CN110161680A - A kind of holographical wave guide display device and its display methods - Google Patents

Abstract

The present application relates to a holographic waveguide display device, including a waveguide, a holographic coupling input unit, a holographic coupling output unit, an image source unit located on the light side of the wave guide, and an image projection unit located on the light side of the wave guide, wherein the image source The unit includes an image source and a relay module, the relay module is located between the image source and the waveguide, and is used for amplifying and collimating the image light waves emitted from the image source into thin beams of parallel light at the same angle. In this application, through the relay module in the image source unit, the image light wave is amplified and collimated into a thin beam of parallel light at the same angle. According to actual needs, the image projection unit can realize the amplification and energy distribution of the image light wave, thereby expanding the field of view corners and large exit pupils.

Description

A holographic waveguide display device and display method thereof

technical field

The present application relates to the field of waveguide display, in particular to a holographic waveguide display device and a display method thereof.

Background technique

The holographic waveguide display device belongs to the field of head-mounted enhancement technology, and its key technology is to replace traditional optical elements with holographic optical elements as waveguide couplers to form a wearable imaging system with high integration.

Most of the existing holographic waveguide display devices are based on the splicing of multiple holographic optical elements in order to expand the field of view. For example, the patent US 9791703B1 discloses that two intermediate gratings are used to divide the field of view into two parts, which are transmitted along the two waveguides respectively. The path is transmitted, and after reaching the coupling output grating, the two parts of the field of view are spliced to form a complete field of view. Another example is the patent US9933684B2, which discloses that the field of view is further subdivided through a multi-layer holographic grating element to achieve high-quality transmission of each field of view, and finally achieve the complete field of view of the human eye at the splicing point.

In order to expand the exit pupil, the pupil is mostly copied based on the turning grating, such as the patent US9874667B2 and the patent US9933684B2, which realize horizontal expansion through the turning grating. Display requirements.

In order to achieve color display, most of them are based on multi-layer waveguide components. For example, patent US9664824B2 uses two additional layers of components to perform color compensation and correction, so as to achieve a display without chromatic aberration. Another example is the patent US995918B2, which transmits red, green and blue light respectively through three-layer waveguides, thereby realizing color display.

However, the above-mentioned solutions are all implemented by combining multiple components, which will increase the complexity, size and volume of the system on the one hand; on the other hand, the complex grating and system structure will greatly increase the processing difficulty and production cost, and reduce the yield rate.

Contents of the invention

The present application provides a holographic waveguide display device, which at least solves at least one problem existing in the prior art.

In order to solve the above problems, in the first aspect, the embodiment of the present application provides a holographic waveguide display device, including a waveguide, a holographic coupling-in unit, a holographic coupling-out unit, an image source unit located on the light side of the wave guide, and an image source unit located on the light side of the wave guide. The image projection unit; wherein, the image source unit includes an image source and a relay module, the relay module is located between the image source and the waveguide, and is used to collimate the image light waves emitted from the image source into the same angle Thin beams of parallel light waves.

Specifically, the relay module includes a double telecentric optical path system.

Specifically, the bi-telecentric optical path system includes a first lens, a second lens and a pinhole, the pinhole is located at the rear focal plane of the first lens and the front focal plane of the second lens, and the second lens The focal length is greater than the focal length of the first lens.

Specifically, the holographic outcoupling unit is a scattering holographic optical element.

Specifically, the holographic coupling-out unit is one of a reflective scattering holographic volume grating and a transmissive scattering holographic volume grating, and the holographic coupling-in unit is one of a reflective holographic volume grating and a transmissive holographic volume grating .

Specifically, the image projection unit includes a half-mirror or a half-mirror array for reflecting the image light waves passing through the holographic coupling-out unit to a target observer.

Specifically, the waveguide includes one of a slab waveguide and a curved waveguide.

