuum.

The liquid crystal sample is completed by sealing the vicinity of the injection port and the degassing port of the cell after injecting the liquid crystal with a sealant.

The liquid crystal sample produced as described above is exposed to interference fringes.

First, with the shutter for adjusting the exposure time closed and without light irradiation, the liquid crystal sample is placed at the optical system fabrication position (the predetermined position of the exposure apparatus), and the shutter is operated for a predetermined time. For example, by opening for about one minute and then closing, exposure using interference fringes is performed as a first exposure step.

As a light source for forming the interference fringes, for example, an A light having an irradiation intensity of about 50 mW to 100 mW is used.
360n wavelength output from r (argon) laser
m or so. The laser light is emitted by a beam expander or the like, for example, with a diameter of 30 mm to
After expanding the beam into a beam of about 50 mm, the beam is split in two directions by a beam splitter or the like, interference fringes are formed through an optical path set by combining a mirror or the like, and the liquid crystal sample is irradiated. The interference fringes are adjusted to, for example, about 1 μm pitch at the position where the liquid crystal sample is arranged by adjusting the mirror and the like.

By the above-mentioned exposure, the liquid crystal in the liquid crystal sample was hardened in the region of the bright portion where the light intensity was high in the interference fringes formed by the interference of two laser beams, and the liquid crystal molecules were initially aligned by the alignment film. The molecular axis is fixed in the direction. That is, for example, when using a liquid crystal having a positive dielectric anisotropy as described above, initially the liquid crystal molecules are uniformly oriented in a direction parallel to the glass substrate, and in the bright region of the interference fringes, This state will be saved. On the other hand, since the light intensity is lower in the dark area of the interference fringes than in the bright area, the liquid crystal molecules hardly harden in this first exposure step.

Next, as a second exposure step, first, an AC electric field of about 5 (V / μm) was applied between ITO electrodes as transparent conductive electrodes formed inside the two glass substrates of the liquid crystal sample. Apply. Due to the application of the electric field, the uncured liquid crystal molecules in the dark portions of the interference fringes are tilted in a direction perpendicular to the glass substrate. The angle of inclination at this time is
Since the magnitude of the electric field is adjusted because it is proportional to the applied electric field, a desired inclination angle, that is, a difference in refractive index can be provided.

In the state where the voltage is applied as described above, for example, one of the laser beams split by the beam splitter is blocked, so that light having a uniform intensity distribution without interference fringes is formed on the entire surface of the liquid crystal sample. For example, irradiation is performed for about 5 minutes to completely cure the entire uncured dark area.

The hologram element 521 having the structure shown in FIG. 18 is manufactured by performing the first exposure step and the second exposure step as described above.

In this case, a cell is manufactured using a glass substrate on which a transparent electrode such as ITO is formed, and the direction of liquid crystal molecules is changed from an initial position by applying an electric field in the second exposure step. Was explained. As another method, the hologram element 521 can be manufactured by performing the second exposure step by changing the direction of liquid crystal molecules by applying a magnetic field without using a transparent electrode.

Further, the polarization direction of the irradiated Ar laser is set to, for example, 90 ° in the first exposure step and the second exposure step.
A method of setting and exposing differently is also conceivable. When a polymer film such as an alignment film is irradiated with linearly polarized light as a light source, molecules whose main chains (or side chains) are oriented mainly in the direction of polarization from randomly oriented polymers mainly emit light. Absorption causes a photoreaction, and the film exhibits optical anisotropy. In a polymer material or the like, the photoreaction process (photoisomerization, photopolymerization, photodecomposition) of the polymer can be controlled by the polarization direction of the irradiated light and the angle formed by the polymer.

Therefore, by controlling the polarization direction of the light in the ultraviolet region constituting the interference fringes, the initial alignment state of the liquid crystal can be set, and the movement of the liquid crystal molecules in the first and second exposure steps can be controlled. It is also possible to do.

When the diffraction efficiency of the device fabricated as described above was measured using a He—Ne laser while changing the incident polarization direction, the transmittance for ordinary light was 98%.
It was before and after, and had high transmittance. Further, the diffraction efficiency in the primary direction with respect to the extraordinary ray was about 90%, and good results were obtained. Therefore, it was confirmed that the diffractive optical element manufactured here had high polarization separation characteristics and diffraction efficiency.

As the optical medium having the refractive index anisotropy, in addition to the liquid crystal, lithium niobate, KD ₂ P
It is also possible to use a uniaxial crystal having an electro-optical effect such as O ₄ , β-BaB ₂ O ₄ , PLZT, etc., and various refraction including a biaxial optical crystal such as KTiPO _4. The same effect can be obtained by using a medium having a rate anisotropy.

(Embodiment 2-2) Another example of the polarization beam splitting element formed by using the hologram element will be described.

As shown in FIG. 20, in this polarization separation element 530, a hologram element 532 similar to that shown in the first or second embodiment is provided on the surface of a total reflection mirror 531. ing. Here, Embodiment 1
Is used in a state where a predetermined voltage is applied between ITO.

The total reflection mirror 531 and the hologram element 532 are arranged such that the normal line forms an angle of 45 ° with the optical axis of the reflector 534 that reflects the light from the lamp 533 of the light source.

In the hologram element 532, light having a polarization direction in a direction perpendicular to the plane of the drawing (S-polarized light) becomes an ordinary ray, and light having a polarization direction in a direction parallel to the plane of the drawing (P-polarized light). (Hereinafter referred to as light) is arranged as an extraordinary ray. The hologram element 532 has 45
The extraordinary ray incident at an incident angle of ° is set to be diffracted and emitted so as to have an exit angle slightly larger than 45 °.

With such a configuration, the s-polarized light, which is an ordinary ray with respect to the hologram element 532,
As described in each of the above-described embodiments, the characteristics are the same as those when passing through a medium having an isotropic and uniform refractive index without being affected by the refractive index distribution composed of the periodic structure of the element. therefore,
The S-polarized light passes through the hologram element 532 as it is, is reflected by the total reflection mirror 531, and is again
2 and exit. That is, the traveling direction of the S-polarized light is bent by 90 ° by the total reflection mirror 531 and emitted.

On the other hand, the P-polarized light that is an extraordinary ray with respect to the hologram element 532 is modulated by the refractive index distribution of the periodic structure formed in the hologram element 532 and diffracted.
As described above, light is emitted at an emission angle slightly larger than 45 °.

Therefore, the light emitted from the lamp 533 via the reflector 534 is
With 0, it is possible to separate out the emitted light whose traveling direction is slightly different between the S-polarized light and the P-polarized light.

(Embodiment 3-1) Embodiment 2
An example of a polarization conversion element configured using two polarization separation elements will be described. This polarization conversion element outputs light having a random polarization direction from a light source to polarized light in a predetermined direction, and is used, for example, in a polarized light illumination device such as a polarization type liquid crystal display device.

FIG. 21 is an explanatory view showing the structure of a polarized light illuminating device including a polarization conversion element 540.

As the lamp 533, a fluorescent lamp, a xenon lamp, a metal halide lamp, a mercury lamp, an L
An ED, an FED, a laser beam, an inorganic or organic EL element, or the like is used. The light from the lamp 533 is reflected by the reflector 53
The light 4 is converted into substantially parallel light and emitted. This substantially parallel light enters the polarization separation element 530 and is separated so that the traveling directions are slightly different between the S polarization light and the P polarization light as described in Embodiment 2-2. Emit.

The S-polarized light and the P-polarized light emitted from the polarization splitting element 530 enter the respective lenses 542a of the first lens group (first fly-eye lens) 542 constituting the integrator 541, and In accordance with the angle of incidence, light is condensed on predetermined regions different from each other in each lens 543a of a second lens group (second fly-eye lens) 543 forming a pair with each lens 542a.

The predetermined region where the S-polarized light and the P-polarized light are converged is set to, for example, a region that roughly divides each lens 543a into two, and each of the lenses 543a in the region where the P-polarized light is condensed. Back side (light traveling direction side)
Is provided with a phase difference plate 544 that is a half-wave plate periodically. Therefore, the S-polarized light incident on the second lens group 543 is emitted as it is as S-polarized light,
The polarization direction of the polarized light is rotated by 90 ° via the phase difference plate 544, and the polarized light is converted into S-polarized light and emitted. That is, any polarized light is emitted while being aligned with the S-polarized light.

The S-polarized light is supplied to the field lens 545
The light enters the image display element (light valve) 547 as a substantially parallel light beam via the condenser lens 546 and is used for image display.

When the amount of light incident on the image display element 547 was compared between the case where the hologram element 532 and the phase difference plate 544 were used and the case where the phase difference plate 544 was not used, the polarization was determined by the hologram element 532 and the phase difference plate 544. When the conversion was performed, the light use efficiency was improved by about 1.2 to 1.6 times, and it was confirmed that the function of the polarization conversion element 540 using the hologram element 532 was excellent.

(Embodiment 3-2) Embodiment 3
An example of the polarization conversion element that arranges the polarization direction by providing the polarization splitting element described in 1 in the optical path between the first lens group and the second lens group forming the integrator will be described. In the present embodiment and the like, components having the same functions as those in the embodiment 3-1 and the like will be denoted by the same reference numerals as appropriate, and detailed description will be omitted.

FIG. 22 is an explanatory view showing the structure of a polarized light illuminating device including a polarization conversion element 545.

The substantially parallel light from the reflector 534 is incident on the polarization separation element 530 via the first lens group 542 constituting the integrator 541. The luminous flux incident on the polarization splitting element 530 is described in Embodiment 2-2.
As described above, the light is separated so that the traveling direction is slightly different between the S-polarized light and the P-polarized light, and the light is emitted from the polarization splitter 530.

The S-polarized light and the P-polarized light emitted from the polarization splitting element 530 are located on the back side of each lens 543a of the second lens group (second fly-eye lens) 543 constituting the integrator 541. Light is condensed on a region where the retardation plate 544 is provided or a region where it is not provided. Therefore, similarly to the above-mentioned Embodiment 3-1, while the S-polarized light is emitted as it is as the S-polarized light, the P-polarized light is rotated by 90 ° through the retardation plate 544, and is converted into the S-polarized light. It is converted and emitted. That is, any polarized light is emitted while being aligned with the S-polarized light.

The polarization conversion element 545 thus configured
Accordingly, the light use efficiency can be improved as in the case of the embodiment 3-1.

(Embodiment 3-3) An example of another polarization conversion element using a hologram element similar to that shown in the embodiment 1 or 2-1 will be described.

FIG. 23 is an explanatory view showing the configuration of a polarized light illuminating device including a polarization conversion element 550. The polarization conversion element 550 of this polarization illuminating device is a quarter-wave plate between the hologram element 551 and the total reflection mirror 531 similar to those described in the first or second embodiment. A phase difference plate 551 is provided.

The light wave including the P-polarized light and the S-polarized light from the lamp 533 is incident on the hologram element 551, and the P-polarized light is applied to the refractive index distribution of the diffractive optical element as described in the first embodiment. The light is diffracted accordingly, and the light is emitted with its course bent in the direction indicated by the one-dot chain line in FIG.

On the other hand, the S-polarized light is
Is transmitted as it is, reflected by the total reflection mirror 531 via the phase difference plate 552, and changes its polarization direction by 90 ° in the process of passing through the phase plate 552 again, and is incident on the hologram element 551 as P-polarized light. Will do. At this time, the incident direction is the total reflection mirror 531 and the reflector 53
4, which is determined by the hologram element 55.
The hologram element 551 transmits the incident light without reflecting it so that the condition is deviated from Bragg's diffraction condition for the periodic structure formed inside 1. That is, as described with respect to the angle dependence of the diffraction efficiency in FIG. 19A, when the angle of incidence on the hologram element deviates to a certain degree from the predetermined angle, the efficiency becomes almost zero, and the diffraction effect does not occur and only the light is transmitted. In some cases, the predetermined angle can be set according to the conditions for forming the diffractive optical element. Therefore, the total reflection mirror 53
1 and converted into P-polarized light by the phase difference plate 552, the hologram element 55 is not diffracted.
1 can be transmitted as it is. In addition,
The light may be diffracted so as to substantially match the propagation direction of the P-polarized light directly diffracted by the hologram element 551.

As described above, the P-polarized light of the light wave from the lamp 533 is diffracted by the hologram element 551, and the S-polarized light transmitted through the hologram element 551 is converted to P-polarized light by the total reflection mirror 531 and the phase plate 552. After the light is transmitted through the hologram element 551 and emitted,
A substantially parallel light beam having a uniform polarization direction can be obtained.

Embodiment 3 of the above-mentioned polarized light illumination device
When the light use efficiency was obtained in the same manner as in -1, the light use efficiency could be obtained about 1.2 to 1.5 times as compared with the case where the hologram element 551 and the phase difference plate 552 were not used.

Further, according to the above configuration, polarization conversion can be performed only by a simple laminated structure of the hologram element, the phase difference plate 552, and the total reflection mirror 531. Are easy to use, and can be used in a wide range of optical devices. Especially,
For example, when the present invention is applied to a device having a folding mirror in advance, such as a color image display device having two dichroic prisms and performing color separation and color synthesis, a mirror having a hologram element is used instead of the mirror. Since it is only necessary to use the light source, the light use efficiency can be improved without increasing the number of parts.

(Embodiment 3-4) An example of still another polarization conversion element using the same hologram element as that shown in the embodiment 1 or 2-1 will be described.

Embodiment 1 or Embodiment 2-1
Two hologram elements 561 and 56 similar to those shown in FIG.
2 was used to construct a polarization illuminating device including a polarization conversion element 560 as shown in FIG.

The light beam including the P-polarized light and the S-polarized light from the lamp 533 enters the hologram element 561 via the reflector 534, and the S-polarized light is transmitted as it is as substantially parallel light. Further, the P-polarized light is diffracted by the hologram element 562 so that the propagation direction changes by approximately 90 ° according to the principle described in the first embodiment and the like.

The light wave further enters the hologram element 562, and is similarly diffracted and emitted so that the propagation direction is substantially equal to the direction of the light beam reflected from the initial reflector 534. Thereafter, the light passes through the phase difference plate 563 which is a half-wave plate, and is emitted as an S-polarized light wave after the polarization direction is rotated by 90 °. That is, the light wave emitted from the lamp 533 and diffracted by the hologram element 561 is emitted by the diffractive optical element 562 and the phase difference plate 563 as a substantially parallel light beam having the same polarization direction as the light wave transmitted through the hologram element 561.

When the reuse ratio of the light wave in the hologram element 562 of the polarized light illumination device as described above was measured, the light flux from the hologram element 562 was converted to the hologram element 5.
A light beam converted into S-polarized light having an intensity ratio of about 90% with respect to the light beam from 61 was obtained.

As described above, hologram elements 561 and 56
The advantage of using 2 is that it is possible to arbitrarily set the separation angle when performing polarization separation. That is, as usual, when polarization separation is performed by combining a polarization beam splitter and a total reflection mirror,
In order to bend the propagation direction by 90 °, it is necessary to incline the reflection surface by 45 ° with respect to the incident light (corresponding to θ in FIG. 24). Therefore, in the depth direction, a size corresponding to the size and inclination of the reflection surface is required, and in the device using the polarized light illumination device, the constraint in the thickness direction is increased.

On the other hand, when the hologram element is used as described above, the polarization separation angle can be arbitrarily set by the refractive index distribution formed inside, so that the diffractive optical element is not affected by the incident light. 24 can be arranged at an angle of 45 ° or less with respect to a vertical plane, and θ in FIG.
The angle can be set at a small angle of 5 ° or less, and the polarization conversion optical system can be configured by arranging the hologram elements in parallel to each other, so that the size in the depth direction can be significantly reduced. . For this reason,
A thin configuration is possible, and a compact system (illumination device, image display device, or the like) can be realized in combination with an illumination optical system such as an integrator to which the polarization-converted polarized light is incident.

(Embodiment 3-5) A hologram element similar to that shown in Embodiment 1 or Embodiment 2-1 is used, and an integrator having a first lens group and a second lens group is used. An example of a polarization conversion element for aligning the polarization direction of output light will be described.

Embodiment 1 or Embodiment 2-1
As shown in FIG. 25, a plurality of pairs of hologram elements 571 and 572 similar to those shown in FIG. 25 are arranged, and a polarization illumination device including a polarization conversion element 570 is configured. Note that FIG. 3 shows an example in which a projection-type image display device is configured by combining an image display element 577, a projection lens 578, and the like.

The light wave including the P-polarized light and the S-polarized light transmitted from the first lens group (not shown) in the integrator enters the second lens group 571, where the light beam is narrowed down.
The light enters the hologram element 572 corresponding to each lens 571a of the lens group 571. Here, the S-polarized light is transmitted as it is, and the P-polarized light is diffracted and enters the adjacent hologram element 572. Then, the light is further diffracted and propagates in a direction substantially equal to the S-polarized light, and the polarization direction is rotated by 90 ° by a phase difference plate 574 which is a half-wave plate.
The light is converted into S-polarized light and emitted.

These steps are performed for each set of a plurality of hologram elements 572 and 573 and a phase difference plate 574, and the light waves that have passed through the second lens group 571 are emitted with their polarization directions aligned. . Further, since the light beam is narrowed down and used in combination with the integrator, it is possible to perform the polarization conversion without largely changing the width of the light beam from the light source.

The luminous flux whose polarization direction has been aligned as described above is incident as a parallel luminous flux by a field lens 575 and a condenser lens 576 on an image display element 578 such as a polarization type liquid crystal display element. After the luminance modulation, the image is enlarged and projected on a screen 579 by a projection lens 579.

When the brightness on the screen was compared between the case where the polarization conversion was performed by the above-described polarization conversion element 570 and the case where the polarization conversion was not performed, the brightness increased by about 30% when the polarization conversion was performed. And a bright image could be obtained.

(Embodiment 3-6) Still another example of a polarization conversion element using the same hologram element as that shown in the embodiment 1 or 2-1 will be described.

As shown in FIG. 26, the third embodiment
A pair of polarization conversion elements 560 similar to
Alternatively, the polarization conversion element 590 may be provided so as to be symmetric with respect to the four optical axes. With this configuration, since the reflector 534 is disposed at, for example, the center in the width direction of the polarized light illuminating device, a uniform space is formed on both sides, and thus other components in the device to which the polarized light illuminating device is applied. Arrangement becomes easy.

(Embodiment 4-1) Embodiment 2
An example in which a projection type image display device configured using the polarization separation element 510 of FIG. 1 (FIG. 13) will be described. As the hologram element included in the polarization separation element 510, the hologram element described in Embodiment 1 or Embodiment 2-1 (FIGS. 10, 18 and the like) can be applied. Here, when the hologram element of Embodiment 1 is used, ITO
It is used while a predetermined voltage is applied between them.

As shown in FIG. 27, the projection type image display device 600 includes a polarization illuminating device 601 composed of a lamp 533, a reflector 534, a polarization separation element 510, and an integrator, and outputs a light beam from the lamp 533 to the reflector. 533, the reflected output light flux β is incident on an image display element 547 such as a transmissive liquid crystal panel via a polarization separation element 510 and an integrator 541, and the brightness-modulated light flux is screened by a projection lens 602. An image is displayed by enlarging and projecting the image (not shown).

Next, the polarization separating element 510 and the integrator used in the projection type image display device 600 will be described. The polarization splitting element 510 used in the present invention includes the first hologram element 511 and the second hologram element 512 as described in Embodiment 2-1.
The P-polarized light is transmitted straight (at an output angle of 0 °) and transmitted, while the S-polarized light is output at an output angle of approximately −7 °.

Each of the first minute lenses forming the first lens group (first fly-eye lens) 542 is connected to each of the second lens groups 543 forming the second lens group (second fly-eye lens). An image of the lamp is formed on the lens. At this time, the P-polarized light γ and the S-polarized light δ are imaged at different positions. For example, a phase plate 544 that is a half-wave plate (λ / 2 plate) as a polarization plane rotating unit is provided in a portion where the S-polarized light δ forms an image, and the S-polarized light transmitted through the phase plate 544 is provided. The light δ is converted into substantially P-polarized light and output. Note that the P-polarized light γ
And the polarization component of the s-polarized light δ to rotate the plane of polarization is determined by the polarization direction of the polarizing plate provided in the image display element 547.

The second lens group 543 displays an image of each minute lens constituting the first lens group 542 on the image display element 54.
By forming an image over almost the entire display image area in 7, the uniformity of the brightness of the display image is ensured.

By constructing the polarized light illuminator 601 as described above, it is possible to efficiently convert non-polarized light output from the lamp 533 to P-polarized light, and realize high projection efficiency. . Further, the polarization separation element 510 as described above can be easily manufactured and can be configured at low cost. In addition, since the polarization separation element 510 has a small dimension in the optical axis direction, a compact polarization separation element having high separation efficiency can be easily configured. In addition, by using the above-described polarization separation element, a projection-type image display device with high light use efficiency can be easily realized.

The lamp 533 and the reflector 53
Embodiments 3-1 to 3-3 if the arrangement of
It is also possible to use a polarization conversion element 530 as shown in FIGS.

The lamp 533 may be a metal halide lamp, a halogen lamp, a xenon lamp,
An ultra-high pressure mercury lamp or the like can be used, but it is preferable to use a lamp having a small light emitting region.

(Embodiment 4-2) A projection type image display of a so-called three-panel type which has three transmission type image display elements and optical elements of a color separation system and a color synthesis system and can display a color image. An example of the device will be described.

This image display device is provided with a color composition system element 620 shown in FIG. 28B below the color separation system element 610 shown in FIG.

The color separation element 610 includes a polarization illuminating device 601 including a polarization conversion element similar to that described in the embodiment 4-1; a dichroic prism 611; and total reflection mirrors 612 to 614. And outputs the light output from the polarization illuminator 601 as R (red), G (green),
The light is decomposed into light of each wavelength of B (blue). On the other hand, the color composition system element 620 includes total reflection mirrors 621 to 62.
3, the image display elements 624 to 626, the dichroic prism 625, and the projection lens 628, and the light of each wavelength guided from the color separation element 610 passes through the image display elements 624 to 626. Then, color synthesis is performed, and an image is projected on the screen 629 by the projection lens 628.

In this image display device, the substantially parallel light beam output from the lamp 533 via the reflector 534 is
As described in Embodiment 4-1 above, after the polarization directions are aligned by the polarization separation element 510 and the integrator 541 and the uniformity of the light beam in the plane is maintained, the dichroic prism 611 Incident on. The dichroic prism 611 has a configuration in which filters of wavelengths of respective bands are formed inside, and white light from the polarized light illuminating device 601 corresponds to the wavelength filter and has three primary colors of R and G. , B are decomposed into light corresponding to the respective wavelengths, and are emitted in the directions indicated by arrows in FIG. Here, the dichroic prism 611 has the same function as the case where a two-piece dichroic mirror is used, but because of the prism configuration, color separation can be performed without using a large space. Thus, a compact display device can be configured.

The light of each color emitted from the dichroic prism 611 is reflected by the total reflection mirrors 612 to 624 and guided to the lower color combining element 620.
The light of each color guided from the color separation system element 610 to the color combining element 620 is reflected with the traveling direction changed by approximately 90 ° via the total reflection mirrors 621 to 623, and is of a transmission type corresponding to the light of each color. After being subjected to luminance modulation by the image display elements 624 to 626, the light enters the dichroic prism 627. The dichroic prism 627 has a function reverse to that of the dichroic prism 611, and performs color synthesis of light that has been split into R, G, and B light components, respectively. The light is emitted toward the lens 628. The light emitted from the dichroic prism 627 is projected on a screen 629 by a projection lens 628 and displayed as an enlarged image.

By providing the polarization conversion element for aligning the polarization direction of the light beam output from the reflector 534 as described above, it is possible to improve the light use efficiency and configure an image display device capable of displaying a bright image. it can.

In the case where a polarization conversion element or the like is applied to an image display device or the like for displaying a color image as described above,
When fabricating a hologram element, a structure is used in which multiple exposures are performed using light interference fringes of red, green, and blue light, and hologram elements optimized for diffraction of each color light are stacked. You may do so.

In place of the polarization splitting element 510 and the phase difference plate 544, Embodiments 3-4 to 3-6 are used.
Even when the polarization conversion element 560 or the like as shown in FIGS. 24 to 26 is used, similarly high light use efficiency can be obtained.

The above-described polarization conversion element 550 and the like include the integrator 541 and the dichroic prism 6.
11 and the same effect can be obtained. Further, the polarization conversion element 550 and the like are provided between the dichroic prism 611 and the image display elements 624 to 626, that is, three polarization conversion elements (and integrators) corresponding to the light of each color after color separation. Is also good. In this case, since the polarization conversion elements are individually provided corresponding to the light of each color, the hologram element is optimized to reduce the influence of chromatic dispersion in accordance with the wavelength of each color, that is, each hologram element, Is a periodic structure corresponding to the wavelength formed? >> etc. can be used,
The light use efficiency can be further improved. Similarly, an integrator may be provided after the dichroic prism 611.

Further, the lamp 533 and the reflector 53
Embodiments 3-1 to 3-3 if the arrangement of
It is also possible to use a polarization conversion element 540 as shown in FIGS.

Even when the reflectors are provided in the same arrangement as in FIG. 28, the polarization conversion element is provided between the dichroic prism 611 and the image display elements 624 to 626, that is, corresponding to the light of each color after color separation. When the three polarized light conversion elements (and the integrators) are provided, the above-described polarized light conversion elements can be applied.
In this case, a total reflection mirror 612 or the like for guiding each color light from the color separation element 610 to the color combining element 620 can also be used as the total reflection mirror 531 of the polarization conversion element. In addition, as described above, a hologram element that matches the wavelength of each color can be used.

When a polarization conversion element is provided in each path after the actual color separation, the brightness of a color-combined image on a screen is 30 times higher than when no polarization conversion element is used. % Could be increased. this is,
The transmission type described above and the reflection type described later were almost the same. Thus, the polarization conversion using the diffractive optical element is also effective for color display.

In the structure shown in FIG. 23, it is also possible to use means for changing the thickness of the phase plate in the plane in order to correct the dependency of the polarization characteristic on the incident angle of the phase plate.

(Embodiment 4-3) Embodiment 4-3
An example of a three-panel projection type image display device that can display a color image using a reflection type image display device with a configuration similar to that of No. 2 will be described.

This image display device is provided with a color composition system element 630 shown in FIG. 29B below the color separation system element 610 shown in FIG. 29A.

As the color separation system element 610, the same one as shown in the embodiment 4-2 is used. On the other hand, the color combining system element 630 is different from the embodiment 4-2 in that the polarizing beam splitters 631 to 633 are provided instead of the total reflection mirrors 621 to 623, and the transmission type image display elements 624 to 624 are provided. The difference is that reflection type image display elements 634 to 636 are provided instead of 626.

The polarization beam splitters 631 to 633
Is designed to reflect only light having a predetermined polarization direction, but since the light actually guided from the color separation element 610 is light whose polarization direction is aligned by the polarization conversion element, almost all light is reflected. The light is reflected and enters the image display elements 634 to 636. The light incident on the image display elements 634 to 636 is reflected after being modulated in the polarization direction according to the display image of each color, and is incident again on the polarization beam splitters 631 to 633, and only the light in the predetermined polarization direction is transmitted. The modulation of the polarization direction is converted into luminance modulation and visualized. After that, as in Embodiment 4-2, color synthesis is performed by the dichroic mirror 637, and an image is projected on the screen 629 by the projection lens 628.

In the reflection type image display element as described above, the polarization conversion element for aligning the polarization direction of the light beam output from the reflector 534 is also provided.
An image display device capable of displaying a bright image with improved light use efficiency can be configured.

Also, in this image display device, various modifications as described in the embodiment 4-2 can be similarly made.

(Embodiment 5-1) An example of an image display device provided with a hologram element will be described.

In the image display apparatus, as shown in FIG. 30, hologram elements 702 and 703 as diffractive optical elements are provided on both sides of a liquid crystal element 701, and a light source having a lamp 704a and a reflector 704b on the back side thereof. 704
Is provided.

In the following description, light having a polarization direction in a direction parallel to the plane of the drawing is referred to as P-polarized light, and light having a polarization direction in a direction perpendicular to the plane of the drawing is referred to as S-polarized light.

As the lamp 704a of the light source 704, for example, a fluorescent lamp, a xenon lamp, a metal halide lamp, a mercury lamp, an LED, an FED, a laser beam,
An inorganic or organic EL element or the like can be used. Lamp 704
The light emitted from a is emitted as substantially parallel light by the reflector 704b. This light source light
P-polarized light and S-polarized light are included.

As the liquid crystal element 701, for example, a twisted nematic liquid crystal in which the directions of liquid crystal molecules are twisted by 90 ° between the light incident surface side and the light emitting surface side is used. The liquid crystal element 701 is provided with a transparent electrode (not shown) formed in a predetermined pattern so that a voltage can be applied to the liquid crystal for each pixel. Therefore, in a pixel (ON) in which a predetermined sufficient voltage (a voltage enough to completely switch the liquid crystal) is applied to the liquid crystal, the liquid crystal molecules are untwisted and the liquid crystal molecules are isotropic with respect to the light incident surface. Standing (homeotropic). Therefore, when the P-polarized light enters the pixel, the P-polarized light passes through the liquid crystal element 701 while maintaining its polarization state without being modulated in the polarization direction. On the other hand, in the pixel (OFF) where no voltage is applied to the liquid crystal, the direction of the liquid crystal molecules is twisted by 90 ° in the thickness direction from the entrance surface to the exit surface. Then, when the P-polarized light enters the pixel, the P-polarized light rotates its polarization plane by 90 ° by the twist nematic effect caused by the twist of the liquid crystal while passing through the liquid crystal element 701 from the incident surface to the emission surface. . Therefore, after passing through the OFF pixel, the light is emitted as S-polarized light.

The hologram elements 702 and 703
For example, the first embodiment or the second embodiment
A hologram element similar to that shown by -1 is used.
Here, when the hologram element of Embodiment 1 is used, the hologram element is used in a state where a predetermined voltage is applied between ITO. As described above, the hologram elements 702 and 703 have different diffraction effects depending on the polarization direction, and have a property of exhibiting high diffraction efficiency in one predetermined direction.

Specifically, for example, the hologram element 70
Since the S-polarized light among the light incident on the hologram elements 703 and 703 functions as an extraordinary light component, it is modulated by the refractive index distribution of the periodic structure formed in the hologram elements 702 and 703, and FIG.
The light is emitted with its traveling direction bent upward. on the other hand,
Since the P-polarized light acts on the hologram elements 702 and 703 as an ordinary light component, the hologram elements 702 and 703
It is not affected by the refractive index distribution having the periodic structure of No. 03, and exhibits the same behavior as that when passing through a medium having an isotropic uniform refractive index. For this reason, the P-polarized light is
703 as it is.

Then, when light including P-polarized light and S-polarized light from the light source 704 enters the hologram element 702,
The S-polarized light is diffracted as described above and hardly enters the liquid crystal element 701, and only the P-polarized light is
02 and enter the liquid crystal element 701. Liquid crystal element 7
As described above, the P-polarized light incident on 01 is emitted as P-polarized light at the ON pixels, while being converted to S-polarized light at the OFF pixels and emitted. That is, the light emitted from the liquid crystal element 701 becomes different polarized light depending on whether the pixel at the passing position is ON or OFF.

When the light emitted from the liquid crystal element 701 enters the hologram element 703, the hologram element 702
Similarly to the above, the S-polarized light is diffracted, and only the P-polarized light travels straight. That is, the direction of light that has passed through each pixel of the liquid crystal element 701 exits from the hologram element 703 depending on whether the pixel is ON or OFF. Therefore, from the observer who sees the image display device from almost the normal direction of the display surface, the light that has passed through the OFF pixel is emitted to the outside of the field of view by the diffraction effect of the hologram element 703 and is not visually recognized. Passes through the hologram element 703 as it is, enters the viewing area of the observer, and is visually recognized as a bright pattern.

Next, an example of an actually manufactured image display device will be described.

In this image display device, the light source 704 used was a fluorescent lamp that had passed through a green filter, and emitted light having a wavelength of about 0.55 μm. As the liquid crystal element 701, a VGA of about 3 inches
The one having a resolution of (640 × 480) was used.
When an image signal was input thereto and observed from almost the normal direction (front) of the display screen, an image corresponding to the image signal input to the liquid crystal element 701 could be correctly viewed.
The contrast was about 10: 1. The direction in which the S-polarized light that has passed through the hologram element 703 diffracts (FIG.
When the observation position was moved to (upward at 0), an image in which the brightness was reversed from that of the previous image was visually recognized. As described above, the refractive index distribution type hologram elements 702 and 703 composed of the optical medium having the refractive index anisotropy are replaced with the liquid crystal element 7.
01, the image can be displayed by emitting the light corresponding to the OFF pixel to the outside of the observer's visual field without blocking (absorbing) the incident light. A good image display device can be manufactured. In addition, unlike the case where a polarizing plate is used, heat generation due to light absorption does not occur.

By controlling the voltage applied to each pixel, the polarization direction of the light passing through the liquid crystal according to the voltage is changed to the intermediate state between the P-polarized light and the S-polarized light, that is, the elliptically polarized light. Can be set to At this time, the light incident on the hologram element 703 is divided into a component that goes straight and a component that is diffracted according to the voltage applied to each pixel, so that a halftone display is also possible.

In the above example, the twisted nematic type liquid crystal element 701 has been described. However, any type of liquid crystal element 701 having a function of modulating the polarization direction of incident light can be used. It may be something. A super twisted nematic (STN) liquid crystal having a twist angle of 90 ° or more can also be used. In addition, the liquid crystal molecules are homogeneously aligned in the thickness direction, and become homeotropic upon application of an electric field, or change from homeotropic to homogeneous. The same effect can be obtained by using such a VA (Vertical Align) mode liquid crystal.

Furthermore, it is also possible to use a ferroelectric liquid crystal or an antiferroelectric liquid crystal in which the alignment direction of liquid crystal molecules differs depending on the polarity of the electric field.

The liquid crystal element 701 as described above is similar to a liquid crystal panel usually used as a liquid crystal display. Therefore, the image display device as described above can be configured simply by replacing the front and rear polarizing plates used in the liquid crystal element with the hologram elements 702 and 703 of the present invention, and the other illumination systems and drive systems are not changed. It is very versatile because it can be applied at

(Embodiment 5-2) Embodiment 5
An image display device as shown in FIG. 31 was constructed using the same hologram elements 702 and 703 as in FIG. That is,
The light source 704 was arranged near the lower side of the hologram element 702, and a so-called side light configuration was used in which light was emitted from an oblique side. Note that the light source 704 is described in Embodiment 5-1.
In the same manner as described above, a fluorescent lamp provided with a green filter was used. Other configurations are the same as those of the embodiment 5-1.

