JP2014110109A - Lighting optical system, projection device, deflection element, non-depolarization diffusion element and wavelength selective divergence state conversion element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lighting optical system which can be miniaturized without causing a loss of an optical system.SOLUTION: A lighting optical system includes a fluorescent element, a mirror element and a reflection type element. A part of light from a light source is reflected by the reflection type element, reflected light is utilized as light of first color and, at the same time, fluorescent emitted from the fluorescence element is utilized as light of a color different from the first color. Therefore, light from the light source is made incident to one side surface of the mirror element, and the fluorescence from the fluorescence element and reflection light from the reflection type element is made incident to the other side surface. When the reflection light from the reflection type element is made incident at least to the mirror element, the polarization direction of the reflection light from the reflection type element is different from the polarization direction of light from the light source, or an area on which the reflection light from the reflection type element is made incident to the mirror element is different from an area on which the light from the light source is emitted from the mirror element.

Description

  In the present invention, a part of the light from the light source is used as it is as the first color light, and the phosphor is excited by the other part of the light from the light source and has a color different from the first color. The present invention relates to an illumination optical system that generates light, a projection apparatus that projects an image using the illumination optical system, and a deflection element, a non-polarization diffusing element, and a wavelength-selective divergence state conversion element used therefor.

  The blue laser light is separated spatially or temporally, part of the blue laser light is used as blue light, the phosphor is excited with part of the blue laser light, and the green light is emitted using the light emitted by the phosphor. In addition, a technique for generating light of red color and using it as a projection device is known.

  For example, Patent Document 1 discloses that, in an illumination optical system, by rotating and driving a fluorescent wheel that is partly a diffusion region and partly a fluorescence emission region, A technique using a certain time period as a blue light source and using a certain time period as excitation light to a phosphor is disclosed.

  Patent Documents 2, 3, and 4 describe techniques relating to common use of the optical path of blue light and the optical path of light of other colors. For example, in Patent Document 2, an optical path of excitation light to a phosphor is formed by forming a reflection surface on a diaphragm portion of a member on which a diaphragm for cutting a part of a pupil of a projection-side optical system is formed. An example is shown. Patent Document 3 shows an example in which an optical path of excitation light to a phosphor is formed by providing a blue reflection region in a part of a dichroic mirror. Patent Document 4 shows an example in which an optical path of excitation light to a phosphor is formed by using two prisms via an air layer.

JP 2012-68465 A JP 2011-59540 A JP 2011-128522 A JP 2012-73489 A

  38 to 40 are schematic views schematically showing a part of the illumination system in the optical system described in Patent Document 1. FIG. FIG. 38 schematically shows the configuration of the optical system and the optical path in the optical system until the blue light beam 901 from a plurality of blue laser light sources irradiates the fluorescent wheel 907. As shown in FIG. 38, in the optical system described in Patent Document 1, the light beam width of the blue light beam 901 is reduced by the lens 902 and the lens 903, transmitted through the dichroic mirror 904, and then collected by the condensing lens 905 and lens 906. The light is condensed on the fluorescent wheel 907. The fluorescent wheel 907 is divided into a diffusion plate region and a phosphor region depending on the region. By rotating this, a time zone for diffusing the blue light beam and a time zone for obtaining the fluorescence emission from the phosphor are generated periodically. I have to.

  FIG. 39 schematically shows an optical path of the blue light beam 901a after the blue light beam 901 from the plurality of blue laser light sources is applied to the diffusion plate region of the fluorescent wheel 907 in the optical system described in Patent Document 1 (thick). (See solid arrow). The diffusion plate region of the fluorescent wheel 907 is formed on a transparent substrate having translucency, and as shown in FIG. 39, the blue light beam 901 incident on the diffusion plate region is transmitted through the diffusion plate region and diffused blue. The light beam 901a is emitted. The blue light beam 901 a after passing through the diffuser region is converted into a divergence angle by a lens 912 and then enters a dichroic mirror 909 via a mirror 913, a lens 914, a mirror 915, and a lens 916. The dichroic mirror 909 has a characteristic of transmitting with respect to the wavelength band of the blue laser light, and the blue light beam 901a passes through the dichroic mirror 909, passes through the lens 910, and is coupled to the integrator rod 911.

  FIG. 40 schematically shows the optical path of the fluorescent light beam 901b after the blue light beam 901 from the plurality of blue laser light sources is applied to the phosphor region of the fluorescent wheel 907 in the optical system described in Patent Document 1. (See dashed arrow). The phosphor region of the fluorescent wheel 907 is formed on the reflector, and as shown in FIG. 40, the blue light beam 901 incident on the phosphor region generates fluorescence, which is emitted from the incident side as a fluorescent light beam 901b. The Thereafter, the divergence angle is converted by the lens 906 and the lens 905 and then enters the dichroic mirror 904. The dichroic mirror 904 has a characteristic of reflecting with respect to the wavelength band of the fluorescence emission, and the fluorescence emission 901b is reflected by the dichroic mirror 904, passes through the lens 908, and enters the dichroic mirror 909. The dichroic mirror 909 has a characteristic of reflecting with respect to the wavelength band of the fluorescence emission, and the fluorescence emission 901b is reflected by the dichroic mirror 909, passes through the lens 910, and is coupled to the integrator rod 911.

  Thus, in the optical system described in Patent Document 1, the optical path of the light beam after entering the fluorescent wheel 907 is separated by the blue light beam 901a and the fluorescent light beam 901b, and the optical system is enlarged. In the configuration of the optical system described in Patent Document 1, when the fluorescent wheel 907 reflects the wavelength band of the blue light beam 901 without converting it, the dichroic mirror 904 transmits the returned blue light beam, and the lens 903. This is because the light is emitted.

  On the other hand, in the optical system described in Patent Document 2, an optical path of excitation light to the phosphor is formed by forming a reflecting surface on the diaphragm portion of a member on which a diaphragm for cutting a part of the pupil is formed. Thus, light in the red, green, and blue wavelength bands can be extracted from the same surface as the excitation light irradiation surface. However, in such a method, if the excitation light including many light beams is reflected, it is necessary to increase the area of the reflecting surface, resulting in loss of the optical system. That is, there is a problem in that the output value of light from the optical system is reduced when some light is not effectively used.

  In addition, in the optical system described in Patent Document 3, the blue light beam emitted from the blue light source, the return fluorescent light beam and the return blue light beam from the fluorescent wheel can pass through one common dichroic mirror. An example in which a reflection region for reflecting blue laser light with high directivity is provided in a part of the center of the dichroic mirror is shown, but this also causes the same problem as in Patent Document 2.

  Moreover, in the optical system described in Patent Document 4, the optical path of the excitation light to the phosphor is formed by using two prisms through the air layer, but when the blue wavelength light is scattered, Since part of the light enters the optical path of the excitation light, this is also a loss of the optical system.

  Therefore, the present invention provides an illumination optical system that obtains light of two or more colors by using fluorescent light emitted from a phosphor and a part of laser light that is excitation light for emitting the phosphor, and An object of the present invention is to reduce the size of a projection apparatus that uses an image to project without causing loss of an optical system.

  The illumination optical system according to the present invention uses a part of the light from the light source as it is as the first color light, and also excites the phosphor with the other part of the light from the light source to obtain the first color. Is an illumination optical system that generates light of different colors, using the light from the light source as excitation light to generate fluorescence and emit it from the incident surface, and transmitting or reflecting the light from the light source Reflects part of the light from the light source and the mirror element that guides the light to the fluorescent element and transmits or reflects at least the fluorescence emitted from the fluorescent element in a direction different from the direction in which the light from the light source enters. A reflection element that emits light from the incident surface, the light reflected by the reflection element is used as the first color light, the light from the light source is incident on one surface of the mirror element, and the other Fluorescent light from the fluorescent element and reflective element on the surface The reflected light from the reflective element has a polarization direction different from that of the light from the light source at least at the point of incidence on the mirror element, or the area incident on the mirror element is the light source. Is different from a region where light from the mirror element is emitted.

  The reflective element is a deflecting element that deflects the incident light so as to be emitted in a direction different from at least a part of the optical path of the incident light when reflecting the incident light, The mirror element includes a region that reflects light in a first wavelength band that is a wavelength band of light from the light source, and a first wavelength according to an incident position of light from the light source and an incident position of reflected light from the reflective element. You may divide | segment into the area | region which permeate | transmits the light of a belt | band | zone.

Further, the deflecting element is provided with a reflecting surface having an inclination by providing at least one convex part or concave part on the surface, and an average inclination angle of the convex part or concave part is | α _avg | If the incident angle of the incident light to β is β, the convex portion or the concave portion may satisfy | α _avg |> | β |.

  The deflecting element is a reflection type diffractive element, and has a concavo-convex portion that acts as a diffraction grating. The concavo-convex portion has a periodic structure of four periods or more, and the pitch is P, and the incident light If the wavelength is λ, it may satisfy P ≦ λ / sin (2 | β |).

  In the illumination optical system of the present invention, incident light having an incident angle in an angle range of 25 ° or less is incident on the deflecting element, and light emitted from the deflecting element is equal to or greater than the maximum incident angle of the incident light and is 75 °. It may be emitted in the following angle range.

  Further, the light emitted from the deflection element may be emitted to a ring-shaped region surrounding the incident light.

  In the illumination optical system of the present invention, a quarter-wave plate is provided between the mirror element and the reflective element. Light from the light source is incident on the mirror element as linearly polarized light. A non-polarization diffusing element that gives a phase difference of 0.7π to 1.3π when reflecting an incident light beam and diffuses and emits the light. The mirror element is a polarization dichroic mirror having wavelength selectivity, and a light source The light in the first wavelength band, which is the wavelength band of light from, is reflected or transmitted according to the polarization, and the light is polarized in the second wavelength band, which is the wavelength band of the fluorescence from the fluorescent element. Regardless, it may be reflected or transmitted.

  The non-polarization diffusing element has a polarization ratio of the outgoing light of 0.8 or more, and when parallel light is incident, the value of the angle γ that is a half value of the central luminance of the outgoing light is 1 ° or more, 60 An element having a temperature of less than or equal to ° may be used.

  The non-polarization diffusing element may have a reflecting surface having an inclination by providing two or more convex portions or concave portions on the surface, and the convex portions or concave portions may have a lens shape.

  The illumination optical system of the present invention may be provided with a divergence state conversion element that changes the divergence state of light used as light of at least one color in the optical path.

Further, in the illumination optical system of the present invention, the divergence conversion element, the first color or the first color to a light used as a light of different colors, at least 2 wavelengths lambda ₁ and lambda ₂ The light of one wavelength band is incident, the divergence angle of the light of wavelength λ ₁ is smaller than the divergence angle of the light of wavelength λ ₂ , and the divergence state conversion element has the divergence angle of the light of wavelength λ ₁ and the wavelength λ ₂ The divergence state of the light having the wavelength λ ₁ may be changed so that the difference in the divergence angle of the light becomes small.

  Further, the divergence state conversion element increases the divergence state of the light of the first color and does not change the divergence state of the light of a color different from the first color or causes the light of the first color to occur. It may cause a change smaller than the change.

  In the illumination optical system of the present invention, the wavelength band of light from the light source may be a blue wavelength band.

  In addition, the projection device of the present invention includes a light source, any one of the illumination optical systems described above, a modulation element that modulates light emitted from the illumination optical system, and a projection that projects the light modulated by the modulation element to the outside. And an optical system.

  Further, the deflecting element according to the present invention deflects the incident light so that the light path of the emitted light is emitted in a direction different from at least a part of the optical path of the incident light when reflecting the incident light. When incident light having an incident angle in the following angle range is incident, the emitted light from the element is emitted in an angle range not less than the maximum incident angle of the incident light beam and not more than 75 °. To do.

  The non-polarization diffusing element according to the present invention is a reflection type element that gives a phase difference of 0.7π to 1.3π with respect to incident light and diffuses and emits it, and the polarization ratio of the emitted light. Is an element in which the value of the angle γ, which is a half value of the central luminance of the emitted light, becomes 1 ° or more and 60 ° or less when parallel light is incident.

In the wavelength selective divergence state conversion element according to the present invention, when light of at least two wavelength bands including light of two wavelength bands of wavelengths λ ₁ and λ ₂ having different light divergence angles is incident on the same surface in its at least for as the difference in wavelength lambda ₁ of the divergence angle of the divergence angle and wavelength lambda ₂ of light of the light becomes smaller, the wavelength lambda the wavelength lambda ₁ of the light divergence angle is smaller than the _second light It is characterized by changing the divergence state.

  According to the present invention, a part of the light from the light source is used as it is as the first color light, and the phosphor is excited by the other part of the light from the light source to be different from the first color. An illumination optical system that generates colored light can be miniaturized without causing loss of the optical system.