On the other hand, the embodiment of the present application discloses a holographic waveguide display method, which is applied to the aforementioned holographic waveguide display device, including the parallel image light waves of thin beams of the same angle output from the image source unit entering the waveguide through the holographic coupling input unit; The final image light wave is output to the image projection unit through the holographic coupling output unit; the image light wave reflected by the image projection unit is displayed and formed.

The holographic waveguide display device disclosed in the embodiment of the present application includes a waveguide, a holographic coupling-in unit, a holographic coupling-out unit, an image source unit located on the light side of the wave guide, and an image projection unit located on the light side of the wave guide, wherein the image The source unit includes an image source and a relay module, the relay module is located between the image source and the waveguide, and is used to collimate the image light waves emitted from the image source into thin parallel light waves of the same angle. In this application, through the relay module in the image source unit, the image light wave is amplified and collimated into a thin beam of parallel light at the same angle. According to actual needs, the image projection unit can realize the amplification and energy distribution of the image light wave, thereby expanding the field of view corners and large exit pupils.

Description of drawings

The features and advantages of the present application will be more clearly understood by referring to the accompanying drawings, which are schematic and should not be construed as limiting the application in any way. In the accompanying drawings:

FIG. 1 is a schematic structural diagram of a holographic waveguide display device according to an embodiment of the present application;

Fig. 2 is a schematic structural diagram of a double telecentric optical path system in an embodiment of the present application;

FIG. 3 is a schematic structural diagram of a holographic waveguide display device according to another embodiment of the present application;

Fig. 4 is a working schematic diagram of the transmissive and reflective holographic coupling-in units in the embodiment of the present application;

Fig. 5 is a working diagram of the transmissive holographic coupling output unit in the embodiment of the present application;

FIG. 6 is a schematic structural diagram of a holographic waveguide display device according to another embodiment of the present application;

FIG. 7 is a holographic waveguide display method according to another embodiment of the present application.

Detailed ways

In order to better understand the above-mentioned purpose, features and advantages of the present application, the present application will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that, in the case of no conflict, the embodiments of the present application and the features in the embodiments can be combined with each other.

In the following description, many specific details are set forth in order to fully understand the application, but the application can also be implemented in other ways different from those described here, therefore, the protection scope of the application is not limited by the specific details disclosed below. EXAMPLE LIMITATIONS.

The embodiment of the present application discloses a holographic waveguide display device, including a waveguide, a holographic coupling input unit, a holographic coupling output unit, an image source unit located on the input side of the waveguide, and an image projection unit located on the output side of the waveguide; wherein, the The image source unit includes an image source and a relay module, the relay module is located between the image source and the waveguide, and is used to collimate the image light waves emitted from the image source into thin parallel light waves of the same angle.

In traditional waveguide display devices, after the image source generates image light waves, the image light waves corresponding to each object point in the image are collimated into wide parallel light with different angles of view, and the wide parallel light with different angles of view is input into the grating through holographic coupling After being coupled into the waveguide and transmitted through the waveguide, the imaging point is finally recovered in the lens of the human eye and imaged on the retina. However, according to the coupling wave theory, the holographic coupling grating has a certain angular bandwidth, which can only allow incident light in a certain angular range to occur. Diffraction, light beyond this angle range cannot be coupled into the waveguide and undergoes total reflection inside, which means that the traditional holographic waveguide display viewing angle is limited by the angular bandwidth of the holographic grating.

In the holographic waveguide display device disclosed in this application, after the image source in the image source unit generates image light waves, the relay module collimates the light of each pixel in the image light waves into thin beams parallel to the image light waves at the same angle, and the image The light wave is incident on the holographic coupling-in unit with parallel light at the same angle, which is diffracted and coupled into the waveguide for transmission. The parallel light of each field of view has the same transmission angle in the waveguide, exits through the holographic coupling-out unit, and finally is transmitted by the image projection unit. It is imaged to the retina together with the lens of the human eye, because the relay module can enlarge the image on the image source according to actual needs, that is, the size of the image projected on the holographic coupling output unit is enlarged. The function of the field size occurs on the side of the image projection unit, and the magnification of the field of view of the image projection unit is directly related to the image size, so enlarging the image can expand the field of view of the output image. Among them, the image source can be a passive display such as LCD, LCOS, DLP or an active display such as OLED, and the display needs to have corresponding units such as lighting and circuits. The image light wave can be a two-dimensional image light wave generated by the image source, or a three-dimensional image light wave, which is specifically determined according to the image generated by the image source.