In this image display device, of the light emitted from the light source 704, the P-polarized light passes through the hologram element 702 as it is and does not enter the liquid crystal element 701. Also,
The S-polarized light is bent at approximately 90 ° with respect to the display screen by the hologram element 702 and enters the liquid crystal element 701. The light passing through the liquid crystal element 701 has its polarization direction modulated in accordance with the signal applied to the pixel, and enters another hologram element 703. Here, the S-polarized light is diffracted upward in the figure and emitted out of the viewing range of the observer. The P-polarized light passes through the hologram element 703 as it is and is visually recognized by an observer. Hologram element 7 from observer's position
When observed from the normal direction of the 03-direction display screen, an image corresponding to the input image signal was correctly visually recognized. Also, the hologram elements 702, 70
It was also possible to observe the outside scenery through 3.
As described above, the image display device configured as described above,
It is possible to visually recognize the image display and the external scenery simultaneously or by switching, and it can be used as a so-called see-through type display.

(Embodiment 5-3) Embodiment 5
3 using one hologram element 702 similar to FIG.
An image display device as shown in FIG. That is, the image display device is configured to display an image by using external light such as natural light or indoor light without having a light source inside. Further, the same liquid crystal element 701 as that in Embodiment Mode 1 was used.

The display principle of this image display device will be described below.

First, when external light 710 including P-polarized light and S-polarized light enters the hologram element 702, the P-polarized light component is transmitted without being modulated by the hologram element 702, and is almost completely transmitted to the liquid crystal element 701. Does not enter. On the other hand, the S-polarized light is diffracted by the hologram element 702, and almost all light enters the liquid crystal element 701. Light that has entered the liquid crystal element 701 passes through the area of each pixel and is reflected by the mirror 711. The mirror 711 can be made of a metal or a dielectric multilayer film. For the actual production, a glass substrate with aluminum evaporated was used.

The light reflected by the mirror 711 passes through the area of each pixel of the liquid crystal element 701 again, and its polarization direction is modulated according to the voltage applied to each pixel, and then enters the hologram element 702. The S-polarized light that has entered the hologram element 702 is diffracted upward in the same figure and is emitted out of the observer's field of view. Further, since the P-polarized light passes through the hologram element 702 as it is, it is visually recognized by an observer, and an image is visually recognized according to the signal voltage applied to each pixel of the liquid crystal element.

Observation of the reflection-type image display device using the above-described mirror actually manufactured with room light illumination revealed an image having a bright and dark pattern.
The contrast was about 10: 1. A white light source, which is room light, was used, but there was almost no deterioration in image quality due to color bleeding or the like. This is because the hologram element 7
The direction of diffraction of the S-polarized light diffracted at 03 differs depending on the wavelength. However, if the diffraction angle is set to be larger than the viewing range of the observer, it will be out of the recognition area, and the influence of the diffraction angle by the wavelength is almost a problem It is thought that it does not become.

Therefore, it is possible to clearly recognize an image in the reflection-type image display device using external light configured as described above, and further, since an internal backlight is not required, low power consumption and low power consumption can be achieved. Suitable for miniaturization.

(Embodiment 5-4) As shown in FIG. 33, the same hologram element 702,
An image display device of the combination type using the external light and the internal light source configured by using the image display device 703 will be described.

In this image display device, the hologram element 7
02 and 703 are the same as those described in the embodiment 5-1.
It is arranged in a state rotated by 90 ° in the same plane as compared with -1. Therefore, the hologram element 702 has
It does not show a diffractive effect on polarized light, but has a diffractive effect on P-polarized light. That is, the hologram element 702,
Reference numeral 703 is configured such that the dependence of the polarization direction on the P-polarized light and the S-polarized light is reversed. The same function can also be provided by performing an alignment process in the hologram element shown in FIG. 18 such that the initial alignment direction of the homogeneous liquid crystal differs by 90 °. That is, it is possible to determine which polarized light has a diffraction effect depending on how the arrangement direction of the liquid crystal molecules is set with respect to the incident light.

The liquid crystal element 701 is the same as that used in the embodiment 5-1. The mirror 711 is formed by vapor deposition of aluminum in the same manner as in Embodiment 5-3. The light source 704 is a fluorescent lamp,
Used as a white light source.

Here, in FIG. 33, solid arrows indicate
The propagation of external light is shown, and the dashed line arrow shows the propagation of light from the light source 704.

[0276] Hereinafter, the display operation using light from the light source 704 will be described first. P light from a light source 704 arranged diagonally on the side of the hologram element 702 as a side light
The light including the polarized light and the S-polarized light is
02, the S-polarized light is transmitted as it is without being subjected to the diffraction effect, and the P-polarized light is bent in a direction of approximately 90 ° with respect to the display screen by diffraction to enter the liquid crystal element 701.

The P-polarized light that has entered the liquid crystal element 701 is modulated by each pixel of the liquid crystal element, and the polarization direction changes. Accordingly, the traveling direction due to the action of the hologram element 703 changes. As a result, the observer can visually recognize the image information corresponding to the input image signal.

Next, the display operation using the external light 710 will be described. Of the external light 710, the P-polarized light is transmitted without being modulated by the hologram element 703,
It does not enter 01. The traveling direction of the S-polarized light is bent by the diffractive action of the diffractive optical element, and
Is almost incident. S passing through each pixel of the liquid crystal element 701
Since the polarized light is not subjected to the diffraction effect on the hologram element 702, it is transmitted as it is and reflected by the mirror 711. After passing through the hologram element 702 again, the light is incident on each pixel of the liquid crystal element 701, the polarization direction is modulated for each pixel, and the light is incident on the hologram element 703. ON
The S-polarized light that has passed through the pixel is diffracted by the hologram element 703 and emitted out of the observer's field of view. The P-polarized light that has passed through the OFF pixel passes through the hologram element 703 as it is, and is recognized as a bright pattern by an observer.

Here, the light and dark patterns corresponding to ON and OFF of the liquid crystal element are inverted between the light from the light source 704 and the external light. This can be dealt with by inverting the pattern of the video signal in correspondence with the selection of the light source.

Strictly speaking, the light from the light source 704 passes through the liquid crystal element only once, while the external light 710
Is reflected by the mirror and passes through the liquid crystal element twice, the forward path and the backward path. Therefore, the modulation ratio in the liquid crystal element 701 is different. This can be dealt with by correcting the video signal in accordance with the selection of the light source since the modulation degree of the single pass and the double pass can be estimated in advance.

As described above, the hologram elements 702, 7
By setting the polarization dependence of 03 differently, it is possible to achieve both the transmission mode and the reflection mode.

As a result of observing the actually manufactured image display device, the image can be clearly recognized by using the light source 704 in a dark room, and the image can be recognized without turning on the light source 704 under bright illumination light. Was able to do. As described above, by using this image display device, it is possible to select a light source according to the environment such as a dark place or a source of bright illumination light. Therefore, it is possible to improve the efficiency of power consumption and improve the visibility of an image under various environments.

Further, it is possible to detect the brightness of the illuminating light in an environment where the image display device is used, and to automatically select the light source or set the intensity of the light source. Can be further improved.

(Embodiment 5-5) FIG. 34 shows an image display apparatus in which hologram elements 702 and 703 similar to those in Embodiment 5-1 are combined with a color filter 721. As a light source 704, a fluorescent lamp was used as white light without passing through a filter. Also, the liquid crystal element 72
0 has the same structure as the liquid crystal element 720 of the embodiment 5-1 but has three times the pixel density, and has the red (R), green (G), and blue (B) in the color filter 721. The three pixels corresponding to the region (a) are grouped to display a color image at the same pixel density as the liquid crystal element 720.

The color filter 721 has R, R, and R for each region of the liquid crystal element 720 corresponding to each pixel.
Light of any wavelength of G or B is selectively transmitted, and light of another wavelength is absorbed.

In this image display device, S-polarized light and P-polarized light and S-polarized light emitted from the light source 704 are diffracted upward in FIG. Therefore, the S-polarized light does not enter the color filter 721, and only the P-polarized light enters the color filter 721.

[0287] R, which has passed through the color filter 721,
Light corresponding to each wavelength of G and B enters each pixel of the liquid crystal element 720. Then, the polarization direction is modulated according to ON / OFF of each pixel. As a result, the light passing through the ON pixels passes through the hologram element 703 as it is and reaches the observer. In addition, since the light that has passed through the OFF pixels is diffracted upward by the hologram element 703 in the same figure, the light falls outside the field of view of the observer, and becomes a dark pattern that is not recognized as light intensity by the observer.

FIG. 34 shows the case where all the pixels corresponding to R, G, and B are ON and OFF for simplicity, but the electric field applied to each pixel to which light of each wavelength is incident is shown. By independently controlling the light to pass through the hologram element 703, the light of the selected color among the light of each wavelength of R, G, and B reaches the observer. A color image can be displayed.

Here, the hologram element 7 for each wavelength
Regarding the influence of the chromatic dispersion of 03, the diffraction angle may be set to be large, and the short-wavelength light having a small diffraction angle may be set to be outside the viewing range of the observer. That is, any light of each wavelength that has passed through the pixel corresponding to OFF is the hologram element 70.
In No. 3, since the light is diffracted out of the viewing range of the observer, the light is not recognized as light intensity, and no problem such as color mixing occurs.

The light that has passed through the ON pixels is not normally subjected to diffraction by the hologram element 703. However, when the liquid crystal material forming the hologram element 703 has wavelength dispersion, Δn = Ne−No may vary depending on the wavelength, and the inside of the element cannot be regarded as an isotropic medium.
In this case, an angle difference occurs in the transmitted light of each wavelength, which is visually recognized by an observer as color bleeding or the like. However, in the case of transmission, if the distance of the observer from the hologram element 703 is not too large, a large deterioration in image quality does not occur.

[0291] R, G, B
Was input and observed at a distance of about 30 cm from the hologram element 703. As a result, a clear color image could be observed with little color mixing or color bleeding.

The combination of the color filters here is not used only in the configuration shown in FIG. 34, but is used in the reflection type shown in FIG. 32, the transmission type and the reflection type shown in FIG. Needless to say, the method can be applied to

(Embodiment 5-6) Embodiment 5
The hologram elements 702 and 703 of the image display device of No. 5 were manufactured by performing multiple exposure using light of each wavelength of R (0.65 μm), G (0.55 μm), and B (0.45 μm). You may. Hereinafter, a manufacturing process of such a hologram element will be described.

First, a liquid crystal sample is manufactured in the same manner as in the case of manufacturing the hologram element of FIG. 18 in Embodiment 2-1. This is set in an optical system using an Ar laser, and G (0.
Exposure is performed using interference fringes corresponding to a wavelength of 55 μm).
Next, the angle of the mirror (reflection mirror) is changed, and the above-described first exposure process is repeated to perform exposure corresponding to the wavelength of R (0.65 μm). Further, an interference fringe corresponding to B (0.45 μm) is similarly formed and exposed. After that, a second exposure step of irradiating the liquid crystal sample with uniform light in the same manner as in Embodiment 2-1 can produce a hologram element on which interference fringes are superimposed.

When the hologram element manufactured as described above is used in place of hologram elements 702 and 703 in FIG. 34, a color video signal is input to liquid crystal element 701 and observed from the position of the observer. Is R,
Because it is optimized for both G and B wavelengths,
A clear image could be recognized without problems such as color bleeding and color mixing. Further, even if the observation position was moved back and forth by about 30 cm, there was no effect such as deterioration of image quality.

(Embodiment 5-7) Embodiment 5
The hologram elements 702 and 703 of the image display device of No. 5 were R (0.65 μm) and G (0.55 μm), respectively.
m) or B (0.45 μm) may be used in which three hologram elements produced by performing exposure with light of each wavelength are laminated.

The hologram element as described above is used in place of hologram elements 702 and 703 in FIG.
When a color video signal is input to the image sensor 01 and observed from the observer's position, the diffractive optical elements of the respective layers independently perform the diffractive action on each of the R, G, and B wavelengths, and the chromatic dispersion is reduced. Eased. As a result, a clear image could be recognized without problems such as color bleeding and color mixing. further,
Even if the observation position was moved back and forth by about 30 cm, there was no influence such as deterioration of image quality.

(Embodiment 5-8) Embodiment 5
The image display device such as 1 can also be applied to an image display / illumination device. Hereinafter, an example of a device capable of displaying road traffic information in a tunnel and performing illumination without a tunnel will be described.

As shown in FIG. 35, the image display device 731
Are installed on the wall surface 732 of the tunnel. This image display device 731 has, for example, a configuration similar to that of the image display device described in the embodiment 5-1.
It is installed so as to face the traveling direction of 33. That is, in the embodiment 5-1, the example in which the display image is visually recognized substantially from the normal direction (front) of the display screen has been described. An image whose brightness is reversed is displayed as the image to be visually recognized. Therefore, by inputting image data in which the brightness is reversed in advance as image data to be input to the image display device, an image that can be visually recognized from a direction inclined with respect to the normal of the display screen is displayed by the diffracted light. Can be done.

Here, the direction in which the diffracted light is emitted, that is, the direction in which the displayed image is visually recognized by the diffracted light, can be set by the inclination or pitch of the periodic structure of the hologram element. Therefore, this display device can be applied to various devices that require a display image to be viewed obliquely.

When an image is displayed by diffracted light, light transmitted through the hologram element is emitted in the normal direction of the display screen. Although an image formed by the emitted light cannot be viewed from an oblique direction, it plays a role as illumination light in an environment where the surroundings are dark at night or in a tunnel or the like, so that it can be used as an illumination device. That is,
A device having both functions of an image display device and a lighting device can be configured. Thus, the functions of the image display device and the illumination device can be provided because in a liquid crystal display using a normal polarizer, light not used for image display is absorbed by the polarizer and cannot be used for illumination. In contrast, a display device using a hologram element as described above is
This is because the transmitted light and the diffracted light are emitted equally in principle.

Hologram elements 702, 7 in the present invention
This is a feature of the image display device having a configuration in which light is split by the light emitting device 03.

Note that the plurality of image display devices 731 are
If it is arranged at 32, it is also possible to use the image information to be recognized step by step by the observer according to the traveling position of the vehicle. It is effective in the case.

Actually, when an image display device 731 was placed in an experiment room that imitated a structure in a tunnel as shown in FIG. 35 and an experiment was performed, an image that can be visually recognized as the position of the observer moved was displayed. I was able to. It was also confirmed that the light emitted to the front of the image display device 731 also served as illumination light in a dark laboratory.

Such an image display / illumination device can be applied not only to the inside of a tunnel but also to traffic information display and illumination on a normal arterial road or an expressway, with priority given to other specific directions. It is needless to say that the present invention can be applied to a method of displaying image information on a screen.

(Embodiment 5-9) Embodiment 5
An example of an image display device having a polarization conversion element configured using the same hologram element as that of Example 1 will be described.

This image display apparatus is described in Embodiment 5-1.
Are provided instead of the hologram element 702 of FIG.
Also, the hologram elements 743 and 744 and the liquid crystal element 701
Between them, there are provided retardation plates (λ / 2 plates) 745 and 746. As the light source 704, a fluorescent lamp having a green filter passed through was used as in Embodiment 5-1. Other configurations are the same as those of the embodiment 5-1.

In this image display device, of the light emitted from the light source 704, the P-polarized light is the diffractive optical element 741, 74.
2 is transmitted as it is and enters the liquid crystal element 701. The s-polarized light is approximately 9 hologram elements 741, 742.
The light is diffracted almost horizontally at an angle of 0 °, and enters the hologram elements 743 and 744 arranged on the respective sides. Light incident on hologram elements 743 and 744 is further diffracted by hologram elements 743 and 744 at an angle of approximately 90 °. The light diffracted by the hologram elements 743 and 744 has its polarization plane rotated by 90 ° by the phase difference plates 745 and 746, and is incident on the liquid crystal element 701 almost vertically as P-polarized light.

That is, the hologram elements 741 to 744
The light from the light source 704 is incident on the liquid crystal element 701 as a light wave having a uniform polarization plane (in this case, P-polarized light). Therefore, the light use efficiency increases (theoretically about twice), and a bright image can be displayed.

Also, the irradiation area of the light source 704 can be expanded, and the light from the light source 704 having a small area can be enlarged to display an image by enlarging the irradiation area. It is also effective in electric power.

[0311] The light passing through the liquid crystal element 701 has its polarization direction modulated in accordance with the signal applied to the pixel, and enters another hologram element 703.

Here, the S-polarized light is diffracted upward on the plane of the paper and emitted out of the viewing range of the observer.

The P-polarized light passes through the hologram element 703 as it is, and is recognized by the observer.

When the direction of the hologram element 703 was observed from the observer's position, the image corresponding to the applied input signal was correctly recognized.

As described above, the image display device configured here can effectively use almost all of the light waves from the light source for image display, and can enlarge the illumination area.

(Embodiment 5-10) Embodiment 5
Another example of a small-sized image display device having a polarization conversion element configured using a hologram element similar to -1 will be described.

FIG. 37 schematically shows a small display device according to the embodiment of the present invention. The light wave from the light source 704 enters the hologram element 751 from the lateral direction, and the P-polarized light is diffracted by approximately 90 ° by the diffractive optical element, and the liquid crystal element 701
Incident on.

The S-polarized light passes through the hologram element 751 and is incident on another hologram element 752.
The diffractive optical element 752 is formed so as to generate a refractive index distribution with respect to the S-polarized light.
The polarized light is diffracted by approximately 90 ° and emitted. After this, λ
/ 2 plate 753, the polarization plane is rotated by 90 °, and P
The light enters the liquid crystal element 701 as polarized light.

Therefore, almost all of the light amount from the light source 704 can be used for the display of the liquid crystal element as in the embodiment 5-10. Further, since light is incident from the lateral direction, a see-through type function or a combination type of an external light source and an internal light source as described in Embodiment 5-4 is also possible.

In the actually manufactured image display device, the light source 7
A fluorescent lamp passed through a green filter as 04 was used to emit light having a wavelength of about 0.55 μm. VGA of about 0.9 inch as liquid crystal element
A small liquid crystal panel having a resolution of (640 × 480) was used. When an image signal is input to this, the liquid crystal element 7
The light passing through 01 is incident on another hologram element 703 after its polarization direction is modulated according to the applied signal of the pixel.

Here, the S-polarized light is diffracted upward from the plane of the paper and is emitted out of the viewing range of the observer. The P-polarized light passes through the hologram element 703 as it is and is recognized by an observer.

In this case, the magnifying optical system 754 was used on the light emission side of the hologram element 703. Here, a planar Fresnel lens was used as the magnifying optical system. As a magnifying optical system, a convex lens or a liquid crystal lens using an in-plane change in refractive index can be used. It is preferable to form a magnifying optical system with a thin lens because a small system can be formed.

When observing the direction of the hologram element 703 from the position of the observer, an image corresponding to the applied input signal was correctly recognized. Also, despite the use of a small 0.9-inch liquid crystal panel this time, the magnifying optical system 75
By the operation of 4, the display image was enlarged by the observer depending on the distance from the hologram element 703, and the observer could clearly recognize the display image.

The configuration as shown in FIG. 37 can reduce the size of the entire system, and is expected to be used as a very small image display device that can be used as a micro display for a portable information terminal.

(Embodiment 6) An image display device using the hologram element described in Embodiment 1 will be described.

FIG. 38A shows the configuration of the image display device. In this image display device, the transmission type liquid crystal panel 8
The hologram element 820 according to the present invention is used for 19 backlight units.

The light flux 824 from the light source 823 is
1 and diffracted in the direction substantially normal to the substrate of the liquid crystal panel 819 by the hologram element 820 of the present invention installed on the back surface while propagating through the light guide 821 while propagating through the light guide 821. The light beam 822 incident on the liquid crystal panel 819 is modulated to display an image.

A reflection mirror 823 is provided on the back surface of the hologram element 820 so that light transmitted through the hologram element 820 can be further reflected. For example, dots (not shown, It is preferable to form a large number of known techniques other than the conventional example 7).

The liquid crystal panel 819 may be of a transmission type, and any type of liquid crystal panel can be used regardless of the driving method and liquid crystal material. Note that a reflective liquid crystal panel that is also used as a transmissive type according to the brightness of external light may be used.

As the light source 823, for example, CCFT can be used, and a reflecting mirror 825 may be provided as disclosed in many examples including the conventional example 8. Light guide 82
As 1, a resin material such as acrylic can be mainly used, and for example, a wedge-shaped shape can be used as disclosed in, for example, Conventional Example 7 and Japanese Patent Application Laid-Open No. 9-5743.

The basic function of the hologram element 820 is as follows.
In the non-polarized light beam 824 incident on the hologram element, a specific polarization component is selectively diffracted in a substantially normal direction of the liquid crystal panel 819 and within a specific solid angle. Or as a mere isotropic medium.

That is, as shown in FIGS. 39 (a) and (b), for example, it can function as a hologram element when no voltage is applied, and can function as an isotropic medium when voltage is applied. When functioning as a hologram element, the hologram element 820 according to the present invention selects only a specific polarization component in the non-polarized incident light beam 824 in a direction substantially normal to the liquid crystal panel and within a specific solid angle. Diffraction occurs.

At this time, if the liquid crystal panel is of a polarization type, that is, a method of modulating only a specific polarized light, and a polarizing plate (not shown) is provided on the light incident side, the polarization direction of the polarizing plate is changed. High efficiency can be realized for the first time by making the polarization direction of the electric field vector of the polarized light transmitted through the polarizer substantially the same as the polarization direction of the polarized light that the hologram element selectively diffracts (the vibration direction of the electric field vector). .

On the other hand, when a voltage is applied, the hologram element 820 of the present invention becomes a substantially isotropic medium, and the incident light flux 82
4 transmits through the hologram element 820, and the light beam scattered by the reflection mirror 823 provided on the back surface enters the liquid crystal panel 819. The liquid crystal panel 81 in this case
The output light flux of No. 9 is almost uniformly diffused by the dots provided on the reflection mirror 823 in the same manner as when illuminated by a conventional backlight.

Thus, the hologram element 82 of the present invention
In the image display device using 0, when no voltage is applied, the illumination light is diffracted within a narrow solid angle substantially in the normal direction, so that the brightness when the liquid crystal panel 819 is observed from the front is extremely high. Further, by applying a voltage, the luminance when observing from the front is reduced, but a wide viewing angle can be secured.

The hologram element is used in the backlight unit of the liquid crystal panel as in the present invention, and the directivity is given to the diffracted light so that the luminance when viewed from the front (when viewed from the normal direction of the liquid crystal panel) is increased. Many examples are disclosed, for example, Conventional Example 7 to Conventional Example 10, but in the above example, the hologram element has only a single function of always diffracting incident light. Element 8
The viewing angle cannot be switched as in the case of 20.

In the prior arts 1 and 2, switchable hologram elements are disclosed, but no specific use as a backlight of a liquid crystal panel is disclosed. As described above, high efficiency can be realized only by making the polarization direction of the polarizing plate of the liquid crystal panel coincide with the polarization direction of light selectively diffracted by the hologram element.

The function of the image display device of the present invention, which can switch the brightness and the viewing angle of an image, is extremely valuable when used as a display of a personal computer or a portable information terminal regardless of whether it is a stationary type or a notebook type. Function.

That is, when an image is viewed by an individual, the viewing angle (meaning equivalent to the range in which the image can be viewed)
It is not necessary to be unnecessarily wide, and a limited range necessary for image observation such as work is sufficient. According to the present invention, an image is output substantially in the direction of a worker observing the image from the front, so that the power consumption of the lamp can be reduced.

On the other hand, when observing an image with a large number of people, it is desirable that the viewing angle is wide. Therefore, the function of changing the viewing angle between the case of observing an image by an individual as in the present invention and the case of observing the image by a large number of people is important. However, strictly, the viewing angle is not changed, and the hologram element 820 of the present invention means that the amount of light flux reflected within a specific narrow solid angle can be controlled by an applied voltage.

Next, a method of manufacturing the hologram element used in the present embodiment will be described.

The hologram element 82 used in the present embodiment
0 is equal to I as described in Embodiments 1 and 4-1.
It can be manufactured by injecting, for example, a mixture of a UV-curable liquid crystal and a non-polymerizable liquid crystal as a photo-curable liquid crystal into a cell formed of two glass substrates 502 on which the TO 501 is formed, and illuminating a two-beam interference document.

However, it is characterized in that the object light is made to enter the substrate almost perpendicularly at the angle at which the light flux enters the reference light.
At this time, by performing two-beam interference exposure in a state where a voltage is applied, a desired interference script as shown in FIG. 39, for example, is formed. The non-polymerizable liquid crystal is separated into the weak portions, and the hologram element 820 of the present invention is manufactured.

In actual production, both the object light and the reference light do not need to be plane waves. For example, a light beam that spreads within a specific solid angle as the object light is used as the reference light.
It is preferable to use a light beam that propagates from the same angle range as the light beam that enters the hologram element after propagating through the hologram element.

Further, in the above configuration, for example, the ITO 501 of the hologram element 820 according to the present invention may be patterned, and the applied voltage may be varied for each region to locally control the refractive index anisotropy. Thereby, the efficiency of the hologram element 820 can be locally optimized. Further, for example, as disclosed in Conventional Example 7, the hologram elements may be arranged in a small mosaic pattern, and the individual micro hologram elements may be optimized so as to exhibit the maximum efficiency with respect to the wavelength of the incident light and the incident angle. .

Further, as shown in FIG. 38B, the λ / 4 plate 27 is provided between the hologram element 820 according to the present invention and the reflection mirror 823, and the reflection mirror 823 is not parallel to the hologram element 820. The hologram element 820 according to the present invention can be arranged at an angle of, for example, about 5 °.
For example, in a mode in which an extraordinary ray is selectively diffracted without applying a voltage to the hologram element 820, the ordinary ray 828 transmitted through the hologram element 820 can be converted into an extraordinary ray and made incident on the hologram element 820 again.

At this time, since the reflection mirror 823 is installed at an angle, the reflected light flux 829 from the reflection mirror 823 is transmitted through the hologram element 820 and reflected by the hologram element 820 due to the angle dependence of the hologram element 820. The same polarized light as the light beam 822 (in this case, P-polarized light) can be incident on the liquid crystal panel 819, and the light use efficiency can be increased.

[0348] As described above, the image display device constructed in this embodiment is a hologram element 820 according to the present invention.
By adjusting the voltage applied to the luminous flux, it is possible to control the amount of luminous flux output within a specific solid angle. This makes it possible to select a bright image display with a narrow viewing angle and a wide viewing angle, which is slightly darker, as required.

The image display device constructed in this embodiment is
It can be used not only as a display for a stationary or notebook personal computer but also as a display for a portable information terminal, a portable communication device, or a head-up display for a vehicle.

(Embodiment 7) An image display device according to the present invention configured as Embodiment 7 of the present invention will be described. The image display device according to the present embodiment is a so-called conventional direct-view type liquid crystal panel. However, as a liquid crystal material, a mixture of a photocurable liquid crystal and a non-polymerizable liquid crystal is provided with lattice-like light (wavelength: A microcell structure surrounding each pixel is formed by irradiating light (wavelength for curing the photocurable liquid crystal) and by photo-induced phase separation phenomenon.

However, ne and no after curing of the photocurable liquid crystal are substantially equal to ne and no of the non-polymerizable liquid crystal, respectively.

With the above-described microcell structure, liquid crystal molecules are aligned in an axially symmetric state stabilized by a photocuring reaction by a self-alignment force in a liquid crystal region, and a wide viewing angle and high contrast can be realized.

Next, the difference between the conventional example and the image display device according to the present embodiment will be described. The effects that the viewing angle improvement and high contrast can be realized by the microcell are as follows.
For example, as disclosed in Conventional Example 6, in Conventional Example 6, a mixture of a photo-curable resin and a liquid crystal is simply illuminated with lattice-like light (wavelength is a wavelength that cures the photo-curable resin), and light-induced Only the microcell structure surrounding each pixel is formed by the phase separation phenomenon, but nothing is described about the refractive index anisotropy of the photocurable resin.

Generally, the photocurable resin has a slight but birefringent property and exhibits a slight refractive index anisotropy. Therefore, when displaying black, the contrast is good for a vertically incident light beam, but there is a disadvantage that the grating portion stands out as a discontinuous region and the uniformity is poor for an obliquely incident light beam. Was.

However, in the image display device of the present embodiment, the photocurable liquid crystal is cured in the same alignment state as that of the non-polymerizable liquid crystal when displaying black, and the optical difference of the photocurable liquid crystal is changed. Since the anisotropy is made almost equal to the optical anisotropy of the non-polymerizable liquid crystal, the microcell part can be conspicuous in black display and the decrease in contrast can be suppressed, and an extremely uniform image can be displayed. Was completed.

(Embodiment 8-1) FIG. 40 shows an outline of an optical information processing apparatus using the volume hologram element shown in Embodiment 2-1 and configured in Embodiment 8-1 of the present invention. Show. Light emitted from the semiconductor laser 901 that emits polarized light passes through the volume hologram element 521 as it is,
The light is focused on the optical storage medium 906 via the quarter-wave plate 905 by the imaging lens 904. In this case, the laser beam passing through the volume hologram element 521 is not diffracted, and almost all the emitted light from the semiconductor laser 901 is focused on the optical storage medium 906.

Next, the light reflected by the optical storage medium 906 passes through the quarter-wave plate 905 again and passes through the imaging lens 904.
Converges. At this time, since the reflected light passes through the quarter-wave plate twice, the polarization direction of the reflected light is rotated by 90 ° with respect to the light emitted from the semiconductor laser 901. Therefore, this time, the reflected light undergoes a diffractive action according to the predetermined wavefront formed on the volume hologram element 521, and is converged on the photodetector 902.

[0358] Here, an optical signal is detected for each of the divided areas on the photodetector 902, and a focus shift, a tracking shift,
And a signal of information recorded on the optical storage medium is detected. At this time, the amount of light guided to the photodetector 902 is substantially determined by the light use efficiency of the volume hologram element 521 due to polarization separation on the outward path and the diffraction efficiency on the return path.

FIG. 41 and FIG. 42 show the principle and structure of the volume hologram element 521 of the present invention. FIG. 41 shows a refractive index ellipsoid of a uniaxial optical crystal. FIG. 41A shows a refractive index ellipsoid when the optical axis is in the Y direction. At this time, the light whose polarization direction exists on the YZ plane becomes an extraordinary ray and shows the refractive index of Ne. XZ
It becomes an ordinary ray for light whose polarization direction exists in the plane,
No indicates the refractive index.

FIG. 41B shows a refractive index ellipsoid when the optical axis of the uniaxial optical crystal is inclined by 90 ° from the Y direction. In this case, the light having the polarization direction in the YZ plane has a No refractive index, and the light having the polarization direction in the XZ plane also has a No refractive index.

In the state where the optical axis is intermediate between (a) and (b), Ne and No (Ne> Ne) corresponding to the state of inclination of the optical axis with respect to light whose polarization direction exists on the YZ plane. No) takes an intermediate value of the refractive index. On the other hand, for light whose polarization direction exists on the XZ plane, the refractive index always indicates No, regardless of the inclination of the optical axis.

As described above, for the optical medium having the refractive index anisotropy, Ne to No.
There is a case where the refractive index distribution is within the range described above and a case where the refractive index distribution is only No, regardless of the inclination of the optical axis.

FIG. 18 is a diagram showing a sectional structure of the volume hologram element. The inside of this element has a periodic layer structure inclined from the surface on which light is incident to the thickness direction. The inclination of the optical axis of the optical medium having the refractive index anisotropy between adjacent layers is one because of the volume hologram element 521.
Are arranged so as to be parallel to the surface, and the other is arranged perpendicular to the surface.

In this volume hologram element 521, light having a polarization direction perpendicular to the plane of FIG. 18 is regarded as an ordinary ray, and light having a polarization direction parallel to the plane of FIG. 18 is regarded as an extraordinary ray. The behavior when the light enters the volume hologram element 521 will be considered.

First, when an ordinary ray is incident, X in FIG.
Since the same treatment is performed as when light having a polarization direction is incident on the -Z plane, the refractive index of each layer is No, regardless of the direction of the optical axis of the optical medium constituting each layer. That is, since a medium having a uniform refractive index of No is present, the ordinary ray incident on the medium is not affected by diffraction, and FIG.
As shown in FIG.

Next, the case where an extraordinary ray is incident will be considered. In a layer in which the optical axis of the optical medium having the refractive index anisotropy is arranged parallel to the incident surface, the polarization direction of the incident light is parallel to the optical axis. This corresponds to the case where light having a polarization direction in the YZ plane of FIG. 41 is incident on an optical medium having an optical axis in the Y direction of (a), and passes through a layer having a refractive index of Ne. become.

For a layer where the optical axis of the optical medium is perpendicular to the incident surface of the volume hologram element 521,
Since this corresponds to the case where light having a polarization direction is incident on the YZ plane with respect to FIG. 41B, this layer is treated as having a refractive index of No.

Therefore, the volume hologram element 521 for an extraordinary ray passes through a plurality of layers having different refractive indexes periodically in the thickness direction which is the traveling direction of the incident light. As a result, the incident light beam is subjected to a so-called Bragg diffraction effect in which the light is condensed in a specific direction corresponding to the inclination angle of the layer and the pitch of the period.

As shown in FIG. 18, after passing through the volume hologram element 521, the extraordinary ray changes its optical path corresponding to the layer structure formed inside the element.

As described above, for the volume hologram element 521 in the configuration of the optical information processing apparatus of FIG. 40, the polarization direction of the light emitted from the semiconductor laser 901 is set so as to correspond to the ordinary ray shown in FIG. At this time, the light emitted from the semiconductor laser 901 is not modulated by the volume hologram element 521, and is not modulated by the imaging lens 904.
The light is focused on the optical storage medium 906 via the four-wavelength plate.

The light reflected here again passes through the quarter-wave plate, and enters the volume hologram element 521 via the imaging lens 904. At this time, the polarization direction is 9
The rotation by 0 ° corresponds to the case of the extraordinary ray shown in FIG. Therefore, the light is focused on a specific direction, in this case, on the photodetector 902 in accordance with the periodic refractive index distribution corresponding to the layer structure formed inside the volume hologram element 521.

By having a structure having a periodic structure in the thickness direction as shown in FIG. 18, the Bragg diffraction condition is applied. This is because when light having a certain wavelength enters each layer forming the periodic structure, the light scattered in each layer causes a phenomenon in which the scattered component strengthens in a specific direction corresponding to the wavelength, the incident angle, and the pitch between the layers. .

This is what is called Bragg's diffraction condition. Such a condition results in a three-dimensional configuration with respect to a conventional two-dimensional diffractive optical element, and is blazed (light is converged in one direction). ).

Therefore, the diffraction efficiency can be dramatically improved as compared with the conventional diffractive optical element, and theoretically 100%
Efficiency is possible. In fact, an efficiency of 90% or more can be expected even when taking into account the loss on the way. On the other hand, if a hologram element as shown in FIG. 40 is constituted by a binary diffractive optical element as described above, the diffracted wave will be diffracted symmetrically to the higher order including the 0th order. As a result, the diffraction efficiency in the primary direction is a maximum of about 40%, which is a low value of 1/2 or less as a percentage of the total amount of light passing through the element.