It is a block diagram which shows typically an example of the illumination optical system concerning 1st Embodiment. In the illumination optical system 100, it is explanatory drawing which shows typically the optical path of the fluorescent light beam 101b which is a light beam used as the light of the green and red wavelength band. 3 is a front view showing an example of a fluorescent wheel 106. FIG. 2 is a configuration diagram illustrating an example of a deflection element 11. FIG. 6 is an explanatory diagram illustrating an example of an optical path of a blue light beam on the deflection element 11. FIG. FIG. 6 is a cross-sectional view of a main part showing another example of the deflection element 11. FIG. 6 is a cross-sectional view of a main part showing another example of the deflection element 11. It is sectional drawing which shows typically the example of the area | region division dichroic mirror 102, and the optical path of the blue light beam on the said element. FIG. 6 is a configuration diagram schematically showing another example of the illumination optical system 100. FIG. 6 is a configuration diagram schematically showing another example of the illumination optical system 100. It is a block diagram which shows typically the example of the other example of the illumination optical system 100, and the example of the rotating wheel 116 used for it. FIG. 6 is a configuration diagram schematically showing another example of the illumination optical system 100. 3 is a schematic cross-sectional view showing an example of a wavelength selective divergence state conversion element 118. FIG. 6 is an explanatory diagram showing an example of a combination of a first medium 32 and a second medium 33 used for the wavelength selective divergence state conversion element 118. FIG. 6 is a schematic cross-sectional view showing another example of the wavelength selective divergence state conversion element 118. FIG. It is explanatory drawing which shows the example of correction | amendment of a divergence state. It is explanatory drawing for demonstrating the example of the angle (gamma) used as a half value according to an effect | action. It is a block diagram which shows typically an example of the illumination optical system concerning 2nd Embodiment. 3 is a front view showing an example of a fluorescent wheel 206. FIG. FIG. 6 is a configuration diagram showing an example of a polarization non-resolving diffusion element 41. 6 is an explanatory diagram illustrating an example of an optical path of a blue light beam on the non-polarization diffusing element 41. FIG. FIG. 10 is a cross-sectional view of a main part showing another example of the polarization non-depolarizing diffusion element 41. FIG. 10 is a cross-sectional view of a main part showing another example of the polarization non-depolarizing diffusion element 41. FIG. 10 is a cross-sectional view of a main part showing another example of the polarization non-depolarizing diffusion element 41. It is explanatory drawing for demonstrating the difference of the polarization | polarized-light non-resolving diffusion element 41 and the general diffusion element 80. FIG. It is a block diagram which shows the other example of the illumination optical system 200 typically. It is a block diagram which shows the other example of the illumination optical system 200 typically. It is a block diagram which shows typically the other example of the illumination optical system 200, and the example of the rotating wheel 216 used for it. It is a block diagram which shows the other example of the illumination optical system 200 typically. It is a block diagram which shows typically the example of the projection apparatus concerning 3rd Embodiment. It is a graph which shows the transmittance | permeability of the multilayer film used for the deflection | deviation element 11 of a 1st Example. It is a graph which shows the transmittance | permeability at 45 degrees of the multilayer film used for the dichroic layer 23 of the area | region division dichroic mirror 102 of 2nd Example. It is a graph which shows the transmittance | permeability of the multilayer film used as one medium which comprises an unevenness | corrugation in the wavelength selection divergence state conversion element 118 of a 3rd Example. It is a graph which shows the effective refractive index of two media which comprise an unevenness | corrugation in the wavelength selection divergence state conversion element 118 of a 3rd Example, and diffraction efficiency by it. It is a graph which shows the transmittance | permeability in the incident angle of 45 degrees of the multilayer film used for the dichroic layer of the wavelength-selective polarization dichroic mirror 202 of a 4th Example. It is a graph which shows the effective refractive index of two media which comprise an unevenness | corrugation in the wavelength selection divergence state conversion element 218 of a 5th Example. It is a graph which shows the transmittance | permeability in the incident angle of 20 degrees of the multilayer film used for the reflective film of a 5th Example. It is a schematic diagram which shows typically a part of illumination system among the optical systems described in Patent Document 1. It is a schematic diagram which shows typically the optical path of the blue light beam 901a in the illumination system shown in FIG. It is a schematic diagram which shows typically the optical path of the fluorescent light beam 901b in the illumination system shown in FIG.

Embodiment 1. FIG.
FIG. 1 is a configuration diagram schematically showing an example of an illumination optical system according to the first embodiment of the present invention. An illumination optical system 100 shown in FIG. 1 includes a region-dividing dichroic mirror 102 that transmits or reflects a blue light beam 101 emitted from a laser light source or the like according to an incident region thereof, a fluorescent wheel 106, and a blue light beam 101 that is converted into a fluorescent wheel. A lens group 105 for condensing the light beam 106, an integrator 111 for homogenizing the distribution of the incident light beam, and an optical device for guiding the blue light beam 101 a and the fluorescent light beam 101 b that are reflected light from the fluorescent wheel 106 to the integrator 111. And an element group 110.

  In the example shown in FIG. 1, the lens group 105 is provided with the lens 103 and the lens 104 for reducing the light beam width of the blue light beam 101 and condensing it on the fluorescent wheel 106, but this is not restrictive. Further, as the optical element group 110, the lens 107 for converting the divergence angle, the mirror 108 for deflecting the light beam emitted from the lens 107 toward the integrator 111, and the light beam reflected by the mirror 108 are condensed on the integrator 111. Although the lens 109 is provided, this is not restrictive. The same applies to other examples.

  FIG. 1 also shows a configuration example of the illumination optical system, and also shows an optical path of the blue light beam 101a after the blue light beam 101 is applied to the fluorescent wheel 106 (see thick solid arrows). Note that the blue light beam 101 a is a light beam used as blue light in the illumination optical system 100. FIG. 2 shows an optical path of the fluorescent light beam 101b generated by irradiating the fluorescent wheel 106 with the blue light beam 101 in the illumination optical system 100 shown in FIG. 1 (see broken line arrows). The fluorescent light beam 101b is a light beam used as light of a color other than blue (green and / or red in this example) in the illumination optical system 100. In the following examples, the blue wavelength band is 450 nm, the green wavelength band is 525 nm, and the red wavelength band is 620 nm. However, the wavelength band of each color light is not limited to the above example, and the performance of the laser light source used It can be appropriately changed depending on the hue of each color required for the illumination optical system.

  FIG. 3 is a front view showing an example of the fluorescent wheel 106. As shown in FIG. 3, the fluorescent wheel 106 includes a region where the deflection element 11 is formed, a green phosphor region 12 where the green phosphor is formed, and a red region where the red phosphor is formed. It is divided into a phosphor region 13 and is driven to rotate. The fluorescent wheel 106 has a mechanism in which a time zone in which incident light is incident on the deflecting element 11, a time zone in which the incident light is incident on the green phosphor, and a time zone in which the light is incident on the red phosphor are periodically generated by this rotational driving. It has become.

  The deflecting element 11 is a reflective element that reflects an incident light beam and emits the light from an incident surface. More specifically, the deflecting element 11 has a direction in which the light path of the emitted light does not overlap the optical path of the incident light at least when entering the mirror. Is an element that emits an optical path deflected in a direction different from at least a part of the optical path of incident light. By such a deflecting element 11, the blue light beam 101 incident on the deflecting element 11 is reflected from the incident surface as a light beam passing through an optical path different from the optical path at the time of incidence (see FIG. 1).

  In the green phosphor region 12 and the red phosphor region 13, the phosphor is formed on the reflector, and the blue light beam 101 incident on the region emits fluorescence in the green or red wavelength region. The fluorescent light beam 101b is emitted from the incident surface (see FIG. 2).

  FIG. 4 is a configuration diagram illustrating an example of the deflection element 11. 4A is a front view of a main part of the deflection element 11, and FIG. 4B is an AB cross-sectional view of the deflection element 11 shown in FIG. 4A. As shown in FIG. 4, the deflecting element 11 may have a configuration in which, for example, conical convex portions 14 are arranged on the surface of the base material 15 without a gap. FIG. 4 shows an example in which the conical convex portion 14 is provided on the base material 15. However, the deflection element 11 has at least the surface of the region where the light is incident to be inclined within a predetermined angle range. The specific configuration is not limited as long as it has a shape. For example, what is provided on the surface may be a convex portion or a concave portion. Further, the substrate and the convex portion or the concave portion may be the same member or different members. Hereinafter, in the deflecting element 11, portions having a surface inclined may be collectively referred to as “an inclined structure 14”.

  FIG. 5 shows an example of an optical path of the blue light beam 101a which is an outgoing light beam when the blue light beam 101 is incident on the deflection element 11. In the example shown in FIG. 5, all of the inclined structures 14 provided on the surface of the deflection element 11 have a shape inclined at an angle α with respect to the surface of the base material 15 when the inclined structure 14 is not provided. . In other words, the deflecting element 11 shown in FIG. 5 is formed in a concavo-convex shape made up of an inclined surface whose reflecting surface is inclined at an angle α. When the blue light beams 101-1 and 101-2 are incident on such a deflecting element 11, the light beams are deflected and reflected as the blue light beams 101 a-1 and 101 a-2 depending on the position of the incident surface of the inclined structure 14.

For example, let us consider a case where the incident light side is upward, the counterclockwise direction from the upward normal direction of the base material 15 is a positive direction, and the blue light beams 101-1 and 101-2 are incident at an incident angle ± | β |. Here, the incident angle refers to an intensity that is 1 / e ² with respect to the intensity of the principal ray of the light beam. The blue light beam 101-1 incident at an angle β is emitted as reflected light deflected in the direction of 2α-β by the inclined structure 14 provided on the element surface. When the maximum incident angle of the incident blue luminous flux 101-1 is | β |, the minimum outgoing angle of the outgoing blue luminous flux 101a-1 is 2 | α |-| β |. Therefore, | α |> | If β |, the outgoing blue light beam 101a-1 is deflected in a direction different from the optical path of the incident blue light beam 101-1. Similarly, in the case of the blue light beam 101-2, when the maximum incident angle of the incident blue light beam 101-2 is | β |, the minimum output angle β ′ of the emitted blue light beam 101a-2 is 2 | Since α | − | β |, if | α |> | β |, the outgoing blue light beam 101a-2 is deflected in a direction different from the optical path of the incident blue light beam 101-2.

  If the tilt angle α exceeds 45 °, the light beam is reflected in the lateral direction and a part of the light cannot be used as reflected light. Therefore, the tilt angle α should satisfy 45 °> | α |.

  By the way, when the above condition (here, at least the condition of | α |> | β |) is satisfied, when the incident angle is large, the emission angle of the emitted light beam also becomes large. When the emission angle is large, the lens group 105 cannot capture light, resulting in loss of light quantity. Therefore, the angle range of the incident angle β is preferably 25 ° or less, more preferably 20 ° or less, and 15 ° or less. Further preferred. Similarly, the angle range of the maximum emission angle is preferably 10 ° to 75 °, and the upper limit is preferably smaller than 60 °, and more preferably smaller than 45 °. Further, when reflected, the reflectance of the surface of the inclined structure 14 is preferably 80% or more, and more preferably 90% or more.

  In order to increase the reflectance of the surface of the inclined structure 14, for example, a reflective film may be laminated on the inclined structure 14. Silver, a silver alloy, aluminum, a multilayer film, or the like can be used as a material that exhibits high reflectance when a blue light beam is incident. When a metal reflective film such as silver is used, a high reflectance can be obtained regardless of the incident angle. In the case of using a multilayer film, a non-absorbing material such as a metal oxide can be used. When there is no material absorption, heat generation due to absorption of the material causes a problem.

  The inclined structure 14 of the deflecting element 11 is not limited to a conical shape as long as it has the above function, that is, a function of deflecting and reflecting an incident light beam in a direction in which an optical path of outgoing light is different from an optical path of incident light. It may be a shape or a blaze shape. For example, the shapes shown in FIGS. 6A to 6E may be used. Moreover, the uneven | corrugated shape which has a longitudinal direction extended in the direction different from a slope may be sufficient when it sees with a top view.

FIG. 6 is a cross-sectional view of a main part showing another example of the deflection element 11. FIG. 6A shows an example in which the size of the inclined structure 14 is different in the plane. FIG. 6B shows an example in which the inclined structures 14 having different inclination angles are provided in the plane. As shown in FIG. 6B, when the inclination angles of the inclined structures 14 are different in the plane, the average inclination angle α _avg satisfies | α _avg |> | β | with respect to the incident angle β. It is more preferable that the minimum inclination angle α _min satisfies | α _min |> | β |. Such an example has the effect of reducing the spatial coherency of the incident light due to the irregularity of the element, such as the effect of making the light quantity distribution of the light beam uniform, and the reduction of speckle when using the light beam from the laser light source. The effect can be obtained.

  Further, FIG. 6C shows an example in which the uneven shape of the surface is formed by one inclined structure 14 like an axicon lens. As shown in FIG. 6C, the deflection element 11 having a surface unevenness formed by one inclined structure 14 is suitable for the case where the deflection element 11 is used not on the fluorescent wheel 106 but fixed. (For example, the configuration of FIG. 9 and FIG. 10B described later). By using a single reflecting surface, scattering or the like hardly occurs, and the blue light beam 101a can be generated efficiently. However, since it is a single reflecting surface, the width of the position where the blue light beam 101 is applied to the inclined structure 14 increases in the depth direction. Therefore, when the lens group 105 having a small focal depth is used, the reflected blue color is reflected. In some cases, the lens group 105 cannot efficiently capture the light beam 101a. In such a case, it is preferable to use another example in which the height of the inclined structure 14 in the depth direction is reduced. The preferred height of one inclined structure 14 depends on the depth of focus of the lens group 105, but is preferably 0.5 mm or less, more preferably 0.1 mm or less, in order to accommodate various lens designs, and 0.05 mm. More preferably, it is as follows.

  FIG. 6D shows an example having a blazed inclined structure 14. When the inclined structure 14 is formed in a blaze shape, for example, the height in the depth direction of the inclined structure 14 shown in FIG. 6C can be reduced.

  FIG. 6 (e) shows an example in which a transflective film 16 that reflects part of a blue light beam and transmits green and red light beams is formed on an inclined structure 14 including red and green phosphors. ing. Such a deflection element 11 can be used in an optical system that uses a spatial light modulation element for each color of blue, green, and red without performing time division by the fluorescent wheel 106 (for example, FIG. Configuration of a)). 6E, the blue light beam 101a reflected by the semi-transmissive reflective film 16 and the fluorescent light beam 101b obtained by exciting the phosphor through the semi-transmissive reflective film 16 are simultaneously obtained. By combining these, blue, green, and red light fluxes can be obtained. Here, as the transflective film 16, for example, a multilayer film designed to transmit light in the red and green wavelength bands and to have a reflectance of about 30% in the blue wavelength band may be used. Although not shown, it is assumed that the deflecting element 11 of this example is formed with a reflective film that reflects fluorescence generated below a member including a phosphor.