The relay module can be an optical element or system designed based on the principle of geometric optics, or a diffractive element or system based on the principle of scalar diffractive optics, or an optical element or system designed based on the principle of micro-nano vector optics, whose magnification can be It depends on the actual choice.

The function of the holographic coupling input unit is to modulate and couple the image light wave output by the relay module to the waveguide at a certain angle. Image projection unit. The holographic coupling-in unit and the holographic coupling-out unit can be single-layer or multi-layer holographic optical elements, and can be monochromatic diffractive or polychromatic diffractive. If it is a polychromatic diffractive holographic optical element, it can be wavelength multiplexed or Single-color sensitive material angle multiplexing processing is realized.

The function of the image projection unit is to amplify the image light wave emitted by the holographic coupling output unit and reflect it to human eyes to form an image of the virtual scene. The image projection unit can be an optical element or system designed based on the principle of geometric optics, a diffraction element or system based on the principle of physical optics, or an optical element or system designed based on the principle of micro-nano optics. The image projection unit is different according to the dimension of the image generated by the image source unit. For example, when the image source generates a two-dimensional image, it corresponds to a two-dimensional image projection unit; when the image source generates a three-dimensional image, it corresponds to a three-dimensional image projection. unit. The image projection unit has a translucent property, and the external scene can be transmitted to human eyes without distortion and aberration.

A holographic waveguide display device disclosed in an embodiment of the present application, as shown in FIG. 1 , the waveguide display device includes a waveguide 104, a holographic coupling input unit 103, a holographic coupling output unit 105, an image source 101 located on the input side of the waveguide, and A relay module 102, and an image projection unit 106 located at the output side of the waveguide. Wherein, the relay module 102 is located between the image source 101 and the waveguide 104, and is used to collimate the image light waves emitted from the image source into thin parallel light waves of the same angle.

In the embodiment of the present application, the image source 101 generates the target image light wave 210, which is transmitted to the relay module 102 and collimated to form a thin beam parallel image light wave 202 at the same angle. Preferably, the image source 101 is a transmissive LCD display screen, and the relay module is a double telecentric optical system.

The above-mentioned image light wave 202 is input to the holographic coupling-in unit 103, and through coupling, the image light wave is modulated at a certain angle 301 and coupled to the waveguide 104, and then transmitted in the waveguide at the above-mentioned fixed transmission angle 301. Wherein, the waveguide can be a parallel waveguide or a curved waveguide; the transmission angle 301 satisfies the following formula

in the formula is the propagation angle of the image signal, and is the full The critical angle of internal reflection, n is the refractive index of the waveguide unit material.

Then, the image light wave 203 transmitted through the waveguide is output through the holographic coupling output unit 105, and modulated and coupled to the image projection unit 106 at a certain angle 302, and finally, the image projection unit 106 projects the image light wave 204 to the target observer 107 , forming a magnified image. Wherein, the above-mentioned image projection unit is a half mirror, which is used to reflect the image light wave projected onto it to the target observer. Optionally, the image projection unit can also be an array of half mirrors, and its specific function is the same as that of the half mirror. Same, no more details.