The volume hologram element 521 of the present invention
If the optical information processing apparatus is configured by using the optical storage medium 90,
Since almost all of the reflected light from 6 can be collected on the photodetector 902, there is no problem such as a decrease in the S / N ratio due to a decrease in the light intensity. Furthermore, since the diffraction efficiency of the volume hologram element 521 is high, there is almost no return light amount to the semiconductor laser. Therefore, the problem of instability of the oscillation of the laser as the light source due to the feedback of the light intensity to the semiconductor laser 901 does not occur.

FIG. 18 shows the case where the optical axis of the optical medium constituting the volume hologram element 521 has the largest difference in the refractive index inclined by 90 ° between the adjacent layers. It is also possible to set the difference to an intermediate value between Ne and No.

Further, it is also possible to adjust the diffraction efficiency by selecting a refractive index distribution utilizing this, and arbitrarily set the detected light intensity and pattern for the photodetector 902.

Also, the area of the volume hologram element 521 is divided into several parts, and light signals are received in different areas of the photodetector 902 by shifting the directions in which they are diffracted, respectively. A configuration in which detection is performed efficiently is also possible.

Further, in the case where a plurality of semiconductor lasers 901 are used at different wavelengths and not only writing of optical information but also recording are performed at the same time, different periodic structures, angles, etc. are set according to the respective light wavelengths. Can be recorded in the volume hologram element 521 in a superimposed manner.

(Embodiment 8-2) FIG. 42 shows a method of manufacturing a diffractive optical element used in an optical information processing apparatus according to the present invention.
This will be described with reference to FIG.

The light emitted from the Ar laser 911 having a wavelength of about 360 nm is passed through a mechanical shutter 912 that can be opened and closed by a beam expander 913 to have a diameter of 30 mm.
The beam can be expanded to about 50 mm. Then, the beam is split in two directions by a beam splitter 915,
Irradiates at an angle corresponding to the structure of the interference fringes formed on the volume hologram element 521. One of the light beams split by the beam splitter 915 has a shutter 4.
05 is arranged.

Next, a process of manufacturing the cell of the volume hologram element 521 will be described.

[0383] Two transparent conductive electrodes formed of, for example, ITO on a glass substrate were prepared. After cleaning these substrates to remove dust, an alignment film made of a polymer, for example, polyimide is applied by a spin coating method or the like, and an alignment film is formed on the substrate by performing a heat treatment or the like.

Thereafter, a rubbing process is performed in a specific direction by a roller or the like, a seal is printed around one substrate, and beads having a diameter of about 5 μm to 20 μm are dispersed on the other substrate. The two substrates were bonded together such that the rubbing directions were paired with each other to form an empty cell.

A liquid crystal was used as the optical medium having the refractive index anisotropy, and the empty cell fabricated here was injected.
Although the liquid crystal used this time has a positive dielectric anisotropy, it is also possible to use a liquid crystal having a negative dielectric anisotropy.

It contains a photopolymerizable liquid crystal monomer or a photocrosslinkable liquid crystal polymer, and has a property that the liquid crystal is cured by irradiation with light having a wavelength in the ultraviolet region of about 360 nm, and the direction of the liquid crystal molecules is fixed. I have. Although the implantation was performed at room temperature in an air atmosphere, the implantation may be performed at a high temperature of about 40 ° C. to 60 ° C. or in a vacuum atmosphere. After the liquid crystal was injected, the injection port and the vicinity of the deaeration port were sealed with a sealant in the cell, and a liquid crystal sample was completed.

The liquid crystal sample produced as described above was set at the position where the volume hologram element 521 was produced in the optical system shown in FIG. First, with the shutters 912 and 405 opened, adjustment was made so that interference fringes having a pitch of about 1 μm were formed at the sample position. At this time, the converging angle of the two light beams by the mirror 906 is 15 ° to 45 °.
°, and the irradiation intensity of the Ar laser is 50 mW to 10 mW.
It is about 0 mW.

Next, a process of forming interference fringes on a liquid crystal sample by a laser will be described. First, the liquid crystal sample is set with the shutter 912 closed and the shutter 405 opened. Then, the shutter 912
Is opened for a predetermined time, here about 1 minute, and then closed.

This is the first step. In this step, the liquid crystal sample is hardened in the liquid crystal sample in the region belonging to the bright portion where the intensity of the interference fringes formed by the interference of the two light beams of the laser is increased. The molecular axis is fixed in the direction in which is initially oriented. Here, since a liquid crystal having a positive dielectric anisotropy is used, the liquid crystal molecules are initially uniformly aligned in a direction parallel to the glass substrate, and this state is preserved. On the other hand, in the region belonging to the dark portion of the interference fringes, the light intensity is lower than that of the bright portion, and therefore, hardening of the liquid crystal molecules is hardly promoted in the first step.

Next, as the second step, the liquid crystal sample 2
An AC electric field of about 5 (V / μm) is applied between ITO electrodes as transparent conductive electrodes formed inside the glass substrates. Due to the application of the electric field, uncured liquid crystal molecules in a region belonging to a dark portion of the interference fringes are tilted in a direction perpendicular to the glass substrate. Since the angle of inclination at this time is proportional to the applied electric field, a desired inclination angle, that is, a refractive index difference can be given by adjusting the magnitude of the electric field.

With the voltage applied as described above, the shutter 405 is closed, and light having a uniform intensity distribution that does not form interference fringes is irradiated onto the entire surface of the volume hologram element 521 for about 5 minutes, and the uncured dark area Is completely cured, including the liquid crystal.

By performing the first and second steps as described above, a volume hologram element 521 having a structure as shown in FIG. 18 was manufactured. The diffraction efficiency of this element is set to He-N
The measurement was performed using an e-laser while changing the incident polarization direction. The transmittance for ordinary light was about 98%, indicating a high transmittance. The diffraction efficiency of the extraordinary ray in the primary direction was about 90%, and good results were obtained. Therefore, the volume hologram element manufactured here has high polarization separation characteristics and diffraction efficiency, and it has been proved that it is promising as a diffractive optical element used for an information processing apparatus.

(Embodiment 8-3) Two glass substrates opposed to each other are used.
The same process as in -2 was performed, and a liquid crystal sample was prototyped. This sample was set in the optical system shown in FIG. 42, and the light portion of the interference fringes was exposed as a first step.

Next, as a second step, in order to change the orientation direction of the liquid crystal molecules in the region belonging to the stripes of the dark portion from the initial position, setting for applying a magnetic field to the volume hologram sample 521 shown in FIG. 42 is performed. Was. Specifically, a magnetic field was formed around the liquid crystal sample by a superconducting magnet.

Since liquid crystal has dielectric anisotropy, the molecular axis of liquid crystal molecules can be changed by applying a magnetic field as well as an electric field. By the application of the magnetic field as described above, the liquid crystal molecules in the dark area are changed in a direction perpendicular to the glass substrate. Then, in this state, as in Embodiment 8-2, the shutter 405 was closed and uniform light irradiation was performed on the liquid crystal sample to cure the entire panel.

When a magnetic field is applied, the liquid crystal sample does not need to be formed with ITO or the like as a transparent conductive electrode. Therefore, this process is omitted, the structure is simple, and a less expensive manufacturing is possible. Further, since the influence of the reflected light due to the difference in the refractive index at the interface between the glass and the ITO is removed, the transmittance is increased and the function as the diffractive optical element is also improved.

The diffraction efficiency with respect to the polarization direction of the volume hologram element manufactured by the above-described process is shown in Embodiment 8.
-2 was measured in the same manner. As a result, it has been found that the diffraction efficiency has a performance of 90% or more, and the direction of liquid crystal molecules can be appropriately controlled even by a method by applying a magnetic field.

(Embodiment 8-4) From the step of applying an alignment film to a glass substrate, a trial production of a liquid crystal sample was performed in the same manner as in Embodiment 8-3. In the present embodiment, polyvinyl cinnamate (PVCi) is used as the alignment film, and the roller rubbing step is omitted. This sample was set in the optical system in FIG. This time, in this system, a polarizer was provided immediately after the beam expander 913, and only the linear polarization component of the laser beam was used.

First, as a first step, exposure of a region belonging to the bright portion of the interference fringes was performed in the same manner as in Embodiment 8-2. At this time, the interference fringe pattern consists of only the linearly polarized light component of the laser light. When a polymer film is irradiated with linearly polarized light as a light source, molecules that have their main chains (or side chains) oriented in the direction of polarization among the randomly oriented polymers absorb light mainly and cause photoreaction. This causes the film to exhibit optical anisotropy. In a polymer material or the like, the photoreaction process (photoisomerization, photopolymerization, photodecomposition) of the polymer can be controlled by the polarization direction of the irradiated light and the angle formed by the polymer.

Therefore, by controlling the polarization direction of the light in the ultraviolet region constituting the interference fringes, the setting was made so that the orientation direction of the liquid crystal molecules was parallel to the glass substrate.

Next, in the second step, a half-wave plate was placed immediately after the polarizer, and the polarization direction of the laser beam was rotated by 90 °. Then, the shutter 405 was closed, and the liquid crystal sample was irradiated with uniform light having a polarization direction in a direction orthogonal to the polarization direction in the first step. In the region belonging to the dark part, the light part is irradiated with light whose polarization direction is rotated by 90 °, so that the alignment direction of the liquid crystal molecules changes from the position in the first step and is fixed.

The above process makes it possible to form a periodic structure in which the directions of the liquid crystal molecules are different in the layers corresponding to the bright and dark portions of the interference fringes. In this case, since the alignment of the liquid crystal molecules is performed by light irradiation, it can be performed together with the exposure of interference fringes, and the manufacturing process can be simplified. Further, the rubbing method using a roller can be carried out in a non-contact manner, dust and the like can be prevented from being mixed, a highly reliable manufacturing process technology can be established, and mass production can be stably supported.

The volume hologram element 521 manufactured here
Were evaluated in the same manner as in Embodiments 8-2 and 3-3. As a result, the diffraction efficiency is about 70%,
Although the diffraction efficiency was slightly lowered, an efficiency of 50% or more was obtained, and it became clear that a diffractive optical element having a three-dimensional periodic structure was produced.

Further, a process of irradiating light of a wavelength in the ultraviolet region having a specific polarization direction after the application of PVCi as an alignment film and before assembling the cell is introduced to improve the alignment of liquid crystal molecules. You may.

(Embodiment 8-5) Using a process similar to that of Embodiment 8-2, a trial production of a liquid crystal sample was performed.
In this case, a mask was applied to a half area of the sample, and the optical system shown in FIG. 42 was set. Then, the first and second steps were performed in the same manner as in Embodiment 8-2 to produce a volume hologram in a region without a mask.

Next, the beam angle of the two light beams was changed by about 5 ° by changing the angle of the mirror 916 shown in FIG. Then, remove the mask part of the previous sample,
The first and second steps were repeated for this portion to produce a volume hologram.

As a result of evaluating the volume hologram element 521 manufactured as described above, light was diffracted in two different angular directions with respect to the irradiation of the extraordinary ray on the entire surface of the element.

At this time, each diffraction efficiency is 90
%, Which indicates that different layer structures can be favorably formed in a plurality of regions. If this is applied to the configuration shown in FIG. 40, since it is divided in two directions by the volume hologram element 521, signal detection is performed at once in different regions on the photodetector 902, and focus shift, tracking shift, etc. Signal detection can be performed efficiently.

(Embodiment 8-6) A liquid crystal sample was manufactured in the same manner as in Embodiment 8-2. This was introduced into the optical system shown in FIG. 42, and the first step was performed to expose a region belonging to the bright portion of the interference fringes. Here, the angle of the mirror 916 was changed by about 5 ° to form interference fringes with different periods, and in this state, the first step was repeated to expose a light area.

Next, in the same manner as in Embodiment 8-2, the shutter 4
The volume hologram element was manufactured by performing the second step of closing 05 and irradiating the volume hologram element 521 with uniform light.

The volume hologram element 521 manufactured as described above was evaluated. Using an extraordinary ray, the angle of the laser for measuring the diffraction efficiency was set in a direction corresponding to two exposures of the interference fringes, and the measurement was performed at different angles. The diffraction efficiency was about 75% to 80% in two cases. Although the diffraction efficiency is somewhat reduced by forming the interference fringes in a superimposed manner as compared with the case where the interference fringes are formed alone, it is considered that this can be improved by adjusting the thickness of the liquid crystal sample to be large. On the other hand, it had a transmittance of about 98% for ordinary rays, as in Embodiment 8-2.

[0412] As described above, the volume hologram element 521 could be manufactured by superimposing interference fringes. This is optical readout using multiple lasers with different wavelengths,
It is considered to be effective in an optical information processing device that performs recording.

As described above, in the present embodiment, the configuration of the diffractive optical element used in the optical information processing apparatus using the optical medium having the refractive index anisotropy and the method of manufacturing the same have been described.

As an optical medium having a refractive index anisotropy,
Lithium niobate, KD2 PO4, β-BaB2 O4,
It is also possible to use a uniaxial crystal having an electro-optical effect such as PLZT or the like, and to obtain an effect by using a medium having a refractive index anisotropy including a biaxial optical crystal such as KTi PO4. It is also possible to demonstrate.

It is needless to say that the apparatus can be used as a recording-only or read-only apparatus.

[0416]

As described above, according to the present invention, it is possible to provide a hologram element in which incident light can be switched between diffraction and straight traveling, and in which diffraction of an extraordinary ray obliquely incident upon straight traveling is extremely small. . In addition, an inexpensive and highly efficient polarization separation function can be realized by using the hologram element of the present invention, and a highly efficient image display can be configured using the function.

Further, by using the hologram element of the present invention, it is possible to switch between a bright image display with a narrow viewing angle but a bright image display and an image display with a low brightness from the front but a wide viewing angle as needed. Can be configured.

Further, by forming a pixel having a microcell structure of a photo-curable liquid crystal in the image display section, a wide viewing angle, high contrast, and uniform image display can be realized.

Note that the image display device according to the present invention can be variously modified based on the gist of the invention, and is not limited to the above configuration.

Further, according to the present invention, an inexpensive, compact, polarization-separating element having high separation efficiency can be constructed. Further, according to the projection type image display device configured using the polarization beam splitter according to the present invention, high light use efficiency can be realized.

The present invention also relates to a polarized light illuminating apparatus using a diffractive optical element having a three-dimensional layer structure as a polarization splitting element using an optical medium having a refractive index anisotropy, and a projection type display using the same. It concerns the device. By using an optical medium having a refractive index anisotropy, a specific polarization component is transmitted, and a polarization component orthogonal to the specific polarization component has selectivity according to a polarization direction such as diffraction. Furthermore, since it is formed from a three-dimensional layer structure, the diffraction efficiency in a specific direction is extremely high, and it is theoretically possible to achieve 100% diffraction efficiency.

Since a polarized light illuminating device is formed using a diffractive optical element having such excellent polarization separation and diffraction efficiency characteristics at the same time, an illuminating device having extremely high light use efficiency can be provided. . In addition, by using this to form a projection display device, a bright image can be obtained with low power consumption.

Further, as described above, it can be widely applied to displays and illumination optical systems, and has great value.

The present invention also relates to a diffractive optical element having a three-dimensional layer structure using an optical medium having refractive index anisotropy, and an image display device and an illuminating device constituted by combining this with a liquid crystal element. is there. By using an optical medium having a refractive index anisotropy, a specific polarization component is transmitted, and a polarization component orthogonal to the specific polarization component has selectivity according to a polarization direction such as diffraction. Furthermore, since it is formed from a three-dimensional layer structure, the diffraction efficiency in a specific direction is extremely high, and it is theoretically possible to achieve 100% diffraction efficiency. An image display device was constructed by combining a liquid crystal element and a diffractive optical element having such excellent polarization separation and diffraction efficiency characteristics at the same time.
Therefore, it is possible to realize a see-through display, a display that is used in combination with external light and an internal light source, and the like, which has high functionality, low power consumption, and compactness. If these image display devices are combined with a magnifying optical system, use as a microdisplay for a portable information terminal can be expected. Furthermore,
It is also possible to use an image display device and a lighting device together. As described above, it can be widely applied to displays and illumination optical systems, and has great value.

Further, the present invention relates to a configuration of a diffractive optical element having a three-dimensional layer structure using an optical medium having a refractive index anisotropy and a method of manufacturing the same. By using a medium, a specific polarization component is transmitted, and a polarization component perpendicular to the specific polarization component has selectivity depending on the polarization direction such as diffraction.

Further, since it is formed from a three-dimensional layer structure, the diffraction efficiency in a specific direction is extremely high, and it is theoretically possible to achieve a diffraction efficiency of 100%.

As described above, the polarization separation element in the illumination optical system such as a display or the like, as well as the optical information processing apparatus for writing and recording an optical signal, because it has excellent polarization separation and diffraction efficiency characteristics at the same time. It can be applied to a wide range of applications, etc., and has great value.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a conventional direct-view type liquid crystal display device.

2A is a diagram illustrating a configuration of a conventional optical switch and a refractive index of each region. FIG. 2B is a diagram illustrating a configuration of a conventional optical switch and a refractive index of each region.

3A is a diagram showing the function of a conventional optical switch with respect to oblique incident light and the refractive index of each region. FIG. 3B is a configuration diagram of a refractive index ellipsoid showing the refractive index anisotropy of a light beam obliquely incident.

FIG. 4 is a configuration diagram of a conventional polarization certifying device.

FIG. 5 is a configuration diagram of another conventional polarization proofing device.

FIG. 6 is a configuration diagram of a conventional projection type image display device.

FIG. 7 is a configuration diagram showing an integrator used in a conventional projection type image display device.

FIG. 8 is a configuration diagram showing a polarization conversion element used in a conventional projection image display device.

FIG. 9 is a configuration diagram of a conventional liquid crystal display device.

10A is a diagram showing the configuration of a hologram element configured in one embodiment, the arrangement of liquid crystal molecules, and the refractive index of each region. FIG. 10B is a diagram illustrating the configuration of a hologram element configured in one embodiment and liquid crystal molecules. Diagram showing the arrangement of and the refractive index of each region

FIG. 11 is a diagram illustrating functions of a hologram element configured in one embodiment with respect to a light beam obliquely incident thereon and a refractive index of each region.

12A is a diagram showing the configuration of a hologram element configured in another embodiment, the arrangement of liquid crystal molecules, and the refractive index of each region. FIG. 12B is a diagram illustrating the configuration of a hologram element configured in another embodiment. Diagram showing the arrangement of liquid crystal molecules and the refractive index of each region

FIG. 13 is a configuration diagram of a polarization separation element configured in one embodiment.

FIG. 14 is a plan view illustrating an alignment state of a liquid crystal in one process of the polarization beam splitter configured in one embodiment.

FIG. 15 is a schematic diagram illustrating an alignment state of a liquid crystal and an intensity distribution of an input interference image in one process of the polarization beam splitter configured in the embodiment.

FIG. 16 is a schematic view illustrating an alignment state of liquid crystal in a polarization separation element configured in one embodiment.

FIG. 17 is a diagram illustrating the efficiency of the polarization beam splitter configured in one embodiment;

FIG. 18 is a sectional view showing an example of the internal configuration of the diffractive optical element.

19A is a diagram illustrating an example of the angle and wavelength dependence of a diffractive optical element. FIG. 19B is a diagram illustrating an example of the angle and wavelength dependence of a diffractive optical element.

FIG. 20 is a configuration diagram of an embodiment of a polarized light illumination device using a diffractive optical element.

FIG. 21 is a configuration diagram of an embodiment of a polarized light illumination device using a diffractive optical element.

FIG. 22 is a configuration diagram of an embodiment of a polarized light illumination device using a diffractive optical element.

FIG. 23 is a configuration diagram of an embodiment of a polarized light illumination device using a diffractive optical element.

FIG. 24 is a configuration diagram of an embodiment of a polarized light illumination device using a diffractive optical element.

FIG. 25 is a configuration diagram of an embodiment of a projection display device using a diffractive optical element.

FIG. 26 is a configuration diagram of an embodiment of a polarized light illumination device using a diffractive optical element.

FIG. 27 is a configuration diagram of an image display device using a hologram element.

28A is a configuration diagram illustrating an embodiment of a transmission type color display type projection display device. FIG. 28B is a configuration diagram illustrating an embodiment of a transmission type color display type projection display device.

29A is a configuration diagram illustrating an embodiment of a reflection type color display type projection display device. FIG. 29B is a configuration diagram illustrating an embodiment of a transmission type color display type projection display device.

FIG. 30 is a configuration diagram of an embodiment of an image display device using a diffractive optical element.

FIG. 31 is a configuration diagram of another embodiment of an image display device using a diffractive optical element.

FIG. 32 is a configuration diagram of an embodiment of a reflection type image display device using a diffractive optical element.

FIG. 33 is a configuration diagram of an embodiment of a reflection type image display device using a diffractive optical element in combination with a backlight.

FIG. 34 is a configuration diagram of an embodiment of an image display device using a diffractive optical element.

FIG. 35 is a configuration diagram of an embodiment as an image display device and a lighting device using a diffractive optical element.

FIG. 36 is a configuration diagram of an embodiment of an image display device using a diffractive optical element.

FIG. 37 is a configuration diagram of an embodiment of a small-sized image display device using a diffractive optical element.

38A is a configuration diagram of an image display device having another configuration using a hologram element. FIG. 38B is a configuration diagram of an image display device having another configuration using a hologram device.

FIG. 39A is a configuration diagram of a hologram element used in an image display device of another embodiment. FIG. 39B is a configuration diagram of a hologram device used in an image display device of another embodiment.

FIG. 40 is a configuration diagram of an embodiment of an optical information processing apparatus using a diffractive optical element.

41A shows an example of refractive index modulation based on a refractive index ellipsoid of a uniaxial optical medium. FIG. 41B shows an example of refractive index modulation based on a refractive index ellipsoid of a uniaxial optical medium.

FIG. 42 is a diagram illustrating an optical system configured according to an embodiment of a method for manufacturing a diffractive optical element.

[Explanation of symbols]

 Reference numeral 405 Shutter 501 ITO 502 Glass substrate 503, 504 region 503a, 504a Liquid crystal molecule 504 region 504a Liquid crystal molecule 510 Polarization separation element 511, 512 Hologram element 512 Hologram element 513, 514 Glass substrate 515 UV curable liquid crystal 515a Liquid crystal molecule 515b Liquid crystal molecule 521 Hologram element 522 Optical medium 530 Polarization separation element 531 Total reflection mirror 532 Hologram element 533 Lamp 534 Reflector 540 Polarization conversion element 541 Integrator 542 Lens group 542a Lens 543 Lens group 543a Lens 544 Phase difference plate 545 Field lens 546 Image display Element 550 Polarization conversion element 551 Hologram element 552 Phase difference plate 560 Polarization conversion element 561,562 Hologram element 562 Hologram element 563 Phase difference plate 570 Polarization conversion element 571 Lens group 571a Lens 572,573 Hologram element 574 Phase difference plate 575 Field lens 576 Condensing lens 577 Image display element 578 Projection lens 579 Screen 590 Polarization conversion element 600 Projection type Image display device 601 Polarized illumination device 602 Projection lens 610 Color separation system element 611 Dichroic prism 612-614 Total reflection mirror 620 Color synthesis system element 621-623 Total reflection mirror 624-626 Image display element 625 Dichroic prism 627 Dichroic prism 628 Projection lens 629 Screen 630 Color composition system element 631-633 Polarizing beam splitter 634-636 Image display element 637 Dichroic Mirror 701 liquid crystal element 702, 703 hologram element 704 light source 704a lamp 704b reflector 710 external light 711 mirror 720 liquid crystal element 721 color filter 731 image display device 732 wall 733 vehicle 741,742 diffractive optical element 741 to 744 hologram element 745, 746 phase difference Plate 751 hologram element 752 diffractive optical element 753 plate 754 magnifying optical system 819 transmissive liquid crystal panel 820 hologram element 821 light guide 822 light flux 823 reflecting mirror 824 light flux 825 reflecting mirror 828 ordinary light 829 reflected light flux 901 semiconductor laser 902 photodetector 90 Imaging lens 905 Liquid crystal element 906 Optical storage medium 907 Observer 911 Laser 912 Shutter 913 Beam expander 915 Beam splitter 916 mirror

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[Procedure amendment]

[Submission date] December 28, 1998

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] Full text

[Correction method] Change

[Correction contents]

[Document Name] Statement

[ Title of the Invention] Image display device, polarized light illumination device, polarized light component
Separation element, diffractive optical element, hologram element,
For manufacturing diffractive optical element and hologram element

[Claims]

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a bright, high-quality
Image display device for displaying a screen, and the image display device
Optical element and hologram element used for
Is what you do.

More specifically , a polarization separation element that separates an incident light beam into different polarization components, and is configured using the same,

[0003] A polarized light illuminating device for obtaining uniform illuminating light with a uniform polarization direction , and a projection type image in which polarized light emitted from the polarized illuminating device is modulated by an image display element (light valve) to enlarge and display an image. The present invention relates to a display device .

[0004] Further, a monitor for displaying images, a display device for portable information terminals, a head-up display for in-vehicle use or personal use, and a reflective or transmissive image display used for road traffic signs or information display, etc. it relates to a device.

[0005] Further, it is used for an optical information processing apparatus including an optical head and an optical pickup for recording and reading information recorded on an optical storage medium such as an optical disk or a magneto-optical disk using a laser beam. It relates to a diffractive optical element.

[0006]

2. Description of the Related Art First, an outline of the prior art shown below will be described.
Will be explained. (Hologram element) Used for conventional optical switches, etc.
The hologram element will be described. (Application example of hologram element) Hologram as described above
Examples of devices used in direct-view type liquid crystal panels, etc.
Will be explained. (Image display device) Conventional general image display device, especially
The light from the light source lamp is reflected by an image display element such as a liquid crystal panel.
Projection type image that is modulated in brightness and enlarged and projected on the screen
The image display device will be described. (Integrator) Mainly in the center of the projected image
Is provided to equalize the brightness of the surrounding area.
The following describes the integrator. (Polarization conversion element) Improve the projection efficiency to produce bright images
About the polarization conversion element provided for displaying
explain. (Other configurations of the integrator and the polarization conversion element)
Of conventional integrators and polarization conversion elements
Will be described. (Image display principle of liquid crystal element)
Image of image display device using liquid crystal element to help grip
The display principle will be briefly described. (Optical information processing device using hologram element)
Hologram element used in optical information processing equipment
explain about. The details will be described below. (Hologram element) First, a conventional hologram element will be described.

In recent years, the interference fringes formed by allowed to interfere with coherent two beams, allowed recording the interference fringes like dichromated gelatin or a photopolymer, development of wavefront renewable hologram element of the recorded light beam Is thriving.

Examples of application fields of hologram elements include interference measurement, holographic optical elements, optical information processing such as pattern recognition, holographic displays, etc., as described in References, Toshihiro Kubota, “Introduction to Holography”. There is.

[0009] When the hologram element is applied to the field of image display, not only a three-dimensional image is displayed but also a hologram element is displayed.
Various applications are being considered.

In the following, examples used for (1) an optical switch and (2) a direct-view type liquid crystal panel will be described.

First, the optical switch will be described. For example, in Japanese Patent Application Laid-Open No. 5-173196 of Conventional Example 1, a mixture of a polymer material that cures at the wavelength of a light beam that forms interference fringes and a liquid crystal that is uncured at the wavelength of the light beam is dried.
By illuminating the interference fringes and forming a region composed of a cured polymer material and a region composed of a non-cured liquid crystal by so-called light-induced phase separation, and controlling the non-cured liquid crystal by an applied voltage, an incident light beam is formed. An optical switch for controlling the diffraction / straight traveling of the optical switch is disclosed.

A number of similar examples have been disclosed before, for example, Applied Physics Letter, No. 64.
Vol. 9, No. 107, pages 1074 to 1076, 1994 (hereinafter abbreviated as Conventional Example 2) discloses a hologram element capable of controlling diffraction efficiency.

[0013] According to this example, similarly to the conventional example 1, a polymer material which is cured by a particular wavelength, interference two light beams of wavelength to the mixture of the liquid crystal material does not cure in this particular wavelength
It is manufactured by illuminating the interference fringes and forming a polymer material in a portion where the light intensity of the interference fringes is high and a region where the liquid crystal material is abundant in a portion where the light intensity of the interference fringes is low.

A hologram element which is not switchable but is formed by using light-induced phase separation by two-beam interference exposure is disclosed in Japanese Patent Application No. 8-162647 (hereinafter, referred to as Japanese Patent Application No. 8-162647).
Conventional example 3), Japanese Patent Application Laid-Open No. 9-324259 (hereinafter abbreviated as Conventional Example 4 in Japanese Patent Application No. 8-142533).
And many other examples are disclosed.

The hologram element manufactured by using such a light-induced phase separation phenomenon is not limited to two-beam interference exposure, but may be formed, for example, on pages 86 to 87 of the Liquid Crystal Symposium on Disclosure '97 (hereinafter referred to as Conventional Example 5). As described in US Pat. No. 6,064,045, a mixture of an ultraviolet curable resin and a liquid crystal material is mixed at an appropriate ratio, and then the mixture is injected into a cell formed using a glass substrate on which a conductive transparent electrode is formed. It may be manufactured by irradiating ultraviolet rays through a patterned photomask.

In each of the above examples, regions having different refractive indices are formed using light-induced phase separation. This technique is described in, for example, Sharp Technical Report, No. 63, pp. 14-17, December 1995. As disclosed in the Moon (hereinafter abbreviated as Conventional Example 6), this is a known technique that is also used to fabricate a microcell structure for widening the viewing angle of a liquid crystal panel.

In this example, a mixture of a photo-curable resin and a liquid crystal is illuminated with lattice-like light (wavelength is a wavelength for curing the photo-curable resin), and each pixel is caused by a photo-induced phase separation phenomenon. Is formed. As a result, the liquid crystal molecules are aligned in an axially symmetrical shape stabilized by the photo-curing reaction by the self-alignment force in the liquid crystal region, thereby realizing a wide viewing angle and a high contrast.

(Application Example of Hologram Element) Next, an example of application to a backlight unit of a direct-view type liquid crystal panel 71 will be described with reference to FIG. The direct-view type liquid crystal panel is classified into a transmission type and a reflection type, and hereinafter, the transmission type will be described as an example. For example,
As disclosed in JP-A-9-178949 (hereinafter abbreviated as Conventional Example 7), the image display device of FIG. 1 includes a cold-cathode tube (hereinafter abbreviated as CCFT) as a light source.
The light from the light guide 73 is incident on the end face of the light guide 72 and the light guide 7
The hologram element 75 and the reflection mirror 74 formed on the rear surface side of the device 2 output the light to the transmission type liquid crystal panel 71 , and the hologram element 75 is a reflection type hologram.

According to the above configuration, it is possible to reduce the number of parts, reduce the weight, and reduce the cost, and at the same time, it can be used as a backlight unit having high brightness uniformity, high efficiency, and directivity. This function is a hologram element
This is realized by making 75 an aggregate of minute holograms. That is, the mosaic-shaped micro hologram is manufactured so as to exhibit the maximum diffraction efficiency at different incident wavelengths and incident angles.

In a similar configuration, for example, Japanese Patent Application Laid-Open No. Hei 9-127894 (hereinafter abbreviated as Conventional Example 8)
Discloses an example in which the uniformity of brightness is further improved by increasing the area density of the reflection type hologram as the distance from the light source increases.

In addition, for example, Proceedings of International Display Workshops '97, pages 411 to 414 (hereinafter abbreviated as Conventional Example 9), or JP-A-9-1383.
As disclosed in Japanese Patent Application Publication No. 96 (hereinafter abbreviated as Conventional Example 10), it is used as a reflector of a reflection type liquid crystal panel, and selectively transmits an incident light beam in a direction substantially perpendicular to the liquid crystal substrate.
In addition, an application is considered in which light is substantially reflected (diffraction) within a specific solid angle, and a bright image is displayed although the viewing angle is narrow. This hologram element is a so-called reflection type volume hologram.

In the conventional examples 7 to 10, a general photopolymer is used as a material, and the hologram element always performs the above-mentioned reflection.

(Image Display Apparatus) Next, the image display apparatus will be described.

In recent years, since it is difficult to increase the size of a conventional direct-view television, development of a projection- type image display device for enlarging and projecting an output image of an image display element that modulates an illumination light beam from a high-intensity lamp has been advanced. (For example, Oplusei, August 1993, pp. 58-101).

FIG . 6 shows a configuration of a conventional general projection type image display device, and shows a configuration example using a liquid crystal panel as an image display element . The output light 3 from the lamp 2 is reflected by the reflector 4, and the output light beam 5 is condensed and propagated by a condensing optical system (not shown), and is red, green, and blue by dichroic mirrors 12 and 13 for color separation. The light is separated into three primary colors and is incident on liquid crystal panels 16 to 18 via a total reflection mirror 14 and a condenser lens 15. The output lights modulated by the liquid crystal panels 16 to 18 are combined by a dichroic prism (not shown) for color synthesis or by dichroic mirrors 19 and 20 and a total reflection mirror 14 and are projected on a screen (not shown) by the projection lens 9. It is projected to be enlarged.

The liquid crystal panels 16 to 18 are mainly classified into a transmissive type and a reflective type, and each of the liquid crystal panels 16 to 18 converts a specific linearly polarized light incident through a polarizing plate or a polarizing beam splitter (hereinafter abbreviated as PBS). An image is displayed by modulating with a liquid crystal material.

The liquid crystal panels 16 to 18 generally use an active matrix system in which thin film transistors (hereinafter abbreviated as TFTs) are arranged in each pixel as switching elements for driving each pixel. It is generally formed of polysilicon.

As the lamp 2, a lamp having a high luminous efficiency, a small luminous body volume, a high luminance and a high color rendering property is required, and a metal halide lamp, a xenon lamp,
Ultra-high pressure mercury lamps and the like are used.

As the reflector 4, a parabolic mirror, an ellipsoidal mirror, a spherical mirror, or the like is used because the reflected light beam 5 can be effectively used effectively. Often located at the focal point or center. The current mainstream method is to use a parabolic mirror and install a light emitter of a lamp near the focal point to obtain a substantially parallel light flux.

[0030] In recent projection-type image display apparatus, when displaying the full white signal, (1) a uniform brightness of the brightness and the peripheral portion of the central portion of the projected image, the total is projected (2) Improving the projection efficiency (lumen / watt), which is defined as the luminous flux (lumen) divided by the lamp power consumption (watt), is the main task of development. For (1), the introduction of an integrator For (2), a solution is attempted by combining a polarization conversion element in addition to combining an integrator with a high-intensity lamp having a small luminous body.