  Further, the deflecting element 11 may utilize a diffractive action as shown in FIG. 7 in addition to a structure having an inclined surface. FIGS. 7A and 7B are cross-sectional views of the main part showing an example of the deflecting element 11 utilizing the diffraction action. The deflecting element 11 shown in FIGS. 7A and 7B has a structure in which an uneven structure 17 that generates diffracted light is formed on a base material 15. FIG. 7A shows an example in which a concavo-convex structure 17 that functions as a binary diffraction grating is formed. In this case, the convex portion 14 or the concave portion 14 having a rectangular cross section may be formed on the base material 15. FIG. 7B shows an example in which a multistage pseudo blaze is used as the uneven structure 17. In this case, the convex part 14 or the concave part 14 having a stepped cross section may be formed on the base material 15. In the case of a diffraction grating, a large polarization dependency may occur when the pitch of the diffraction grating is smaller than twice the wavelength, but the longitudinal direction of such a diffraction grating and the polarization direction of incident light are the same. A high diffraction efficiency can be obtained by arranging the diffraction gratings in the direction.

Thus, when a diffractive element is used as the deflecting element 11, the distribution of the emitted light is given by the Fourier transform of the basic structure of the diffractive element. Further, the pitch of the basic structure of the diffraction element is P, the wavelength of the light beam incident on the diffraction element is λ, the incident angle is θ _in , the angle of the emitted light beam is θ _out , and the order of the diffracted light is m. In this case, sin θ _out = sin θ _in + mλ / P is established. Therefore, the distribution of the emitted light can be adjusted by designing the basic structure of the diffraction element and adjusting the pitch of the basic structure.

That is, the pitch P and the order m of the diffracted light may be adjusted so that | θ _out |> | β |. In particular, when diffracting an incident light beam with θ _in = 0 ° as ± first-order diffracted light, θ _out ≧ 2 | β | can diffract the emitted light beam in the direction of θ _out ± β. Overlap can be reduced. In this case, it is only necessary to satisfy P ≦ λ / sin (2 | β |) as the pitch of the diffraction elements.

  Further, when the concavo-convex structure 17 has a shape having a longitudinal direction in a plane like a diffraction grating, the shape having a longitudinal direction in an arc shape having a center of curvature at the center of the fluorescent wheel 106, Alternatively, a plurality of regions where the concavo-convex structure 17 having a longitudinal direction in a predetermined direction is combined to form the concavo-convex structure 17 having two or more different longitudinal directions in the plane. The concavo-convex structure 17 preferably has two or more periods of protrusions or recesses, and if it is four or more periods, the emission direction of diffracted light becomes discrete, which is more preferable because it can be separated from incident light.

  Note that the deflection element 11 is not limited to the one that emits the emitted light to an annular region surrounding the incident light flux. For example, regardless of the position of the incident surface, the light may be emitted while being deflected only in the positive direction or only in the negative direction in the positive and negative directions shown in FIG.

  The deflection element 11 can be processed by press molding or cutting. A highly accurate uneven shape can be obtained by such a method. Further, a processing method combining photolithography and etching may be used. Photolithography and etching are preferably used in the case of a rectangular uneven shape like a diffraction element. Moreover, an organic material such as an inorganic material such as glass or metal or a resin can be used as a member of the base material 15 or the convex portion 14. When glass is used, if quartz or heat-resistant glass is used, the thermal expansion is small, so that destruction does not easily occur due to a temperature rise caused by laser irradiation. Moreover, when using resin material, methods, such as an imprint and injection molding which fill and harden resin in the base material which opposes a type | mold, can be used. It is preferable to use a heat resistant resin such as epoxy or silicone resin as the resin.

  FIG. 8A is a cross-sectional view schematically showing an example of the area division dichroic mirror 102. FIG. 8B schematically shows the optical paths of various light beams incident on the area-dividing dichroic mirror 102. The region-dividing dichroic mirror 102 includes a region that transmits light in the blue wavelength band and reflects light in the green and red wavelength bands and a region that reflects light in the blue, green, and red wavelength bands in predetermined regions. What is necessary is just to be provided separately. The area division dichroic mirror 102 shown in FIG. 8 is on the same surface as the base material 21, the antireflection film 22 provided on one surface thereof, the dichroic layer 23 provided on the other surface, and the dichroic layer 23. The reflection layer 24 is provided in a partial region.

  Here, the antireflection film 22 is an optical film that transmits light in the blue wavelength band (more specifically, the blue light beam 101). The dichroic layer 23 is an optical film that transmits light in the blue wavelength band (more specifically, the blue light beam 101) and reflects light in the green and red wavelength bands (more specifically, the fluorescent light beam 101b). It is. The reflective layer 24 is an optical film that reflects light in the blue, green, and red wavelength bands (more specifically, the blue light beam 101a and the fluorescent light beam 101b). Here, the dichroic layer 23 is provided at least in a region where the blue light beam 101 is incident. Moreover, the reflective layer 24 should just be provided in the area | region in which the blue light beam 101a injects at least. Note that either the dichroic layer 23 or the reflective layer 24 may be provided in a region where neither the blue light beam 101 nor the light beam 101a is incident and the region where the fluorescent light beam 101b is incident.

  For example, the region division dichroic mirror 102 can be realized by adding the reflection layer 24 on a partial region of the dichroic layer of the dichroic mirror 904 used in the conventional optical system shown in FIG.

  As the reflective layer 24, an optical multilayer film or a metal film can be used. In addition, the area division | segmentation dichroic mirror 102 is not restricted to the structure which laminates | stacks the reflection layer 24 on the dichroic layer 23 as shown to Fig.8 (a), A area | region is divided | segmented on the base material 21, and the dichroic layer 23 and The reflective layer 24 may be provided by patterning or the like.

  Further, as the integrator 111, for example, an integrator rod or a fly-eye lens can be used.

  Next, the optical path of the light beam of this embodiment will be described. In the illumination optical system 100 shown in FIG. 1, the blue light beam 101 is focused on the fluorescent wheel 106 by the lens group 105 after passing through the dichroic layer of the area-divided dichroic mirror 102. At this time, when the blue light beam 101 is applied to the deflecting element 11, the blue light beam 101 is reflected by the incident surface of the deflecting element 11, and the blue light beam 101 a passes through an optical path different from the incident optical path. Then exit.

  Thereafter, the blue light beam 101 a again enters the lens group 105, and after the divergence angle is converted by the lens group 105, the blue light beam 101 a enters the reflection layer of the region-divided dichroic mirror 102. Then, after being reflected by the reflection layer of the region-dividing dichroic mirror 102, the light is guided to the integrator 111 by the optical element group 110.

  On the other hand, as shown in FIG. 2, when the blue light beam 101 is transmitted through the region-dividing dichroic mirror 102 and the lens group 105 and then irradiated to the green phosphor region 12 or the red phosphor region 13 of the phosphor wheel 106, The luminous flux 101 excites the phosphor to generate green or red wavelength band fluorescence. The generated fluorescence is reflected by a reflecting material provided on the fluorescent wheel 106 and is emitted as fluorescent light emission 101b.

  Thereafter, the fluorescent light emission 101b is incident on the lens group 105, and after the divergence angle is converted by the lens group 105, the fluorescent light emission 101b is incident on the dichroic layer or the reflective layer of the region-divided dichroic mirror 102. Then, after being reflected by the dichroic layer or the reflective layer of the region-divided dichroic mirror 102, the light is guided to the integrator 111 by the optical element group 110.

  The light beams 101a and 101b guided to the integrator 111 are irradiated to a spatial light modulation element (not shown), and an image formed by the spatial light modulation element is projected onto a projection surface by a projection lens (not shown). As the spatial light modulator, LCOS (Liquid crystal on silicon), DMD (digital micromirror device) or the like can be used.

  Although FIG. 1 shows an example in which the deflection element 11 is provided on the fluorescent wheel 106, the deflection element 11 does not necessarily have to be on the fluorescent wheel 106. For example, an arrangement as shown in FIG. 9 may be used. FIG. 9 is a configuration diagram showing another arrangement example of the deflecting element 11 in the illumination optical system 100. FIG. 9 shows only the part related to the optical path from when the blue light beam 101 is incident on the region-dividing dichroic mirror 102 to when it is incident on the region-dividing dichroic mirror 102 again as the blue light beam 101a. In the illumination optical system 100 shown in FIG. 9, the fluorescent wheel 106 has a region including a fluorescent substance in a part thereof, but does not have the deflection element 11 and instead transmits a blue light beam 101. It is set as the structure which has. In addition, a deflection element 11 is provided behind such a fluorescent wheel 106.

  In the case of this example, the blue light beam 101 applied to the region transmitting the blue light beam 101 on the fluorescent wheel 106 is transmitted through the fluorescent wheel 106 and applied to the deflection element 11 provided behind the fluorescent light wheel 106. The blue light beam 101 applied to the deflecting element 11 is deflected by the deflecting element 11 and, as a result, is emitted from the incident surface as a blue light beam 101a passing through an optical path different from the optical path at the time of incidence.

  Further, in FIG. 1, the region-dividing dichroic mirror 102 transmits the blue light beam 101 to guide the fluorescent wheel 106 in a certain direction, and reflects the blue light beam 101a and the fluorescent light beam 101b as return blue light. Although an example of guiding in a direction different from the direction in which the blue light beam 101 has entered is shown, the positional relationship between the region-dividing dichroic mirror 102 and the fluorescent wheel 106 is not limited to this. For example, the region-dividing dichroic mirror 102 reflects the blue light beam 101 to guide the fluorescent wheel 106 in a certain direction, and transmits the blue light beam 101a and the fluorescent light beam 101b, which are return blue light, so that the blue light beam 101 is incident. It is also possible to configure to lead in a direction different from the direction that has been performed.

  In such a case, the region-dividing dichroic mirror 102 is configured to form a region in which a dichroic layer that reflects light in the blue wavelength band and transmits light in the green and red wavelength bands is formed, and in the blue, green, and red wavelength bands. What is necessary is just to divide into the area | region in which the permeation | transmission layer which permeate | transmits light is formed. Note that the dichroic layer may be provided in a region where the blue light beam 101 is incident. The transmissive layer may be provided in a region where the blue light beam 101b is incident without the blue light beam 101 being incident. For example, if the deflecting element 11 emits the emitted light in a state where there is no light flux near the center, that is, in the form of an annular zone, the region-dividing dichroic mirror 102 has a transmissive layer on a base material such as translucent glass. In addition, a dichroic layer may be provided only in the region where the central blue light beam is incident.

  Further, when a spatial light modulator is used for each of blue, green, and red colors, the fluorescent wheel 106 need not be driven to rotate. In this case, an arrangement as shown in FIG. 10A or FIG. 10B may be used.

  FIG. 10 is a configuration diagram schematically showing another example of the illumination optical system 100. FIG. 10A shows only a portion related to the optical path from when the blue light beam 101 is incident on the region-dividing dichroic mirror 102 to when the blue light beam 101a is incident on the region-dividing dichroic mirror 102 again. The illumination optical system 100 shown in FIG. 10A includes a fluorescent element 113 with a blue deflection reflection function instead of the fluorescent wheel 106. When the blue light beam 101 is incident, the fluorescent element 113 with a blue deflection reflection function reflects part of the incident light while deflecting it as blue light, and uses part of the incident light for excitation of the phosphor. Emits emitted light. Note that the fluorescent element 113 with the blue deflection reflection function of the present invention emits the emitted light by deflecting it so that it passes through an optical path different from the incident light when reflecting a part of the blue light beam. As such a fluorescent element 113 with a blue deflection reflection function, for example, the deflection element 11 shown in FIG.

  Further, the example shown in FIG. 10B is an example in which the blue light beam 101 is branched by the area division beam splitter 115 and the blue light beam 101a and the fluorescent light beam 101b are generated in different optical paths and then combined. In FIG. 10B, only the portion related to the optical path from when the blue light beam 101 enters the area-divided dichroic mirror 102 to the blue light beam 101a and the fluorescent light beam 101b again enters the area-divided dichroic mirror 102. It is shown.

  In the illumination optical system 100 shown in FIG. 10B, the blue light beam 101 passes through the dichroic layer of the region-dividing dichroic mirror 102 and then travels toward the lens group 105 a by the beam splitter layer of the region-dividing beam splitter 115. It is divided into luminous fluxes traveling toward the group 105b. The blue light beam 101 traveling toward the lens group 105a is applied to the deflection element 11 by the lens group 105a. On the other hand, the blue light beam 101 directed toward the lens group 105b is irradiated to the fluorescent element 114 by the lens group 105b.

  The blue light beam 101 irradiated on the deflecting element 11 becomes a blue light beam 101a deflected in a direction different from the direction of the incident light, is emitted from the incident surface, and is incident on the region dividing beam splitter 115. In addition, the blue light beam 101 incident on the fluorescent element 114 causes fluorescent emission by the phosphor included in the fluorescent element 114. The generated fluorescent light is emitted from the incident surface as a fluorescent light beam 101b and enters the region split beam splitter 115.

  Although the region-dividing beam splitter 115 of this example is omitted in the drawing, there are a region that transmits a part of the light in the blue wavelength band and reflects a part thereof, and a region that reflects all the light in the blue wavelength band. These may be provided separately in predetermined areas. In any region, light in the green and red wavelength bands is transmitted. The region dividing beam splitter 115 includes, for example, a base material, an antireflection film that transmits light in the green and red wavelength bands provided on one surface thereof, and a blue wavelength band provided in a partial region on the other surface. A beam splitter layer that transmits part of the light in the blue wavelength band, reflects part of the light in the blue wavelength band and transmits light in the green and red wavelength bands, and is provided in a partial region on the same plane as the beam splitter layer And a blue reflection layer that reflects all the light in the blue wavelength band and transmits the light in the green and red wavelength bands. Here, the beam splitter layer is provided at least in a region where the blue light beam 101 is incident. The blue reflective layer is provided at least in a region where the blue light beam 101a is incident. It should be noted that either the beam splitter layer or the blue reflecting layer may be provided in the region where neither the blue light beam 101 or 101a is incident but the region where the fluorescent light beam 101b is incident.

  Even with such a configuration, the blue light beam 101, at least a part of which is excitation light, the blue light beam 101a used as blue light, and the fluorescent light beam 101b used as light of a color other than blue are shared. Therefore, the optical system can be reduced in size.