Optionally, the holographic coupling-out unit is a scattering holographic optical element, which is obtained by interference of a plane wave and a scattered light wave. During reproduction, when parallel light is incident, the scattered light wave during recording will be obtained. Each thin beam on the parallel image light is a pixel. When it is incident on the holographic coupling output unit, this thin beam will be scattered into light within a certain angle. When the light at this angle is projected by the image When collected by the unit and reflected to the human eye, the beam aperture will increase. The beam aperture is positively correlated with the scattering angle of the holographic coupling output unit, and the light returning from the image projection unit has a large aperture, thereby achieving a large exit pupil. Both the holographic coupling-in unit and the holographic coupling-out unit may be one of a reflective holographic volume grating and a transmissive holographic volume grating. In the embodiment of the present application, both are transmissive holographic volume gratings. The positions are respectively on the light incident side and the light exit side of the waveguide. As shown in the figure, the two are located on different sides of the waveguide.

In the holographic waveguide display device disclosed in the embodiment of the present application, the image source in the image source unit generates the target image light wave, and after passing through the relay module, the image light wave is collimated into thin beams parallel to the image light wave at the same angle, and then undergoes holographic coupling The input unit enters the waveguide for transmission and output, because the relay module can enlarge the image on the image source according to actual needs, that is, enlarge the size of the image projected on the holographic coupling output unit, combined with the enlargement function of the image projection unit , so the field of view of the output image can be enlarged.

Furthermore, in the embodiment of the present application, the holographic coupling-out unit is a scattering holographic optical element, which is obtained by the interference of plane waves and scattered light waves. When reproducing, parallel light is incident to obtain scattered light waves during recording. Each thin beam on the parallel image light is a pixel. When it is incident on the holographic coupling output unit, this thin beam will be scattered into light within a certain angle. When the light at this angle is projected by the image When collected by the unit and reflected to the human eye, the beam aperture will increase. The beam aperture is positively correlated with the scattering angle of the holographic coupling output unit, thereby achieving a large exit pupil.

Optionally, the relay module in the embodiment of the present application is a double-telecentric optical path system, and its specific structure is shown in Figure 2. The double-telecentric optical path system includes two aplanatic first lenses 1021, second 1023 and Small holes 1020 are formed. Wherein, the image source 101 is placed on the front focal plane of the first lens 1021, the light 201 emitted by it is collimated by the lens 1021, and the pinhole 1020 is placed on the back focal plane of the lens 1021 and the front focal plane of the second lens 1023, which acts as The aperture screens out a thin beam of central light, which is further incident on the second lens 1023 and then collimated into the required image light 202 . Since the focal length f3 of the second lens 1023 is greater than the focal length f1 of the first lens 1021, the final output image light is larger than the light source, which realizes the expansion of the image, and finally realizes the effect of expanding the viewing angle and large exit pupil.

In another embodiment of the present application, as shown in Figure 3, the holographic coupling-in unit is a reflective holographic volume grating, and the holographic coupling-out unit is a transmissive holographic volume grating. In this embodiment, the holographic coupling-in unit and the holographic coupling-out unit on the same side of the waveguide. It is easy to understand that the holographic coupling-in unit may be a transmissive holographic volume grating, and the holographic coupling-out unit may be a reflective holographic volume grating, or both may be transmissive volume gratings, which will not be further described here.

Specifically, as shown in FIG. 4 , the transmission and reflection working modes of the holographic coupling-in unit are described. The image light 202 is incident to the transmissive holographic coupling-in unit 103 and is diffracted into parallel light at the same angle. Specifically, ray R1 is diffracted into r1, ray R2 is diffracted into r2, and ray R3 is diffracted into r3. The reflective holographic coupling-in unit and the transmissive holographic coupling-in unit work in the same mode, and both work under Bragg diffraction conditions, which will not be repeated here.