(Integrator) First, the integrator will be described. The integrator is described in, for example, JP-A-3-111806 and JP-A-5-34655.
As disclosed in Japanese Patent Application Laid-Open No. 7-107, two types of fly-eye lenses configured by arranging micro lenses two-dimensionally are configured. FIG. 7 shows a specific configuration example of the integrator. By means of the reflector 44 and the first fly-eye lens 49, an image of the illuminator of the lamp 42 is formed on each lens of the second fly-eye lens 50 corresponding to each lens of the first fly-eye lens 49. Imaged. Each lens of the second fly-eye lens 50 displays the image of the first fly-eye lens 49 on the image display element 47.
It is configured to form an image on the top.

With the above arrangement, the second fly-eye lens 50
An image formed by each lens on the image display element 47 is obtained by finely dividing the output light having a large luminance distribution output from the reflector 44 by each lens of the first fly-eye lens 49,
The result of superimposing them on the image display element 47 is obtained. According to such a principle, it is possible to increase the brightness of the peripheral part with respect to the central part of the projected image to 70% or more.

Also, by introducing an integrator, the projection efficiency can be improved. Generally reflector 4
Light beam 45 reflected by 4 is substantially circular, the image table
The indicating element 47 is, for example, a 4: 3 rectangle. Hence the painting
When illuminating the image display element 47 in a circular shape, only the area ratio of the rectangle inscribed in the circle was effectively used. This is called rectangle conversion efficiency, and an image table with a 4: 3 rectangle as its outer shape
When the indicating element 47 is used, the rectangular conversion efficiency is about 61
%Met. However, the opening shape of the lens used for the first fly-eye lens 49 of the integrator is disclosed in
4: 3,459 as disclosed in FIG.
By arranging as, it is possible to increase to about 80%.

(Polarization Conversion Element) Next, the polarization conversion element will be described. The projection type image display device using the polarization display means such as the liquid crystal panel described above has a drawback that only the polarization component in a specific direction can be effectively used in the output light of the lamp, and the projection efficiency is low and the brightness is low. In order to obtain an image, there is a problem that a light source having a large output must be used. A polarization conversion element has been developed with the aim of solving these problems. A polarization component that is absorbed by a polarizing plate or a polarization component that is not incident on a liquid crystal panel with PBS is a polarization component that has a polarization plane that is substantially orthogonal to the polarization component. Is effectively converted to

The polarization conversion element is described, for example, in Japanese Patent Laid-Open No. 5-107.
505, JP-A-6-20294, JP-A-7-20
Although many publications are disclosed, such as Japanese Patent Application Laid-Open Nos. 294906, 8-234205, and 9-105936, they basically consist of a combination of a polarization splitting element and a polarization plane rotating element.

FIG. 8 shows a configuration diagram of a general polarization conversion element 58. Non-polarized light (randomly polarized light flux) 62 is converted into polarization components orthogonal to each other by the polarization separation element 60, that is, P-polarized light (a light flux having a polarization direction parallel to the sheet of paper that is transmitted without being reflected by the polarization separation element) 63, The light is separated into s-polarized light (a light beam reflected by the polarization separation means and having a polarization direction perpendicular to the paper surface) 64, and only the s-polarized light 64 is used as the reflection means 60 '(generally, a film of the same type as the polarization separation means 60 is used. ) And is converted by the polarization plane rotation element 61 into P-polarized light 63 ′.

In recent years, in many cases, the configuration described above is combined with the lens array 66, and the contents described in the above five publications can also be used in combination with the lens array 66. The configuration is slightly different.

One method is a method in which the width of a light beam incident on the polarization conversion element 58 is made approximately half by the lens array 66, and the light beam is incident only on the polarization separation element 60 to perform polarization separation and polarization plane rotation ( See FIG. 8 ). In this case, in many cases, the lens array 66 is configured as a fly-eye lens forming an integrator, thereby simultaneously ensuring the uniformity of the brightness of the projected image as described above. That is,
A configuration has been considered in which the lens array is used as a second fly-eye lens of the integrator.

On the other hand, as disclosed in JP-A-6-202094 and JP-A-8-234205,
An image is formed on the second fly-eye lens by installing a polarization splitting element on the lamp side of the first fly-eye lens and changing the exit angle of the light beam after the polarization separation by several degrees according to the polarization component. A method has been devised in which the position is changed for each polarization component, and only one of the polarization components rotates the plane of polarization. As an application of this method, a configuration in which a polarization splitting element is provided between the first fly-eye lens and the second fly-eye lens has been considered.

In a conventional polarization conversion element, a dielectric multilayer film formed by laminating a plurality of dielectric layers is mostly used as a polarization separation element. A hologram element having polarization selectivity as a polarization splitting element is conventionally known, but an example in which the hologram element is combined with an integrator to form a polarization conversion element and applied to an illumination optical system of a projection type image display device is disclosed. It has not been.

In the hologram element having polarization selectivity disclosed in Japanese Patent Application Laid-Open No. Hei 8-234143 and US Pat. No. 5,161,039, polarization selection is performed by using a liquid crystal polymer or a polysilane polymer material having a nonlinear light absorption effect. It has a function as a so-called volume hologram for each polarized light.

(Other than the integrator and the polarization conversion element)
In the use of a projector, there is a high demand for a bright projected image that can be recognized even when the room is not too dark, so it is important to improve the light use efficiency of the liquid crystal display element (liquid crystal light valve). . As an optical system for improving the uniformity of the illumination area, Japanese Patent Application Laid-Open Nos. Hei 3-11180 and Hei 5-346557 disclose an integrator optical system using two lens plates.

This is basically the same as that used in the exposure machine. The parallel light beam from the light source is divided by a plurality of rectangular lenses, and the image of each rectangular lens is applied to each rectangular lens.
This is to superimpose and form an image on a liquid crystal display element by a relay lens corresponding to one.

Japanese Patent Application Laid-Open No. 6-202094 proposes an illumination optical system in which a polarization conversion method is combined with an integrator illumination method. This schematic is shown in FIG. Light emitted from the light source 1101 enters a polarization splitting element using liquid crystal, and is split into a P-wave 1106 and an S-wave 1107. These lights are transmitted to the first lens group 11 constituting the integrator.
03 and the second lens group 1104, the second lens 110
4 are imaged at different positions of the phase plate 1105 arranged behind. In the phase plate 1105, a half-wave plate is periodically formed in approximately half the area of one lens forming the second lens group.

For this reason, for example, the P-wave 1106 imaged at the position of the half-wave plate is emitted as an S-wave with the polarization direction rotated by 90 °. The S wave 1107 is imaged in a region where the half-wave plate is not formed, and is transmitted as it is.
In other words, the light waves emitted from the phase plate 1105 have substantially the same polarization direction.

JP-A-7-294906 reports a polarization conversion element in which a lens plate and a prism are combined. This is shown schematically in FIG. This is because a light beam incident on a lens plate 1201 having an array of lenses formed thereon is focused on a light beam and is incident on a prism 1202. Where S
The wave 1204 passes through as it is, and the P wave 1205 is reflected by the prism, enters the adjacent prism, is reflected again, and
° Change the angle.

Then, the light passes through a half-wave plate placed in the optical path and is rotated as 90 degrees by the polarization direction and emitted as an S-wave. As described above, the lens plate 1201 and the prism 1202
The light wave emitted from the light beam becomes a light beam having a uniform polarization direction.

(Principle of Image Display of Liquid Crystal Element) Here, the principle of image display of the liquid crystal element will be described with reference to FIG. For example, a light source 9 such as a fluorescent lamp or a metal halide lamp
Light emitted from 01 is composed of a P-wave 902 having a polarization direction parallel to the paper surface and an S-wave having a polarization direction perpendicular to the paper surface. This light beam enters the polarizer 904, where a specific polarization component is absorbed and the remaining components are transmitted. The polarizer 904 is configured to absorb an S-wave component and transmit a P-wave. The light transmitted through the polarizer 904 is applied to the liquid crystal element 9.
05.

Here, as the liquid crystal element 905, a twisted nematic liquid crystal in which the directions of liquid crystal molecules are twisted by 90 ° between the entrance surface and the exit surface will be described as an example. A patterned transparent electrode is formed on the liquid crystal element 905, and an electric field can be applied to each pixel. The pixel (ON) to which an electric field enough to completely switch the liquid crystal is applied is in a state in which the liquid crystal molecule is untwisted and the liquid crystal molecule isotropically stands on the incident surface (homeotropic). Therefore, the P-wave incident on this pixel passes through the liquid crystal element while maintaining its polarization state without being modulated.

Next, a pixel (OF) to which no electric field is applied
In F), the liquid crystal molecules are in a state where the angle of the liquid crystal molecules is twisted by 90 ° in the thickness direction from the incident surface to the emission surface. For this reason, the P-wave component incident on the pixel rotates its polarization plane by 90 ° due to the twist nematic effect caused by the twist of the liquid crystal while passing from the entrance plane to the exit plane. Therefore, after passing through the OFF pixel, the previous light is S
It will be emitted as waves.

After passing through the liquid crystal element, the polarization direction of the light differs depending on the presence or absence of the electric field of the pixel corresponding to the passing position. Next, these lights are incident on the polarizer 906. Here, the polarizer 906 is set so that the axis direction passing the polarization component is inclined by 90 ° with respect to the polarizer 904 described above. That is, the polarizers 904 and 906 are arranged in crossed Nicols. Therefore, of the light that has passed through the liquid crystal element, the P-wave is absorbed by the polarizer 906, and the S-wave passes through the polarizer 906.

As described above, the light passing through each pixel of the liquid crystal element has its polarization direction modulated according to the electric field applied to the pixel, and as a result, the intensity of the light passing through the polarizer 906 differs. . The observer 907 gives the polarizer 90
Since the amount of light passing through 6 differs, an image as a light and dark pattern corresponding to each pixel is recognized.

Also, by controlling the amount of electric field applied to each pixel, the polarization direction of light passing through the liquid crystal can be set to an intermediate state between the P-wave and S-wave states. It becomes possible.

(Optical Information Processing Apparatus Using Hologram Element )
Location) Next, a description will be given of an optical information processing apparatus.

An optical information processing apparatus for recording and reading information stored in an optical storage medium such as an optical disk or a magneto-optical disk mainly includes a semiconductor laser as a light source and a light emitted from the semiconductor laser on an optical storage medium. And a hologram element as a diffractive optical element for guiding the laser light reflected on the optical storage medium to the light receiving element.

At one end, light emitted from the semiconductor laser passes through the hologram element and is focused on the surface of an optical disk as an optical storage medium by an imaging lens. The light that is reflected and spreads at the intensity according to the recorded information on the surface of the optical disk,
Once again converged by the lens, part returns to the semiconductor laser,
A part is divided in two directions by, for example, a hologram element divided into two regions, an image is formed on a light receiving element divided into several regions, and defocusing and tracking are performed using a technique such as a knife edge method. The detection of the displacement, the information signal, and the like are performed.

As described above, the light emitted from the laser passes through the hologram element as the diffractive optical element twice, on the outward path and the return path. If the light is strongly diffracted after passing through the hologram element on the outward path, the amount of light condensed on the surface of the optical disk will decrease, and sufficient light intensity will not be obtained on the disk, hindering accurate detection of signal information. May come. For this reason, usually, the hologram element is required to have a function in which the diffraction efficiency is different between the forward path and the return path.

Since a semiconductor laser as a light source has a polarization characteristic, selectivity of diffraction efficiency depending on a polarization direction is often used. More specifically, the light emitted from the semiconductor laser is transmitted as it is without diffracting the light in the direction of polarization, and thereafter, a quarter of the way in the optical path with the disk.
A phase plate such as a wave plate is arranged so that the direction of polarization is rotated by 90 ° compared to the initial stage when reflected by the disk and passed through the hologram again. At this time, the hologram element has a diffraction function, and the light passing through the hologram element is guided to a light receiving element for detecting an information signal or the like.

A hologram having such a polarization selectivity is produced using an optical medium having a refractive index anisotropy. For example, a mask is formed by photolithography or holographic exposure on a predetermined region of the surface of an optical medium having a refractive index anisotropy such as lithium niobate, and benzoic acid or the like is used on an exposed region of the surface. Perform ion exchange. Then, a refractive index distribution does not occur for a specific polarization direction, and the object can be handled as a uniform object.

However, for light in the polarization direction orthogonal to the above polarization direction, a refractive index distribution corresponding to the region formed by the mask is generated, and a diffraction phenomenon corresponding to this pattern is generated. An optical information processing apparatus is configured using a hologram element having such characteristics.

[0061]

All of the hologram elements disclosed in the above-mentioned conventional examples 1 to 6 are optically substantially isotropic light-curing type elements which do not always have refractive index anisotropy. And a liquid crystal material that does not cure at a wavelength that cures the photocurable polymer material (hereinafter abbreviated as non-polymerizable liquid crystal), which forms a fine region. Things. Therefore, for example, in the conventional example 1, even if a voltage is applied to the region of only the non-polymerizable liquid crystal so as not to cause diffraction, for example, a light beam obliquely incident acts as a hologram. There was a disadvantage. This situation will be described with reference to FIGS.

As shown in FIG. 2 (a), a conventional hologram element comprises a region 1 (having a refractive index of n1) made of a photocurable polymer material which is optically substantially isotropic, and a non-polymerizable liquid crystal. Region 2 (the liquid crystal molecules have refractive index anisotropy as shown in the figure, and the refractive indices for the ordinary ray and the extraordinary ray are no and n, respectively).
e).

Here, n1 and no are selected to be substantially equal. When a voltage is applied to the transparent conductive electrode 1 (hereinafter abbreviated as ITO) and the liquid crystal molecules in the region 2 are switched, the liquid crystal molecules are arranged substantially perpendicular to the glass substrate 2.

In this case, the vertically incident light beam is optically isotropic (region 1) with respect to the P-polarized light (polarized light component parallel to the paper) and the S-polarized light (polarized light perpendicular to the paper). ,
2 both have a refractive index of approximately no), so that the light beam goes straight without being diffracted.

When no voltage is applied to the region 2, FIG.
As shown in (b), the liquid crystal molecules are arranged substantially parallel to the glass substrate 2, and the region 2 has a refractive index anisotropy.

As a result, for example, the P-polarized light acts as a hologram element whose refractive index alternately changes to ne and n1, whereas for the S-polarized light, all regions have almost the same refractive index no. Acts as an isotropic medium. Therefore enter
P-polarized light is diffracted in the emitted light beam , and S-polarized light travels straight.

However, as shown in FIG. 3A, even in the mode in which the voltage is applied to the obliquely incident light beam to arrange the liquid crystal molecules vertically and make the incident light beam go straight, the region 2 Causes anisotropy of refractive index. That is, the refractive index no for ordinary rays (in this case, S-polarized light)
Although the light beam travels straight because it acts as an isotropic medium, the refractive index of the region 2 is n e for extraordinary rays (in this case, P-polarized light).
(Θ), and the incident light is diffracted as a hologram. Therefore, for example, when it is used as an optical switch, there is a disadvantage that complete control cannot be performed except for vertical incidence.

Actually, even if the region 1 is formed using a photocurable polymer material which does not originally have a refractive index anisotropy, if it is formed between glasses having a narrow gap, the refractive index is slightly reduced due to stress or the like. Develop anisotropy. However, the difference is small and the above-mentioned phenomenon appears essentially.

The slight refractive index anisotropy may cause a problem. For example, in the case of Conventional Example 6, when displaying black, the grid portion becomes a discontinuous region, which is particularly conspicuous when displaying a high-contrast image, and has the disadvantage of impairing uniformity.

The problems described in detail above are problems that always occur in a system in which a mixture of an optically isotropic photocurable polymer material and a liquid crystal material is used as a material to exhibit phase separation. is there.

On the other hand, there has been reported an example in which a liquid crystal polymer composite retardation film is produced using a mixture of an ultraviolet curable liquid crystal, which has recently attracted particular attention as a photocurable liquid crystal, and several types of non-polymerizable liquid crystals. (Eg, '97 Liquid Crystal Symposium Proceedings, pp. 168-169, 1997). However, in the above example, the entire surface is simply and uniformly irradiated with UV light, and only the entire surface is uniformly cured.
No mention is made of the formation of interference fringes due to light-induced phase separation by two-beam interference exposure, and the effect of the present invention that diffraction does not occur even for oblique incident light, which is expected from the configuration of the present invention.

In Japanese Patent Application Laid-Open Nos. 9-281330 and 9-288206, for example, a photocurable liquid crystal is injected into a cell in which a stripe-shaped ITO is formed, and a voltage is applied to align the liquid crystal molecules. The light-curing is performed in a state where is partially different to form a diffraction element.

However, in the above example, the liquid crystal material is formed using an essentially homogeneous liquid crystal material, and there is no disclosure regarding the use of a mixture with a non-polymerizable liquid crystal. Sex is equal, but not switchable and essentially different from the present invention.

In the case where the present invention is applied to a direct-view type liquid crystal panel disclosed in Conventional Examples 7 to 10, the hologram element always realizes the above-described functions. No example of changing the function is disclosed.

Further, in the conventional image display device, when the polarization splitting means is formed by using a dielectric multilayer film, since a plurality of thin film dielectric layers are laminated, it takes a long time to manufacture and has a disadvantage that the cost is high. there were.

Further, a plurality of prisms are laminated to each other, and a dielectric multilayer film is formed on a joint surface.
The polarizing beam splitters disclosed in Japanese Patent Application Laid-Open No. 294906 and Japanese Patent Application Laid-Open No. 9-105936 have problems such as difficulty in manufacturing, high cost, and heat resistance of the adhesive.

JP-A-5-107505, JP-A-8-107505
In JP-A-234205, a thick parallel flat plate or a rectangular prism is used, and it is difficult to make a compact configuration. Further, in JP-A-6-20294, it is difficult to manufacture a saw-tooth shape. As described above, the polarization separation element using the dielectric multilayer film has a disadvantage that the cost is high and the production is difficult.

The polarization splitting device using a hologram device having a polarization selectivity disclosed in Japanese Patent Application Laid-Open No. Hei 8-234143 and US Pat. No. 5,161,039 employs an illumination optical system in a projection type image display apparatus as described above. As a system, no application example as a polarization conversion element combined with an integrator is disclosed. Assuming that the conventional hologram element is incorporated in the polarization conversion element as a polarization separation element,
Even if it is applied to a projection type image display device, it is difficult to realize high efficiency for the following reasons.

For example, consider a case where a polarization splitting element is provided in front of the first fly-eye lens of the integrator. What enters the polarization separation element is a substantially parallel light beam. These light beams are, of course, unpolarized light. In this case, the difference between the emission angles of the two polarized light beams output from the polarized light separating element after the polarized light separation and whose polarization directions are orthogonal to each other is preferably at most several degrees. This is because two images of the illuminator of the lamp are formed on each micro lens of the second fly-eye lens corresponding to each micro lens of the first fly-eye lens. If this angle difference is too large, the diameter of each lens of the second fly-eye lens must be increased.

That is, as the polarization splitting element, it is necessary to separate substantially parallel light beams into different polarization components and then output each of them with an angle difference of several degrees. This means that the difference between the incident angles of the reference light and the object light at the time of manufacturing the hologram element must be as small as several degrees at most. However, in general, in order to increase the efficiency of the volume hologram sufficiently high enough to be usable, the difference between the incident angles of the reference beam and the object beam is required to be at least 20 degrees or more. Efficiency is reduced. Therefore, the first type of polarization conversion element cannot be formed by using the conventional hologram element as the polarization separation element.

As a diffraction element, for example, Japanese Patent Application Laid-Open
As disclosed in Japanese Unexamined Patent Publication (Kokai) No. 173196, examples using a normal nematic liquid crystal, or Japanese,
Journal, Ob, Applied, Physics, No. 36
Vol. 1997, pages 589-590 using UV curable liquid crystals, or as disclosed in Chemical, Materials 1993, Vol. 5, pp. 1533-1538. Is also known, but the one disclosed in the above publication only discloses that it has a polarization separation function, and does not disclose any application as a polarization conversion element.

As described above, when a polarization conversion element combined with an integrator is formed using a polarization separation element formed of a conventional dielectric multilayer film and applied to a projection type image display device, (1) And (3) there are problems such as high cost, (2) difficulty in manufacturing, and (3) difficulty in compact configuration.

In general, the hologram element is used as a polarization splitting element of a projection type image display device in combination with (2) an integrator because (1) efficiency is low unless a difference between an incident angle and an output angle is increased. It was difficult.

Further, in the conventional diffractive element, 1) it merely discloses that it has a polarization splitting function, 2) it does not disclose any combination with an integrator, and a projection type image display is performed. It is not applicable to the device.

Further, a polarization splitting element using liquid crystal has a configuration in which liquid crystal is sandwiched between a glass substrate and a prism substrate having sawtooth grooves. Since liquid crystals exhibit refractive index anisotropy, the difference in the refractive index differs depending on the polarization direction, such as ordinary light or extraordinary light.

The light wave incident on the polarization splitting element generates a phase distribution corresponding to the sawtooth shape, and functions as a phase type diffraction grating. Further, the refractive index difference when passing through the liquid crystal layer differs depending on the polarization direction. For this reason, since the phase distribution differs depending on the polarization direction of the incident light wave, the ordinary light and the extraordinary light, that is, the directions diffracted by the P wave and the S wave are emitted differently.

In order to separate the P wave and the S wave in the second lens array, a diffraction angle that can be separated is required. For this reason, it is necessary to reduce the sawtooth pitch of the polarization separation element to about several tens of μm. At this time, it is necessary to uniformly and strictly design the sawtooth inclination. This is because the inclination of the sawtooth shape corresponds to the blaze angle of the diffraction element, and this shape and uniformity affect the efficiency of the diffracted wave. That is,
If the sawtooth-shaped groove deviates from the design, a problem arises in that the diffracted wave is dispersed and the degree of separation by the polarization separation element is reduced.

If the width of the gap between the sawtooth-shaped grooves is increased, the pitch of the sawtooth-shaped groove can be increased and the processing can be facilitated. In this case, if the separation angle is maintained and used to the same extent as the original case, it is necessary to increase the cell gap of the liquid crystal. However, it is difficult to uniformly align the liquid crystal in a thick cell gap, and a phenomenon such as white turbidity occurs, which causes a new problem that the transmittance of the polarization separation element is reduced and the light use efficiency is reduced.

In a polarization beam splitting element using a prism, a light beam is incident on a prism array at every other stop by a lens plate. Since the prism has the function of a polarizing beam splitter, for example, the S wave is transmitted and the P wave is reflected at a right angle, and further reflected at a right angle by an adjacent prism, so that the light propagates in the same direction as the preceding S wave. After this, one placed in the optical path
The polarization direction is rotated by 90 ° by a / 2 wavelength plate, and the light is emitted as a P wave.

Since the above-described operation is performed for each prism, it is possible to obtain a light beam having a uniform polarization direction from the light wave incident on the lens plate without largely changing the width of the light beam. The prism has a cube shape filled with liquid or solid for refractive index matching with the dielectric multilayer film. In order to increase the degree of polarization separation, it is necessary to form a multi-layer dielectric multilayer film, which increases the manufacturing cost. Also, since the separation film bends the light propagation direction by 90 °,
It is arranged at 5 °. For this reason, the size of the separation element in the thickness direction is fixed by the size of the separation film constituting one prism, and there is a problem that the element cannot be made thin and small.

The present invention solves the above-mentioned problems of the prior art,
To provide a polarization illuminating device with high light use efficiency using a diffraction optical element having excellent polarization selection and high diffraction efficiency as a polarization splitting element, and to form a bright projection image by combining this polarization illuminating device and a projection optical system. Possible projection type drawing
It is an object to realize an image display device.

In recent years, the use of monitors for car navigation and portable displays for personal viewing of video and image information has been increasing. It is positioned as a low power consumption type display for portable information terminals such as mobile phones. Common conditions required for such a display include small size, light weight, thin shape, and low power consumption. In the head-up display, there is also a need to switch between the display screen and the outside world, and it is desirable that the screen is transparent, that is, a see-through screen.

At present, a display using a liquid crystal element is considered as a display suitable for the above requirements.
A liquid crystal display has a smaller depth area and can be made thinner than a conventional display such as a CRT. In addition, higher definition has been achieved by downsizing the pixel size, increasing the capacity, introducing TFT elements, etc., and the image quality has been further improved.

However, in general, the principle of image display of a display using a liquid crystal element modulates the polarization direction of incident light depending on the magnitude of an electric field applied to the liquid crystal element. By combining polarizers arranged in crossed Nicols before and after the liquid crystal element, image information such as light and dark is displayed by utilizing the difference in the transmittance of the polarizer depending on the polarization state of incident light.

In such a method, the light transmittance is not so high because the polarizer is of the absorption type. Furthermore, since the polarizers are combined in crossed Nicols, the light transmittance is almost nil in the state of only the combination of the polarizers, and the state is black. Therefore, it is difficult to obtain external information through the liquid crystal panel together with the image display, and there is a problem that it cannot be used as a see-through type head-up display.

Since the polarizer is configured to transmit only a specific polarization component by absorbing light, the light absorbed by the polarizer is internally converted into heat. When the amount of incident light increases, the influence of heat generation inside the polarizer cannot be ignored, and problems such as a decrease in the light modulation function of the polarizer and deterioration of the element occur.

Since the liquid crystal display is not a self-luminous type device such as a CRT, a dedicated light source is required for displaying images. Of the power consumption of the liquid crystal display, the ratio of the power used for the light source accounts for about half of the whole, which is a barrier to lowering the power consumption. For this reason, a method of displaying an image without using a dedicated light source for illumination has been studied. As a method for this, there is a reflection type image display device in which a liquid crystal element and a reflection plate are combined using external light such as natural light or indoor illumination light as a light source. According to this configuration, a dedicated light source is not required,
Low power consumption can be achieved.

In the above method, the display state of an image changes depending on the state of external light used as illumination light. For example, it is difficult to view image information in a room where nighttime illumination is dark or where illumination light cannot be used. For this reason, it is desirable to adopt a configuration that switches between a backlight as an internal light source and external light in accordance with a place where the external light is used, environmental conditions, and the like, and has both low power consumption and convenience in viewing image information. .

However, in order to use external light, it is suitable to adopt a reflection type configuration in which one polarizer is placed on the entire surface of the liquid crystal element. It is suitable to adopt a transmissive configuration in which polarizers are arranged in crossed Nicols before and after. In order to satisfy both of these methods simultaneously, it is conceivable to adopt a configuration using two polarizers. However, when an absorption type polarizer is used, the transmittance is low, and the reflection type image by external light is used. In display, the brightness of the screen is significantly reduced and the image quality is degraded. Therefore, there is a problem that it is difficult to use the internal light source and the external light in combination.

The present invention has solved the above-mentioned problems of the prior art,
An image display device is constructed by combining a diffractive optical element with excellent polarization selectivity and high diffraction efficiency with a liquid crystal element, enabling see-through display, and a low-light that can be used in combination with an internal light source backlight and external light. It is an object to provide a power consumption type image display device. Furthermore, by using a diffractive optical element as a transmission type having a modulation in the refractive index distribution,
The aim is to increase the efficiency of light utilization and achieve versatile application as an illumination device for illumination light simultaneously with image display.

On the other hand, when detecting a signal from an optical storage medium using a hologram element having polarization selectivity manufactured by ion exchange or the like, the signal detection is greatly affected by the diffraction efficiency of the hologram element. Specifically, the light is reflected by an optical disk or the like, is changed by a phase plate so that the polarization direction is orthogonal to the initial direction, and is incident on the hologram element.

At this time, if the diffraction efficiency of the hologram element is low, the intensity of light reaching the light receiving element is weak and noise increases, making it difficult to detect a signal accurately. Furthermore, since the component transmitted without being diffracted is irradiated to the semiconductor laser, which is the light source, instability of laser oscillation occurs due to an increase in the amount of light returning to the semiconductor laser. Come up.

To solve this problem, it is necessary to improve the polarization selectivity and diffraction efficiency of the hologram element. At present, as a form that can be used as a hologram element having polarization selectivity, there is a two-dimensional diffractive optical element type. This has a refractive index distribution corresponding to a rectangular lattice shape, and causes a phase difference of 0 and π for each adjacent lattice with respect to the wavelength of incident light. Light passing therethrough is diffracted as a result of being intensified in a specific direction corresponding to the spacing of the rectangular grating.

In such a hologram element composed of a rectangular lattice, a diffracted wave is generated symmetrically due to a two-dimensional binary shape. Therefore, the diffraction intensity 1
Even with ideal diffraction efficiency focused in the next direction, 40%
There is a problem that it is limited to the extent. Further, when the grating shape deviates from the design value, the intensity ratio of the diffracted light to higher orders other than the first-order light intensity including the zero-order light intensity increases. Therefore, not only is the required primary light intensity reduced, but the higher-order diffracted light acts as return light to the semiconductor laser, causing noise to the laser oscillation as described above. Problems arise.

The present invention has solved the above-mentioned problems of the prior art,
It is an object of the present invention to provide a diffractive optical element used for an optical information processing device having excellent polarization selectivity and high diffraction efficiency, and a highly reliable manufacturing method of the element.

[0106]

According to the present invention, there is provided a photocurable liquid crystal having a plurality of regions having different compositions of materials, wherein the plurality of regions are cured by at least a specific wavelength and have a refractive index anisotropy. And a second region composed of a non-curable liquid crystal (hereinafter abbreviated as a non-polymerizable liquid crystal) according to the wavelength, and a refractive index of the photo-curable liquid crystal to ordinary light after curing. And the refractive index for the extraordinary ray is substantially equal to the refractive index for the ordinary ray and the extraordinary ray of the non-polymerizable liquid crystal.

The present invention comprises at least plate-shaped first and second hologram elements having polarization anisotropy with respect to an incident light beam and selectively diffracting substantially only a first polarization component. An angle θ0 formed between the incident light beam incident on the first hologram element and the optical axis, an angle θ1 formed between the incident light beam and a first output light beam diffracted by the first hologram element and the optical axis; The angle θ2 formed by the output light beam and diffracted after being incident on the second hologram element and output from the second light beam satisfies the following expression: | θ1−θ2 |> 20 | θ0−θ2 | <15 It is characterized by the following.

The first and second hologram elements are disposed substantially parallel to each other and selectively diffract predetermined polarization components substantially equal to each other.
And the diffracted light beam diffracted by the first and second hologram elements and emitted from the second hologram element, and the diffracted light flux incident on the first hologram element, The angle between the transmitted luminous flux transmitted from the second hologram element and the transmitted light flux emitted from the second hologram element is greater than 0 ° and less than 15 °, and is incident on the first hologram element. In the light beam diffracted by the first and second hologram elements, the angle formed by the light beam incident on each hologram element and the light beam diffracted by each hologram element exceeds 20 °.

[0109]

(Embodiment 1) An example of a hologram element which is a polarization-selective diffractive optical element having a different diffraction effect depending on the polarization direction of incident light will be described.

As shown in FIG. 10, this hologram element is provided between two glass substrates 502 on each of which a conductive transparent electrode (hereinafter, referred to as “ITO”) 501 is formed. A region 503 including molecules 503a and a region 504 including, for example, non-polymerizable liquid crystal molecules 504a are formed. The UV-curable liquid crystal is a photocurable liquid crystal having a refractive index anisotropy, which is cured by a light beam having a specific wavelength. On the other hand, a non-polymerizable liquid crystal is a liquid crystal material that does not cure with respect to a light beam having a wavelength that cures the UV-curable liquid crystal.

Here, the expression relating to “optical anisotropy” is
It will be described. In general liquid crystal materials and optical materials having refractive index anisotropy as seen in uniaxial optical crystals, the refractive index for ordinary light and the refractive index for extraordinary light can be defined. The ordinary ray is polarized light whose refractive index does not depend on the incident angle of the ray, and the extraordinary ray is polarized light having a different refractive index depending on the incident angle. The refractive index of the extraordinary ray according to the incident angle is shown in FIG.
So-called refractive index ellipsoids (references: for example, Kudo,
(Uehara, “Basic Optics”, published by Hyundai Kogakusha, p. 202)
Can be obtained by Therefore, "optical anisotropy of each region with respect to the incident light beam" is simply abbreviated as "optical anisotropy of each region" unless otherwise specified, and the meaning is "with respect to the incident light beam of each region. Anisotropy of the refractive index for ordinary light and extraordinary light. " Also,
“The optical anisotropy of the region 503 and the region 504 is substantially equal”
Means that the refractive index for the incident ordinary ray and the refractive index for the extraordinary ray are substantially equal to each other in both regions. Similarly, the “region 503”
"The optical anisotropy of the region 504 differs from that of the region 504" means that "the refractive index for the incident ordinary ray is substantially equal in both regions, but the refractive index for the extraordinary ray is different in both regions." I do. The terms "optical anisotropy" and "refractive index anisotropy" are used in the same meaning.

In the state where no voltage is applied between the ITO 501, the hologram element has the liquid crystal molecules 50 in both the region 503 and the region 504 as shown in FIG.
3a and 504a are oriented in substantially the same direction (direction substantially parallel to the glass substrate 502), and the region 503 (after curing) and the region 5
04 have almost the same optical anisotropy. That is, the refractive indices for the ordinary ray are almost equal between the area 503 and the area 504 (the value is no), and the refractive indices for the extraordinary ray are almost equal (the value is n).
e). On the other hand, when a predetermined voltage is applied between the ITOs 501, as shown in FIG. 10B, only the liquid crystal molecules 504a in the region 504 are aligned (switched) in the direction of the lines of electric force, and the regions 503 and 504 Optical anisotropy
It is different .

The hologram element configured as described above functions as a hologram element for P-polarized light (extraordinary light) by applying a voltage between the ITOs 50, and changes the incident light flux to the pitch between the regions 503 and 504. And diffracted in a direction corresponding to the film thickness. That is, only the P-polarized light is selectively diffracted, and the S-polarized light (ordinary ray) goes straight (FIG. 10).
(B)). Thus, the selective diffraction of only P-polarized light is
The same applies to the case where the light beam enters the hologram element from an oblique direction. On the other hand, when no voltage is applied, both the P and S polarized lights go straight (FIG. 10A). Further, in the hologram element, when no voltage is applied, even when the light enters from an oblique direction, both the P and S polarized lights can be made to travel straight. That is, as shown in FIG. 11, when a light beam enters from an oblique direction, the refractive index for the ordinary ray is not equal to no in both the regions 503 and 504, and the refractive index for the extraordinary ray is also in the regions 503 and 50.
4 are equal in ne (θ), so that not only ordinary rays but also extraordinary rays can be made to travel straight without diffraction.

As described above, according to the above-mentioned hologram element, it is ensured that the ordinary light beam and the extraordinary ray can be made to go straight or the extraordinary ray alone can be selectively diffracted even with respect to the light beam incident from an oblique direction. Can be.

Next, a method of manufacturing the hologram element as described above will be described. This hologram element can be formed by so-called light-induced phase separation, for example, by irradiating interference fringes of two light beams.

(1) First, an alignment film (not shown) is applied to two glass substrates 502 on which ITO 501 has been formed, and an alignment process is performed.