  Further, in each of the above examples, an example in which two types of phosphors, that is, a green phosphor and a red phosphor, are used. However, the type of the phosphor to be used is not limited to this. For example, one type of fluorescence of the green phosphor is used. Only the body may be used, and red light may be separately emitted from a light source such as an LED, and combined by the area division dichroic mirror 102 or the like.

  By the way, the blue light beam 101a obtained as a result of deflecting the blue light beam 101 by the deflecting element 11 and the fluorescent light beam 101b in the green and red wavelength regions may have different divergence states. In such a case, an element that corrects the difference in the divergence state may be provided in a part of the optical path or in a part of the lens group 105, the region division dichroic mirror 102, the optical element group 110, or the like. For example, the divergence state conversion element 117 and the wavelength selective divergence state conversion element 118 may be provided in a region where the blue light beam 101a is transmitted. By doing so, the influence on the tendency of the green and red wavelength regions can be reduced. As the divergence state conversion element 117 and the wavelength selective divergence state conversion element 118, elements having diffraction, scattering, and lens effects can be used.

  FIG. 11 is a configuration diagram schematically showing another example of the illumination optical system 100 and an example of the rotating wheel 116 used therein. FIG. 11A is a configuration diagram illustrating an example of the illumination optical system 100 in which the divergence state conversion element 117 is provided in the optical path of the blue light beam 101a. In the example shown in FIG. 11A, a rotating wheel 116 is newly added in front of the integrator 111. FIG. 11B is a front view of the rotating wheel 116. As shown in FIG. 11 (b), the rotating wheel 116 of this example is provided with a divergence state conversion element 117 on a partial area thereof, and the rotation is synchronized between the fluorescent wheel 106 and the rotating wheel 116. Thus, the divergence state conversion element 117 is irradiated with the blue light beam 101a during the time zone in which the deflection element 11 is irradiated with the blue light beam 101. In this way, the light divergence state does not change with respect to the green or red fluorescent light beam 101b, and the light divergence state changes only with respect to the blue light beam 101a.

  FIG. 12 is a configuration diagram showing an example of an illumination optical system 100 provided with a wavelength selective divergence state conversion element 118 having wavelength selectivity. In the example shown in FIG. 12, a wavelength selective divergence state conversion element 118 is added in front of the integrator 111 instead of the rotating wheel 116.

  The wavelength selective divergence state conversion element 118 exhibits, for example, a large scattering effect and lens effect for light in the blue wavelength band, but acts on the blue wavelength for light in the green and red wavelength bands. As long as they exhibit a small effect.

FIG. 13 is a schematic cross-sectional view showing an example of the wavelength selective divergence state conversion element 118. The example shown in FIG. 13 is an example in which the divergence state of light in the blue wavelength band is changed using diffraction. In the wavelength selective divergence state conversion element 118 shown in FIG. 13, irregularities made of a first medium 32 and a second medium 33 acting as a diffraction grating are formed on a base material 31, and the refractive index of the irregularities. It is configured to generate diffraction depending on the difference. The wavelength selective divergence state conversion element 118 shown in FIG. 13 changes the divergence state by diffracting a part of the light beam by diffracting it when the light beam of the wavelength λ _{1 in} the blue wavelength band is incident. When a light beam having a wavelength λ _{2 in} the green wavelength band is incident, it is diffused by diffracting a part of the light beam, but most of the light beam is emitted as a component that passes straight through, and the divergence state is obtained. Do not change much. Further, when the light flux of wavelength lambda ₃ of the red wavelength band is incident, the light flux of the majority does not change the divergence state be emitted as a component straightly transmitted.

The magnitude of the change in the divergence state can be represented by the ratio of the amount of light of the component that travels straight ahead sufficiently when the light beam is incident and the component that diffuses. When the ratio of the light amount of the diffusing component at the wavelength λ and the sum of the light amount of the component that passes straight through and the component that diffuses is q (λ), the wavelength selective divergence state conversion element 118 has q (λ ₁ )> q It is only necessary to satisfy (λ ₂ ) and q (λ ₁ )> q (λ ₃ ).

Therefore, when the refractive index of the first medium 32 at the wavelength λ is n ₁ (λ) and the refractive index of the second medium 33 is n ₂ (λ), it is the difference between the two refractive indexes | Δn ( λ) | = | n ₁ (λ) −n ₂ (λ) | is | Δn (λ ₁ ) |> | Δn (λ ₂ ) | and | Δn (λ ₁ ) |> | Δn (λ ₃ ) | Try to meet.

Note that | Δn (λ ₂ ) | and | Δn (λ ₃ ) | are preferably 0.05 or less, and preferably 0.03 or less because the influence of diffraction and scattering caused by the difference in refractive index can be reduced. Further, | Δn (λ ₁ ) | is 0.03 or more under the condition that | Δn (λ ₁ ) |> | Δn (λ ₂ ) | and | Δn (λ ₁ ) |> | Δn (λ ₃ ) | Is preferable, and it is more preferable in it being 0.05 or more. If | Δn (λ ₁ ) | is small, the effect of diffraction or scattering will not be exhibited unless the concavo-convex structure is made large. Thus, the shape of the concavo-convex can be reduced.

  FIG. 14 is an explanatory diagram showing an example of a combination of the first medium 32 and the second medium 33 used for the wavelength selective divergence state conversion element 118. As a combination of materials that cause a difference in refractive index as described above, a combination of a material having a high Abbe number and a material having a low Abbe number as shown in FIG. 14A, or a refractive index as shown in FIG. 14B. A combination of a material that exhibits anomalous dispersion and a material that does not exhibit anomalous refractive index dispersion can be used.

  Further, as the first medium 32 or the second medium 33, an organic substance or a hybrid material of an organic substance and an inorganic substance can be used. However, when the intensity of light in the optical system is high, the wavelength selection with high reliability can be achieved by using the inorganic substance. The divergent state conversion element 118 can be obtained.

  In this case, as the first medium 32, one or more selected from titanium oxide, niobium oxide, zinc sulfide, zinc oxide, bismuth oxide, barium titanate and strontium titanate, silicon oxide and aluminum oxide By using a material containing either or both of these materials, or a material that does not contain these materials and is porous of titanium oxide, niobium oxide, zinc sulfide, zinc oxide, bismuth oxide, barium titanate, and strontium titanate, the Abbe number can be increased. Low material can be obtained. As the second medium 33, a material containing one or more selected from tantalum pentoxide, yttrium oxide, zirconium oxide, silicon oxynitride, silicon nitride, diamond, and diamond-like carbon is used. A material with a high Abbe number can be obtained. The combination of the first medium 32 and the second medium 33 may be reversed.

  Further, as anomalous dispersion of the refractive index, anomalous dispersion caused by absorption of pigments or dyes, or anomalous dispersion caused by a phase delay generated in the vicinity of the reflection band of the multilayer film may be used. That is, as a material showing anomalous dispersion of the refractive index, a material provided with an absorption band or a reflection band that causes anomalous dispersion outside the incident wavelength band so as to draw a steep curve near the blue wavelength band may be used.

  Further, the wavelength selective divergence state conversion element 118 is not limited to the element that diffuses the blue wavelength light using diffraction, but may be the element that diffuses the blue wavelength light using scattering or a lens effect, for example. Good. FIG. 15 is a schematic cross-sectional view showing another example of the wavelength selective divergence state conversion element 118. In the example shown in FIG. 15A, uneven unevenness is formed on the base material 31 by the first medium 32 and the second medium 33, and the unevenness causes the scattering to generate the blue wavelength band. Light is diffused. In the example shown in FIG. 15B, the first medium 32 and the second medium 33 form lens-shaped irregularities, and light in the blue wavelength band is diffused by producing a lens effect. . When the light beam is diffused by diffraction as shown in FIG. 14, the diffused light can be discrete, so that more uniform diffusion can be obtained than when the elements as shown in FIGS. 15A and 15B are used. .

  In addition, the example shown in FIG. 15C is an example in which the concavo-convex shape is made a blaze shape and has the same function as an axicon lens. Even when the blue light beam 101a is guided by the deflecting element 11 in a state where there is no light beam near the center, the light beam can be collected again near the center by using an element as shown in FIG.

  The wavelength selective divergence state conversion element 118 may include an antireflection film 34 and an antireflection film 36 at the air interface of the element as shown in FIG. Further, when the refractive index difference between the first medium 32 or the second medium 33 and the refractive index of the base material 31 is large, such as 0.1 or more, a loss of light amount occurs due to reflection inside the element. In such a case, an antireflection film 35 may be provided inside the element.

  By irradiating the wavelength selective divergence state conversion element 118 with the blue light beam 101a that is the light emitted from the deflecting element 11, the light divergence state changes with respect to the green or red fluorescent light beam 101b. The light divergence state is changed only by the blue light beam 101a.

In each of the above examples, the configuration, shape, and the like of the wavelength selective divergence state conversion element 118 have been described. However, in the case of the divergence state conversion element 117, the first medium 32 in the configuration of the wavelength selection divergence state conversion element 118 is described. And the second medium 33 may be a combination having a refractive index difference of a predetermined value or more at least at the wavelength λ ₁ in the blue wavelength band. For example, | Δn (λ ₁ ) | is preferably 0.03 or more, and more preferably 0.05 or more. If | Δn (λ ₁ ) | is small, the effect of diffraction or scattering will not be exhibited unless the concavo-convex structure is made large. Thus, the shape of the concavo-convex can be reduced. Note that the second medium 33 may be air.

  When the blue light beam 101 uses a laser as a light source, the deflected blue light beam 101a is generally a light beam with high directivity, and therefore its diverging state is small. In addition, a light beam using fluorescent light or LED as a light source is generally low in directivity and large in a divergent state. Since the angle distribution in such a divergent state is preserved even after the light beam passes through the integrator 111, when the light beam having such a divergent state is irradiated to the spatial light modulator, it causes uneven illumination and uneven color. May be. The divergence state conversion element 117 or the wavelength selective divergence state conversion element 118 corrects such a divergence state of the light beam.

  FIG. 16 is an explanatory diagram showing an example of correction of the divergence state by the wavelength selective divergence state conversion element 118. FIG. 16A shows the angular distribution of the luminance of each of the blue, green, and red light fluxes before passing through the wavelength selective divergence state conversion element 118. FIG. 16B shows the angular distribution of the luminance of each of the blue, green, and red light beams after passing through the wavelength selective divergence state conversion element 118. When the diverging state conversion element 117 is used, the angular distribution of the luminance of each of the green and red luminous fluxes shown in FIG. 16B is the angular distribution of the luminance of each of the green and red luminous fluxes shown in FIG. You can replace it with.

As shown in FIG. 16A, before passing through the divergence state conversion element 117 or the wavelength selective divergence state conversion element 118, it is assumed that the blue light beam has high directivity and the light beam is distributed in a narrow angle range. . Here, φ _B , φ _G , and φ _R are angles at which the center luminance is half value in the blue, green, and red diagrams before passing through the divergence state conversion element 117 or the wavelength selective divergence state conversion element 118, respectively. In addition, in each of the blue, green, and red diagrams after passing through the divergence state conversion element 117 or the wavelength selection divergence state conversion element 118, the angles at which the center luminance is half value are φ ′ _B , φ ′ _G , and φ ′ _R , respectively. . When the diverging state conversion element 117 is used, φ ′ _G ≈φ _{G and} φ ′ _R ≈φ _R.

As shown in FIG. 16, as a result of only the blue light beam being diffused by the divergence state conversion element 117 or the wavelength selective divergence state conversion element 118, the difference in half value of the angle between blue after transmission and other colors, that is, | φ ' It is only necessary that _B −φ ′ _G | and | φ ′ _B −φ ′ _R | are smaller than those before transmission, that is, | φ _B −φ _G | and | φ _B −φ _R |.

  As a method for adjusting the divergence state, an angle γ which is a half value of the center luminance of the emitted light when a blue light beam of parallel light is incident on the divergence state conversion element 117 or the wavelength selective divergence state conversion element 118 is adjusted. Can take the way.

When the angular distribution of luminance of the blue light beam 101a is g _i (θ) and the angular distribution of luminance when parallel light is incident on the divergence state conversion element 117 or the wavelength selective divergence state conversion element 118 is h (θ), The angular distribution g _o (θ) of the luminance of the blue light beam emitted from the divergence state conversion element 117 or the wavelength selective divergence state conversion element 118 is g _o (θ) = (g _i * h) (θ). Here, “*” represents a convolution integral.

For example, assuming that δ = ln (2), the angle distribution of the luminance of the incident light beam of the blue light beam 101a is g _o (θ) = Aexp {−δ (θ / φ _B ) ² }, and h ₁ (θ) = Bexp { If the ^{-δ (θ / γ) 2}} , the angular distribution of the luminance of the emitted light becomes _{g o (θ) αexp [-δ} {θ 2 / (φ B 2 + γ 2)}]. Here, A and B are constants. Therefore, the half value of the angular distribution of the emitted light is φ ′ _B = (φ _B ² + γ ² ) ^0.5 . Such h (θ) holds in the case of a scattering plate or the like.

When a parallel light is incident and a distribution that can be approximated to a top hat is generated as in a lens array, h ₂ (θ, γ) = C (0 ≦ θ ≦ γ), 0 (θ> γ) can be obtained. Φ ′ _B can be obtained. Φ ′ _B obtained in this way is 0.5 × Min (| φ _G |, | φ _R |) ≦ φ ′ _B ≦ 1.5 × Max (| φ _G |, | φ _R |) is preferably _{to, 0.75 × Min (| φ G} |, | φ R |) ≦ φ 'B ≦ 1.25 × Max (| φ G |, | φ R |) and so as to have more _{preferably, Min (| φ G |,} | φ R |) ≦ φ 'B ≦ Max (| φ G |, | φ R |) when a more preferred.

  FIG. 17 is an explanatory diagram for explaining an example of the angle γ for each action used for conversion of the divergent state. For example, as shown in FIG. 17 (a), when the divergent state is converted using diffraction, the diffracted light as the emitted light can be discrete, but the luminance peak of the diffracted light with respect to the angle By obtaining the envelope of the intensity distribution in the plotted diagram, the half-angle angle γ can be obtained. As the diffraction element, a diffraction grating, DOE (Differential Optical Element), or Fresnel lens can be used.