The holographic outcoupling unit is in a transmissive working mode, as shown in FIG. 5 , the collimated light 203 is incident on the transmissive holographic outcoupling unit 105 and is scattered into divergent light at a certain angle. Specifically, the ray r1 is diffracted into a ray in the range t1, the ray r2 is diffracted into a ray in the range t2, and the ray r3 is diffracted into a ray in the range t3. The reflective holographic coupling-in unit and the transmissive holographic coupling-in unit work in the same mode, which will not be repeated here. About the manufacturing method of the transmissive holographic coupling-out unit. The parallel light 401 is incident on the scattering element 501 and is scattered into a divergent light 402 at a certain angle. This angle range is the same as t1, t2, and t3 in the above-mentioned embodiment, and the divergent light is object light. Another beam of inclined plane wave 403 is incident, and this inclined plane wave is the reference light. The object light and the reference light interfere on the holographic substrate 502 to form a holographic coupling-out unit. The optical path during reproduction and the working mode of the holographic coupling-out unit in the above embodiment.

In this embodiment, other structures of the holographic waveguide display device are the same as those in the above embodiments, and will not be repeated here.

Another embodiment of the present application, as shown in FIG. 6 , has an overall structure similar to that of the first embodiment, except that the waveguide is a curved waveguide, which can achieve an ergonomic conformal design of the corner of the human eye compared to a flat waveguide. The image projection unit is a concave magnifying glass array, and the corresponding images incident on the holographic coupling output unit are sub-image arrays in the integrated imaging, and each sub-image corresponds to a concave magnifying glass. According to the integrated imaging principle, the waveguide display device realizes three-dimensional display.

Another embodiment of the present application discloses a holographic waveguide display method, which is applied to the aforementioned holographic waveguide display device, as shown in FIG. 7 . Specifically, the parallel image light waves of thin beams of the same angle output from the image source unit enter the waveguide through the holographic coupling input unit; the image light waves transmitted through the waveguide are emitted to the image projection unit through the holographic coupling output unit; The image of the light wave display imaging.

Wherein, the image source unit includes an image source and a relay module, and the relay module amplifies the image light wave and collimates it into a thin beam of parallel light at the same angle. According to actual needs, the image projection unit can amplify the image light wave And energy distribution, thereby expanding the field of view and large exit pupil.

The above descriptions are only preferred embodiments of the present application, and are not intended to limit the present application. For those skilled in the art, there may be various modifications and changes in the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of this application shall be included within the protection scope of this application.

Claims (8)

1. A holographic waveguide display device, characterized in that it comprises a waveguide, a holographic coupling-in unit, a holographic coupling-out unit, an image source unit positioned at the light-introducing side of the waveguide, and an image projection unit positioned at the light-guiding side of the waveguide; wherein , the image source unit includes an image source and a relay module, the relay module is located between the image source and the waveguide, and is used to amplify and collimate the image light waves emitted from the image source into thin beam parallel light waves at the same angle . 2. The holographic waveguide display device according to claim 1, wherein the relay module comprises a double telecentric optical path system. 3. The holographic waveguide display device according to claim 2, wherein the bi-telecentric optical path system comprises a first lens, a second lens and a small hole, and the small hole is located on the rear focal plane of the first lens and the front focal plane of the second lens, and the focal length of the second lens is greater than the focal length of the first lens. 4. The holographic waveguide display device according to claim 1, wherein the holographic coupling-out unit is a scattering holographic optical element. 5. The holographic waveguide display device according to claim 4, wherein the holographic coupling-in unit is one of a reflective scattering holographic volume grating and a transmissive scattering holographic volume grating, and the holographic coupling-in unit is One of reflective holographic volume grating and transmissive holographic volume grating. 6. The holographic waveguide display device according to claim 1, wherein the image projection unit includes a half-mirror or a half-mirror array for reflecting the image light wave passing through the holographic coupling-out unit to the object for observation By. 7. The holographic waveguide display device according to claim 1, wherein the waveguide comprises one of a slab waveguide and a curved waveguide. 8. A holographic waveguide display method, applied to the holographic waveguide display device according to any one of claims 1-7, characterized in that it comprises: The thin beam parallel image light waves output from the image source unit at the same angle enter the waveguide through the holographic coupling input unit; The image light wave transmitted by the waveguide is output to the image projection unit through the holographic coupling output unit; The image light waves reflected by the image projection unit display imaging.