(2) For example, beads of a predetermined diameter (not shown) are dispersed to secure a cell gap, and two glass substrates 502 are bonded together (instead of dispersing beads, use is made of silicon oxide or photopolymer). A column having a predetermined height may be formed.)

(3) For example, a liquid crystal material in which a non-polymerizable liquid crystal and a UV-curable liquid crystal are mixed at a weight ratio of, for example, 1: 1 is injected and sealed.

(4) Irradiation of interference fringes with a desired pitch by two-beam interference exposure,
The cured liquid crystal is cured, and most of the UV cured liquid crystal molecules in the mixed liquid crystal are gathered in the cured portion due to the photo-induced phase separation phenomenon, and good region separation is performed.

Here, in the above process (4),
If a two-beam interference exposure is performed with a voltage applied between the ITOs 501 and the liquid crystal molecules are oriented substantially perpendicular to the glass substrate 501, for example, as shown in FIG. The anisotropy is almost equal and both the P-polarized light and the S-polarized light in the incident light beam go straight, but when no voltage is applied, the optical anisotropy of each region becomes different, and only the P-polarized light is diffracted, A reverse mode hologram element in which polarized light travels straight can be manufactured.

As a method of driving the element, it is generally preferable to apply an AC voltage. However, when a non-polymerizable liquid crystal, for example, a ferroelectric liquid crystal is used, a pulse-like voltage is utilized by taking advantage of its memory property. May be applied.

Here, the difference between the hologram element of the present invention and the conventional hologram element will be described. For example, the above operation principle is basically the same as that of the conventional example 1. However, in the conventional example 1, only the photocurable polymer material is used for the region 1 , and the refractive index anisotropy is not changed. Not disclosed. On the other hand, in the hologram element of the present invention, the photocurable liquid crystal has a refractive index anisotropy, and ne after the curing.
, No is the same as the non-polymerizable liquid crystal in the region 504, and therefore, the incident angle characteristics can be improved. For example, consider a vertically incident light beam (see FIG. 2A).

In Conventional Example 1, since the region 1 made of a photocurable polymer material does not have a refractive index anisotropy, the refractive index is always a value n1 substantially equal to no of the liquid crystal. In the first conventional example, by controlling the liquid crystal molecules to have a configuration as shown in FIG. 2A , the incident light beam can travel straight without being diffracted.

However, as shown in FIG. 3 (a) , for a light beam obliquely incident, an ordinary ray (in this case, S-polarized light ) can travel straight, but an extraordinary ray (in this case, P
(Polarized light ), while the region 1 remains at the refractive index n1 ,
Since the refractive index of the region 2 is ne (θ), it is diffracted. As shown in FIG. 3B , the refractive index for an extraordinary ray can be obtained from a refractive index ellipsoid.

The above phenomenon is caused by, for example, Conventional Example 2 to Conventional Example 6
And the like, there is a problem common to all conventional devices in which the polymer material to be cured does not have essentially the refractive index anisotropy.

Although the conventional example 6 is not a hologram element, it does not disclose any refractive index between the photocurable polymer material and the non-polymerizable liquid crystal. In this case, the polymer material has a narrow gap. The problem is the slight anisotropy of the refractive index that occurs when formed inside.

(Embodiment 2-1) An example of a polarization splitting element constituted by using a hologram element will be described. This polarization separation element separates an incident light beam into, for example, S- and P-polarized light and emits them at slightly different emission angles.
For example, it is used for a polarization conversion element for obtaining a light beam having a uniform polarization direction.

As shown in FIG. 13, the polarization separation element 510 is formed by bonding a first hologram element 511 and a second hologram element 512 together. First
When a light flux α substantially parallel to the normal direction (Z-axis direction in the figure) of the hologram element 511 is incident, for example, an S-polarized component (a polarized component having a plane of polarization parallel to the X-axis shown in the figure) is diffracted. For example, the light is emitted at an emission angle of 45 ° (an angle between the Z axis and the traveling direction of the incident light with respect to the substrate normal, that is, the Z axis), and is incident on the second hologram element 512 at an incident angle of 45 °. It has become. On the other hand, a P-polarized light component (a polarized light component having a plane of polarization parallel to the Y-axis) is transmitted through the first hologram element 511 as it is.

The S-polarized light that has entered the second hologram element 512 at the incident angle of 45 ° is diffracted by the second hologram element 512 and is emitted at an emission angle of, for example, -7 °, while P The polarized light is applied to the first hologram element 5
As in the case of 11, the light is transmitted parallel to the Z axis.
That is, in the polarization separation element 510, the P-polarized light
The polarized light can be separated and output at a difference of 7 ° in the traveling direction.

As the hologram elements 511 and 512, for example, the hologram elements of the first embodiment can be used.
The above operation can be performed by applying a predetermined voltage to O. Also, a hologram element that performs the above-described diffraction without applying a voltage may be used. Such a hologram element can be manufactured, for example, as follows.

(1) A conductive transparent electrode (for example, ITO: not shown) is formed on a pair of glass substrates 513 and 514 .

(2) An alignment film (not shown) is applied on each conductive transparent electrode, and a rubbing process is performed.

(3) Disperse spherical beads (not shown) having a desired diameter on the conductive transparent electrode.

(4) A sealing material (not shown) is applied to the periphery of the glass substrate 513.

(5) The glass substrates 513 and 514 are bonded together, and the sealing material is cured by heat treatment.

(6) For example, a UV curable liquid crystal 515 is injected as a hologram material from an injection port (not shown).

(7) The UV curable liquid crystal 515 is exposed by a two-beam interference optical system using a UV laser beam to form a predetermined interference fringe described later.

(8) UV light is again irradiated while applying a predetermined voltage between the conductive transparent electrodes.

Note that such a method of manufacturing a cell is a known technique in the field of optics, and the hologram is itself manufactured by a two-beam interference optical system by dividing a coherent laser beam into two parts and forming the hologram at a predetermined angle. This is a known technique for forming interference fringes in a predetermined direction and pitch by irradiation.

Next, the principle of forming a hologram element having polarization selectivity by the above-described manufacturing method will be described. The UV-curable liquid crystal is a liquid crystal that is cured by irradiating UV light, for example, light having a wavelength near 360 nanometers. Due to the rubbing treatment of the above (2), in the state before the UV exposure after the injection of the (6) and (7), the molecules 515a of the liquid crystal are oriented in a direction substantially rubbed as schematically shown in FIG. ing.

In this state, when the UV-curable liquid crystal 515 is irradiated with interference fringes formed by the two-beam interference optical system as described later, the UV-curable liquid crystal 515 is cured according to the light intensity of the interference fringes . Specifically, for example, as schematically shown in FIG. 15, interference having a light intensity distribution in the Y-axis direction in FIG.
When the stripes are formed, only the liquid crystal molecules 515b in the high-strength portion are hardened.

Thereafter, when a voltage is applied between the conductive transparent electrodes, as shown in FIG. 16, only the liquid crystal molecules 515a in the portion where the light intensity of the interference fringes is low are aligned (switched) in the direction of the electric force lines. When the entire surface is irradiated with UV light again in this state, the hologram element maintains the alignment state of the liquid crystal molecules as shown in FIG. 16 even when the application of the voltage is stopped. That is, a region where the liquid crystal is switched and a region where the liquid crystal is not switched are formed at a minute pitch of the interference fringes . Therefore, since the liquid crystal molecules have optically uniaxial refractive index anisotropy, in the example of FIG. 16, the liquid crystal molecules act as a phase type diffraction element with respect to the polarized light component oscillating in the X-axis direction. On the other hand, it functions as a diffractive element having polarization anisotropy that outputs a polarized component vibrating in the Y-axis direction without diffracting as an isotropic element.

In the present embodiment 2-1 , specifically, each of hologram elements 511, 5
No. 12 was produced.

Tilt angle of interference fringes of first hologram element: 22.5 ° Pitch of interference fringes of first hologram element: 0.757 μ
m Thickness of the first hologram element: 9 μm Inclination angle of interference fringes of the second hologram element: 19 ° Pitch of interference fringes of the second hologram element: 0.651 μ
m Thickness of the second hologram element: 9 μm Average refractive index of liquid crystal: 1.593 Change in refractive index: 0.083 FIG. 17 shows the diffraction efficiency for S-polarized light of the polarization separation element 510 manufactured as described above.
Shown in The horizontal axis is the angle of incidence on the first hologram element 511. As shown in the figure, a high polarization separation characteristic of 90% or more was realized in the range of ± 2 °.

When a UV-curable liquid crystal that can be oriented by a magnetic field is used as the liquid crystal material, the glass substrate 513,
There is no need to form a conductive transparent electrode on the surface of 514,
In the process (8), a magnetic field may be applied instead of applying an electric field.

In addition, a hologram element may be manufactured by photo-induced phase separation using a mixture of a photopolymer and a liquid crystal polymer having sensitivity to a specific wavelength region as a hologram material .

Further, in the present embodiment 2-1 , the optical axis defined as the normal line of the glass substrates 513 and 514 almost coincides with the incident light beam, but it is not always necessary that they coincide.

As the hologram element used for the above-mentioned polarization splitting element, for example, the one shown in FIG. 18 can be used. The hologram element 521 is formed using an optical medium 522 having a refractive index anisotropy such as a liquid crystal and has a thickness of about 10 μm.
The refractive index distribution is periodically distributed also in the thickness direction. For this reason, the diffractive action differs depending on the polarization direction, and the diffractive action has a characteristic of exhibiting high diffraction efficiency in one direction.

Hereinafter, the hologram element 521 will be described in detail.

The inside of the element has a layer structure in which a layer inclined with respect to the thickness direction is periodically formed from the surface on which light enters. In the layers adjacent to each other, one is arranged so that the inclination of the optical axis of the optical medium 522 having the refractive index anisotropy is parallel to the surface of the hologram element 521, and the other is arranged in the direction perpendicular to the surface. doing.

Optical medium 522 having the above-mentioned refractive index anisotropy
Is incident on the optical medium 522, the polarization direction of the light is
When the light beam is parallel to the optical axis, the beam becomes an extraordinary ray, and the refractive index indicates the value of Ne. Further, the polarization direction is changed to the optical medium 522.
When the light is perpendicular to the optical axis, the ray becomes an ordinary ray, and shows a refractive index of No. Here, Ne> No.

Next, the hologram element 521 shown in FIG.
The behavior when these lights are incident on the hologram element 521 with light having a polarization direction perpendicular to the paper as an ordinary ray and light having a polarization direction parallel to the paper as an extraordinary ray will be described. .

First, when an ordinary ray is incident, its polarization direction is perpendicular to the optical axis of any optical medium 522 constituting each layer. For this reason, the refractive index of each layer is No, regardless of the direction of the optical axis between the layers. That is, since a medium having a uniform refractive index is equal to that of a medium having no refractive index, an ordinary ray incident on the medium is not affected by diffraction, and is transmitted as it is, as shown in FIG.

On the other hand, when an extraordinary ray is incident, in the layer where the optical axis of the optical medium 522 having the refractive index anisotropy is arranged parallel to the incident surface, the polarization direction of the incident light is aligned with the optical axis. Be parallel. This corresponds to the case where the light passes through a layer having a refractive index of Ne. Also, for a layer in which the optical axis of the optical medium 522 is perpendicular to the incident surface of the hologram element 521, this layer corresponds to the case where the polarization direction is perpendicular to the optical axis, and this layer has a refractive index of No. Works with things. Therefore, for an extraordinary ray, the hologram element 521
In the thickness direction, which is the traveling direction of the incident light, the light passes through a plurality of layers having different refractive indexes periodically. As a result, the incident light beam is subjected to a so-called Bragg diffraction effect in which the light is condensed in a specific direction corresponding to the inclination angle of the layer and the pitch of the period. Therefore, as shown in the figure, after passing through the hologram element 521, the extraordinary ray changes the optical path corresponding to the layer structure formed inside the element.

That is, by having a periodic structure in the thickness direction as described above, the Bragg diffraction condition is applied. This is because when light having a certain wavelength enters each layer forming the periodic structure, the light scattered in each layer causes a phenomenon in which the scattered component strengthens in a specific direction corresponding to the wavelength and the incident angle and the pitch between the layers. . This is called Bragg's diffraction condition, and such a condition is three times larger than that of a conventional two-dimensional diffractive optical element.
It has a dimensional configuration and has the effect of blazing (focusing light in one direction).

Therefore, the diffraction efficiency can be greatly improved as compared with the conventional diffractive optical element, and theoretically, an efficiency of 100% is possible. In practice, an efficiency of 90% or more can be expected even when taking into account the loss on the way. On the other hand, in a binary two-dimensional diffractive optical element, the diffracted wave is diffracted to the higher order symmetrically, including the 0th order, so that the diffraction efficiency in the primary order is at most about 40%. Which is a low value as a percentage of the total amount of light passing through the element.

FIG. 19 shows the calculation result of the theoretical diffraction efficiency of the hologram element 521 by "Bell System Technology".
Jay "(H. Kogelnik, (Bell Sys
t. Tech. J. , 48,1969, pp. 290
9-2947)). The diffraction efficiency is the ratio of the amount of light diffracted in the primary direction to the total amount of incident light. Table 1 summarizes various parameters of the diffractive optical element.

[Table 1]

In FIG. 19, (a) shows the change in the diffraction efficiency when the incident angle deviates from the Bragg angle, that is, the dependence of the diffraction efficiency on the incident angle, and (b) shows the case where the incident wavelength deviates from the design value. , Ie, the dependence of the diffraction efficiency on the incident wavelength.

The angle dependence in FIG. 19A corresponds to the efficiency when the light beam incident on the hologram element 521 deviates from the parallel light (when the incident angle deviates from a predetermined angle). The incident wavelength dependency of b) corresponds to the study of the efficiency at the time of illumination by a white light source. As shown in the figure, it is expected that a theoretical diffraction efficiency of 1, that is, a high diffraction efficiency of nearly 100% can be obtained by appropriately setting various parameters. According to the figure, the characteristic is flat with respect to the wavelength around ± 100 nm, and high efficiency can be expected for white light.

In FIG. 18, the hologram element 521
The optical axis of the optical medium 522 constituting
Although the case where the refractive index difference is the largest by tilting by 0 ° is shown, the refractive index difference can be changed from Ne to No by setting this angle arbitrarily.
Can also be set to an intermediate value. Further, it is also possible to adjust the diffraction efficiency by selecting a refractive index distribution using this.

It is also possible to divide the area of the hologram element 521 into several parts and shift the directions of diffraction respectively.

Further, R: red (0.6
G: green (0.55 μm), B: blue (0.45 μm)
μm), a layer having a different periodic structure, an angle, and the like is formed according to each of the center wavelengths, and these layers are laminated to form a hologram element 521, or a hologram element is formed by superposing these structures. By recording information in the area 521, a configuration in which the influence of chromatic dispersion or angle dependence is reduced is also possible.

Next, a method of manufacturing the hologram element 521 will be described.

First, for example, ITO is formed as a transparent conductive electrode on each of a pair of glass substrates.

Next, these substrates are washed to remove adhering dust, and then an alignment film made of a polymer, for example, a polyimide is applied by a spin coating method or the like, and the alignment is performed by performing a heat treatment or the like. A film is formed on a substrate.

Thereafter, the alignment film is subjected to a rubbing treatment in a specific direction using a roller or the like, and then a seal is printed around one substrate, and the other substrate is coated with a diameter of 5 μm to 20 μm.
Disperse beads of about μm. The two substrates are bonded together so that the rubbing directions are paired with each other to form an empty cell.

As the optical medium 522 having the refractive index anisotropy, for example, a liquid crystal having a positive dielectric anisotropy is injected into the empty cell. Note that a liquid crystal having a negative dielectric anisotropy can be used. More specifically, the liquid crystal contains, for example, a photopolymerizable liquid crystal monomer or a photocrosslinkable liquid crystal polymer. The liquid crystal is cured by irradiation with light having a wavelength in the ultraviolet region of about 360 nm, and the direction of the liquid crystal molecules is fixed. Use the one with the characteristics specified. The above-described implantation can be performed at room temperature in an air atmosphere, but may be performed at a high temperature of about 40 ° C. to 60 ° C. or in a vacuum.

The liquid crystal sample is completed by sealing the vicinity of the injection port and the degassing port of the cell after injecting the liquid crystal with a sealant.

The liquid crystal sample produced as described above is exposed to interference fringes.

First, with the shutter for adjusting the exposure time closed and without light irradiation, the liquid crystal sample is placed at the optical system fabrication position (the predetermined position of the exposure apparatus), and the shutter is operated for a predetermined time. For example, by opening for about one minute and then closing, exposure using interference fringes is performed as a first exposure step.

As a light source for forming the interference fringes, for example, an A light having an irradiation intensity of about 50 mW to 100 mW is used.
360n wavelength output from r (argon) laser
m or so. The laser light is emitted by a beam expander or the like, for example, with a diameter of 30 mm to
After expanding the beam into a beam of about 50 mm, the beam is split in two directions by a beam splitter or the like, interference fringes are formed through an optical path set by combining a mirror or the like, and the liquid crystal sample is irradiated. The interference fringes are adjusted to, for example, about 1 μm pitch at the position where the liquid crystal sample is arranged by adjusting the mirror and the like.

By the above-mentioned exposure, the liquid crystal in the liquid crystal sample was hardened in the region of the bright portion where the light intensity was high in the interference fringes formed by the interference of two laser beams, and the liquid crystal molecules were initially aligned by the alignment film. The molecular axis is fixed in the direction. That is, for example, when using a liquid crystal having a positive dielectric anisotropy as described above, initially the liquid crystal molecules are uniformly oriented in a direction parallel to the glass substrate, and in the bright region of the interference fringes, This state will be saved. On the other hand, since the light intensity is lower in the dark area of the interference fringes than in the bright area, the liquid crystal molecules hardly harden in this first exposure step.

Next, as a second exposure step, first, an AC electric field of about 5 (V / μm) was applied between ITO electrodes as transparent conductive electrodes formed inside the two glass substrates of the liquid crystal sample. Apply. Due to the application of the electric field, the uncured liquid crystal molecules in the dark portions of the interference fringes are tilted in a direction perpendicular to the glass substrate. The angle of inclination at this time is
Since the magnitude of the electric field is adjusted because it is proportional to the applied electric field, a desired inclination angle, that is, a difference in refractive index can be provided.

In the state where the voltage is applied as described above, for example, one of the laser beams split by the beam splitter is blocked, so that light having a uniform intensity distribution without interference fringes is formed on the entire surface of the liquid crystal sample. For example, irradiation is performed for about 5 minutes to completely cure the entire uncured dark area.

The hologram element 521 having the structure shown in FIG. 18 is manufactured by performing the first exposure step and the second exposure step as described above.

In this case, a cell is manufactured using a glass substrate on which a transparent electrode such as ITO is formed, and the direction of liquid crystal molecules is changed from an initial position by applying an electric field in the second exposure step. Was explained. As another method, the hologram element 521 can be manufactured by performing the second exposure step by changing the direction of liquid crystal molecules by applying a magnetic field without using a transparent electrode.

Further, the polarization direction of the irradiated Ar laser is set to, for example, 90 ° in the first exposure step and the second exposure step.
A method of setting and exposing differently is also conceivable. When a polymer film such as an alignment film is irradiated with linearly polarized light as a light source, molecules whose main chains (or side chains) are oriented mainly in the direction of polarization from randomly oriented polymers mainly emit light. Absorption causes a photoreaction, and the film exhibits optical anisotropy. In a polymer material or the like, the photoreaction process (photoisomerization, photopolymerization, photodecomposition) of the polymer can be controlled by the polarization direction of the irradiated light and the angle formed by the polymer.

Therefore, by controlling the polarization direction of the light in the ultraviolet region constituting the interference fringes, the initial alignment state of the liquid crystal can be set, and the movement of the liquid crystal molecules in the first and second exposure steps can be controlled. It is also possible to do.

When the diffraction efficiency of the device fabricated as described above was measured using a He—Ne laser while changing the incident polarization direction, the transmittance for ordinary light was 98%.
It was before and after, and had high transmittance. Further, the diffraction efficiency in the primary direction with respect to the extraordinary ray was about 90%, and good results were obtained. Therefore, it was confirmed that the diffractive optical element manufactured here had high polarization separation characteristics and diffraction efficiency.

As the optical medium having the refractive index anisotropy, in addition to the liquid crystal, lithium niobate, KD ₂ PO ₄ ,
It is also possible to use a uniaxial crystal having an electro-optic effect or the like such as β-BaB ₂ O ₄ or PLZT.
The same effect can be obtained by using a medium having various refractive index anisotropies including a biaxial optical crystal such as iPO ₄ .

(Embodiment 2-2) Another example of the polarization beam splitting element formed by using the hologram element will be described.

As shown in FIG. 20, in this polarization separation element 530, a hologram element 532 similar to that shown in the first or second embodiment is provided on the surface of a total reflection mirror 531. ing. Here, Embodiment 1
Is used in a state where a predetermined voltage is applied between ITO.

The total reflection mirror 531 and the hologram element 532 are arranged such that the normal line forms an angle of 45 ° with the optical axis of the reflector 534 that reflects the light from the lamp 533 of the light source.

In the hologram element 532, light having a polarization direction in a direction perpendicular to the plane of the drawing (referred to as S-polarized light) becomes an ordinary ray, and light having a polarization direction in a direction parallel to the plane of the drawing (P-polarized light). (Hereinafter referred to as light) is arranged as an extraordinary ray. The hologram element 532 has 45
The extraordinary ray incident at an incident angle of ° is set to be diffracted and emitted so as to have an exit angle slightly larger than 45 °.

With such a configuration, the s-polarized light, which is an ordinary ray with respect to the hologram element 532,
As described in each of the embodiments 1-1 and the like, it is not affected by the refractive index distribution composed of the periodic structure of the element, and exhibits the same characteristics as when passing through a medium having an isotropic uniform refractive index. . Therefore, the S-polarized light passes through the hologram element 532 as it is, is reflected by the total reflection mirror 531, passes through the hologram element 532 again, and exits. That is, the traveling direction of the S-polarized light is bent by 90 ° by the total reflection mirror 531 and emitted.

On the other hand, the P-polarized light that is an extraordinary ray with respect to the hologram element 532 is modulated by the refractive index distribution of the periodic structure formed in the hologram element 532 and diffracted.
As described above, light is emitted at an emission angle slightly larger than 45 °.

Therefore, the light emitted from the lamp 533 via the reflector 534 is
With 0, it is possible to separate out the emitted light whose traveling direction is slightly different between the S-polarized light and the P-polarized light.

(Embodiment 3-1) Embodiment 2
An example of a polarization conversion element configured using two polarization separation elements will be described. This polarization conversion element outputs light having a random polarization direction from a light source to polarized light in a predetermined direction, and is used, for example, in a polarized light illumination device such as a polarization type liquid crystal display device.

FIG. 21 is an explanatory view showing the structure of a polarized light illuminating device including a polarization conversion element 540.

As the lamp 533, a fluorescent lamp, a xenon lamp, a metal halide lamp, a mercury lamp, an L
An ED, an FED, a laser beam, an inorganic or organic EL element, or the like is used. The light from the lamp 533 is reflected by the reflector 53
The light 4 is converted into substantially parallel light and emitted. This substantially parallel light enters the polarization separation element 530 and is separated so that the traveling directions are slightly different between the S polarization light and the P polarization light as described in Embodiment 2-2. Emit.

The S-polarized light and the P-polarized light emitted from the polarization splitting element 530 enter the respective lenses 542a of the first lens group (first fly-eye lens) 542 constituting the integrator 541, and In accordance with the angle of incidence, light is condensed on predetermined regions different from each other in each lens 543a of the second lens group (second fly-eye lens) 543 paired with each lens 542a .

The predetermined region where the S-polarized light and the P-polarized light are converged is set to, for example, a region that roughly divides each lens 543a into two, and each of the lenses 543a in the region where the P-polarized light is condensed. Back side (light traveling direction side)
Is provided with a phase difference plate 544 that is a half-wave plate periodically. Therefore, the S-polarized light incident on the second lens group 543 is emitted as it is as S-polarized light,
The polarization direction of the polarized light is rotated by 90 ° via the phase difference plate 544, and the polarized light is converted into S-polarized light and emitted. That is, any polarized light is emitted while being aligned with the S-polarized light.

The S-polarized light is condensed by the condenser lens 545 and
The light is incident on the image display element (light valve) 547 as a substantially parallel light beam via the field lens 546, and is used for image display.

When the amount of light incident on the image display element 547 was compared between the case where the hologram element 532 and the phase difference plate 544 were used and the case where the phase difference plate 544 was not used, the polarization was determined by the hologram element 532 and the phase difference plate 544. When the conversion was performed, the light use efficiency was improved by about 1.2 to 1.6 times, and it was confirmed that the function of the polarization conversion element 540 using the hologram element 532 was excellent.

(Embodiment 3-2) Embodiment 3
An example of the polarization conversion element that arranges the polarization direction by providing the polarization splitting element described in 1 in the optical path between the first lens group and the second lens group forming the integrator will be described. In Embodiment 3-2 and the like, Embodiment 3
Constituent elements having the same function as -1 and the like are denoted by the same reference numerals as appropriate, and detailed description is omitted.

FIG. 22 is an explanatory view showing the configuration of a polarized light illuminating device including a polarization conversion element 548 .

The substantially parallel light from the reflector 534 is incident on the polarization separation element 530 via the first lens group 542 constituting the integrator 541. The luminous flux incident on the polarization splitting element 530 is described in Embodiment 2-2.
As described above, the light is separated so that the traveling direction is slightly different between the S-polarized light and the P-polarized light, and the light is emitted from the polarization splitter 530.

The S-polarized light and the P-polarized light emitted from the polarization splitting element 530 are located on the back side of each lens 543a of the second lens group (second fly-eye lens) 543 constituting the integrator 541. Light is condensed on a region where the retardation plate 544 is provided or a region where it is not provided. Therefore, similarly to the above-mentioned Embodiment 3-1, while the S-polarized light is emitted as it is as the S-polarized light, the P-polarized light is rotated by 90 ° through the retardation plate 544, and is converted into the S-polarized light. It is converted and emitted. That is, any polarized light is emitted while being aligned with the S-polarized light.

The polarization conversion element 548 thus configured
Accordingly, the light use efficiency can be improved as in the case of the embodiment 3-1.

(Embodiment 3-3) An example of another polarization conversion element using a hologram element similar to that shown in the embodiment 1 or 2-1 will be described.

FIG. 23 is an explanatory view showing the configuration of a polarized light illuminating device including a polarization conversion element 550. The polarization conversion element 550 of this polarization illuminating device is a quarter-wave plate between the hologram element 551 and the total reflection mirror 531 similar to those described in the first or second embodiment. A phase difference plate 551 is provided.

The light wave including the P-polarized light and the S-polarized light from the lamp 533 is incident on the hologram element 551, and the P-polarized light is applied to the refractive index distribution of the diffractive optical element as described in the first embodiment. The light is diffracted accordingly, and the light is emitted with its course bent in the direction indicated by the one-dot chain line in FIG.

On the other hand, the S-polarized light is
Is transmitted as it is, reflected by the total reflection mirror 531 via the phase difference plate 552, and changes its polarization direction by 90 ° in the process of passing through the phase plate 552 again, and is incident on the hologram element 551 as P-polarized light. Will do. At this time, the incident direction is the total reflection mirror 531 and the reflector 53
4, which is determined by the hologram element 55.
The hologram element 551 transmits the incident light without reflecting it so that the condition is deviated from Bragg's diffraction condition for the periodic structure formed inside 1. That is, as described with respect to the angle dependence of the diffraction efficiency in FIG. 19A, when the angle of incidence on the hologram element deviates to a certain degree from the predetermined angle, the efficiency becomes almost zero, and the diffraction effect does not occur and only the light is transmitted. In some cases, the predetermined angle can be set according to the conditions for forming the diffractive optical element. Therefore, the total reflection mirror 53
1 and converted into P-polarized light by the phase difference plate 552, the hologram element 55 is not diffracted.
1 can be transmitted as it is .

As described above, the P-polarized light of the light wave from the lamp 533 is diffracted by the hologram element 551, and the S-polarized light transmitted through the hologram element 551 is converted to P-polarized light by the total reflection mirror 531 and the phase plate 552. After the light is transmitted through the hologram element 551 and emitted,
A substantially parallel light beam having a uniform polarization direction can be obtained.

Embodiment 3 of the above-mentioned polarized light illumination device
When the light use efficiency was obtained in the same manner as in -1, the light use efficiency could be obtained about 1.2 to 1.5 times as compared with the case where the hologram element 551 and the phase difference plate 552 were not used.

Further, according to the above configuration, polarization conversion can be performed only by a simple laminated structure of the hologram element, the phase difference plate 552, and the total reflection mirror 531. Are easy to use, and can be used in a wide range of optical devices. Especially,
For example, when the present invention is applied to a device having a folding mirror in advance, such as a color image display device having two dichroic prisms and performing color separation and color synthesis, a mirror having a hologram element is used instead of the mirror. Since it is only necessary to use the light source, the light use efficiency can be improved without increasing the number of parts.

(Embodiment 3-4) An example of still another polarization conversion element using the same hologram element as that shown in the embodiment 1 or 2-1 will be described.

Embodiment 1 or Embodiment 2-1
Two hologram elements 561 and 56 similar to those shown in FIG.
2 was used to construct a polarization illuminating device including a polarization conversion element 560 as shown in FIG.

The light beam including the P-polarized light and the S-polarized light from the lamp 533 enters the hologram element 561 via the reflector 534, and the S-polarized light is transmitted as it is as substantially parallel light. Further, the P-polarized light is diffracted by the hologram element 562 so that the propagation direction changes by approximately 90 ° according to the principle described in the first embodiment and the like.

The light wave further enters the hologram element 562, and is similarly diffracted and emitted so that the propagation direction is substantially equal to the direction of the light beam reflected from the initial reflector 534. Thereafter, the light passes through the phase difference plate 563 which is a half-wave plate, and is emitted as an S-polarized light wave after the polarization direction is rotated by 90 °. That is, the light wave emitted from the lamp 533 and diffracted by the hologram element 561 is emitted by the diffractive optical element 562 and the phase difference plate 563 as a substantially parallel light beam having the same polarization direction as the light wave transmitted through the hologram element 561.

When the reuse ratio of the light wave in the hologram element 562 of the polarized light illumination device as described above was measured, the light flux from the hologram element 562 was converted to the hologram element 5.
A light beam converted into S-polarized light having an intensity ratio of about 90% with respect to the light beam from 61 was obtained.

As described above, hologram elements 561 and 56
The advantage of using 2 is that it is possible to arbitrarily set the separation angle when performing polarization separation. That is, as usual, when polarization separation is performed by combining a polarization beam splitter and a total reflection mirror,
In order to bend the propagation direction by 90 °, it is necessary to incline the reflection surface by 45 ° with respect to the incident light (corresponding to θ in FIG. 24). Therefore, in the depth direction, a size corresponding to the size and inclination of the reflection surface is required, and in the device using the polarized light illumination device, the constraint in the thickness direction is increased.

On the other hand, when the hologram element is used as described above, the polarization separation angle can be arbitrarily set by the refractive index distribution formed inside, so that the diffractive optical element is not affected by the incident light. 24 can be arranged at an angle of 45 ° or less with respect to a vertical plane, and θ in FIG.
The angle can be set at a small angle of 5 ° or less, and the polarization conversion optical system can be configured by arranging the hologram elements in parallel to each other, so that the size in the depth direction can be significantly reduced. . For this reason,
A thin configuration is possible, and a compact system (illumination device, image display device, or the like) can be realized in combination with an illumination optical system such as an integrator to which the polarization-converted polarized light is incident.

(Embodiment 3-5) A hologram element similar to that shown in Embodiment 1 or Embodiment 2-1 is used, and an integrator having a first lens group and a second lens group is used. An example of a polarization conversion element for aligning the polarization direction of output light will be described.

Embodiment 1 or Embodiment 2-1
As shown in FIG. 25, a plurality of pairs of hologram elements 572 and 573 similar to those shown in FIG. 25 were arranged, and a polarization illuminating device including a polarization conversion element 570 was constructed. Note that FIG. 3 shows an example in which a projection-type image display device is configured by combining an image display element 577, a projection lens 578, and the like.

The light wave including the P-polarized light and the S-polarized light transmitted from the first lens group (not shown) in the integrator enters the second lens group 571, where the light beam is narrowed down.
The light enters the hologram element 572 corresponding to each lens 571a of the lens group 571. Here, the S-polarized light is transmitted as it is, and the P-polarized light is diffracted and enters the adjacent hologram element 572. Then, the light is further diffracted, propagates in a direction substantially equal to that of the S-polarized light, is rotated by 90 ° by a phase difference plate 574, which is a half-wave plate, is converted into S-polarized light, and is emitted. I do.

These steps are performed for each set of a plurality of hologram elements 572 and 573 and a phase difference plate 574, and the light waves that have passed through the second lens group 571 are emitted with their polarization directions aligned. . Further, since the light beam is narrowed down and used in combination with the integrator, it is possible to perform the polarization conversion without largely changing the width of the light beam from the light source.

The light beam whose polarization direction is aligned as described above is incident as a parallel light beam by a condenser lens 575 and a field lens 576 on an image display element 577 such as a polarization type liquid crystal display element. after being brightness modulation, investment
The image is magnified and projected on the screen 579 by the projection lens 578 .

When the brightness on the screen was compared between the case where the polarization conversion was performed by the above-described polarization conversion element 570 and the case where the polarization conversion was not performed, the brightness increased by about 30% when the polarization conversion was performed. And a bright image could be obtained.

(Embodiment 3-6) Still another example of a polarization conversion element using the same hologram element as that shown in the embodiment 1 or 2-1 will be described.

As shown in FIG. 26, the third embodiment
A pair of polarization conversion elements 560 similar to
Alternatively, the polarization conversion element 590 may be provided so as to be symmetric with respect to the four optical axes. With this configuration, since the reflector 534 is disposed at, for example, the center in the width direction of the polarized light illuminating device, a uniform space is formed on both sides, and thus other components in the device to which the polarized light illuminating device is applied. Arrangement becomes easy.

(Embodiment 4-1) Embodiment 2
An example in which a projection type image display device configured using the polarization separation element 510 of FIG. 1 (FIG. 13) will be described. As the hologram element included in the polarization separation element 510, the hologram element described in Embodiment 1 or Embodiment 2-1 (FIGS. 10, 18 and the like) can be applied. Here, when the hologram element of Embodiment 1 is used, ITO
It is used while a predetermined voltage is applied between them.

As shown in FIG. 27, the projection type image display device 600 includes a polarization illuminating device 601 composed of a lamp 533, a reflector 534, a polarization separation element 510, and an integrator, and outputs a light beam from the lamp 533 to the reflector. 533, the reflected output light flux β is incident on an image display element 547 such as a transmissive liquid crystal panel via a polarization splitter 510 and an integrator 541, and the brightness-modulated light flux is screened by a projection lens 602. (Not shown), an image is displayed by performing enlarged projection .