  Further, for example, when the divergence state is converted using scattering as shown in FIG. 17B, the angle γ is adjusted by adjusting the roughness of the interface between the first medium 32 and the second medium 33. Can be set to a desired value. In general, the angle γ increases when the roughness of the interface is rough.

  Further, for example, when the divergent state is converted using diffusion by a lens as shown in FIG. 17C, the angle γ can be set to a desired value by adjusting the curvature R of the lens. The focal length f of the lens can be obtained by f = R / Δn (λ), and the angle γ can be approximated by tan γ = d / f from the distance d from the center on the individual lens to the lens boundary. Further, the angle γ may be determined using a method such as ray tracing without using such approximation.

FIG. 16 (a) shows a case where the blue light beam 101a has a luminance peak at 0 °, but depending on the optical system, there are two peaks: an angle and an angle obtained by multiplying the angle by minus. There may be such cases. Even in such a case, when the luminance distribution after the light beam is transmitted through the divergence state conversion element 117 or the wavelength selective divergence state conversion element 118 is approximated by an approximate curve such as Gaussian, the angle φ ′ _B satisfies the above relationship. What is necessary is just to determine angle (gamma) so that it may satisfy | fill.

In the above description, the case where the divergence state conversion element 117 or the wavelength selective divergence state conversion element 118 acts on the light flux in the blue wavelength region has been described. Instead, the difference in the divergence state may be corrected by giving a diffraction or scattering effect to the light flux in the green or red wavelength region. For example, a divergence state conversion element 117 that provides diffraction and scattering effects to a light flux in the green and red wavelength regions is provided on a partial region of the rotating wheel 116 so that the blue light flux 101 is in the green phosphor region 42 and the red phosphor. You may synchronize with the fluorescence wheel 106 so that the fluorescent light beam 101b may be irradiated to the divergence state conversion element 117 in the time zone when the region 43 is irradiated. Further, for example, a wavelength selective divergence state conversion element 118 that does not act on a light beam in a blue wavelength region and that has a diffraction or scattering effect on a light beam in a green or red wavelength region may be provided in the optical path. . In such a case, the wavelength selective divergence state conversion element 118 uses a combination of materials in which | Δn (λ ₁ ) | is small and | Δn (λ ₂ ) | and | Δn (λ ₃ ) | are large. May be. Even in such a case, the divergence state conversion element 117 or the wavelength selective divergence state conversion element 118 sets | Δn (λ) | to 0.03 or more with respect to the wavelength λ of the wavelength band where the diffraction or scattering effect is desired. Preferably, it is more preferably 0.05 or more.

  In addition, the examples of FIGS. 11 and 12 are simple in design in that the final divergence state of light only needs to be corrected. Therefore, the divergence state conversion element 117 or the wavelength selective divergence state conversion element 118 is provided. Although it is an example arrange | positioned just before the integrator 111, these arrangement | positionings are not restricted to this position. It suffices to be disposed at least in the optical path of the blue light beam 101a. Further, when the wavelength selective divergence state conversion element 118 is used, it may be provided as a part of the lens group 105, the region division dichroic mirror 102, the optical element group 110, or the like, not as a single element.

  As described above, in this embodiment, by using at least the deflection element 11 and the region-dividing dichroic mirror 102 in combination, the blue light beam 101 that is also used as excitation light is transmitted by one mirror element, and the reflection is performed. Since both the blue light beam 101a used as light and blue light and the fluorescent light beam 101b used as green and red light can be reflected, the optical paths of the blue, red and green light can be made common, and therefore the optical system Can be miniaturized. For example, the optical elements 912 to 916 can be omitted as compared with the optical system shown in FIG. Further, in order to form an optical path of the blue light beam 101, a part of which becomes excitation light, a reflection surface for reflecting the blue light beam 101 on the optical path of the blue light beam 101a that is reflected light and used as blue light. Since there is no need to provide a reflection region or the like, even when excitation light including many light beams is used, a part of the blue light beam 101a is lost and no loss of the optical system occurs.

  Further, if the divergence state conversion element 217 or the wavelength selective divergence state conversion element 218 is provided in the optical path, even if the difference in the light divergence state occurs between the colors due to the common optical path, uneven illuminance due to the difference It is possible to reduce the size of the optical system while preventing color unevenness.

Embodiment 2. FIG.
Next, a second embodiment of the present invention will be described. FIG. 18 is a configuration diagram schematically illustrating an example of an illumination optical system according to the second embodiment of the present invention. The illumination optical system 200 shown in FIG. 18 transmits the p-polarized light of the blue light beam 201, reflects the s-polarized light and reflects the fluorescent light beam 201b, a quarter-wave plate 212, a fluorescent light Wheel 206, lens group 205 for condensing light to fluorescent wheel 206, integrator 211 for homogenizing the distribution of incident light flux, and blue light beam 201 a and fluorescent light beam 201 b that are reflected light from fluorescent wheel 206 are integrated into integrator 211. And an optical element group 210 for guiding the light.

  In the present embodiment, the blue light beam 201 of the illumination optical system 200 is p-polarized light, but may be s-polarized light. In this case, the blue light beam 201a incident on the wavelength selective polarization dichroic mirror 202 is p-polarized light. In addition, the wavelength-selective polarization dichroic mirror 202 is efficient in reflecting s-polarized light due to its characteristics. Therefore, when the blue light beam 201 of the illumination optical system 200 is s-polarized light, the blue light beam 201 is converted into the wavelength-selective polarization dichroic mirror 202. It is desirable that the illumination optical system be configured to reflect light.

  In the example shown in FIG. 18, the lens group 205 includes the lens 203 and the lens 204 for reducing the light beam width of the blue light beam 201 and condensing it on the fluorescent wheel 206, but this is not restrictive. Further, as the optical element group 210, the lens 207 for converting the divergence angle, the mirror 208 for deflecting the light beam emitted from the lens 207 toward the integrator 211, and the light beam reflected by the mirror 208 are condensed on the integrator 211. Although the lens 209 is provided, this is not restrictive. The same applies to other examples.

  FIG. 18 also schematically shows a configuration example of the illumination optical system and also shows an optical path of the blue light beam 201a after the blue light beam 201 is applied to the fluorescent wheel 206 (see thick solid arrows). Note that the blue light beam 201 a is a light beam used as blue light in the illumination optical system 200. In FIG. 18, the optical path of the fluorescent light beam 201b generated when the blue light beam 201 is applied to the fluorescent wheel 206 is not shown, but the fluorescent light beam 201b follows the same path as the blue light beam 201a. Unlike the blue light beam 201a, the polarization state of the fluorescent light beam 201b does not matter. That is, the polarized light may be stored, non-polarized light, or random polarized light. Note that the fluorescent light beam 201b is a light beam used as light of a color other than blue (green and / or red in this example) in the illumination optical system 200.

  FIG. 19 is a front view showing an example of the fluorescent wheel 206. As shown in FIG. 19, the fluorescent wheel 206 is divided into a region where the non-polarization diffusing element 41 is formed, a green phosphor region 42, and a red phosphor region 43, and is driven to rotate. By this rotational driving, a time zone in which incident light enters the non-polarization diffusing element 41, a time zone in which the incident light enters the green phosphor region 42, and a time zone in which the light enters the red phosphor region 43 are periodically generated. It is a mechanism.

  The non-polarization diffusing element 41 is an element that diffuses and emits an incident light beam from its incident surface without depolarizing the incident light beam. More specifically, it may be a reflection-type diffusing element that is diffused and emitted while giving a phase difference of approximately π to the incident light beam.

  In the green phosphor region 42 and the red phosphor region 43, the phosphor is formed on the reflection plate, and the blue light beam 201 incident on the region where the phosphor is formed emits fluorescence. The generated fluorescence is emitted from the incident surface as a fluorescent light beam 201b.

  FIG. 20 is a configuration diagram showing an example of the non-polarization diffusing element 41. FIG. 20A is a front view of a main part of the non-polarization diffusing element 41, and FIG. 20B is an AB cross-sectional view of the non-polarization diffusing element 41 shown in FIG. FIG. 20 shows an example of the non-polarization diffusing element 41 in which the conical convex portions 44 are arranged on the surface of the base material 45 without a gap. FIG. 20 shows an example in which the conical convex portion 44 is provided on the base material 45. However, the non-polarization diffusing element 41 has at least the surface of the region where light is incident within a predetermined angular range. The specific configuration is not particularly limited as long as it has a shape having an inclination. For example, what is provided on the surface may be a convex portion or a concave portion. Further, the substrate and the convex portion or the concave portion may be the same member or different members. Hereinafter, in the non-polarized light diffusing element 41, the portion having the inclined surface may be collectively referred to as “an inclined structure 44”.

  FIG. 21 shows an example of the optical path of the outgoing blue light beam 201a when the blue light beam 201 is incident on the non-polarization diffusing element 41. In the example shown in FIG. 21, all the inclined structures 44 provided on the surface of the non-polarization diffusing element 41 have a shape inclined at an angle α with respect to the surface of the substrate 45. That is, the non-polarization diffusing element 41 shown in FIG. 21 is formed in a concavo-convex shape composed of an inclined surface whose reflecting surface is inclined at an angle α. When the blue light beams 201-1 and 201-2 enter the non-polarization diffusing element 41, the light beams are deflected and reflected as the blue light beams 201 a-1 and 201 a-2 depending on the position of the incident surface of the inclined structure 44. The

For example, let us consider a case where the incident surface side is the upper side, the counterclockwise direction from the upward normal direction of the base material 45 is a positive direction, and the blue light beams 201-1 and 201-2 are incident at an incident angle ± | β |. Here, the incident angle refers to an intensity that is 1 / e ² with respect to the intensity of the principal ray of the light beam. The blue light beam 201-1 incident at an angle β is emitted as reflected light deflected in the direction of 2α-β by the inclined structure 44 provided on the element surface. If the inclination angle of the inclined surface of the inclined structure 44 exceeds 45 °, the light beam is reflected in the lateral direction and a part of the light cannot be used as reflected light, so the inclination angle α satisfies 45 °> | α |. It is good to do so. In particular, since the maximum emission angle of the blue light beam 201a is 2 | α | + | β |, it is more preferable that 90 °> 2 | α | + | β |.

  In this embodiment, the reflectance of the surface of the inclined structure 44 is preferably 80% or more, and more preferably 90% or more.

  In addition, the inclined structure 44 provided in the non-polarization diffusing element 41 is not limited to the conical shape as long as it has the above function, that is, the function of diffusing and reflecting while giving a phase difference of approximately π to the incident light beam. It may be a pyramid shape or a blazed shape. For example, the shapes shown in FIGS. 22A to 22E may be used. Moreover, the uneven | corrugated shape which has a longitudinal direction extended in the direction different from a slope may be sufficient when it sees with a top view.

FIG. 22 is a cross-sectional view of a main part showing another example of the non-polarization diffusing element 41. FIG. 22A shows an example in which the size of the inclined structure 44 is different in the plane. FIG. 22B shows an example in which the inclined structures 44 having different inclination angles are provided in the plane. As shown in FIG. 22B, when the inclination angles of the inclined structures 44 are different in the plane, the average inclination angle α _avg may satisfy 45 °> | α _avg |, and 90 °> It is more preferable to satisfy 2 | α _min | + | β |. In such an example, there is an effect that the spatial coherency of the incident light can be reduced due to the irregularity of the element, such as an effect of making the light quantity distribution of the light flux uniform, and a speckle reduction when using the light flux from the laser light source. An effect can be obtained.

  FIG. 22C shows an example of the non-polarization diffusing element 41 having a surface unevenness formed by one inclined structure 44 like an axicon lens. As shown in FIG. 22C, the non-polarization diffusing element 41 in which only one inclined structure 44 is formed is used when the non-polarization diffusing element 41 is used not on the fluorescent wheel 206 but fixed. It is suitable (for example, the configuration of FIG. 26 and FIG. 27B described later). By using a single reflecting surface, scattering or the like hardly occurs, and the blue light beam 201a can be generated efficiently. However, since the width of the position where the blue light beam 201 is applied to the inclined structure 44 increases in the depth direction because it is a single reflecting surface, the first implementation is performed when the lens group 205 with a small focal depth is used. Similar to the deflecting element 11 of the embodiment, it is preferable to use another example in which the height in the depth direction of the inclined structure 44 is reduced. The preferred height of one inclined structure 44 depends on the depth of focus of the lens group 205, but is preferably 0.5 mm or less, more preferably 0.1 mm or less in order to be able to cope with various lens designs, and 0.05 mm. More preferably, it is as follows.

  FIG. 22D shows an example having a blazed inclined structure 44. When the inclined structure 44 is blazed, for example, the height in the depth direction of the inclined structure 44 shown in FIG. 22C can be reduced.

  FIG. 22E shows an example in which a semi-transmissive reflection film 46 that reflects part of a blue light beam and transmits green or red light beam is formed on an inclined structure 44 including a phosphor. Such a non-polarization diffusing element 41 can be used in an optical system that uses a spatial light modulation element for each color of blue, green, and red without performing time division by the fluorescent wheel 206 (for example, described later). Configuration of FIG. 22E, both the blue light beam 201a deflected and reflected by the transflective film 46 and the fluorescent light beam 201b obtained by exciting the phosphor through the transflective film 46 are obtained. By combining these, it is possible to obtain blue, green, and red luminous fluxes. Here, as the semi-transmissive reflective film 46, for example, the same film as the semi-transmissive reflective film 16 shown in FIG. 6E of the first embodiment can be used. Although not shown in the figure, the non-polarization diffusing element 41 of this example is formed with a reflective film that reflects fluorescence generated below a member including a phosphor.

  FIG. 23 is a cross-sectional view of the main part showing another example of the non-polarization diffusing element 41. The non-polarization diffusing element 41 may use a diffractive action as shown in FIG. 23 in addition to a structure having an inclined surface. 23A and 23B has a structure in which a concavo-convex structure 47 that generates diffracted light is formed on a base material 45. FIG. 23A shows an example in which a concavo-convex structure 47 that functions as a binary diffraction grating is formed. In this case, a convex portion 44 or a concave portion having a rectangular cross section may be formed on the substrate 45. FIG. 23B shows an example in which a multistage pseudo blaze is used as the concavo-convex structure 47.