Next, the polarization separating element 510 and the integrator used in the projection type image display device 600 will be described. The polarization splitting element 510 used in the present invention includes the first hologram element 511 and the second hologram element 512 as described in Embodiment 2-1.
The P-polarized light is transmitted straight (at an output angle of 0 °) and transmitted, while the S-polarized light is output at an output angle of approximately −7 °.

Each of the first minute lenses forming the first lens group (first fly-eye lens) 542 is connected to each of the second lens groups 543 forming the second lens group (second fly-eye lens). An image of the lamp is formed on the lens. At this time, the P-polarized light γ and the S-polarized light δ are imaged at different positions. For example, a phase plate 544 that is a half-wave plate (λ / 2 plate) as a polarization plane rotating unit is provided in a portion where the S-polarized light δ forms an image, and the S-polarized light transmitted through the phase plate 544 is provided. The light δ is converted into substantially P-polarized light and output. Note that the P-polarized light γ
And the polarization component of the s-polarized light δ to rotate the plane of polarization is determined by the polarization direction of the polarizing plate provided in the image display element 547.

The second lens group 543 displays an image of each minute lens constituting the first lens group 542 on the image display element 54.
By forming an image over almost the entire display image area in 7, the uniformity of the brightness of the display image is ensured.

By constructing the polarized light illuminating device 601 as described above, the unpolarized light output from the lamp 533 can be efficiently converted to P-polarized light, and high projection efficiency can be realized. . Further, the polarization separation element 510 as described above can be easily manufactured and can be configured at low cost. In addition, since the polarization separation element 510 has a small dimension in the optical axis direction, a compact polarization separation element having high separation efficiency can be easily configured. In addition, by using the above-described polarization separation element, a projection type image display device having high light use efficiency can be easily realized.

The lamp 533 and the reflector 53
Embodiments 3-1 to 3-3 if the arrangement of
It is also possible to use a polarization separation element 530 as shown in FIGS.

The lamp 533 may be a metal halide lamp, a halogen lamp, a xenon lamp,
An ultra-high pressure mercury lamp or the like can be used, but it is preferable to use a lamp having a small light emitting region.

(Embodiment 4-2) A projection type image display of a so-called three-panel type which has three transmission type image display elements and optical elements of a color separation system and a color synthesis system and can display a color image. An example of the device will be described.

This image display device is provided with a color composition system element 620 shown in FIG. 28B below the color separation system element 610 shown in FIG.

The color separation element 610 includes a polarization illuminating device 601 including a polarization conversion element similar to that described in the embodiment 4-1; a dichroic prism 611; and total reflection mirrors 612 to 614. And outputs the light output from the polarization illuminator 601 as R (red), G (green),
The light is decomposed into light of each wavelength of B (blue). On the other hand, the color composition system element 620 includes total reflection mirrors 621 to 62.
3, the image display elements 624 to 626, the dichroic prism 627, and the projection lens 628, and the light of each wavelength guided from the color separation element 610 passes through the image display elements 624 to 626. Then, color synthesis is performed, and an image is projected on the screen 629 by the projection lens 628.

In this image display device, the substantially parallel light beam output from the lamp 533 via the reflector 534 is
As described in Embodiment 4-1 above, after the polarization directions are aligned by the polarization separation element 510 and the integrator 541 and the uniformity of the light beam in the plane is maintained, the dichroic prism 611 Incident on. The dichroic prism 611 has a configuration in which filters of wavelengths of respective bands are formed inside, and white light from the polarized light illuminating device 601 corresponds to the wavelength filter and has three primary colors of R and G. , B are decomposed into light corresponding to the respective wavelengths, and are emitted in the directions indicated by arrows in FIG. Here, the dichroic prism 611 has the same function as the case where a two-piece dichroic mirror is used, but because of the prism configuration, color separation can be performed without using a large space. Thus, a compact display device can be configured.

The light of each color emitted from the dichroic prism 611 is reflected by the total reflection mirrors 612 to 614 and guided to the lower color combining element 620.
The light of each color guided from the color separation element 610 to the color combining element 620 is reflected by the total reflection mirrors 621 to 623 with its traveling direction changed by approximately 90 °, and a transmissive image display corresponding to the light of each color is performed. After being subjected to luminance modulation by the elements 624 to 626, the light enters the dichroic prism 627.
The dichroic prism 627 has a function opposite to that of the dichroic prism 611,
The light is divided into light of each color of G and B, and is subjected to color synthesis of the light incident thereon. The synthesized light is emitted toward the projection lens 628. The light emitted from the dichroic prism 627 is transmitted by the projection lens 628 to the screen 6.
29, and is displayed as an enlarged image.

By providing the polarization conversion element for aligning the polarization direction of the light beam output from the reflector 534 as described above, it is possible to improve the light use efficiency and configure an image display device capable of displaying a bright image. it can.

In the case where a polarization conversion element or the like is applied to an image display device or the like for displaying a color image as described above,
When fabricating a hologram element, a structure is used in which multiple exposures are performed using light interference fringes of red, green, and blue light, and hologram elements optimized for diffraction of each color light are stacked. You may do so.

In place of the polarization splitting element 510 and the phase difference plate 544, Embodiments 3-4 to 3-6 are used.
Even when the polarization conversion element 560 or the like as shown in FIGS. 24 to 26 is used, similarly high light use efficiency can be obtained.

The above-described polarization conversion element 550 and the like include the integrator 541 and the dichroic prism 6.
11 and the same effect can be obtained. Further, the polarization conversion element 550 and the like are provided between the dichroic prism 611 and the image display elements 624 to 626, that is, three polarization conversion elements (and integrators) corresponding to the light of each color after color separation. Is also good. In this case, since the polarization conversion elements are individually provided corresponding to the light of each color, the hologram element is optimized to reduce the influence of chromatic dispersion in accordance with the wavelength of each color, that is, each hologram element, etc. can be used as the periodic structure corresponding to the wavelength is formed, it is possible to improve further the light use efficiency. Further, it may be provided later than the dichroic prism 611 to the integrator as well.

Further, the lamp 533 and the reflector 53
Embodiments 3-1 to 3-3 if the arrangement of
It is also possible to use a polarization conversion element 540 as shown in FIGS.

Even when the reflectors are provided in the same arrangement as in FIG. 28, the polarization conversion element is provided between the dichroic prism 611 and the image display elements 624 to 626, that is, corresponding to the light of each color after color separation. When the three polarized light conversion elements (and the integrators) are provided, the above-described polarized light conversion elements can be applied.
In this case, a total reflection mirror 612 for guiding the light of each color from the color separation element 610 to the color combining element 620 can also be used as the total reflection mirror 531 of the polarization conversion element. In addition, as described above, a hologram element that matches the wavelength of each color can be used.

When a polarization conversion element is provided in each path after the actual color separation, the brightness of a color-combined image on a screen is 30 times higher than when no polarization conversion element is used. % Could be increased. this is,
The transmission type described above and the reflection type described later were almost the same. Thus, the polarization conversion using the diffractive optical element is also effective for color display.

In the structure shown in FIG. 23, it is also possible to use means for changing the thickness of the phase plate in the plane in order to correct the dependency of the polarization characteristic on the incident angle of the phase plate.

(Embodiment 4-3) Embodiment 4-3
An example of a three-panel projection type image display device that can display a color image using a reflection type image display device with a configuration similar to that of No. 2 will be described.

This image display device is provided with a color composition system element 630 shown in FIG. 29B below the color separation system element 610 shown in FIG. 29A.

As the color separation system element 610, the same one as shown in the embodiment 4-2 is used. On the other hand, the color combining system element 630 is different from the embodiment 4-2 in that the polarizing beam splitters 631 to 633 are provided instead of the total reflection mirrors 621 to 623, and the transmission type image display elements 624 to 624 are provided. The difference is that reflection type image display elements 634 to 636 are provided instead of 626.

The polarization beam splitters 631 to 633
Is designed to reflect only light having a predetermined polarization direction, but since the light actually guided from the color separation element 610 is light whose polarization direction is aligned by the polarization conversion element, almost all light is reflected. The light is reflected and enters the image display elements 634 to 636. The light incident on the image display elements 634 to 636 is reflected after being modulated in the polarization direction according to the display image of each color, and is incident again on the polarization beam splitters 631 to 633, and only the light in the predetermined polarization direction is transmitted. The modulation of the polarization direction is converted into luminance modulation and visualized. After that, as in Embodiment 4-2, color synthesis is performed by the dichroic mirror 637, and an image is projected on the screen 629 by the projection lens 628.

In the reflection type image display element as described above, the polarization conversion element for aligning the polarization direction of the light beam output from the reflector 534 is also provided.
An image display device capable of displaying a bright image with improved light use efficiency can be configured.

Also, in this image display device, various modifications as described in the embodiment 4-2 can be similarly made.

(Embodiment 5-1) An example of an image display device provided with a hologram element will be described.

In the image display apparatus, as shown in FIG. 30, hologram elements 702 and 703 as diffractive optical elements are provided on both sides of a liquid crystal element 701, and a light source having a lamp 704a and a reflector 704b on the back side thereof. 704
Is provided.

In the following description, light having a polarization direction in a direction parallel to the plane of the drawing is referred to as P-polarized light, and light having a polarization direction in a direction perpendicular to the plane of the drawing is referred to as S-polarized light.

As the lamp 704a of the light source 704, for example, a fluorescent lamp, a xenon lamp, a metal halide lamp, a mercury lamp, an LED, an FED, a laser beam,
An inorganic or organic EL element or the like can be used. Lamp 704
The light emitted from a is emitted as substantially parallel light by the reflector 704b. This light source light
P-polarized light and S-polarized light are included.

As the liquid crystal element 701, for example, a twisted nematic liquid crystal in which the directions of liquid crystal molecules are twisted by 90 ° between the light incident surface side and the light emitting surface side is used. The liquid crystal element 701 is provided with a transparent electrode (not shown) formed in a predetermined pattern so that a voltage can be applied to the liquid crystal for each pixel. Therefore, in a pixel (ON) in which a predetermined sufficient voltage (a voltage enough to completely switch the liquid crystal) is applied to the liquid crystal, the liquid crystal molecules are untwisted and the liquid crystal molecules are isotropic with respect to the light incident surface. Standing (homeotropic). Therefore, when the P-polarized light enters the pixel, the P-polarized light passes through the liquid crystal element 701 while maintaining its polarization state without being modulated in the polarization direction. On the other hand, in the pixel (OFF) where no voltage is applied to the liquid crystal, the direction of the liquid crystal molecules is twisted by 90 ° in the thickness direction from the entrance surface to the exit surface. Then, when the P-polarized light enters the pixel, the P-polarized light rotates its polarization plane by 90 ° by the twist nematic effect caused by the twist of the liquid crystal while passing through the liquid crystal element 701 from the incident surface to the emission surface. . Therefore, after passing through the OFF pixel, the light is emitted as S-polarized light.

The hologram elements 702 and 703
For example, the first embodiment or the second embodiment
A hologram element similar to that shown by -1 is used.
Here, when the hologram element of Embodiment 1 is used, the hologram element is used in a state where a predetermined voltage is applied between ITO. As described above, the hologram elements 702 and 703 have different diffraction effects depending on the polarization direction, and have a property of exhibiting high diffraction efficiency in one predetermined direction.

Specifically, for example, the hologram element 70
Since the S-polarized light among the light incident on the hologram elements 703 and 703 functions as an extraordinary light component, it is modulated by the refractive index distribution of the periodic structure formed in the hologram elements 702 and 703, and FIG.
The light is emitted with its traveling direction bent upward. on the other hand,
Since the P-polarized light acts on the hologram elements 702 and 703 as an ordinary light component, the hologram elements 702 and 703
It is not affected by the refractive index distribution having the periodic structure of No. 03, and exhibits the same behavior as that when passing through a medium having an isotropic uniform refractive index. For this reason, the P-polarized light is
703 as it is.

Then, when light including P-polarized light and S-polarized light from the light source 704 enters the hologram element 702,
The S-polarized light is diffracted as described above and hardly enters the liquid crystal element 701, and only the P-polarized light is
02 and enter the liquid crystal element 701. Liquid crystal element 7
As described above, the P-polarized light incident on 01 is emitted as P-polarized light at the ON pixels, while being converted to S-polarized light at the OFF pixels and emitted. That is, the light emitted from the liquid crystal element 701 becomes different polarized light depending on whether the pixel at the passing position is ON or OFF.

When the light emitted from the liquid crystal element 701 enters the hologram element 703, the hologram element 702
Similarly to the above, the S-polarized light is diffracted, and only the P-polarized light travels straight. That is, the direction of light that has passed through each pixel of the liquid crystal element 701 exits from the hologram element 703 depending on whether the pixel is ON or OFF. Therefore, from the observer who sees the image display device from almost the normal direction of the display surface, the light that has passed through the OFF pixel is emitted to the outside of the field of view by the diffraction effect of the hologram element 703 and is not visually recognized. Passes through the hologram element 703 as it is, enters the viewing area of the observer, and is visually recognized as a bright pattern.

Next, an example of an actually manufactured image display device will be described.

In this image display device, the light source 704 used was a fluorescent lamp that had passed through a green filter, and emitted light having a wavelength of about 0.55 μm. As the liquid crystal element 701, a VGA of about 3 inches
The one having a resolution of (640 × 480) was used.
When an image signal was input thereto and observed from almost the normal direction (front) of the display screen, an image corresponding to the image signal input to the liquid crystal element 701 could be correctly viewed.
The contrast was about 10: 1. The direction in which the S-polarized light that has passed through the hologram element 703 diffracts (FIG.
When the observation position was moved to (upward at 0), an image in which the brightness was reversed from that of the previous image was visually recognized. As described above, the refractive index distribution type hologram elements 702 and 703 composed of the optical medium having the refractive index anisotropy are replaced with the liquid crystal element 7.
01, the image can be displayed by emitting the light corresponding to the OFF pixel to the outside of the observer's visual field without blocking (absorbing) the incident light. A good image display device can be manufactured. In addition, unlike the case where a polarizing plate is used, heat generation due to light absorption does not occur.

By controlling the voltage applied to each pixel, the polarization direction of the light passing through the liquid crystal according to the voltage is changed to the intermediate state between the P-polarized light and the S-polarized light, that is, the elliptically polarized light. Can be set to At this time, the light incident on the hologram element 703 is divided into a component that goes straight and a component that is diffracted according to the voltage applied to each pixel, so that a halftone display is also possible.

In the above example, the twisted nematic type liquid crystal element 701 has been described. However, any type of liquid crystal element 701 having a function of modulating the polarization direction of incident light can be used. It may be something. A super twisted nematic (STN) liquid crystal having a twist angle of 90 ° or more can also be used. In addition, the liquid crystal molecules are homogeneously aligned in the thickness direction, and become homeotropic upon application of an electric field, or change from homeotropic to homogeneous. VA (Vertical Alignment)
The same effect can be obtained by using a liquid crystal of the t ) mode.

Furthermore, it is also possible to use a ferroelectric liquid crystal or an antiferroelectric liquid crystal in which the alignment direction of liquid crystal molecules differs depending on the polarity of the electric field.

The liquid crystal element 701 as described above is similar to a liquid crystal panel usually used as a liquid crystal display. Therefore, the image display device as described above can be configured simply by replacing the front and rear polarizing plates used in the liquid crystal element with the hologram elements 702 and 703 of the present invention, and the other illumination systems and drive systems are not changed. It is very versatile because it can be applied at

(Embodiment 5-2) Embodiment 5
An image display device as shown in FIG. 31 was constructed using the same hologram elements 702 and 703 as in FIG. That is,
The light source 704 was arranged near the lower side of the hologram element 702, and a so-called side light configuration was used in which light was emitted from an oblique side. Note that the light source 704 is described in Embodiment 5-1.
In the same manner as described above, a fluorescent lamp provided with a green filter was used. Other configurations are the same as those of the embodiment 5-1.

In this image display device, of the light emitted from the light source 704, the P-polarized light passes through the hologram element 702 as it is and does not enter the liquid crystal element 701. Also,
The S-polarized light is bent at approximately 90 ° with respect to the display screen by the hologram element 702 and enters the liquid crystal element 701. The light passing through the liquid crystal element 701 has its polarization direction modulated in accordance with the signal applied to the pixel, and enters another hologram element 703. Here, the S-polarized light is diffracted upward in the figure and emitted out of the viewing range of the observer. The P-polarized light passes through the hologram element 703 as it is and is visually recognized by an observer. Hologram element 7 from observer's position
When observed from the normal direction of the 03-direction display screen, an image corresponding to the input image signal was correctly visually recognized. Also, the hologram elements 702, 70
It was also possible to observe the outside scenery through 3.
As described above, the image display device configured as described above,
It is possible to visually recognize the image display and the external scenery simultaneously or by switching, and it can be used as a so-called see-through type display.

(Embodiment 5-3) Embodiment 5
3 using one hologram element 702 similar to FIG.
An image display device as shown in FIG. That is, the image display device is configured to display an image by using external light such as natural light or indoor light without having a light source inside. Further, the same liquid crystal element 701 as that in Embodiment Mode 1 was used.

The display principle of this image display device will be described below.

First, when external light 710 including P-polarized light and S-polarized light enters the hologram element 702, the P-polarized light component is transmitted without being modulated by the hologram element 702, and is almost completely transmitted to the liquid crystal element 701. Does not enter. On the other hand, the S-polarized light is diffracted by the hologram element 702, and almost all light enters the liquid crystal element 701. Light that has entered the liquid crystal element 701 passes through the area of each pixel and is reflected by the mirror 711. The mirror 711 can be made of a metal or a dielectric multilayer film. For the actual production, a glass substrate with aluminum evaporated was used.

The light reflected by the mirror 711 passes through the area of each pixel of the liquid crystal element 701 again, and its polarization direction is modulated according to the voltage applied to each pixel, and then enters the hologram element 702. The S-polarized light that has entered the hologram element 702 is diffracted upward in the same figure and is emitted out of the observer's field of view. Further, since the P-polarized light passes through the hologram element 702 as it is, it is visually recognized by an observer, and an image is visually recognized according to the signal voltage applied to each pixel of the liquid crystal element.

Observation of the reflection-type image display device using the above-described mirror actually manufactured with room light illumination revealed an image having a bright and dark pattern.
The contrast was about 10: 1. A white light source, which is room light, was used, but there was almost no deterioration in image quality due to color bleeding or the like. This is because the hologram element 7
The direction of diffraction of the S-polarized light diffracted at 03 differs depending on the wavelength. However, if the diffraction angle is set to be larger than the viewing range of the observer, it will be out of the recognition area, and the influence of the diffraction angle by the wavelength is almost a problem It is thought that it does not become.

Therefore, it is possible to clearly recognize an image in the reflection-type image display device using external light configured as described above, and further, since an internal backlight is not required, low power consumption and low power consumption can be achieved. Suitable for miniaturization.

(Embodiment 5-4) As shown in FIG. 33, the same hologram element 702,
An image display device of the combination type using the external light and the internal light source configured by using the image display device 703 will be described.

In this image display device, the hologram element 7
02 and 703 are the same as those described in the embodiment 5-1.
It is arranged in a state rotated by 90 ° in the same plane as compared with -1. Therefore, the hologram element 702 has
It does not show a diffractive effect on polarized light, but has a diffractive effect on P-polarized light. That is, the hologram element 702,
Reference numeral 703 is configured such that the dependence of the polarization direction on the P-polarized light and the S-polarized light is reversed. The same function can also be provided by performing an alignment process in the hologram element shown in FIG. 18 such that the initial alignment direction of the homogeneous liquid crystal differs by 90 °. That is, it is possible to determine which polarized light has a diffraction effect depending on how the arrangement direction of the liquid crystal molecules is set with respect to the incident light.

The liquid crystal element 701 is the same as that used in the embodiment 5-1. The mirror 711 is formed by vapor deposition of aluminum in the same manner as in Embodiment 5-3. The light source 704 is a fluorescent lamp,
Used as a white light source.

Here, in FIG. 33, solid arrows indicate
The propagation of external light is shown, and the dashed line arrow shows the propagation of light from the light source 704.

[0276] Hereinafter, the display operation using light from the light source 704 will be described first. P light from a light source 704 arranged diagonally on the side of the hologram element 702 as a side light
The light including the polarized light and the S-polarized light is
02, the S-polarized light is transmitted as it is without being subjected to the diffraction effect, and the P-polarized light is bent in a direction of approximately 90 ° with respect to the display screen by diffraction to enter the liquid crystal element 701.

The P-polarized light that has entered the liquid crystal element 701 is modulated by each pixel of the liquid crystal element, and the polarization direction changes. Accordingly, the traveling direction due to the action of the hologram element 703 changes. As a result, the observer can visually recognize the image information corresponding to the input image signal.

Next, the display operation using the external light 710 will be described. Of the external light 710, the P-polarized light is transmitted without being modulated by the hologram element 703,
It does not enter 01. The traveling direction of the S-polarized light is bent by the diffractive action of the diffractive optical element, and
Is almost incident. S passing through each pixel of the liquid crystal element 701
Since the polarized light is not subjected to the diffraction effect on the hologram element 702, it is transmitted as it is and reflected by the mirror 711. After passing through the hologram element 702 again, the light is incident on each pixel of the liquid crystal element 701, the polarization direction is modulated for each pixel, and the light is incident on the hologram element 703. ON
The S-polarized light that has passed through the pixel is diffracted by the hologram element 703 and emitted out of the observer's field of view. The P-polarized light that has passed through the OFF pixel passes through the hologram element 703 as it is, and is recognized as a bright pattern by an observer.

Here, the light and dark patterns corresponding to ON and OFF of the liquid crystal element are inverted between the light from the light source 704 and the external light. This can be dealt with by inverting the pattern of the video signal in correspondence with the selection of the light source.

Strictly speaking, the light from the light source 704 passes through the liquid crystal element only once, while the external light 710
Is reflected by the mirror and passes through the liquid crystal element twice, the forward path and the backward path. Therefore, the modulation ratio in the liquid crystal element 701 is different. This can be dealt with by correcting the video signal in accordance with the selection of the light source since the modulation degree of the single pass and the double pass can be estimated in advance.

As described above, the hologram elements 702, 7
By setting the polarization dependence of 03 differently, it is possible to achieve both the transmission mode and the reflection mode.

As a result of observing the actually manufactured image display device, the image can be clearly recognized by using the light source 704 in a dark room, and the image can be recognized without turning on the light source 704 under bright illumination light. Was able to do. As described above, by using this image display device, it is possible to select a light source according to the environment such as a dark place or a source of bright illumination light. Therefore, it is possible to improve the efficiency of power consumption and improve the visibility of an image under various environments.

Further, it is possible to detect the brightness of the illuminating light in an environment where the image display device is used, and to automatically select the light source or set the intensity of the light source. Can be further improved.

(Embodiment 5-5) FIG. 34 shows an image display apparatus in which hologram elements 702 and 703 similar to those in Embodiment 5-1 are combined with a color filter 721. As a light source 704, a fluorescent lamp was used as white light without passing through a filter. Also, the liquid crystal element 72
0 has the same structure as the liquid crystal element 720 of the embodiment 5-1 but has three times the pixel density, and has the red (R), green (G), and blue (B) in the color filter 721. The three pixels corresponding to the region (a) are grouped to display a color image at the same pixel density as the liquid crystal element 720.

The color filter 721 has R, R, and R for each region of the liquid crystal element 720 corresponding to each pixel.
Light of any wavelength of G or B is selectively transmitted, and light of another wavelength is absorbed.

In this image display device, S-polarized light and P-polarized light and S-polarized light emitted from the light source 704 are diffracted upward in FIG. Therefore, the S-polarized light does not enter the color filter 721, and only the P-polarized light enters the color filter 721.

[0287] R, which has passed through the color filter 721,
Light corresponding to each wavelength of G and B enters each pixel of the liquid crystal element 720. Then, the polarization direction is modulated according to ON / OFF of each pixel. As a result, the light passing through the ON pixels passes through the hologram element 703 as it is and reaches the observer. In addition, since the light that has passed through the OFF pixels is diffracted upward by the hologram element 703 in the same figure, the light falls outside the field of view of the observer, and becomes a dark pattern that is not recognized as light intensity by the observer.

FIG. 34 shows the case where all the pixels corresponding to R, G, and B are ON and OFF for simplicity, but the electric field applied to each pixel to which light of each wavelength is incident is shown. By independently controlling the light to pass through the hologram element 703, the light of the selected color among the light of each wavelength of R, G, and B reaches the observer. A color image can be displayed.

Here, the hologram element 7 for each wavelength
Regarding the influence of the chromatic dispersion of 03, the diffraction angle may be set to be large, and the short-wavelength light having a small diffraction angle may be set to be outside the viewing range of the observer. That is, any light of each wavelength that has passed through the pixel corresponding to OFF is the hologram element 70.
In No. 3, since the light is diffracted out of the viewing range of the observer, the light is not recognized as light intensity, and no problem such as color mixing occurs.

The light that has passed through the ON pixels is not normally subjected to diffraction by the hologram element 703. However, when the liquid crystal material forming the hologram element 703 has wavelength dispersion, Δn = Ne−No may vary depending on the wavelength, and the inside of the element cannot be regarded as an isotropic medium.
In this case, an angle difference occurs in the transmitted light of each wavelength, which is visually recognized by an observer as color bleeding or the like. However, in the case of transmission, if the distance of the observer from the hologram element 703 is not too large, a large deterioration in image quality does not occur.

[0291] R, G, B
Was input and observed at a distance of about 30 cm from the hologram element 703. As a result, a clear color image could be observed with little color mixing or color bleeding.

The combination of the color filters here is not used only in the configuration shown in FIG. 34, but is used in the reflection type shown in FIG. 32, the transmission type and the reflection type shown in FIG. Needless to say, the method can be applied to

(Embodiment 5-6) Embodiment 5
The hologram elements 702 and 703 of the image display device of No. 5 were manufactured by performing multiple exposure using light of each wavelength of R (0.65 μm), G (0.55 μm), and B (0.45 μm). You may. Hereinafter, a manufacturing process of such a hologram element will be described.

First, a liquid crystal sample is manufactured in the same manner as in the case of manufacturing the hologram element of FIG. 18 in Embodiment 2-1. This is set in an optical system using an Ar laser, and G (0.
Exposure is performed using interference fringes corresponding to a wavelength of 55 μm).
Next, the angle of the mirror (reflection mirror) is changed, and the above-described first exposure process is repeated to perform exposure corresponding to the wavelength of R (0.65 μm). Further, an interference fringe corresponding to B (0.45 μm) is similarly formed and exposed. After that, a second exposure step of irradiating the liquid crystal sample with uniform light in the same manner as in Embodiment 2-1 can produce a hologram element on which interference fringes are superimposed.

When the hologram element manufactured as described above is used in place of hologram elements 702 and 703 in FIG. 34, a color video signal is input to liquid crystal element 701 and observed from the position of the observer. Is R,
Because it is optimized for both G and B wavelengths,
A clear image could be recognized without problems such as color bleeding and color mixing. Further, even if the observation position was moved back and forth by about 30 cm, there was no effect such as deterioration of image quality.

(Embodiment 5-7) Embodiment 5
The hologram elements 702 and 703 of the image display device of No. 5 were R (0.65 μm) and G (0.55 μm), respectively.
m) or B (0.45 μm) may be used in which three hologram elements produced by performing exposure with light of each wavelength are laminated.

The hologram element as described above is used in place of hologram elements 702 and 703 in FIG.
When a color video signal is input to the image sensor 01 and observed from the observer's position, the diffractive optical elements of the respective layers independently perform the diffractive action on each of the R, G, and B wavelengths, and the chromatic dispersion is reduced. Eased. As a result, a clear image could be recognized without problems such as color bleeding and color mixing. further,
Even if the observation position was moved back and forth by about 30 cm, there was no influence such as deterioration of image quality.

(Embodiment 5-8) Embodiment 5
The image display device such as 1 can also be applied to an image display / illumination device. Hereinafter, an example of a device that can display road traffic information in a tunnel and illuminate the inside of the tunnel will be described.

As shown in FIG. 35, the image display device 731
Are installed on the wall surface 732 of the tunnel. This image display device 731 has, for example, a configuration similar to that of the image display device described in the embodiment 5-1.
It is installed so as to face the traveling direction of 33. That is, in the embodiment 5-1, the example in which the display image is visually recognized substantially from the normal direction (front) of the display screen has been described. An image whose brightness is reversed is displayed as the image to be visually recognized. Therefore, by inputting image data in which the brightness is reversed in advance as image data to be input to the image display device, an image that can be visually recognized from a direction inclined with respect to the normal of the display screen is displayed by the diffracted light. Can be done.

Here, the direction in which the diffracted light is emitted, that is, the direction in which the displayed image is visually recognized by the diffracted light, can be set by the inclination or pitch of the periodic structure of the hologram element. Therefore, this display device can be applied to various devices that require a display image to be viewed obliquely.

When an image is displayed by diffracted light, light transmitted through the hologram element is emitted in the normal direction of the display screen. Although an image formed by the emitted light cannot be viewed from an oblique direction, it plays a role as illumination light in an environment where the surroundings are dark at night or in a tunnel or the like, so that it can be used as an illumination device. That is , a device having both functions of the image display device and the illumination device can be configured. Thus, the functions of the image display device and the illumination device can be provided because in a liquid crystal display using a normal polarizer, light not used for image display is absorbed by the polarizer and cannot be used for illumination. In contrast, a display device using a hologram element as described above is
This is because the transmitted light and the diffracted light are emitted equally in principle.

Hologram elements 702, 7 in the present invention
This is a feature of the image display device having a configuration in which light is split by the light emitting device 03.

Note that the plurality of image display devices 731 are
If it is arranged at 32, it is also possible to use the image information to be recognized step by step by the observer according to the traveling position of the vehicle. It is effective in the case.

Actually, when an image display device 731 was placed in an experiment room that imitated a structure in a tunnel as shown in FIG. 35 and an experiment was performed, an image that can be visually recognized as the position of the observer moved was displayed. I was able to. It was also confirmed that the light emitted to the front of the image display device 731 also served as illumination light in a dark laboratory.

Such an image display / illumination device can be applied not only to the inside of a tunnel but also to traffic information display and illumination on a normal arterial road or an expressway, with priority given to other specific directions. It is needless to say that the present invention can be applied to a method of displaying image information on a screen.

(Embodiment 5-9) Embodiment 5
An example of an image display device having a polarization conversion element configured using the same hologram element as that of Example 1 will be described.

This image display device has the structure shown in FIG.
To, in place of the hologram element 702 of the embodiment 5-1, it arranged hologram element on the same plane 741-7
44 are provided. Also, the hologram element 743,
744 and the liquid crystal element 701, a retardation plate (λ / 2
Plates 745, 746 are provided. The light source 704 is
A fluorescent lamp having a green filter passed through was used as in Embodiment 5-1. Other configurations are the same as those of the embodiment 5-1.

In this image display device, of the light emitted from the light source 704, the P-polarized light is the diffractive optical element 741, 74.
2 is transmitted as it is and enters the liquid crystal element 701. Further, the S-polarized light is diffracted in a substantially horizontal direction at an angle of about 90 ° by the hologram elements 741 and 742, and is incident on the hologram elements 743 and 744 arranged on the respective sides. Light incident on hologram elements 743 and 744 is further diffracted by hologram elements 743 and 744 at an angle of approximately 90 °. The light diffracted by hologram elements 743 and 744 has a polarization plane of 9 by phase difference plates 745 and 746.
The light is rotated by 0 ° and is incident on the liquid crystal element 701 almost vertically as P-polarized light.

That is, the hologram elements 741 to 744
The light from the light source 704 is incident on the liquid crystal element 701 as a light wave having a uniform polarization plane (in this case, P-polarized light). Therefore, the light use efficiency increases (theoretically about twice), and a bright image can be displayed.

Also, the irradiation area of the light source 704 can be expanded, and the light from the light source 704 having a small area can be enlarged to display an image by enlarging the irradiation area. It is also effective in electric power.

[0311] The light passing through the liquid crystal element 701 has its polarization direction modulated in accordance with the signal applied to the pixel, and enters another hologram element 703.

Here, the S-polarized light is diffracted upward on the plane of the paper and emitted out of the viewing range of the observer.

The P-polarized light passes through the hologram element 703 as it is, and is recognized by the observer.

When the direction of the hologram element 703 was observed from the observer's position, the image corresponding to the applied input signal was correctly recognized.

As described above, the image display device configured here can effectively use almost all of the light waves from the light source for image display, and can enlarge the illumination area.

(Embodiment 5-10) Embodiment 5
Another example of a small-sized image display device having a polarization conversion element configured using a hologram element similar to -1 will be described.

[0317] shows a schematic of a small display device constructed in the form 5-10 of the present invention in FIG. 37. The light wave from the light source 704 is incident on the hologram element 751 from the lateral direction, and the P-polarized light is diffracted by approximately 90 ° by the diffractive optical element and is incident on the liquid crystal element 701.

The S-polarized light passes through the hologram element 751 and is incident on another hologram element 752.
The diffractive optical element 752 is formed so as to generate a refractive index distribution with respect to the S-polarized light.
The polarized light is diffracted by approximately 90 ° and emitted. After this, λ
/ 2 plate 753, the polarization plane is rotated by 90 °, and P
The light enters the liquid crystal element 701 as polarized light.

Therefore, almost all of the light amount from the light source 704 can be used for the display of the liquid crystal element as in the embodiment 5-10. Further, since light is incident from the lateral direction, a see-through type function or a combination type of an external light source and an internal light source as described in Embodiment 5-4 is also possible.

In the actually manufactured image display device, the light source 7
A fluorescent lamp passed through a green filter as 04 was used to emit light having a wavelength of about 0.55 μm. VGA of about 0.9 inch as liquid crystal element
A small liquid crystal panel having a resolution of (640 × 480) was used. When an image signal is input to this, the liquid crystal element 7
The light passing through 01 is incident on another hologram element 703 after its polarization direction is modulated according to the applied signal of the pixel.

Here, the S-polarized light is diffracted upward from the plane of the paper and is emitted out of the viewing range of the observer. The P-polarized light passes through the hologram element 703 as it is and is recognized by an observer.

In this case, the magnifying optical system 754 was used on the light emission side of the hologram element 703. Here, a planar Fresnel lens was used as the magnifying optical system. As a magnifying optical system, a convex lens or a liquid crystal lens using an in-plane change in refractive index can be used. It is preferable to form a magnifying optical system with a thin lens because a small system can be formed.

When observing the direction of the hologram element 703 from the position of the observer, an image corresponding to the applied input signal was correctly recognized. Also, despite the use of a small 0.9-inch liquid crystal panel this time, the magnifying optical system 75
By the operation of 4, the display image was enlarged by the observer depending on the distance from the hologram element 703, and the observer could clearly recognize the display image.

The configuration as shown in FIG. 37 can reduce the size of the entire system, and is expected to be used as a very small image display device that can be used as a micro display for a portable information terminal.

(Embodiment 6) An image display device using the hologram element described in Embodiment 1 will be described.

FIG. 38A shows the configuration of the image display device. In this image display device, the transmission type liquid crystal panel 8
The hologram element 820 according to the present invention is used for 19 backlight units.

The light flux 824 from the light source 823 is
1 and diffracted in the direction substantially normal to the substrate of the liquid crystal panel 819 by the hologram element 820 of the present invention installed on the back surface while propagating through the light guide 821 while propagating through the light guide 821. The light beam 822 incident on the liquid crystal panel 819 is modulated to display an image.

[0328] Incidentally, a reflection mirror 826 provided on the back surface of the hologram element 820 has a structure capable of further reflecting the light transmitted through the hologram element 820, for example, a dot (not shown allowed to scatter light to the reflecting mirror 826, It is preferable to form a large number of known techniques other than the conventional example 7).

The liquid crystal panel 819 may be of a transmission type, and any type of liquid crystal panel can be used regardless of the driving method and liquid crystal material. Note that a reflective liquid crystal panel that is also used as a transmissive type according to the brightness of external light may be used.

As the light source 823, for example, CCFT can be used, and a reflecting mirror 825 may be provided as disclosed in many examples including the conventional example 8. Light guide 82
As 1, a resin material such as acrylic can be mainly used, and for example, a wedge-shaped shape can be used as disclosed in, for example, Conventional Example 7 and Japanese Patent Application Laid-Open No. 9-5743.

The basic function of the hologram element 820 is as follows.
In the non-polarized light beam 824 incident on the hologram element, a specific polarization component is selectively diffracted in a substantially normal direction of the liquid crystal panel 819 and within a specific solid angle. Or as a mere isotropic medium.

That is, as shown in FIGS. 39 (a) and (b), for example, it can function as a hologram element when no voltage is applied, and can function as an isotropic medium when voltage is applied. When functioning as a hologram element, the hologram element 820 according to the present invention selects only a specific polarization component in the non-polarized incident light beam 824 in a direction substantially normal to the liquid crystal panel and within a specific solid angle. Diffraction occurs.

At this time, if the liquid crystal panel is of a polarization type, that is, a method of modulating only a specific polarized light, and a polarizing plate (not shown) is provided on the light incident side, the polarization direction of the polarizing plate is changed. High efficiency can be realized for the first time by making the polarization direction of the electric field vector of the polarized light transmitted through the polarizer substantially the same as the polarization direction of the polarized light that the hologram element selectively diffracts (the vibration direction of the electric field vector). .

On the other hand, when a voltage is applied, the hologram element 820 of the present invention becomes a substantially isotropic medium, and the incident light flux 82
4 transmits the hologram element 820, and the light beam scattered by the reflection mirror 826 provided on the back surface enters the liquid crystal panel 819. The liquid crystal panel 81 in this case
The output light flux of No. 9 is almost uniformly diffused by the dots provided on the reflection mirror 826 in the same manner as when illuminated by a conventional backlight.

Thus, the hologram element 82 of the present invention
In the image display device using 0, when no voltage is applied, the illumination light is diffracted within a narrow solid angle substantially in the normal direction, so that the brightness when the liquid crystal panel 819 is observed from the front is extremely high. Further, by applying a voltage, the luminance when observing from the front is reduced, but a wide viewing angle can be secured.

The hologram element is used in the backlight unit of the liquid crystal panel as in the present invention, and the directivity is given to the diffracted light so that the luminance when viewed from the front (when viewed from the normal direction of the liquid crystal panel) is increased. Many examples are disclosed, for example, Conventional Example 7 to Conventional Example 10, but in the above example, the hologram element has only a single function of always diffracting incident light. Element 8
The viewing angle cannot be switched as in the case of 20.

In the prior arts 1 and 2, switchable hologram elements are disclosed, but no specific use as a backlight of a liquid crystal panel is disclosed. As described above, high efficiency can be realized only by making the polarization direction of the polarizing plate of the liquid crystal panel coincide with the polarization direction of light selectively diffracted by the hologram element.

The function of the image display device of the present invention, which can switch the brightness and the viewing angle of an image, is extremely valuable when used as a display of a personal computer or a portable information terminal regardless of whether it is a stationary type or a notebook type. Function.

That is, when an image is viewed by an individual, the viewing angle (meaning equivalent to the range in which the image can be viewed)
It is not necessary to be unnecessarily wide, and a limited range necessary for image observation such as work is sufficient. According to the present invention, an image is output substantially in the direction of a worker observing the image from the front, so that the power consumption of the lamp can be reduced.

On the other hand, when observing an image with a large number of people, it is desirable that the viewing angle is wide. Therefore, the function of changing the viewing angle between the case of observing an image by an individual as in the present invention and the case of observing the image by a large number of people is important. However, strictly, the viewing angle is not changed, and the hologram element 820 of the present invention means that the amount of light flux reflected within a specific narrow solid angle can be controlled by an applied voltage.

Next, a method of manufacturing the hologram element used in the sixth embodiment will be described.

Hologram element 8 used in Embodiment 6
As described in Embodiments 1 and 4-1, 20 is
For example, a mixture of a UV-curable liquid crystal and a non-polymerizable liquid crystal is injected as a photo-curable liquid crystal into a cell formed of two glass substrates 502 on which ITO 501 is formed, and is illuminated with two-beam interference fringes. it can.

However, it is characterized in that the object light is made to enter the substrate almost perpendicularly at the angle at which the light flux enters the reference light.
At this time, by performing two-beam interference exposure in a state where a voltage is applied, a desired interference as shown in FIG.
The fringes are formed, and the UV-curable liquid crystal is separated from the portions where the intensity of the interference fringes is high, and the non-polymerizable liquid crystal is separated from the portions where the intensity is low, thereby producing the hologram element 820 of the present invention.

In actual production, both the object light and the reference light do not need to be plane waves. For example, a light beam that spreads within a specific solid angle as the object light is used as the reference light.
It is preferable to use a light beam that propagates from the same angle range as the light beam that enters the hologram element after propagating through the hologram element.

Further, in the above configuration, for example, the ITO 501 of the hologram element 820 according to the present invention may be patterned, and the applied voltage may be varied for each region to locally control the refractive index anisotropy. Thereby, the efficiency of the hologram element 820 can be locally optimized. Further, for example, as disclosed in Conventional Example 7, the hologram elements may be arranged in a small mosaic pattern, and the individual micro hologram elements may be optimized so as to exhibit the maximum efficiency with respect to the wavelength of the incident light and the incident angle. .

Also, as shown in FIG. 38B, a λ / 4 plate 827 is provided between the hologram element 820 according to the present invention and the reflection mirror 826 , and the reflection mirror 826 is not parallel to the hologram element 820. The hologram element 82 according to the present invention can be arranged at an angle of, for example, about 5 °.
In a mode in which an extraordinary ray is selectively diffracted without applying a voltage to 0, for example, the ordinary ray 828 passing through the hologram element 820 can be converted into an extraordinary ray and then incident on the hologram element 820 again.

At this time, since the reflection mirror 826 is installed at an angle, the reflected light flux 829 from the reflection mirror 826 is transmitted through the hologram element 820 and reflected by the hologram element 820 due to the angle dependence of the hologram element 820. The same polarized light as the light beam 822 (in this case, P-polarized light) can be incident on the liquid crystal panel 819, and the light use efficiency can be increased.

[0348] As described above, the image display apparatus constructed in the sixth embodiment has the hologram element 82 according to the present invention.
By adjusting the applied voltage to zero, it is possible to control the amount of light flux output within a particular solid angle. As a result, a bright image display with a narrow viewing angle but
Although it becomes slightly darker, a wide viewing angle can be selected.

The image display device according to the sixth embodiment can be used not only as a display for a stationary or notebook personal computer but also as a display for a portable information terminal, a portable communication device, or a head-up for a vehicle. It can be used as a display.

(Embodiment 7) An image display device according to the present invention configured as Embodiment 7 of the present invention will be described. The image display device according to the seventh embodiment is a so-called conventional direct-view type liquid crystal panel. As a liquid crystal material, a mixture of a photocurable liquid crystal and a non-polymerizable liquid crystal is mixed with a grid-like light (wavelength) equivalent to the pixel pitch. Illuminates the light-curable liquid crystal) to form a microcell structure surrounding each pixel by a photo-induced phase separation phenomenon.

However, ne and no after curing of the photocurable liquid crystal are substantially equal to ne and no of the non-polymerizable liquid crystal, respectively.

With the above-described microcell structure, liquid crystal molecules are aligned in an axially symmetric state stabilized by a photocuring reaction by a self-alignment force in a liquid crystal region, and a wide viewing angle and high contrast can be realized.

Next, the difference between the conventional example and the image display device according to the seventh embodiment will be described. The effect of improving the viewing angle and realizing high contrast by the microcell is disclosed, for example, in Conventional Example 6. However, in Conventional Example 6, lattice-like light (wavelength: The photocurable resin is illuminated with a wavelength) to form a microcell structure surrounding each pixel by a photo-induced phase separation phenomenon, but there is no description about the refractive index anisotropy of the photocurable resin. I haven't.

Generally, the photocurable resin has a slight but birefringent property and exhibits a slight refractive index anisotropy. Therefore, when displaying black, the contrast is good for a vertically incident light beam, but there is a disadvantage that the grating portion stands out as a discontinuous region and the uniformity is poor for an obliquely incident light beam. Was.

However, in the image display device of the seventh embodiment, the photo-curable liquid crystal is cured in the same alignment state as that of the non-polymerizable liquid crystal when displaying black, and the optical In order to make the anisotropy substantially equal to the optical anisotropy of the non-polymerizable liquid crystal, the portion of the microcell is conspicuous during black display, and it is possible to suppress a decrease in contrast,
An extremely uniform image could be displayed.

(Embodiment 8-1) FIG. 40 shows an outline of an optical information processing apparatus using the volume hologram element shown in Embodiment 2-1 and configured in Embodiment 8-1 of the present invention. Show. Light emitted from the semiconductor laser 901 that emits polarized light passes through the volume hologram element 521 as it is,
The light is focused on the optical storage medium 906 via the quarter-wave plate 905 by the imaging lens 904. In this case, the laser beam passing through the volume hologram element 521 is not diffracted, and almost all the emitted light from the semiconductor laser 901 is focused on the optical storage medium 906.

Next, the light reflected by the optical storage medium 906 passes through the quarter-wave plate 905 again and passes through the imaging lens 904.
Converges. At this time, since the reflected light passes through the quarter-wave plate twice, the polarization direction of the reflected light is rotated by 90 ° with respect to the light emitted from the semiconductor laser 901. Therefore, this time, the reflected light undergoes a diffractive action according to the predetermined wavefront formed on the volume hologram element 521, and is converged on the photodetector 902.

[0358] Here, an optical signal is detected for each of the divided areas on the photodetector 902, and a focus shift, a tracking shift,
And a signal of information recorded on the optical storage medium is detected. At this time, the amount of light guided to the photodetector 902 is substantially determined by the light use efficiency of the volume hologram element 521 due to polarization separation on the outward path and the diffraction efficiency on the return path.

FIG. 41 and FIG. 42 show the principle and structure of the volume hologram element 521 of the present invention. FIG. 41 shows a refractive index ellipsoid of a uniaxial optical crystal. FIG. 41A shows a refractive index ellipsoid when the optical axis is in the Y direction. At this time, the light whose polarization direction exists on the YZ plane becomes an extraordinary ray and shows the refractive index of Ne. XZ
It becomes an ordinary ray for light whose polarization direction exists in the plane,
No indicates the refractive index.

FIG. 41B shows a refractive index ellipsoid when the optical axis of the uniaxial optical crystal is inclined by 90 ° from the Y direction. In this case, the light having the polarization direction in the YZ plane has a No refractive index, and the light having the polarization direction in the XZ plane also has a No refractive index.

In the state where the optical axis is intermediate between (a) and (b), Ne and No (Ne> Ne) corresponding to the state of inclination of the optical axis with respect to light whose polarization direction exists on the YZ plane. No) takes an intermediate value of the refractive index. On the other hand, for light whose polarization direction exists on the XZ plane, the refractive index always indicates No, regardless of the inclination of the optical axis.

As described above, for the optical medium having the refractive index anisotropy, Ne to No.
There is a case where the refractive index distribution is within the range described above and a case where the refractive index distribution is only No, regardless of the inclination of the optical axis.

FIG. 18 is a diagram showing a sectional structure of the volume hologram element. The inside of this element has a periodic layer structure inclined from the surface on which light is incident to the thickness direction. The inclination of the optical axis of the optical medium having the refractive index anisotropy between adjacent layers is one because of the volume hologram element 521.
Are arranged so as to be parallel to the surface, and the other is arranged perpendicular to the surface.

In this volume hologram element 521, light having a polarization direction perpendicular to the plane of FIG. 18 is regarded as an ordinary ray, and light having a polarization direction parallel to the plane of FIG. 18 is regarded as an extraordinary ray. The behavior when the light enters the volume hologram element 521 will be considered.

First, when an ordinary ray is incident, X in FIG.
Since the same treatment is performed as when light having a polarization direction is incident on the -Z plane, the refractive index of each layer is No, regardless of the direction of the optical axis of the optical medium constituting each layer. That is, since a medium having a uniform refractive index of No is present, the ordinary ray incident on the medium is not affected by diffraction, and FIG.
As shown in FIG.

Next, the case where an extraordinary ray is incident will be considered. In a layer in which the optical axis of the optical medium having the refractive index anisotropy is arranged parallel to the incident surface, the polarization direction of the incident light is parallel to the optical axis. This corresponds to the case where light having a polarization direction in the YZ plane of FIG. 41 is incident on an optical medium having an optical axis in the Y direction of (a), and passes through a layer having a refractive index of Ne. become.

For a layer where the optical axis of the optical medium is perpendicular to the incident surface of the volume hologram element 521,
Since this corresponds to the case where light having a polarization direction is incident on the YZ plane with respect to FIG. 41B, this layer is treated as having a refractive index of No.

Therefore, the volume hologram element 521 for an extraordinary ray passes through a plurality of layers having different refractive indexes periodically in the thickness direction which is the traveling direction of the incident light. As a result, the incident light beam is subjected to a so-called Bragg diffraction effect in which the light is condensed in a specific direction corresponding to the inclination angle of the layer and the pitch of the period.

As shown in FIG. 18, after passing through the volume hologram element 521, the extraordinary ray changes its optical path corresponding to the layer structure formed inside the element.

As described above, for the volume hologram element 521 in the configuration of the optical information processing apparatus of FIG. 40, the polarization direction of the light emitted from the semiconductor laser 901 is set so as to correspond to the ordinary ray shown in FIG. At this time, the light emitted from the semiconductor laser 901 is not modulated by the volume hologram element 521, and is not modulated by the imaging lens 904.
The light is focused on the optical storage medium 906 via the four-wavelength plate.

The light reflected here again passes through the quarter-wave plate, and enters the volume hologram element 521 via the imaging lens 904. At this time, the polarization direction is 9
The rotation by 0 ° corresponds to the case of the extraordinary ray shown in FIG. Therefore, the light is focused on a specific direction, in this case, on the photodetector 902 in accordance with the periodic refractive index distribution corresponding to the layer structure formed inside the volume hologram element 521.

By having a structure having a periodic structure in the thickness direction as shown in FIG. 18, the Bragg diffraction condition is applied. This is because when light having a certain wavelength enters each layer forming the periodic structure, the light scattered in each layer causes a phenomenon in which the scattered component strengthens in a specific direction corresponding to the wavelength, the incident angle, and the pitch between the layers. .

This is what is called Bragg's diffraction condition. Such a condition results in a three-dimensional configuration with respect to a conventional two-dimensional diffractive optical element, and is blazed (light is converged in one direction). ).

Therefore, the diffraction efficiency can be dramatically improved as compared with the conventional diffractive optical element, and theoretically 100%
Efficiency is possible. In fact, an efficiency of 90% or more can be expected even when taking into account the loss on the way. On the other hand, if a hologram element as shown in FIG. 40 is constituted by a binary diffractive optical element as described above, the diffracted wave will be diffracted symmetrically to the higher order including the 0th order. As a result, the diffraction efficiency in the primary direction is a maximum of about 40%, which is a low value of 1/2 or less as a percentage of the total amount of light passing through the element.

The volume hologram element 521 of the present invention
If the optical information processing apparatus is configured by using the optical storage medium 90,
Since almost all of the reflected light from 6 can be collected on the photodetector 902, there is no problem such as a decrease in the S / N ratio due to a decrease in the light intensity. Furthermore, since the diffraction efficiency of the volume hologram element 521 is high, there is almost no return light amount to the semiconductor laser. Therefore, the problem of instability of the oscillation of the laser as the light source due to the feedback of the light intensity to the semiconductor laser 901 does not occur.

FIG. 18 shows the case where the optical axis of the optical medium constituting the volume hologram element 521 has the largest difference in the refractive index inclined by 90 ° between the adjacent layers. It is also possible to set the difference to an intermediate value between Ne and No.

Further, it is also possible to adjust the diffraction efficiency by selecting a refractive index distribution utilizing this, and arbitrarily set the detected light intensity and pattern for the photodetector 902.

Also, the area of the volume hologram element 521 is divided into several parts, and light signals are received in different areas of the photodetector 902 by shifting the directions in which they are diffracted, respectively. A configuration in which detection is performed efficiently is also possible.

Further, in the case where a plurality of semiconductor lasers 901 are used at different wavelengths and not only writing of optical information but also recording are performed at the same time, different periodic structures, angles, etc. are set according to the respective light wavelengths. Can be recorded in the volume hologram element 521 in a superimposed manner.

(Embodiment 8-2) FIG. 42 shows a method of manufacturing a diffractive optical element used in an optical information processing apparatus according to the present invention.
This will be described with reference to FIG.

The light emitted from the Ar laser 911 having a wavelength of about 360 nm is passed through a mechanical shutter 912 that can be opened and closed by a beam expander 913 to have a diameter of 30 mm.
The beam can be expanded to about 50 mm. The beam is split in two directions by a beam splitter 914 ,
Irradiates at an angle corresponding to the structure of the interference fringes formed on the volume hologram element 521. One of the light beams split by the beam splitter 914 has a shutter 9.
15 are arranged.

Next, a process of manufacturing the cell of the volume hologram element 521 will be described.

[0383] Two transparent conductive electrodes formed of, for example, ITO on a glass substrate were prepared. After cleaning these substrates to remove dust, an alignment film made of a polymer, for example, polyimide is applied by a spin coating method or the like, and an alignment film is formed on the substrate by performing a heat treatment or the like.

Thereafter, a rubbing process is performed in a specific direction by a roller or the like, a seal is printed around one substrate, and beads having a diameter of about 5 μm to 20 μm are dispersed on the other substrate. The two substrates were bonded together such that the rubbing directions were paired with each other to form an empty cell.

A liquid crystal was used as the optical medium having the refractive index anisotropy, and the empty cell fabricated here was injected.
Although the liquid crystal used this time has a positive dielectric anisotropy, it is also possible to use a liquid crystal having a negative dielectric anisotropy.

It contains a photopolymerizable liquid crystal monomer or a photocrosslinkable liquid crystal polymer, and has a property that the liquid crystal is cured by irradiation with light having a wavelength in the ultraviolet region of about 360 nm, and the direction of the liquid crystal molecules is fixed. I have. Although the implantation was performed at room temperature in an air atmosphere, the implantation may be performed at a high temperature of about 40 ° C. to 60 ° C. or in a vacuum atmosphere. After the liquid crystal was injected, the injection port and the vicinity of the deaeration port were sealed with a sealant in the cell, and a liquid crystal sample was completed.

The liquid crystal sample produced as described above was set at the position where the volume hologram element 521 was produced in the optical system shown in FIG. First, with the shutters 912 and 915 opened, the sample position was adjusted so that interference fringes having a pitch of about 1 μm were formed. At this time, the converging angle of the two light beams by the mirror 906 is 15 ° to 45 °.
°, and the irradiation intensity of the Ar laser is 50 mW to 10 mW.
It is about 0 mW.

Next, a process of forming interference fringes on a liquid crystal sample by a laser will be described. First, the liquid crystal sample is set with the shutter 912 closed and the shutter 915 opened. Then, the shutter 912
Is opened for a predetermined time, here about 1 minute, and then closed.

This is the first step. In this step, the liquid crystal sample is hardened in the liquid crystal sample in the region belonging to the bright portion where the intensity of the interference fringes formed by the interference of the two light beams of the laser is increased. The molecular axis is fixed in the direction in which is initially oriented. Here, since a liquid crystal having a positive dielectric anisotropy is used, the liquid crystal molecules are initially uniformly aligned in a direction parallel to the glass substrate, and this state is preserved. On the other hand, in the region belonging to the dark portion of the interference fringes, the light intensity is lower than that of the bright portion, and therefore, hardening of the liquid crystal molecules is hardly promoted in the first step.

Next, as the second step, the liquid crystal sample 2
An AC electric field of about 5 (V / μm) is applied between ITO electrodes as transparent conductive electrodes formed inside the glass substrates. Due to the application of the electric field, uncured liquid crystal molecules in a region belonging to a dark portion of the interference fringes are tilted in a direction perpendicular to the glass substrate. Since the angle of inclination at this time is proportional to the applied electric field, a desired inclination angle, that is, a refractive index difference can be given by adjusting the magnitude of the electric field.

With the voltage applied as described above, the shutter 915 is closed, and the entire surface of the volume hologram element 521 is irradiated with light having a uniform intensity distribution without forming interference fringes for about 5 minutes. Is completely cured, including the liquid crystal.

By performing the first and second steps as described above, a volume hologram element 521 having a structure as shown in FIG. 18 was manufactured. The diffraction efficiency of this element is set to He-N
The measurement was performed using an e-laser while changing the incident polarization direction. The transmittance for ordinary light was about 98%, indicating a high transmittance. The diffraction efficiency of the extraordinary ray in the primary direction was about 90%, and good results were obtained. Therefore, the volume hologram element manufactured here has high polarization separation characteristics and diffraction efficiency, and it has been proved that it is promising as a diffractive optical element used for an information processing apparatus.

(Embodiment 8-3) Two glass substrates opposed to each other are used.
The same process as in -2 was performed, and a liquid crystal sample was prototyped. This sample was set in the optical system shown in FIG. 42, and the light portion of the interference fringes was exposed as a first step.

Next, as a second step, in order to change the orientation direction of the liquid crystal molecules in the region belonging to the stripes of the dark portion from the initial position, setting for applying a magnetic field to the volume hologram sample 521 shown in FIG. 42 is performed. Was. Specifically, a magnetic field was formed around the liquid crystal sample by a superconducting magnet.

Since liquid crystal has dielectric anisotropy, the molecular axis of liquid crystal molecules can be changed by applying a magnetic field as well as an electric field. By the application of the magnetic field as described above, the liquid crystal molecules in the dark area are changed in a direction perpendicular to the glass substrate. Then, in this state, as in Embodiment 8-2, the shutter 915 was closed, and uniform light irradiation was performed on the liquid crystal sample to cure the entire panel.

When a magnetic field is applied, the liquid crystal sample does not need to be formed with ITO or the like as a transparent conductive electrode. Therefore, this process is omitted, the structure is simple, and a less expensive manufacturing is possible. Further, since the influence of the reflected light due to the difference in the refractive index at the interface between the glass and the ITO is removed, the transmittance is increased and the function as the diffractive optical element is also improved.

The diffraction efficiency with respect to the polarization direction of the volume hologram element manufactured by the above-described process is shown in Embodiment 8.
-2 was measured in the same manner. As a result, it has been found that the diffraction efficiency has a performance of 90% or more, and the direction of liquid crystal molecules can be appropriately controlled even by a method by applying a magnetic field.

(Embodiment 8-4) From the step of applying an alignment film to a glass substrate, a trial production of a liquid crystal sample was performed in the same manner as in Embodiment 8-3. In Embodiment 8-4 , polyvinyl cinnamate (PVCi) was used as the alignment film, and the step of roller rubbing was omitted. This sample was set in the optical system in FIG. this time,
In this system, a polarizer is provided immediately after the beam expander 913, and only the linear polarization component of the laser light is used.

First, as a first step, exposure of a region belonging to the bright portion of the interference fringes was performed in the same manner as in Embodiment 8-2. At this time, the interference fringe pattern consists of only the linearly polarized light component of the laser light. When a polymer film is irradiated with linearly polarized light as a light source, molecules that have their main chains (or side chains) oriented in the direction of polarization among the randomly oriented polymers absorb light mainly and cause photoreaction. This causes the film to exhibit optical anisotropy. In a polymer material or the like, the photoreaction process (photoisomerization, photopolymerization, photodecomposition) of the polymer can be controlled by the polarization direction of the irradiated light and the angle formed by the polymer.

Therefore, by controlling the polarization direction of the light in the ultraviolet region constituting the interference fringes, the setting was made so that the orientation direction of the liquid crystal molecules was parallel to the glass substrate.

Next, in the second step, a half-wave plate was placed immediately after the polarizer, and the polarization direction of the laser beam was rotated by 90 °. Then, the shutter 915 was closed, and the liquid crystal sample was irradiated with uniform light having a polarization direction in a direction orthogonal to the polarization direction in the first step. In the region belonging to the dark part, the light part is irradiated with light whose polarization direction is rotated by 90 °, so that the alignment direction of the liquid crystal molecules changes from the position in the first step and is fixed.

The above process makes it possible to form a periodic structure in which the directions of the liquid crystal molecules are different in the layers corresponding to the bright and dark portions of the interference fringes. In this case, since the alignment of the liquid crystal molecules is performed by light irradiation, it can be performed together with the exposure of interference fringes, and the manufacturing process can be simplified. Further, the rubbing method using a roller can be carried out in a non-contact manner, dust and the like can be prevented from being mixed, a highly reliable manufacturing process technology can be established, and mass production can be stably supported.

The volume hologram element 521 manufactured here
Were evaluated in the same manner as in Embodiments 8-2 and 3-3. As a result, the diffraction efficiency is about 70%,
Although the diffraction efficiency was slightly lowered, an efficiency of 50% or more was obtained, and it became clear that a diffractive optical element having a three-dimensional periodic structure was produced.

Further, a process of irradiating light of a wavelength in the ultraviolet region having a specific polarization direction after the application of PVCi as an alignment film and before assembling the cell is introduced to improve the alignment of liquid crystal molecules. You may.

(Embodiment 8-5) Using a process similar to that of Embodiment 8-2, a trial production of a liquid crystal sample was performed.
In this case, a mask was applied to a half area of the sample, and the optical system shown in FIG. 42 was set. Then, the first and second steps were performed in the same manner as in Embodiment 8-2 to produce a volume hologram in a region without a mask.

Next, the beam angle of the two light beams was changed by about 5 ° by changing the angle of the mirror 916 shown in FIG. Then, remove the mask part of the previous sample,
The first and second steps were repeated for this portion to produce a volume hologram.

As a result of evaluating the volume hologram element 521 manufactured as described above, light was diffracted in two different angular directions with respect to the irradiation of the extraordinary ray on the entire surface of the element.

At this time, each diffraction efficiency is 90
%, Which indicates that different layer structures can be favorably formed in a plurality of regions. If this is applied to the configuration shown in FIG. 40, since it is divided in two directions by the volume hologram element 521, signal detection is performed at once in different regions on the photodetector 902, and focus shift, tracking shift, etc. Signal detection can be performed efficiently.

(Embodiment 8-6) A liquid crystal sample was manufactured in the same manner as in Embodiment 8-2. This was introduced into the optical system shown in FIG. 42, and the first step was performed to expose a region belonging to the bright portion of the interference fringes. Here, the angle of the mirror 916 was changed by about 5 ° to form interference fringes with different periods, and in this state, the first step was repeated to expose a light area.

Next, in the same manner as in Embodiment 8-2, the shutter 9
15 , the volume hologram element was manufactured by performing a second step of irradiating the volume hologram element 521 with uniform light.

The volume hologram element 521 manufactured as described above was evaluated. Using an extraordinary ray, the angle of the laser for measuring the diffraction efficiency was set in a direction corresponding to two exposures of the interference fringes, and the measurement was performed at different angles. The diffraction efficiency was about 75% to 80% in two cases. Although the diffraction efficiency is somewhat reduced by forming the interference fringes in a superimposed manner as compared with the case where the interference fringes are formed alone, it is considered that this can be improved by adjusting the thickness of the liquid crystal sample to be large. On the other hand, it had a transmittance of about 98% for ordinary rays, as in Embodiment 8-2.

[0412] As described above, the volume hologram element 521 could be manufactured by superimposing interference fringes. This is optical readout using multiple lasers with different wavelengths,
It is considered to be effective in an optical information processing device that performs recording.

As described above, Embodiments 8-1 to 8-6
In the above, the configuration of the diffractive optical element used in the optical information processing device by using the optical medium having the refractive index anisotropy and the manufacturing method thereof have been described.

As an optical medium having a refractive index anisotropy,
Lithium niobate, KD ₂ PO ₄ , β-BaB ₂ O ₄ , PL
It is also possible to use a uniaxial crystal having an electro-optical effect such as ZT, and to obtain an effect by using a medium having a refractive index anisotropy including a biaxial optical crystal such as KTi PO _4. It is also possible to demonstrate.

It is needless to say that the apparatus can be used as a recording-only or read-only apparatus.

[0416]

As described above, according to the present invention, it is possible to provide a hologram element in which incident light can be switched between diffraction and straight traveling, and in which diffraction of an extraordinary ray obliquely incident upon straight traveling is extremely small. . Further, using the hologram element of the present invention, an inexpensive and highly efficient polarization separation element, and
And a polarized lighting device.
It can be configured with high efficiency, i.e. an image display device capable of displaying a bright image with.

Further, by using the hologram element of the present invention, it is possible to switch between a bright image display with a narrow viewing angle but a bright image display and an image display with a low brightness from the front but a wide viewing angle as needed. Can be configured.

Further, by forming a pixel having a microcell structure of a photo-curable liquid crystal in the image display section, a wide viewing angle, high contrast, and uniform image display can be realized.

Note that the image display device according to the present invention can be variously modified based on the gist of the invention, and is not limited to the above configuration.

Further, according to the present invention, an inexpensive, compact, polarization-separating element having high separation efficiency can be constructed. Further, according to the projection type image display device configured using the polarization splitting element according to the present invention, high light use efficiency can be realized.

Also, the present invention relates to a polarized light illuminating apparatus using a diffractive optical element having a three-dimensional layer structure as a polarization splitting element using an optical medium having refractive index anisotropy, and a projection type image using the same. The present invention relates to a display device. By using an optical medium having a refractive index anisotropy, a specific polarization component is transmitted, and a polarization component orthogonal to the specific polarization component has selectivity according to a polarization direction such as diffraction. Furthermore, since it is formed from a three-dimensional layer structure, the diffraction efficiency in a specific direction is extremely high, and it is theoretically possible to achieve 100% diffraction efficiency.

Since a polarized light illuminating device is formed using a diffractive optical element having such excellent polarization separation and diffraction efficiency characteristics at the same time, an illuminating device having extremely high light use efficiency can be provided. . In addition, investment by using this
By configuring a projection- type display device, a bright image can be obtained with low power consumption.

Further, as described above, it can be widely applied to displays and illumination optical systems, and has great value.

The present invention also relates to a diffractive optical element having a three-dimensional layer structure using an optical medium having refractive index anisotropy, and an image display device and an illuminating device constituted by combining this with a liquid crystal element. is there. By using an optical medium having a refractive index anisotropy, a specific polarization component is transmitted, and a polarization component orthogonal to the specific polarization component has selectivity according to a polarization direction such as diffraction. Furthermore, since it is formed from a three-dimensional layer structure, the diffraction efficiency in a specific direction is extremely high, and it is theoretically possible to achieve 100% diffraction efficiency. An image display device was constructed by combining a liquid crystal element and a diffractive optical element having such excellent polarization separation and diffraction efficiency characteristics at the same time.
Therefore, it is possible to realize a see-through display, a display that is used in combination with external light and an internal light source, and the like, which has high functionality, low power consumption, and compactness. If these image display devices are combined with a magnifying optical system, use as a microdisplay for a portable information terminal can be expected. Furthermore,
It is also possible to use an image display device and a lighting device together. As described above, it can be widely applied to displays and illumination optical systems, and has great value.

Further, the present invention relates to a configuration of a diffractive optical element having a three-dimensional layer structure using an optical medium having a refractive index anisotropy and a method of manufacturing the same. By using a medium, a specific polarization component is transmitted, and a polarization component perpendicular to the specific polarization component has selectivity depending on the polarization direction such as diffraction.

Further, since it is formed from a three-dimensional layer structure, the diffraction efficiency in a specific direction is extremely high, and it is theoretically possible to achieve a diffraction efficiency of 100%.

As described above, the polarization separation element in the illumination optical system such as a display or the like, as well as the optical information processing apparatus for writing and recording an optical signal, because it has excellent polarization separation and diffraction efficiency characteristics at the same time. It can be applied to a wide range of applications, etc., and has great value.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a conventional direct-view type liquid crystal display device.
You.

FIG. 2 shows the configuration of a conventional optical switch and the refractive index of each region.
FIG.

FIG. 3A shows a conventional optical switch for oblique incident light.
FIG. 4 is a diagram showing a function of a switch and a refractive index of each region. (B)
Is a refractive index ellipse that represents the refractive index anisotropy of the obliquely incident light flux
It is a block diagram of a body.

FIG. 4 is a configuration diagram of a conventional polarized light illumination device.

FIG. 5 is a configuration diagram of another conventional polarized light illumination device.

FIG. 6 is a configuration diagram of a conventional projection image display device.

FIG. 7 shows an integration used in a conventional projection type image display device.
FIG.

FIG. 8 shows polarization conversion used in a conventional projection type image display device.
It is a block diagram showing an element.

FIG. 9 is a configuration diagram of a conventional liquid crystal display device.

FIG. 10 shows a hologram element configured in the first embodiment.
Diagram showing the configuration, arrangement of liquid crystal molecules, and the refractive index of each region
It is.

FIG. 11 shows the hologram element configured in the first embodiment.
Functions for obliquely incident light flux and refractive index of each area
FIG.

FIG. 12 shows another hologram element configured in the first embodiment.
The composition of the liquid crystal, the arrangement of the liquid crystal molecules, and the refractive index of each region are shown.
FIG.

FIG. 13 shows a polarization beam splitter configured in Embodiment 2-1.
FIG.

FIG. 14 illustrates a diffraction optical element used in Embodiment 2-1.
The plan view showing the alignment state of the liquid crystal in the manufacturing process
is there.

FIG. 15 shows a diffraction optical element used in Embodiment 2-1.
The alignment state of the liquid crystal in the manufacturing process and the input
FIG. 4 is a schematic diagram illustrating an intensity distribution of interference fringes.

FIG. 16 shows a diffraction optical element used in Embodiment 2-1.
FIG. 3 is a schematic diagram illustrating an alignment state of a liquid crystal in the embodiment.