Thus, when a diffractive element is used as the non-polarization diffusing element 41, the distribution of the emitted light is given by the Fourier transform of the basic structure of the diffractive element. Further, the pitch of the basic structure of the diffraction element is P, the wavelength of the light beam incident on the diffraction element is λ, the incident angle is θ _in , the angle of the emitted light beam is θ _out , and the order of the diffracted light is m. In this case, sin θ _out = sin θ _in + mλ / P is established. Therefore, the distribution of the outgoing light, that is, the blue light beam 201a can be adjusted by designing the basic structure of the diffraction element and adjusting the pitch of the basic structure. In the case of this example, the pitch P and the order m of the diffracted light may be adjusted so that 45 °> | θ _out |.

  Further, the non-polarization diffusing element 41 may have a lens shape or a curved surface shape as shown in FIGS. 24A and 24B in addition to the structure having a monotonous inclined surface. FIG. 24A shows an example in which a convex lens-shaped convex portion 44 is formed on the base material 45, and FIG. 24B shows a concave lens-shaped concave portion 44 formed on the base material 45. An example is shown. In this way, the surface may be curved. In such a case as well, the inclination angle α of the curved surface may satisfy 45 °> | α |, and more preferably 90 °> 2 | α | + | β |.

  FIG. 25 is an explanatory diagram for explaining the difference between the non-polarization diffusing element 41 of the present invention and a general diffusing element 80. FIG. 25A is an explanatory diagram showing a state of reflection when a light beam is incident on the non-polarization diffusing element 41 at an angle, and FIG. 25B is an angle on a general diffusing element 80. It is explanatory drawing which shows the mode of reflection when a light beam injects.

  In the non-polarization diffusing element 41 of the present invention, as shown in FIG. 25 (a), the incident light beam 201 is reflected once by the convex portion 44, and becomes a circularly polarized light orthogonal to the phase difference caused by the reflection at this time. Are emitted. On the other hand, in the general diffusing element 80, as shown in FIG. 25B, the incident light beam 801 may be reflected twice by the convex portion 81, and when reflected twice, the emitted light beam 801a is emitted as the original polarized light.

  In such a case, the polarization state of the reflected light beam is disturbed by the emission of two orthogonally polarized light beams, and when the light is transmitted through the quarter-wave plate, a part of the emitted light beam 801a is s-polarized light. Thus, the light passes through the polarization dichroic mirror 302 without being reflected, resulting in a loss of light quantity. In contrast, the non-polarization diffusing element 41 of the present invention can be rephrased as an element configured to emit reflected light by one reflection on the surface, and the reflected light is emitted by one reflection. The ratio of the luminous flux is preferably 80% or more, and more preferably 90% or more.

  This is because the polarization ratio is preferably 80% or more and 90% or more when the ratio of the sum of the polarization state and the light amount in the orthogonal polarization state to the light amount in the polarization state of the reflected light flux is defined as the polarization ratio. In other words, it is more preferable. When measuring the polarization ratio, in the case of a divergent light beam, the polarization state is measured in a direction perpendicular to each emission angle, or is converted by the lens group 205 so that the divergent state of the light beam is small. The intensity ratio of two orthogonal polarizations can be measured. The polarization state here and the polarization state orthogonal thereto may be a combination of p-polarization and s-polarization linear polarization, or a combination of left circular polarization and right circular polarization. Moreover, the combination of the elliptically polarized light orthogonal to it with respect to a certain elliptically polarized light may be sufficient.

  Further, the phase difference of the light generated when the light is reflected by the non-polarization diffusing element 41 is preferably π, but it may be approximately π. In the present invention, when “substantially π” is related to the phase difference of light accompanying reflection, it specifically refers to a range of 0.7π to 1.3π. If the phase difference deviates from π, the polarization ratio may decrease, but if the phase difference that occurs during reflection is 0.7π to 1.3π, the polarization of the s-polarized light after passing through the quarter-wave plate The ratio is 80% or more. It is more preferable that the phase difference generated during reflection is 0.8π to 1.2π because the polarization ratio of the s-polarized light after passing through the quarter-wave plate is 90% or more. Such calculation of the polarization ratio can be performed using the Jones vector. In addition, such a phase difference deviation can occur even when light is incident obliquely on the reflecting surface. Therefore, the polarization is not canceled so that the phase difference generated during reflection falls within the above range. It is preferable to adjust the shape of the diffusing element 41.

  Further, since the non-polarization diffusing element 41 of the present invention performs diffusion, the effect of reducing the speckle of the light source, the effect of eliminating the uneven brightness on the projection surface, and the effect of reducing the angular distribution of the brightness with the tendency of green and red are obtained. It is done.

Scattering effect by the polarization non-eliminated diffusing element 41 is a relationship incidence angle and exit angle, as in the case of the first divergence shown in embodiment transducer 117 or wavelength selective divergence conversion element 118 g _{o (θ)} = (G _i * h) (θ). When the diffusion by the non-polarization diffusing element 41 is large, the above-described speckle reduction effect is easily obtained. However, when the diffusion is large, the lens group 305 cannot capture light, resulting in a loss of light quantity. Accordingly, when parallel light is incident on the non-polarization diffusing element 41, the value of the angle γ, which is a half value of the center luminance of the emitted light, is preferably 1 ° or more and 60 ° or less, and preferably 1 ° or more and 45 ° or less. More preferably, it is 1 ° or more and 30 ° or less.

  The wavelength-selective polarization dichroic mirror 202 transmits p-polarized light for light in the same blue wavelength band as the blue light beam 201, reflects s-polarized light, and for light in the same green and red wavelength bands as the fluorescent light beam 201b. Any material that reflects regardless of the polarization state may be used. The wavelength-selective polarizing dichroic mirror 202 may have a configuration in which, for example, a dichroic layer having the above characteristics is provided on a base material. Such a dichroic layer can be realized by, for example, a multilayer film.

  Next, the optical path of the light beam of this embodiment will be described. As shown in FIG. 18, in the illumination optical system 200 of the present embodiment, a blue light beam 201 emitted from a blue laser light source or the like enters a wavelength selective dichroic mirror 202 with p-polarized light. The blue light beam 201 incident on the wavelength selective polarization dichroic mirror 202 passes through the wavelength selective polarization dichroic mirror 202 and then enters the quarter wavelength plate 212. The blue light beam 201 incident on the quarter-wave plate 212 is converted from s-polarized light to clockwise circularly-polarized light and emitted.

  The blue light beam 201 converted to the clockwise circularly polarized light is condensed on the fluorescent wheel 206 by the lens group 205. At this time, when the blue light beam 201 is irradiated to the non-polarization diffusing element 41, the blue light beam 201 is reflected and diffused by the non-polarization diffusing element 41, and left by the phase difference of approximately π generated at the time of reflection. It is converted into circularly polarized light and becomes a blue light beam 201a which is emitted from the incident surface.

  The blue light beam 201 a that has been converted into counterclockwise polarized light and reflected and diffused is converted in divergence angle by the lens group 205 and is incident on the quarter-wave plate 212 again. The blue light beam 201a incident on the quarter-wave plate 212 is converted from counterclockwise circularly polarized light to s-polarized light and emitted.

  The blue light beam 201 a converted into s-polarized light is reflected by the wavelength selective polarization dichroic mirror 202 and then guided to the integrator 211 by the optical element group 210.

  On the other hand, when the blue light beam 201 passes through the wavelength-selective polarization dichroic mirror 202 and the lens group 205 and then irradiates the green phosphor region 42 or the red phosphor region 43 of the fluorescent wheel 206, the green and red wavelength regions Of fluorescence. The generated fluorescent light emission is emitted from the incident surface as a fluorescent light beam 201b by a reflector provided on the fluorescent wheel 206. The divergence angle is converted by the lens group 205, reflected by the wavelength-selective polarization dichroic mirror 202, and then guided to the integrator 211 by the optical element group 210.

  The light beam guided to the integrator 211 is irradiated to a spatial light modulation element (not shown), and an image formed by the spatial light modulation element is projected onto a projection plane by a projection lens (not shown). As the spatial light modulator, LCOS (Liquid crystal on silicon), DMD (digital micromirror device) or the like can be used.

  FIG. 18 shows an example in which the non-polarization diffusing element 41 is provided on the fluorescent wheel 206, but the non-polarization diffusing element 41 does not necessarily have to be on the fluorescent wheel 206.

  For example, an arrangement as shown in FIG. 26 may be used. FIG. 26 is a configuration diagram showing another arrangement example of the non-polarization diffusing element 41 in the illumination optical system 200. FIG. 26 shows only the part related to the optical path from when the blue light beam 201 is incident on the wavelength selective polarization dichroic mirror 202 to when it is incident on the wavelength selective polarization dichroic mirror 202 again as the blue light beam 201a. In the illumination optical system 200 shown in FIG. 26, the fluorescent wheel 206 is driven to rotate, and has a region including a fluorescent substance in a part thereof. However, the non-polarization diffusing element 41 is not provided on the wheel, and the blue light beam 201 is transmitted instead of the non-polarization diffusing element 41.

  In the case of this example, the blue light beam 201 applied to the region transmitting the blue light beam 201 on the fluorescent wheel 206 is transmitted through the fluorescent wheel 206 and applied to the non-polarization diffusing element 41 provided behind it. The blue light beam 201 applied to the non-polarization diffusing element 41 is reflected and diffused by the non-polarization diffusing element 41, and as a result, the blue light beam 201b converted into counterclockwise polarized light is emitted from the incident surface.

  Further, when a spatial light modulator is used for each of blue, green, and red colors, the fluorescent wheel 206 need not be driven to rotate. In this case, an arrangement as shown in FIG. 27A or FIG. 27B may be used.

  FIG. 27 is a configuration diagram schematically illustrating another example of the illumination optical system 200. FIG. 27 (a) shows only the portion related to the optical path from when the blue light beam 201 is incident on the wavelength selective polarization dichroic mirror 202 to when it is incident on the wavelength selective polarization dichroic mirror 202 again as the blue light beam 201a. Has been. In FIG. 27A, the optical path of the fluorescent light beam 201b is not shown, but the same path as that of the blue light beam 201a is used in this example. However, the polarization state of the fluorescent light beam 201b is not particularly limited.

  An illumination optical system 200 shown in FIG. 27A includes a fluorescent element 213 with a blue diffuse reflection function in place of the fluorescent wheel 206. When the blue light beam 201 is incident, the fluorescent element 213 with a blue diffuse reflection function reflects part of the incident light as blue light and causes part of the incident light to emit fluorescence. Further, when a part of the blue light beam is reflected and emitted, a phase difference of approximately π is given, and then diffused and emitted from the incident surface. As such a fluorescent element 213 with a blue diffuse reflection function, for example, a non-polarization diffusing element 41 shown in FIG.

  The example of FIG. 27B is an example in which the blue light beam 201 is branched by the polarization selection beam splitter 215, and the blue light beam 201a and the fluorescent light beam 201b are generated in different optical paths and then combined. In FIG. 27B, the optical path from when the blue light beam 201 enters the wavelength selective polarization dichroic mirror 202 to the blue light beam 201a or the fluorescent light beam 201b enters the wavelength selective polarization dichroic mirror 202 again. Only the part related to is shown.

  In the illumination optical system 200 shown in FIG. 27B, the blue light beam 201 passes through the wavelength-selective polarization dichroic mirror 202 and then travels toward the lens group 205a by the polarization-selective beam splitter 215 and toward the lens group 205b. It is divided into luminous flux. The blue light beam 201 traveling toward the lens group 205a is converted into clockwise circularly polarized light by passing through the quarter wavelength plate 212, and then irradiated to the non-polarization diffusing element 41 by the lens group 205a. On the other hand, the blue light beam 201 directed to the lens group 205b is irradiated to the fluorescent element 214 by the lens group 205b.

  The clockwise circularly polarized blue light beam 201 irradiated on the non-polarization diffusing element 41 is reflected and diffused by the non-polarization diffusing element 41, and converted into counterclockwise polarized light by a phase difference of approximately π generated at the time of reflection. A blue light beam 201a is emitted from the incident surface. Then, the light passes through the quarter-wave plate 212 again and is emitted as s-polarized light. In addition, the blue light beam 201 incident on the fluorescent element 216 causes fluorescent light emission by the phosphor included in the fluorescent element 214. The generated fluorescent light emission is emitted from the incident surface as a fluorescent light beam 201b.

  Although not shown in the figure, the polarization selective beam splitter 215 of this example reflects a part of the light in the blue wavelength band while transmitting a part of the p-polarized light and s-polarized light in the light in the blue wavelength band. Are reflected, and light in the green and red wavelength bands is transmitted. For example, the polarization selective beam splitter 215 includes a base material, an antireflection film that transmits light in the green and red wavelength bands provided on one surface thereof, and p of light in the blue wavelength band provided on the other surface. A beam splitter that transmits part of the polarized light, reflects part of the p-polarized light in the blue wavelength band, reflects all the s-polarized light in the blue wavelength band, and transmits the light in the green and red wavelength bands The structure provided with the layer may be sufficient.

  Even with such a configuration, at least a part of the blue light beam 201 serving as the excitation light, the blue light beam 201a serving as the blue light source light, and the fluorescent light beam 201b serving as the light source light of another color are combined with the same element ( In this example, since the light can be incident on 202 and 214), the optical system can be reduced in size without causing loss of the optical system.

  In each of the above examples, two types of phosphors, green phosphor and red phosphor, are used. However, the type of phosphor used is not limited to this. For example, only one phosphor of green phosphor is used. The red light source light may be separately emitted from a light source such as an LED and combined by the wavelength selective polarization dichroic mirror 202 or the like.

  Also in the present embodiment, the blue light beam 201a obtained as a result of reflecting and diffusing the blue light beam 201 by the non-polarization diffusing element 41 and the fluorescent light beam 201b in the green and red wavelength regions have different divergence states. There may be. In such a case, as in the first embodiment, a divergence state in which a difference in divergence state is corrected in the optical path or in a part of the lens group 205, the wavelength selective polarization dichroic mirror 202, the optical element group 210, or the like. A conversion element 217 and a wavelength selective divergence state conversion element 218 may be provided.

  FIG. 28 is a configuration diagram schematically showing another example of the illumination optical system 200 and an example of the rotating wheel 216 used therein. FIG. 28A is a configuration diagram illustrating an example of the illumination optical system 200 in which the divergence state conversion element 217 is provided in the optical path of the blue light beam 201b. In the example shown in FIG. 28A, a rotating wheel 216 is newly added in front of the integrator 211. FIG. 28B is a front view of the rotating wheel 216. As shown in FIG. 28B, the rotating wheel 216 of this example is provided with a divergence state conversion element 217 in a partial region, and the rotation synchronization is achieved between the fluorescent wheel 206 and the rotating wheel 216. Thus, the divergence state conversion element 217 is irradiated with the blue light beam 201a in the time zone in which the non-polarization diffusing element 41 is irradiated with the blue light beam 201. By doing so, the light divergence state does not change with respect to the green or red fluorescent light beam 201b, and the light divergence state changes only with respect to the blue light beam 201a.

  FIG. 29 is a configuration diagram showing an example of an illumination optical system 200 provided with a divergence state conversion element 218 having wavelength selectivity. In the example shown in FIG. 29, a wavelength selective divergence state conversion element 218 is newly added in front of the integrator 211 instead of the rotating wheel 216.

  The configuration, shape, and the like of the divergence state conversion element 217 and the wavelength selection divergence state conversion element 218 may be the same as those of the divergence state conversion element 117 and the wavelength selection divergence state conversion element 118 in the first embodiment. The same applies to the diverging state conversion method. In FIGS. 27A and 28, the design is simple in that the final divergence state of light only needs to be corrected. Therefore, the divergence state conversion element 217 or the wavelength selective divergence state conversion element 218 is used. However, the arrangement is not limited to this position. It may be arranged somewhere in the optical path. Further, in the case of the wavelength selective divergence state conversion element 218, it may be provided as a part of the lens group 205, the wavelength selective polarization dichroic mirror 202, the optical element group 210, etc., not as a single element.

  When the divergence state conversion element 217 or the wavelength selection divergence state conversion element 218 is provided, the diffusion state can be adjusted by the divergence state conversion element 217 or the wavelength selection divergence state conversion element 218. A reflecting mirror having a flat surface may be arranged.

  Further, instead of the wavelength selective divergence state conversion element 218, a divergence state of the blue light beam 201a may be adjusted by arranging a polarization divergence state conversion element between the wavelength selective polarization dichroic mirror 202 and the fluorescent wheel 206. . The polarization divergence state conversion element may be any element that transmits light in a certain polarization state and diffuses light in a polarization state orthogonal thereto by diffraction, scattering, lens action, and the like. For example, it can be produced by filling an uneven birefringent material with an isotropic material equal to the ordinary light or extraordinary light refractive index of the birefringent material. As the birefringent material, an inorganic crystal such as crystal or lithium niobate, or an organic material such as liquid crystal can be used.

  As described above, in this embodiment, one wavelength-selective polarization dichroic mirror 202 transmits the incident blue light beam 201 serving as excitation light, while emitting the blue light beam 201a emitted from the fluorescent wheel serving as the blue light source light and the green light. And the fluorescent light beam 201b emitted from the fluorescent wheel serving as the red light source light can be reflected, and the light paths of the blue, red, and green colors are made common as in the first embodiment. Therefore, the optical system can be miniaturized. Further, when sharing the optical path, it is not necessary to separately provide a reflection surface or a reflection region for forming the optical path of the excitation light, and no optical system loss is caused thereby. Further, by performing diffusion using the polarization non-resolving element 41, the divergence state conversion element 217, and the wavelength selective divergence state conversion element 218, the speckle reduction effect of the light source, the effect of eliminating the luminance unevenness on the projection surface, the tendency of green and red The effect of reducing the angular distribution of the brightness is also obtained.

Embodiment 3. FIG.
Next, a third embodiment of the present invention will be described. FIG. 30 is a configuration diagram schematically illustrating an example of a projection apparatus according to the third embodiment of the present invention. A projection apparatus 300 shown in FIG. 30 includes an illumination optical system 100 according to the first embodiment, a spatial light modulation element 305 that modulates light emitted from the illumination optical system 100, and light emitted from the illumination optical system 100. An optical element group for guiding the light to the spatial light modulation element 305 and a projection optical system for projecting the light modulated by the spatial light modulation element 305 to the outside are provided.

  Although not shown in FIG. 30, the projection apparatus 300 includes a light source that emits light that is partially used as light of a certain color in the projection apparatus 300. The light source may be, for example, a plurality of laser light sources that emit light in a blue wavelength band. The illumination optical system 100 may generate light of at least two colors using the light from the light source and output them as illumination light.

  In the present embodiment, the illumination light emitted from the illumination optical system 100 is illuminated onto the spatial light modulation element 305 using the lens 301, the mirror 302, the lens 303, and the mirror 304. Then, as a result of being modulated by the spatial light modulation element 305, it is emitted as a projected image. The projection image generated by the spatial light modulation element 305 is projected outside the projection apparatus using the projection lens 306.

  As the illumination optical system, not only the illumination optical system 100 of the first embodiment other than the illumination optical system 100 shown in FIG. 1 but also the illumination optical system 200 shown in the second embodiment can be used. Further, the optical element group for illuminating the spatial light modulation element 305 with the light beam from the illumination optical system is not limited to the lens 301, the mirror 302, the lens 303, and the mirror 304, and various optical elements can be used. Further, as the spatial light modulation element 305, LCOS (Liquid crystal on silicon), DMD (digital micromirror device), or the like can be used.

  As described above, according to the present embodiment, since the illumination optical system is provided in which the optical path of the light of each color is made common without causing loss of the optical system, without reducing the light output value, The device can be miniaturized.

  Hereinafter, the illumination optical system described above and optical elements used in the illumination optical system will be described using specific numerical values.

Example 1.
The first example is an example of the deflection element 11 used in the illumination optical system 100 of the first embodiment, and is an example of the deflection element 11 shown in FIG. In this example, it is assumed that a blue light beam 101 having an incident angle β within 20 ° is incident on the deflection element 11. In the deflecting element 11 of the present embodiment, the inclined structure 14 provided on the surface of the base material 15 has an inclination angle α of 20 °, and a conical shape having a bottom surface of 0.2 mm square in a plane with a pitch of 0.2 mm. It is arranged.

  Such a deflection element 11 is obtained by molding Pyrex (registered trademark) glass by press molding so that the maximum thickness is 0.5 mm. Thereafter, a multilayer film having the structure shown in Table 1 below is formed on the uneven surface by vacuum deposition.

Here, the refractive index of Pyrex glass at 450 nm is 1.481, the refractive index of SiO ₂ is 1.474, and the refractive index of Ta ₂ O ₅ is 2.256. When the transmittance at 0 ° and 40 ° in such a multilayer film is obtained by calculation, it is as shown in FIG. 31, and it can be seen that good reflection characteristics are shown at 450 nm.

  According to the deflection element 11 of the present embodiment, for example, in FIG. 5, the blue light beam 101-1 having an incident angle β of −20 ° has a normal direction of 0 ° toward the incident surface side of the substrate 15. Then, the light is deflected and emitted in the direction of 2 | α | -β = 60 °. When the incident angle β is 20 °, the light is deflected in the direction of 2 | α | −β = 20 ° and emitted. Therefore, the blue light beam 101a deflected by the deflecting element 11 of this embodiment does not have optical path overlap at a position sufficiently away from the deflecting element 11.

Example 2
The second example is an example of the deflection element 11 used in the illumination optical system 100 of the first embodiment, and is an example of the deflection element 11 shown in FIG. In this example, it is assumed that a blue light beam 101 having an incident angle β within 20 ° is incident on the deflection element 11. The deflecting element 11 of this embodiment has a structure having a rectangular uneven structure 17 having a pitch of 1.26 μm and a height of 225 nm on one surface of a base material 15.

Such a deflection element 11 is obtained by processing the surface of a quartz substrate into a rectangular uneven shape by photolithography and etching. In addition, in this example, 200 nm of silver and 5 nm of SiO ₂ are further formed by sputtering on the surface irregularities. Here, silver is formed to improve reflection efficiency, and SiO ₂ is formed as a protective film for preventing scratches and oxidation.

  When the diffraction angle is calculated by the grating equation with the wavelength of the blue light beam 101 being 450 nm, when the incident angle is 0 °, the ± first-order diffracted light emitted from the deflecting element 11 of this embodiment is directed to the incident surface side of the substrate 15. If the normal direction is 0 °, the light is diffracted and emitted in the direction of ± 20.9 °. When the incident angle is 10 °, the + 1st order diffracted light is diffracted in the direction of 32.1 °, and the −1st order diffracted light is diffracted in the direction of −10.6 ° and emitted. Further, the higher-order diffracted light is diffracted at an angle further outside than the ± first-order diffracted light and is emitted. Therefore, the blue light beam 101a deflected and reflected by the deflecting element 11 of this embodiment does not have optical path overlap at a position sufficiently away from the deflecting element 11.

Example 3
The third example is an example of the illumination optical system 100 of the first embodiment shown in FIG. In this example, the blue light beam 101 having an effective diameter of φ5 mm is irradiated onto the fluorescent wheel 106 using a lens group 105 having a focal length of 7.9 mm, an effective diameter of φ15 mm, and a numerical aperture of 0.95.

The fluorescent wheel 106 is divided into a region where the deflection element 11 is provided, a green phosphor region 12, and a red phosphor region 13. In addition, in the area division dichroic mirror 102, a multilayer film having the structure shown in Table 2 below is formed as a dichroic layer 23 in an area where the blue light beam 101 directed to the fluorescent wheel 106 is transmitted on one surface of the quartz substrate. In other regions, 200 nm of silver and 5 nm of SiO ₂ are formed as the reflective layer 24 so as to be laminated on the multilayer film.

  FIG. 32 shows the transmittance when light is incident on the multilayer film shown in Table 2 functioning as the dichroic layer 23 at an incident angle of 45 °.

  In the present embodiment, with the arrangement shown in FIG. 6, the blue light beam 101 is applied to the dichroic layer 23 of the region division dichroic mirror 102 and is transmitted through the region division dichroic mirror 102. Then, the blue light beam 101 having a diameter of 5 mm is applied to the fluorescent wheel 106 by the lens group 105 at an incident angle of 18.5 °. The deflection element 11 provided on the fluorescent wheel 106 is the same as that in the first embodiment.

  Of the blue light beam 101, the light beam applied to the deflecting element 11 is deflected by the deflecting element 11 to become a blue light beam 101 a and is incident on the lens group 105 again. Then, after passing through the lens group 105, an annular blue light beam 101 a having a light beam outside φ5 mm is obtained. Thereafter, the blue light beam 101a is applied to the reflective layer 24 of the region-dividing dichroic mirror 102, and is reflected toward the optical element group 110 by being reflected by the reflective layer 24.

  On the other hand, of the blue luminous flux 101, the green phosphor region 12 or the red phosphor region 13 irradiated with fluorescent light is generated by the phosphor provided in the region. The generated fluorescent light is emitted from the incident surface as a fluorescent light beam 101b. Thereafter, the fluorescent light beam 101b is applied to the dichroic layer 23 and the reflective layer 24 of the region-divided dichroic mirror 102, reflected by the dichroic layer 23 or the reflective layer 24, and applied to the optical element group 110.

  In this example, the blue light beam 101a and the fluorescent light beam 101b transmitted through the optical element group 110 are incident on the wavelength selective divergence state conversion element 118, respectively. The wavelength selective divergence state conversion element 118 mainly scatters the blue light beam 101a, thereby correcting the difference in the divergence state between the blue light beam 101a and the fluorescent light beam 101b.

The wavelength selective divergence state conversion element 118 of this example has a configuration shown in FIG. 15D, and a multilayer film having a configuration shown in Table 3 below is used as the first medium 32, and the second medium 33 is used as the second medium 33. SiO _x N _y is used.

  The multilayer film shown in Table 3 has a reflection band in the wavelength range of 320 nm to 430 nm, and the transmittance of the multilayer film is calculated as shown in FIG.

  The wavelength selective divergence state conversion element 118 of this example is obtained as follows. First, on the quartz substrate, the multilayer film shown in Table 3 is processed into a concavo-convex shape by photolithography and etching. And SiON is formed into a film by CVD method (chemical vapor deposition), The recessed part is filled. After the surface of the filled SiON is flattened by polishing, an antireflection film 34 and an antireflection film 36 are formed on both sides of the element to obtain the wavelength selective divergence state conversion element 118. The wavelength selective divergence state conversion element 118 of this example is not provided with the antireflection film 35.

  FIG. 34A shows the effective refractive index of the multilayer film constituting the convex portion and the SiON constituting the concave portion of the wavelength selective divergence state conversion element 118 thus obtained. As shown in FIG. 34 (a), the effective refractive index of the multilayer film constituting the convex portion of the wavelength selective divergence state conversion element 118 of this example is steep due to anomalous dispersion caused by the reflection band of the multilayer film. The difference from the effective refractive index of SiON constituting the recess is as large as 0.090 at 450 nm which is the blue wavelength band, and 0.025 at 525 nm which is the green wavelength band, and at the red wavelength band. At a certain 620 nm, it is approximately equal to 0.003. When the efficiency of the diffracted light generated by the unevenness formed by such a combination of members is obtained by calculation, it is as shown in FIG. 34B, and the diffraction efficiency is high in the blue wavelength band.

  As described above, according to the present embodiment, the optical paths of the light sources of blue, red, and green can be shared, and the diffusion state of the blue light beam 101a can be adjusted.