FIG. 17 shows the diffraction optical element used in Embodiment 2-1.
It is a figure showing the diffraction efficiency.

FIG. 18 illustrates a diffraction optical element used in Embodiment 2-1.
It is sectional drawing which shows an example of an internal structure.

FIG. 19 shows a diffraction optical element used in Embodiment 2-1.
It is a figure showing an example of angle and wavelength dependence.

FIG. 20 is a diagram illustrating the use of the diffractive optical element according to the embodiment 2-2.
FIG. 2 is a configuration diagram of a polarized light separating element.

FIG. 21 shows an example using the diffractive optical element of Embodiment 3-1.
FIG. 2 is a configuration diagram of a polarized illumination device.

FIG. 22 is a diagram illustrating the use of the diffractive optical element according to the embodiment 3-2.
FIG. 2 is a configuration diagram of a polarized illumination device.

FIG. 23 shows the case of using the diffractive optical element of the embodiment 3-3.
FIG. 2 is a configuration diagram of a polarized illumination device.

FIG. 24 shows the structure using the diffractive optical element according to the embodiment 3-4.
FIG. 2 is a configuration diagram of a polarized illumination device.

FIG. 25 shows a case where the diffractive optical element according to the embodiment 3-5 is used.
FIG. 2 is a configuration diagram of a polarized illumination device.

FIG. 26 shows the case using the diffractive optical element according to the embodiment 3-6.
FIG. 2 is a configuration diagram of a polarized illumination device.

FIG. 27 uses the hologram element of Embodiment 4-1.
FIG. 2 is a configuration diagram of the image display device.

FIG. 28 is a transmissive color display of Embodiment 4-2.
Showing an embodiment of a projection type image display device of the type
FIG.

FIG. 29 is a reflective color display according to Embodiment 4-3.
Showing an embodiment of a projection type image display device of the type
FIG.

FIG. 30 shows a case where the diffractive optical element of Embodiment 5-1 is used.
FIG. 1 is a configuration diagram of an image display device according to an embodiment.

FIG. 31 shows an example using the diffractive optical element according to the embodiment 5-2.
FIG. 1 is a configuration diagram of an image display device according to an embodiment.

FIG. 32 shows the case using the diffractive optical element according to the embodiment 5-3.
1 is a configuration diagram of a reflection type image display device.

FIG. 33 shows the case using the diffractive optical element according to the embodiment 5-4.
Configuration diagram of a reflective image display device combined with a backlight
is there.

FIG. 34 shows the case using the diffractive optical element of the embodiment 5-5.
FIG. 1 is a configuration diagram of an image display device according to an embodiment.

FIG. 35 shows a case using the diffractive optical element according to the embodiment 5-8.
FIG. 2 is a configuration diagram of an image display device and a lighting device according to an embodiment.

FIG. 36 shows an example using the diffractive optical element of the embodiment 5-9.
FIG. 1 is a configuration diagram of an image display device according to an embodiment.

FIG. 37 shows the case where the diffractive optical element according to the embodiment 5-10 is used.
1 is a configuration diagram of a small image display device.

FIG. 38 shows a case where the hologram element of Embodiment 6 is used.
FIG. 2 is a configuration diagram of an image display device.

FIG. 39 is used for the image display device according to the sixth embodiment.
It is a block diagram of a hologram element.

FIG. 40 shows the case of using the diffractive optical element of Embodiment 8-1.
FIG. 1 is a configuration diagram of an optical information processing apparatus according to an embodiment.

FIG. 41 is based on a refractive index ellipsoid of a uniaxial optical medium
It is a figure showing an example of refractive index modulation.

FIG. 42 shows a method of manufacturing the diffractive optical element according to Embodiment 8-2.
It is a figure showing an optical system of a method.

DESCRIPTION OF SYMBOLS 501 ITO 502 Glass substrates 503, 504 Regions 503a, 504a Liquid crystal molecules 504 Region 504a Liquid crystal molecules 510 Polarization separation elements 511, 512 Hologram elements 512 Hologram elements 513, 514 Glass substrate 515 UV curable liquid crystal 515a Liquid crystal molecules 515b Liquid crystal molecules 521 Hologram element 522 Optical medium 530 Polarization separation element 531 Total reflection mirror 532 Hologram element 533 Lamp 534 Reflector 540 Polarization conversion element 541 Integrator 542 Lens group 542a Lens 543 Lens group 543a Lens 544 Phase difference plate 545 Condensing lens 546 Field lens 547 image display device 550 the polarization conversion element 551 hologram element 552 retarder 560 the polarization conversion element 561, 562 a hologram element 562 Program element 563 retarder 570 the polarization conversion element 571 lens unit 571a lens 572 and 573 a hologram element 574 retardation plate 575 a condenser lens 576 field lens 577 image display device 578 a projection lens 579 screen 590 the polarization conversion element 600 projection type image display device 601 Polarization illumination device 602 Projection lens 610 Color separation system element 611 Dichroic prism 612-614 Total reflection mirror 620 Color synthesis system element 621-623 Total reflection mirror 624-626 Image display element 627 Dichroic prism 628 Projection lens 629 Screen 630 Color synthesis system Elements 631 to 633 Polarizing beam splitters 634 to 636 Image display element 637 Dichroic mirror 701 Liquid crystal element 702, 703 Hologram element 704 Light source 704a Pump 704b Reflector 710 External light 711 Mirror 720 Liquid crystal element 721 Color filter 731 Image display device 732 Wall 733 Vehicle 741,742 Diffractive optical element 741-744 Hologram element 745,746 Phase difference plate 751 Hologram element 752 Diffractive optical element 754 Plate 754 Enlarge Optical system 819 Transmissive liquid crystal panel 820 Hologram element 821 Light guide 822 Light flux 824 Light flux 825 Reflecting mirror 826 Reflecting mirror 828 Normal ray 829 Reflected light flux 901 Semiconductor laser 902 Photodetector 904 Imaging lens 905 Liquid crystal element 906 Optical storage medium 907 Observation 's 911 laser 912 shutter 913 beam expander 914 beam splitter 916 mirror

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──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI G09F 19/12 G09F 19/12 L G11B 7/135 G11B 7/135 A (31) Priority claim number Japanese Patent Application No. 9-335352 ( 32) Priority date Hei 9 (1997) December 5 (33) Priority claiming country Japan (JP) (31) Priority claim number Japanese Patent Application No. 10-10215 (32) Priority date Hei 10 (1998) January 22 Date (33) Priority claim country Japan (JP) (31) Priority claim number Japanese Patent Application No. 10-10195 (32) Priority date Hei 10 (1998) January 22 (33) Priority claim country Japan (JP)

Claims (82)

[Claims] A first region comprising a photo-curable liquid crystal that is cured by at least a specific wavelength and has a refractive index anisotropy; The wavelength is formed from a second region composed of a non-curable liquid crystal (hereinafter, abbreviated as a non-polymerizable liquid crystal), and the refractive index of the photo-curable liquid crystal to ordinary light and the refractive index to extraordinary light after curing are as described above. A hologram element, wherein a refractive index of a non-polymerizable liquid crystal for an ordinary ray and a refractive index for an extraordinary ray are substantially equal to each other. 2. The method according to claim 1, wherein a switching state of the non-polymerizable liquid crystal is controlled by a voltage applied to the non-polymerizable liquid crystal to control a refractive index of the second region with respect to an incident extraordinary ray. 2. The hologram element according to claim 1. 3. A liquid crystal mixture obtained by substantially uniformly mixing the photocurable liquid crystal and the non-polymerizable liquid crystal is injected between two parallel plate-shaped glass substrates arranged at a specific interval. 2. The method according to claim 1, wherein the plurality of regions are formed by subjecting the injected mixed liquid crystal to interference exposure with a laser beam having a wavelength for curing the photocurable liquid crystal. . 4. A hologram element according to claim 1, further comprising: illuminating means for illuminating the hologram element; and image display means for displaying an image by modulating an output light beam of the hologram element. An image display device characterized by the above-mentioned. 5. The image display device according to claim 4, wherein the hologram element selectively changes only an exit angle of a specific polarized light component from an unpolarized incident light beam. 6. The hologram element has a function of diffracting a specific polarization component (hereinafter abbreviated as a first polarization component) in the incident light from the illumination means in a direction substantially normal to the image display means. The image display device according to claim 4, wherein the hologram element controls the function by controlling a voltage applied to the second region. 7. The image display means has a function of modulating only a specific polarized light component (hereinafter, abbreviated as a second polarized light component), and the image display means selectively diffracts the light by the hologram element. The image display device according to claim 4, wherein the directions in which the electric field vectors of the first polarization component and the second polarization component vibrate are substantially equal. 8. The hologram element further comprising a λ / 4 wavelength plate and a reflection mirror on the back surface of the hologram element, wherein the angle of the reflection mirror is at least 5 ° with respect to the hologram element. 5. The image display device according to 4. 9. A microcell structure surrounded by a photocurable liquid crystal cured at least for each pixel, a non-polymerizable liquid crystal is provided in the microcell, and the photocurable liquid crystal is cured. An image display device, wherein a refractive index for a later ordinary ray and a refractive index for an extraordinary ray are substantially equal to the refractive index of the non-polymerizable liquid crystal for ordinary rays and the refractive index for extraordinary rays, respectively. 10. The first and second hologram elements having at least polarization anisotropy with respect to an incident light beam and selectively diffracting substantially only a first polarization component. An angle θ0 between the incident light beam incident on the hologram element and the optical axis; an angle θ1 between the incident light beam and the first output light beam diffracted by the first hologram element with the optical axis; the first output light beam Is incident on the second hologram element and then diffracted and output.
2 satisfies the following expression: | θ1−θ2 |> 20 | θ0−θ2 | <15. 11. The polarization beam splitting element according to claim 1, wherein the polarization beam splitting element is constituted by holding a hologram material by a glass substrate. 12. The polarization separation element according to claim 1, wherein the hologram material is a UV-curable liquid crystal. 13. The polarization splitting device according to claim 1, wherein the hologram material is a mixture of a photopolymer and a liquid crystal polymer having sensitivity to a wavelength in a specific region. 14. A projection type image display device comprising at least a polarization type image display means and an illuminating means for illuminating said polarization type image display means, wherein said polarization type image display means comprises: An image is displayed by modulating and outputting a specific polarization component in illumination light from the illumination unit incident on the unit, and the illumination unit condenses at least a light emitting unit and an output light flux of the light emitting unit. A first condensing means, the polarization splitting element, and an integrator including first and second fly-eye lenses in which a plurality of microlenses are two-dimensionally arranged in an array; The polarization splitting element is disposed between the first fly-eye lens and the first focusing means, diffracts a first polarization component in the incident light beam, and outputs the diffracted light as the second light beam. A second polarization direction having a polarization direction orthogonal to the polarization component; Is output as a third light flux without being substantially diffracted, and each lens of the first minute lens group forming the first fly-eye lens is the second lens forming the second fly-eye lens. Polarization plane rotating means for forming an image of the light emitting means on the corresponding minute lens in the group of minute lenses, and rotating the polarization direction by approximately 90 ° at a position where the second light beam or the third light beam is imaged. A projection type image display device comprising: 15. A plate-like first and second hologram element arranged substantially parallel to each other and selectively diffracting predetermined polarization components substantially equal to each other, and incident on the first hologram element, A diffracted light beam diffracted by the first and second hologram elements and emitted from the second hologram element; and a diffracted light beam incident on the first hologram element and transmitted through the first and second hologram elements. The angle formed by the transmitted light flux emitted from the second hologram element exceeds 0 ° and is less than 15 °, and is incident on the first hologram element, and the first and second hologram elements Angle of the light beam incident on each hologram element and the light beam diffracted by each hologram element in the light beam diffracted by A polarization splitting element characterized by exceeding 20 ° each. 16. A polarization splitting device according to claim 1, wherein said first and second hologram elements are formed by disposing a hologram material between a pair of glass substrates. Isolation element. 17. The polarization separation element according to claim 2, wherein the hologram material is formed by curing an ultraviolet-curable liquid crystal. 18. The polarization separation element according to claim 2, wherein the hologram material is obtained by curing a mixture of a photopolymer and a liquid crystal polymer having curability with respect to irradiation of light having a predetermined wavelength. The polarization separation element characterized by the above-mentioned. 19. A polarized light separating element for making optical paths of polarized light components in different directions different from each other in a light beam incident on a light emitting means, and a diffracted light beam and a transmitted light beam which are emitted from the polarized light separating means are respectively different from each other. 2. An image display apparatus comprising: a light condensing means for condensing light at a position 2; and a polarization plane rotating means for rotating the polarization direction of an incident polarization component at one of the first and second positions. The polarization splitting means includes first and second plate-shaped hologram elements arranged substantially parallel to each other and selectively diffracting predetermined polarization components substantially equal to each other, and is incident on the first hologram element. A diffracted light beam diffracted by the first and second hologram elements and emitted from the second hologram element; The angle between the transmitted light beam, the transmitted light beam transmitted through the first and second hologram elements, and emitted from the second hologram element exceeds 0 ° and is less than 15 °; Of the light beam incident on the hologram element and diffracted by the first and second hologram elements, the angle between the light beam incident on each hologram element and the light beam diffracted by each hologram element is 20 °. A polarized light separating element, 20. The image display device according to claim 5, further comprising a first and a second fly-eye lens each having a plurality of microlenses arranged therein, and further comprising: Each of the minute lenses comprises an integrator for forming an image of the light emitting means on the corresponding minute lens of the minute lens constituting the second fly-eye lens, and the light condensing means comprises a first light source of the integrator. An image display device comprising a fly-eye lens. 21. The image display device according to claim 5, wherein the diffracted light beam and the transmitted light beam are light beams whose polarization directions are orthogonal to each other, and the polarization plane rotating means changes the polarization direction of the incident light beam. An image display device characterized by being rotated by approximately 90 °. 22. At least a light source, a diffractive optical element having refractive index anisotropy, and a total reflection mirror disposed adjacent to the light source, and a one-way polarization component (P) of light emitted from the light source is provided. Wave or S wave) passes through the diffractive optical element, is reflected by the reflection mirror, exits again through the diffractive optical element, and is substantially orthogonal to the emitted light (S wave or P wave).
When the wave is emitted while changing its propagation direction by the diffractive action of the diffractive optical element, the propagation directions of the diffracted wave from the diffractive optical element and the reflected wave from the total reflection mirror are substantially the same, and A predetermined wavefront of the diffractive optical element is formed so as to have different emission angles. 23. A light source, a diffractive optical element having refractive index anisotropy, a total reflection mirror disposed adjacent to the light source, and a polarization direction of light reflected from the total reflection mirror is changed to a polarization direction of light at the time of emission. In order to rotate in a direction substantially perpendicular to the optical axis, at least a phase plate disposed in the optical path to the diffractive optical element is provided, and a polarization component (P wave or S wave) in one direction of light emitted from the light source is A component that is transmitted through the diffractive optical element, reflected by the reflection mirror, exits through the phase plate and the diffractive optical element, and is substantially orthogonal to the emitted light (S wave or P
When the wave is emitted while changing its propagation direction due to the diffractive action of the diffractive optical element, the directions of propagation of the diffracted wave from the diffractive optical element and the reflected wave from the total reflection mirror are substantially equal to form a substantially parallel light beam. The polarized illuminating device wherein the predetermined wavefront of the diffractive optical element is formed as described above. 24. The polarization illuminating apparatus according to claim 2, wherein the directions of polarization of the diffracted wave from the diffractive optical element and the light wave reflected and emitted by the total reflection mirror are substantially equal. 25. A polarized light illuminating apparatus according to claim 2, wherein said diffractive optical element substantially transmits a light wave reflected by said total reflection mirror and passing through a phase plate. 26. A light source, a pair of diffractive optical elements having refractive index anisotropy, and a phase plate for rotating a polarization direction of an incident light wave in a substantially right angle direction, at least as constituent elements, and light emitted from the light source. Is incident on one diffractive optical element, is transmitted or diffracted for each polarization component (P wave or S wave), and the diffracted wave is incident on the other diffractive optical element, is further diffracted, and exits. In a configuration in which a phase plate is arranged in one of the optical paths of the transmitted wave or the diffracted wave of the optical element, one set is formed so that the light flux transmitted or diffracted by the one set of diffractive optical elements becomes substantially parallel light flux. A polarizing illuminator, wherein the diffractive optical element is arranged. 27. A tilt angle of the set of diffractive optical elements with respect to a plane in which light incident surfaces of the set of diffractive optical elements are substantially parallel to each other and perpendicular to an optical axis of light emitted from the light source. Is less than or equal to 45 °. 28. The polarized light illuminating apparatus according to claim 5, wherein the polarization directions of the substantially parallel light beams emitted from the pair of diffractive optical elements are substantially equal. 29. A set of a diffractive optical element for transmitting or diffracting light emitted from a light source for each polarization component (P wave or S wave) and another diffractive optical element for further diffracting the diffracted wave; When the phase plate arranged in the optical path of either the transmitted wave or the diffracted wave of the set of diffractive optical elements is one constituent unit, the constituent unit composed of the set of diffractive optical elements and the phase plate is plural. A polarized light illuminating device, which is arranged side by side adjacently. 30. The polarized light illuminating apparatus according to claim 8, wherein the light beams emitted from the plurality of constituent units are substantially parallel light beams and have substantially the same polarization direction. 31. The polarized light illuminating apparatus according to claim 8, wherein said phase plate has a function of rotating a polarization direction of an incident light wave in a substantially right-angle direction. 32. The pair of diffractive optical elements forming the plurality of constituent units, the light wave incident surfaces of which are substantially parallel to each other and the one set of which are perpendicular to the optical axis of light emitted from the light source. 9. The polarization illuminating device according to claim 8, wherein the inclination angle of the diffractive optical element is 45 ° or less. 33. The diffractive optical element, wherein a periodic structure is formed using an optical medium having a refractive index anisotropy, and the periodic structure with respect to a polarized component (P wave or S wave) of incident light in one direction. It has a function of producing a refractive index distribution corresponding to the structure, diffracting light by this refractive index difference, and preferentially going straight to a component (S-wave or P-wave) that is substantially orthogonal to the incident light. The polarized illumination device according to any one of claims 1, 2, 5, and 8, wherein 34. The polarized light illuminating device according to claim 12, wherein the periodic structure of the diffractive optical element is formed by the inclination of the optical axis of an optical medium having refractive index anisotropy. 35. The diffractive optical element is constituted by including liquid crystals arranged uniformly, and a photopolymerizable monomer or a photocrosslinkable liquid crystal polymer is added, and the molecular axis of the liquid crystal in response to light irradiation in an ultraviolet region. 13. The polarized light illuminating device according to claim 12, wherein the direction is fixed. 36. The polarized light illuminating apparatus according to claim 1, wherein said diffractive optical element includes a structure in which a plurality of different periodic structures are superposed. 37. The polarized light illuminator according to claim 1, wherein the diffractive optical element has a laminated structure of a plurality of diffractive optical elements having different periodic structures. 38. A first lens array configured by arranging a plurality of lenses in the polarized light illuminating device according to claim 1, and a second lens paired with the first lens array.
A projection display apparatus comprising at least a lens array, a light valve, and a projection optical system for enlarging and projecting an optical image on the light valve. 39. A light flux from a light source is substantially R (red), G
6. A diffractive optical element that separates color into three light beams having different wavelengths corresponding to (green) and B (blue), and that has a different wavefront formed for the light beams having different wavelengths. 8. A polarized light illuminating device according to any one of claims 8 to 8, wherein a first lens array configured by arranging a plurality of lenses, a second lens array paired with the first lens array, a light valve, and the light A projection display device comprising at least a projection optical system for enlarging and projecting an optical image on a bulb. 40. A liquid crystal element having a liquid crystal layer sandwiched between two opposing transparent insulating substrates each having a light source and transparent conductive electrodes patterned to form pixels, and disposed on both sides of the liquid crystal element. And at least one diffracted optical element. The emitted light from the light source is incident on one diffractive optical element and diffracted, and approximately の of the amount of light incident on the diffractive optical element is incident on the liquid crystal element. An image display apparatus, wherein an image is displayed by an operation in which light is modulated for each pixel of the element, and the propagation direction of light after passing through the other diffractive optical element varies depending on the degree of modulation. 41. A liquid crystal element having a liquid crystal layer sandwiched between two opposing transparent insulating substrates each having a transparent conductive electrode patterned to form a pixel, a mirror disposed on one side of the liquid crystal element, and A diffractive optical element, and the incident light to the diffractive optical element by external light is diffracted, passes through the liquid crystal element, is reflected by the mirror, passes through the liquid crystal element again, and thereby each of the liquid crystal elements An image display device, wherein an image is displayed by an operation in which light is modulated for each pixel and a propagation direction of light emitted from the diffractive optical element is different according to the degree of modulation. 42. A liquid crystal element having a liquid crystal layer sandwiched between two opposing transparent insulating substrates having a light source and transparent conductive electrodes patterned to form pixels, and disposed on one side of the liquid crystal element. It is configured to include at least a mirror and a diffractive optical element disposed on both sides of the liquid crystal element. Light emitted from a light source is incident on one diffractive optical element and diffracted, and is approximately 1/1 of the amount of light incident on the diffractive optical element. 2 enters the liquid crystal element, is modulated for each pixel of the liquid crystal element, and an image is displayed by an action in which the propagation direction of light after passing through the other diffractive optical element differs according to the degree of modulation. Light incident on the diffractive optical element by external light is diffracted, passes through the liquid crystal element, is reflected by the mirror, is reflected again through the liquid crystal element, and is modulated for each pixel of the liquid crystal element, according to the modulation degree. hand In a configuration in which an image is displayed by an action in which the propagation direction of light after exiting the diffractive optical element is different, the image is displayed by selectively switching between the light source disposed inside and the external light. Image display device. 43. The diffractive optical element has a periodic structure formed by using an optical medium having a refractive index anisotropy, and the periodic structure is such that a polarization component (P-wave or S-wave) of incident light in one direction is generated. It has a function of generating a refractive index distribution corresponding to the structure, diffracting light by this refractive index difference, and preferentially going straight to a component (S wave or P wave) substantially orthogonal to the incident light. The image display device according to claim 1, wherein: 44. One of the diffractive optical elements has a function of diffracting a P wave of a polarization component of incident light and preferentially traveling an S wave, and the other of the diffractive optical elements diffracts an S wave. And a function for preferentially going straight through the P wave.
The image display device according to any one of claims 1 to 4. 45. The image display device according to claim 4, wherein the periodic structure of the diffractive optical element is formed by inclination of an optical axis of an optical medium having refractive index anisotropy. 46. The diffractive optical element is composed of a liquid crystal arranged uniformly, and a photopolymerizable monomer or a photocrosslinkable liquid crystal polymer is added, and the molecular axis of the liquid crystal in response to light irradiation in the ultraviolet region. The image display device according to claim 4, wherein the direction is fixed. 47. The method according to claim 1, wherein an electric field applied to each pixel formed in said liquid crystal layer is controlled to modulate light incident on each pixel. Image display device. 48. The image display device according to claim 1, wherein said diffractive optical element has a structure in which a plurality of different periodic structures are formed so as to overlap with each other. 49. The image display device according to claim 1, wherein said diffractive optical element has a laminated structure of a plurality of diffractive optical elements having different periodic structures. 50. The image display device according to claim 1, wherein one side of said liquid crystal element is combined with a color filter comprising red (R), green (G), and blue (B). An image display device characterized by the above-mentioned. 51. The image display device according to claim 1, wherein the light emitted from the diffraction grating is divided into approximately two directions, one of which is for image display and the other is for illumination light. An image display device and a lighting device, wherein the image display device is used as 52. A liquid crystal element having a liquid crystal layer sandwiched between two opposing transparent insulating substrates each having a light source and a transparent conductive electrode patterned to form a pixel, and one side of the liquid crystal element being refracted. Having a diffractive optical element having a refractive index anisotropy and a phase plate for rotating the polarization direction of the incident light wave in a substantially right-angle direction, and further having a refractive index anisotropy disposed on the other side of the liquid crystal element And at least a diffracting optical element, and the emitted light from the light source is a polarization component (P wave or S wave) substantially equal to the diffractive optical element and the phase plate.
Is converted into a liquid crystal element, and is modulated for each pixel of the liquid crystal element, and an image is displayed by an action in which the propagation direction of light after passing through the other diffractive optical element differs depending on the degree of modulation. Image display device. 53. A small-sized image display comprising at least a combination of the image display device according to claim 1, and an enlargement optical system for enlarging and displaying an optical image from said image display device. A small-sized image display device comprising the device. 54. A liquid crystal element for modulating the polarization direction of incident light according to an applied voltage, and arranged on both sides of the liquid crystal element to selectively diffract a predetermined polarization component. An image display device comprising: a first and a second pair of diffractive optical elements that transmit a predetermined polarization component and a polarization component having a polarization direction orthogonal to the first polarization component. 55. The image display device according to claim 1, wherein the first diffractive optical element is one of a transmitted polarized light component and a diffracted polarized light component of a light beam incident from the outside. Is incident on the liquid crystal element, and the second diffractive optical element has a polarized light component transmitted through the second diffractive optical element and a polarized light component diffracted by the diffractive optical element in a light beam emitted from the liquid crystal element. The image display device is configured to emit light in directions different from each other. 56. The image display device according to claim 2, further comprising a light source, wherein said first diffractive optical element converts a polarization component of a light beam from said light source transmitted through said diffractive optical element to said liquid crystal element. An image display device, wherein the image display device is configured to be incident on the image display device. 57. The image display device according to claim 2, further comprising: a light source arranged in a normal direction of said first diffractive optical element, wherein said first diffractive optical element receives light from said light source. An image display device, wherein a polarized component of a light beam transmitted through the diffractive optical element is incident on the liquid crystal element. 58. The image display device according to claim 2, further comprising a light source disposed in a direction inclined from a normal line direction of said first diffractive optical element, wherein said first diffractive optical element comprises: An image display device, wherein a polarized light component diffracted by the first diffractive optical element in a light beam from the light source is incident on the liquid crystal element. 59. The image display device according to claim 2, further comprising: reflection means provided at a predetermined interval outside of said first diffractive optical element; and said first diffractive optical element. And a light source for causing a light beam to enter the diffractive optical means from a direction inclined from the normal line of the diffractive optical element via a distance between the first diffractive optical element and the reflecting means. A polarized light component diffracted by the first diffractive optical element and a polarized light component incident from the reflecting means and transmitted through the first diffractive optical element are incident on the liquid crystal element. An image display device characterized by the above-mentioned. 60. A liquid crystal element for modulating the polarization direction of incident light in accordance with an applied voltage, and disposed on one side of the liquid crystal element to selectively diffract a predetermined polarization component. An image display device comprising: a diffractive optical element that transmits a polarized light component having a polarization direction orthogonal to a predetermined polarized light component; and reflecting means disposed on the other surface side of the liquid crystal element. 61. The image display device according to claim 1, wherein said diffractive optical element has a periodic structure formed by using an optical medium having a refractive index anisotropy, and a P wave in incident light. And a refractive index difference corresponding to the periodic structure is generated for any one of the polarization components of the S-wave and the component that causes diffraction of light due to the refractive index difference and is substantially orthogonal to the incident light. Is an image display device having a function of traveling straight ahead with priority. 62. The image display device according to claim 1, wherein one of the diffractive optical elements has a function of diffracting a P wave of a polarization component of incident light and preferentially traveling an S wave. An image display device, wherein the other of the diffractive optical elements has a function of diffracting an S-wave and preferentially traveling a P-wave straight. 63. The image display device according to claim 8, wherein the periodic structure of the diffractive optical element is formed by inclination of an optical axis of an optical medium having refractive index anisotropy. apparatus. 64. The image display device according to claim 8, wherein the diffractive optical element is configured to include liquid crystals arranged uniformly, and a photo-polymerizable monomer or a photo-crosslinkable liquid crystal polymer is added. An image display device, wherein a direction of a molecular axis of a liquid crystal is fixed with respect to light irradiation of a region. 65. The image display device according to claim 1, wherein said diffractive optical element includes a structure formed by superimposing a plurality of different periodic structures. 66. The image display device according to claim 1, wherein said diffractive optical element includes a laminated structure of a plurality of diffractive optical elements having different periodic structures. 67. The image display device according to claim 1, further comprising a color filter having red, green, and blue regions formed on one side of said liquid crystal element. An image display device characterized by the above-mentioned. 68. The image display device according to claim 1, further comprising an enlargement optical unit for enlarging and displaying a display image. 69. A liquid crystal element having a liquid crystal layer sandwiched between two opposing transparent insulating substrates each having a light source and a transparent conductive electrode patterned to form a pixel, and one side of the liquid crystal element being refracted. Having a diffractive optical element having a refractive index anisotropy and a phase plate for rotating the polarization direction of the incident light wave in a substantially right-angle direction, and further having a refractive index anisotropy disposed on the other side of the liquid crystal element And at least a diffracting optical element, and the emitted light from the light source is a polarization component (P wave or S wave) substantially equal to the diffractive optical element and the phase plate.
Is converted into a liquid crystal element, and is modulated for each pixel of the liquid crystal element, and an image is displayed by an action in which the propagation direction of light after passing through the other diffractive optical element differs depending on the degree of modulation. Image display device. 70. A laser emitting polarized light, an optical lens for converging laser light emitted from the laser on an optical storage medium, and a polarization direction of the laser light reflected by the optical storage medium. A phase plate for rotating in a direction substantially perpendicular to the polarization direction, a diffractive optical element arranged in an optical path of the reflected light to generate a predetermined wavefront, and a light receiving element for detecting light diffracted by the diffractive optical element A diffractive optical element used for an optical information processing device having at least an element as a constituent element, wherein the diffractive optical element is formed using an optical medium having a refractive index anisotropy, and The predetermined wavefront is formed so that the ratio of the amount of light reflected and diffracted in the primary direction to the total amount of laser light after passing through the diffractive optical element is approximately 1/2 or more. Diffractive optical element. 71. An incident light having a periodic structure in the thickness direction.
A refractive index distribution corresponding to the periodic structure is generated with respect to the polarization component in the direction, a diffraction of light is caused by the difference in the refractive index, and a priority is given to a component orthogonal to the polarization component of the incident light. 2. The diffractive optical element according to claim 1, wherein the diffractive optical element has a function of causing the light to travel straight. 72. The optical recording medium according to claim 2, having a periodic structure in a thickness direction, wherein said periodic structure is formed by inclination of an optical axis of an optical medium having refractive index anisotropy. Diffractive optical element. 73. A photopolymerizable liquid crystal monomer or a photocrosslinkable liquid crystal polymer is added, wherein the liquid crystal molecules are uniformly arranged, and the direction of the molecular axis of the liquid crystal is fixed with respect to the irradiation of light in the ultraviolet region. The diffractive optical element according to claim 2, wherein the diffractive optical element is formed. 74. The apparatus according to claim 1, wherein the polarization direction of the laser light incident on the diffractive optical element is substantially parallel or perpendicular to the optical axis of the optical medium having the refractive index anisotropy.
The diffractive optical element according to the above. 75. An optical medium having refractive index anisotropy is sealed in a region sandwiched between transparent insulating substrates provided with two opposing transparent conductive electrodes, and a polymer is provided on the transparent conductive electrodes. A method for producing a diffractive optical element having a structure in which a thin film subjected to an alignment treatment is formed, wherein light having two wavelengths in an ultraviolet wavelength range interferes on the diffractive optical element, and has a periodic intensity. A first step of generating interference fringes consisting of a bright portion and a dark portion corresponding to the distribution, and fixing the optical axis of the optical medium in a region belonging to the bright portion of the interference fringes in the initially oriented direction; and An electric field is applied between the electrodes, and in a state where the optical axis of the optical medium in a region belonging to the dark portion of the interference fringe is moved from the direction in which the optical alignment is initially aligned, light irradiation in a uniform ultraviolet region is performed on the entire surface of the diffractive optical element. Including the second step of fixing the optical axis direction by performing Method for manufacturing a diffractive optical element, characterized in that. 76. An electric field applied to the diffractive optical element,
7. The method for manufacturing a diffractive optical element according to claim 6, wherein the positive electrode and the negative electrode are composed of alternating electric fields generated alternately. 77. An optical medium having a refractive index anisotropy is sealed in a region sandwiched between two opposing transparent insulating substrates, and an alignment process made of a polymer is performed on the transparent insulating substrate. A method for manufacturing a diffractive optical element having a structure in which a thin film is formed, comprising: a light portion corresponding to a periodic intensity distribution, wherein light divided into two in an ultraviolet wavelength range interferes on the diffractive optical element; A first step of generating an interference fringe composed of a dark portion and fixing the optical axis of the optical medium in a region belonging to the bright portion of the interference fringe in a direction in which the optical alignment is initially oriented, and applying a magnetic field between the transparent insulating substrates. ,
With the optical axis of the optical medium in a region belonging to the dark portion of the interference fringes being moved from the direction in which the optical alignment was initially oriented, the optical axis direction is fixed by uniformly irradiating light in the ultraviolet region over the entire surface of the diffractive optical element. A method of manufacturing a diffractive optical element, comprising a second step of forming a diffractive optical element. 78. A structure in which an optical medium having refractive index anisotropy is sealed in a region sandwiched between two opposing transparent insulating substrates, and a thin film made of a polymer is formed on the transparent insulating substrate. A method of manufacturing a diffractive optical element having: a light portion corresponding to a periodic intensity distribution by causing light split into two in an ultraviolet wavelength region having a polarized component in one direction to interfere with the diffractive optical element. A first step of causing an interference fringe consisting of a dark part and arranging and fixing the optical axis of the optical medium in a region belonging to the bright part of the interference fringe in a uniform direction depending on the polarization direction of the polarization component. By irradiating the entire surface of the diffractive optical element with light in a uniform ultraviolet region having a polarization direction in a direction substantially orthogonal to the polarization component, the optical axis direction of the optical medium is moved from an initial position and fixed. Diffractive optics, comprising a second step of forming Device manufacturing method. 79. An optical medium having a refractive index anisotropy comprising liquid crystals arranged uniformly, and a photopolymerizable liquid crystal monomer or a photocrosslinkable liquid crystal polymer is added. The method for manufacturing a diffractive optical element according to claim 6, wherein: 80. The interference fringe applied to the diffractive optical element is a highly coherent light source made of a He-Cd laser or an Ar laser, and has a wavelength range of 300 nm to 400 nm. A method for manufacturing a diffractive optical element according to claim 6. 81. The diffractive optical element according to claim 6, wherein the periodic structure is formed by irradiating light to the diffractive optical element a plurality of times for each divided area of the surface of the diffractive optical element. 3. The method for producing a diffractive optical element according to item 1. 82. The diffractive optical element according to claim 6, 8 or 9, wherein a different periodic structure is formed in the diffractive optical element by performing light irradiation on the diffractive optical element a plurality of times. Or a method for manufacturing a diffractive optical element.