Example 4
The fourth example is an example of the non-polarization diffusing element 41 used in the illumination optical system 200 of the second embodiment, and is an example of the non-polarization diffusing element 41 shown in FIG. In this example, it is assumed that a blue light beam 201 having an incident angle β within 20 ° is incident on the non-polarization diffusing element 41. The non-polarization diffusing element 41 of this embodiment has a structure in which concave hemispheres having a radius of curvature of 1.36 mm are arranged on one surface of a substrate 45 with a pitch of 0.2 mm. The maximum inclination angle of the hemisphere is 5 °, and incident light of 0 ° is reflected in the direction of 10 °.

Such a non-polarization diffusing element 41 is obtained by processing a silicon substrate into a concave lens array by photolithography and wet etching. In this example, 200 nm of silver and 5 nm of SiO ₂ are further formed on the surface irregularities by sputtering.

  Since the non-polarization diffusing element 41 of the present embodiment is configured to reflect the incident blue light beam 201 only once on the surface of the non-polarization diffusing element 41, for example, the blue light beam incident as right circularly polarized light. 101 is emitted as left circularly polarized light. Further, at the time of reflection, the light is diffused and emitted by the inclination of the concave hemisphere provided on the surface.

Example 5 FIG.
The fifth example is an example of the illumination optical system 200 of the second embodiment shown in FIG. In this embodiment, after the p-polarized blue light beam 201 having an effective diameter of φ10 mm is converted into clockwise circularly polarized light by the quarter wavelength plate 212, the focal length is 7.9 mm, the effective diameter is φ15 mm, and the numerical aperture is 0.95. The lens group 205 is used to irradiate the fluorescent wheel 206.

  The fluorescent wheel 206 is divided into a region where the non-polarization diffusing element 41 is present, a green phosphor region 42, and a red phosphor region 43. The wavelength selective polarization dichroic mirror 202 has a multilayer film having a structure shown in Table 4 below formed as a dichroic layer on one surface of a quartz substrate.

  FIG. 35 shows the transmittance when light is incident on the multilayer film shown in Table 4 at an incident angle of 45 °. As shown in FIG. 35, the multilayer film of Table 4 shows a transmittance of nearly 100% for p-polarized light and a transmittance of less than 5% for s-polarized light in the vicinity of 450 nm which is the blue wavelength band. In the vicinity of 525 nm which is the green wavelength band and 620 nm which is the red wavelength band, both p-polarized light and s-polarized light have transmittances of less than 5%.

  In this embodiment, with the arrangement shown in FIG. 28, the blue light beam 201 is p-polarized light and enters the wavelength-selective polarization dichroic mirror 202 and passes through the wavelength-selective polarization dichroic mirror 202. Then, the blue light beam 201 having a diameter of 10 mm is applied to the fluorescent wheel 206 by the lens group 205 at an incident angle of 39.3 °. The non-polarization diffusing element 41 provided in the fluorescent wheel 206 is the same as that in the fourth embodiment.

  Of the blue light beam 201, the light beam applied to the non-polarization diffusing element 41 is reflected and diffused by the non-polarization diffusing element 41, and is converted into left circularly polarized light upon reflection to form a blue light beam 201a again. Incident to 205. Then, after passing through the lens group 205, it passes through the quarter-wave plate 212 and becomes s-polarized light. The s-polarized blue light beam 201a is applied to the dichroic layer of the wavelength-selective polarizing dichroic mirror 202, and is reflected toward the optical element group 210 by being reflected by the dichroic layer.

  On the other hand, the blue light beam 201 that is irradiated on the green phosphor region 42 or the red phosphor region 43 causes fluorescence emission by the phosphor provided in the region. The generated fluorescent light is emitted from the incident surface as a fluorescent light beam 201b. Thereafter, the fluorescent light beam 201b is irradiated onto the dichroic layer of the wavelength selective polarization dichroic mirror 202, and is reflected by the dichroic layer and irradiated toward the optical element group 210, like the blue light beam 201a.

  In this example, the blue light beam 201a and the fluorescent light beam 201b that have passed through the optical element group 210 are incident on the wavelength selective divergence state conversion element 218, respectively. Then, the wavelength selective divergence state conversion element 118 mainly scatters the blue light beam 201a, thereby correcting the difference in the divergence state between the blue light beam 201a and the fluorescent light beam 201b.

The wavelength selective divergence state conversion element 218 of this example has a configuration further including antireflection films 34, 35, and 36 in addition to the configuration shown in FIG. 15A, and Ta ₂ O ₅ as the first medium 32. The second medium 33 is a mixture of TiO ₂ and 3.5% SiO ₂ . Such a wavelength selective divergence state conversion element 218 is obtained as follows, for example. First, after forming the antireflection film 35 on the quartz substrate 31, a Ta ₂ O ₅ film is formed thereon by vacuum deposition, and processed into a concavo-convex shape by blasting. On top of that, TiO ₂ and SiO ₂ are formed by sputtering so as to have a desired mixing ratio, and the recesses are filled. Then, after the surfaces of the filled TiO ₂ and SiO ₂ are flattened by polishing, an antireflection film 34 and an antireflection film 36 are formed on both surfaces of the element.

  The refractive indexes of the first medium 32 and the second medium 33 in this example are shown in FIG. The refractive index difference between the first medium 32 and the second medium 33 is as large as 0.068 at the blue wavelength band of 450 nm, 0.019 at the green wavelength band of 525 nm, and −0 .0 at the red wavelength band of 620 nm. It almost matches 014. The unevenness formed by such a combination of members can cause scattering only in the blue wavelength band, and the diffusion state of the blue light beam 201a can be adjusted.

Example 6
The sixth embodiment is an example of the transflective films 16 and 46 used in the deflection element 11 shown in FIG. 6E and the non-polarization diffusing element 41 shown in FIG. The transflective film reflects a part of the blue light beam and transmits the green or red light beam. In this embodiment, for example, a multilayer film having the structure shown in Table 5 below is used as the semi-transmissive reflective film.

  FIG. 37 shows the transmittance when light is incident on the multilayer film of Table 5 at an incident angle of 20 °. As shown in FIG. 37, the multilayer film in Table 5 shows a transmittance of about 70% near the blue wavelength band of 450 nm, and is close to 100% near the green wavelength band of 525 nm and the red wavelength band of 620 nm. The transmittance is shown. Therefore, according to the transflective film of this embodiment, about 30% of the blue light beam 101 is reflected to form the blue light beam 101a, and the remaining about 70% of the blue light beam 101 is transmitted to irradiate the phosphor. It is done. Further, the green or red fluorescent light beam 101b generated by exciting about 70% of the transmitted blue light beam also passes through the transflective film.

  The present invention is not limited to the use for reducing the size of an illumination optical system, but in an optical system that uses a part of excitation light to a phosphor as it is as light of a certain color and uses fluorescence emission as light of another color. The present invention can be suitably applied when it is desired that the light of each color is combined by at least one common mirror or the like.

DESCRIPTION OF SYMBOLS 101 Blue light beam 101a Blue light beam used as blue light 101b Fluorescent light beam used as green and red light 102 Area division | segmentation dichroic mirror 105 Lens group 106 Fluorescent wheel 110 Optical element group 111 Integrator 113 Fluorescent element with a blue deflection | reflecting reflection function DESCRIPTION OF SYMBOLS 114 Fluorescence element 115 Area | region division | segmentation beam splitter 116 Rotating wheel 117 Divergence state conversion element 118 Wavelength selection divergence state conversion element 11 Deflection element 12 Green fluorescent substance area 13 Red fluorescent substance area 14 Inclined structure (convex part or concave part)
DESCRIPTION OF SYMBOLS 15 Base material 16 Transflective film 17 Uneven structure 21 Base material 22 Antireflection film 23 Dichroic layer 24 Reflective layer 31 Base material 32 1st medium 33 2nd medium 34, 35, 36 Antireflection film 201 Blue light beam 201a Blue Blue light beam 201b used as light of light 201b Fluorescent light beam used as green and red light 202 Wavelength selective polarization dichroic mirror 205 Lens group 206 Fluorescent wheel 210 Optical element group 211 Integrator 212 1/4 wavelength plate 213 Blue deflection reflection function Fluorescent element 214 Fluorescent element 215 Polarization selective beam splitter 216 Rotating wheel 217 Divergence state conversion element 218 Wavelength selection divergence state conversion element 41 Non-polarization diffusion element 42 Green phosphor region 43 Red phosphor region 44 Inclined structure (convex or concave) )
45 Substrate 46 Transflective film 47 Uneven structure 300 Projector 305 Spatial light modulator 306 Projection lens

Claims (17)

A part of the light from the light source is used as it is as the light of the first color, and the phosphor is excited by another part of the light from the light source to generate light of a color different from the first color. An illumination optical system,
A fluorescent element that emits fluorescence from the incident surface by using light from the light source as excitation light; and
The light from the light source is transmitted or reflected and guided to the fluorescent element, and at least the fluorescence emitted from the fluorescent element is transmitted or reflected to a direction different from the direction in which the light from the light source is incident. A guiding mirror element;
A reflective element that reflects part of the light from the light source and emits it from the incident surface;
Utilizing the light reflected by the reflective element as the first color light,
Light from the light source is incident on one surface of the mirror element, and fluorescence from the fluorescent element and reflected light from the reflective element are incident on the other surface,
The reflected light from the reflective element has a polarization direction different from that of the light from the light source at least at the point of incidence on the mirror element, or the area incident on the mirror element is the light from the light source. An illumination optical system, wherein the illumination optical system is different from a region emitted from the mirror element. The reflective element is a deflecting element that deflects incident light so as to be emitted in a direction different from at least a part of the optical path of incident light when reflecting incident light,
The mirror element has a region that reflects light in a first wavelength band that is a wavelength band of light from the light source according to an incident position of light from the light source and an incident position of reflected light from the reflective element. The illumination optical system according to claim 1, wherein the illumination optical system is divided into a region through which light in the first wavelength band is transmitted. The deflecting element has a reflecting surface having an inclination by providing at least one convex portion or concave portion on the surface,
Average inclination angle of the projections or recesses | alpha _{avg |} claim satisfying _|, When the incident angle of the incident light to the deflection element beta, the projections or recesses is _| α _{avg |>} | β 2. The illumination optical system according to 2. The deflecting element is a reflective diffractive element, and has a concavo-convex portion that acts as a diffraction grating,
The illumination according to claim 2, wherein the concavo-convex portion has a periodic structure of four cycles or more, and satisfies P ≦ λ / sin (2 | β |) where P is a pitch and λ is a wavelength of incident light. Optical system. Incident light having an incident angle in an angle range of 25 ° or less is incident on the deflection element,
The illumination optical system according to any one of claims 2 to 4, wherein the light emitted from the deflecting element is emitted in an angle range of not less than a maximum incident angle of incident light and not more than 75 °. The illumination optical system according to any one of claims 2 to 5, wherein the emitted light from the deflection element is emitted to a ring-shaped region surrounding the incident light. A quarter wave plate is provided between the mirror element and the reflective element,
Light from a light source is incident on the mirror element as linearly polarized light,
The reflective element is a non-polarization diffusing element that gives a phase difference of 0.7π to 1.3π with respect to incident light and diffuses and emits the light,
The mirror element is a polarization dichroic mirror having wavelength selectivity, and reflects or transmits light in a first wavelength band, which is a wavelength band of light from the light source, according to polarization, and from the fluorescent element. The illumination optical system according to claim 1, wherein light in the second wavelength band, which is a fluorescent wavelength band, is reflected or transmitted regardless of polarization. In the non-polarization diffusing element, the polarization ratio of the outgoing light is 0.8 or more, and when the parallel light is incident, the value of the angle γ that is a half value of the central luminance of the outgoing light is 1 ° or more and 60 °. The illumination optical system according to claim 7, wherein the illumination optical system is: In the non-polarization diffusing element, a reflecting surface having an inclination is formed by providing two or more convex portions or concave portions on the surface,
The illumination optical system according to claim 7, wherein the convex portion or the concave portion has a lens shape. The divergence state conversion element which changes the divergence state with respect to the light utilized as light of at least one color is provided in the optical path. Illumination optical system. The divergence state conversion element is light that is used as light of the first color or a color different from the first color, and light in at least two wavelength bands of wavelengths λ ₁ and λ ₂ is incident And
The divergence angle of the light of wavelength λ ₁ is smaller than the divergence angle of the light of wavelength λ ₂ ,
The divergence state conversion element changes a divergence state of the light of the wavelength λ ₁ so that a difference between a divergence angle of the light of the wavelength λ ₁ and a divergence angle of the light of the wavelength λ ₂ is reduced. The illumination optical system described. The divergence state conversion element increases a divergence state of the light of the first color and does not change a divergence state of light of a color different from the first color or occurs with respect to the light of the first color. The illumination optical system according to claim 10 or 11, wherein a change smaller than the changed change is generated. The illumination optical system according to any one of claims 1 to 12, wherein a wavelength band of light from the light source is a blue wavelength band. A light source;
The illumination optical system according to any one of claims 1 to 13,
A modulation element for modulating light emitted from the illumination optical system;
And a projection optical system that projects the light modulated by the modulation element to the outside. A reflective element,
When reflecting incident light, the incident light is deflected and emitted so that the optical path of the emitted light is emitted in a direction different from at least a part of the optical path of the incident light,
When incident light having an incident angle in an angle range of 25 ° or less is incident, the emitted light from the element is emitted in an angle range of not less than the maximum incident angle of the incident light and not more than 75 °. A characteristic deflection element. A reflective element,
While giving a phase difference of 0.7π to 1.3π with respect to the incident light, it is diffused and emitted,
It is an element in which the polarization ratio of the emitted light is 0.8 or more, and when the parallel light is incident, the value of the angle γ that is a half value of the central luminance of the emitted light is 1 ° or more and 60 ° or less. A non-polarization diffusing element characterized. When light of at least two wavelength bands including light of two wavelength bands of wavelengths λ ₁ and λ ₂ having different light divergence angles is incident on the same surface, at least the divergence angle of the light of the wavelength λ ₁ The divergence state of the light having the wavelength λ ₁ having a smaller divergence angle than that of the light having the wavelength λ ₂ is changed so that a difference in the divergence angle of the light having the wavelength λ ₂ is reduced. Wavelength selective divergence state conversion element.

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