Optical waveguide and display device

Abstract

The embodiment of the invention relates to the technical field of optical waveguides, and provides an optical waveguide and a display device. The optical waveguide comprises a substrate, a coupling-in element and a coupling-out element. The coupling-in element is arranged on the substrate and used for coupling light of different incident angles into the substrate. The out-coupling element is disposed on the substrate and has a plurality of out-coupling regions. The plurality of outcoupling regions are configured to selectively outcouple light according to an incident angle. The plurality of out-coupling regions comprise a first region, a second region and a third region which are sequentially arranged along the propagation direction of light. The first region is configured to selectively couple out light within a first range of angles of incidence and limit out light within a second range of angles of incidence. The second region is configured to couple out light within the first range of angles of incidence and light within the second range of angles of incidence. The third region is configured to selectively couple out light within the second range of angles of incidence and restrict light within the first range of angles of incidence. The first incident angle range and the second incident angle range partially overlap.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of optical waveguide technology, and more specifically, to an optical waveguide and a display device. Background Art

[0002] Augmented Reality (AR) technology allows users to interact with digital content more naturally by integrating the virtual world with the real world. For display devices using AR technology, indicators such as the size of the image field of view (FOV), the size of the eye box, the continuity of the image, and the color uniformity will affect the user experience.

[0003] For display devices that combine diffraction light waveguide technology and AR technology, the current method of increasing their field of view angle is to either increase the thickness of the diffraction light waveguide or reduce the light utilization rate of the AR device. Summary of the invention

[0004] In view of this, it is necessary to provide an optical waveguide and a display device to improve the eye box of a display device combining diffraction optical waveguide technology and AR technology without increasing the thickness of the optical waveguide and reducing light utilization.

[0005] In a first aspect, the present application provides an optical waveguide. The optical waveguide includes a substrate, a coupling element, and a coupling element. The coupling element is disposed on the substrate, and is used to couple light of different incident angles into the substrate. The coupling element is disposed on the substrate. The coupling element has a plurality of coupling regions. The plurality of coupling regions are configured to selectively couple light according to the incident angle. The plurality of coupling regions include a first region, a second region, and a third region arranged in sequence along the propagation direction of the light. The first region is configured to selectively couple light within a first incident angle range, and limit coupling light within a second incident angle range. The second region is configured to couple light within a first incident angle range and light within a second incident angle range. The third region is configured to selectively couple light within a second incident angle range, and limit coupling light within the first incident angle range. The first incident angle range and the second incident angle range partially overlap.

[0006] The optical waveguide of the embodiment of the present application can effectively expand the eye box by selectively coupling out light at different angles in different regions. Compared with single-angle coupling, multi-angle multiplexing can cover a wider angle range.

[0007] In addition, the traditional multi-angle multiplexing uses the same multiplexing method in the entire outcoupling area, resulting in some light being coupled out in inappropriate areas and unable to enter the human eye, causing waste. The optical waveguide of the embodiment of the present application controls the light of a specific angle to be coupled out in a specific area by partitioning the outcoupling element. Compared with the traditional multi-angle multiplexing, the optical waveguide of the embodiment of the present application can avoid unnecessary light outcoupling, reduce light waste, thereby improving light utilization, and further improving the overall screen brightness of the display device using the optical waveguide.

[0008] In addition, the optical waveguide of the embodiment of the present application achieves the expansion of the eye box and the improvement of light utilization by optimizing the structural design of the outcoupling zone, without increasing the number of layers of the waveguide sheet, and thus does not increase the thickness of the optical waveguide.

[0009] The second aspect of the present application provides a display device. The display device includes an optical machine and the optical waveguide provided in the first aspect of the present application. The optical waveguide is used to receive light projected by the optical machine.

[0010] The display device of the second aspect of the present application has at least the same advantages as the optical waveguide of the first aspect of the present application, which will not be described in detail. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 Figures (a) and (b) are schematic structural diagrams of a single-chip optical waveguide and a multi-chip optical waveguide in the related art, respectively.

[0012] Figure 2 Figures (a), (b) and (c) are schematic diagrams of the structure, shooting architecture and FOV of a single-angle VHOE in the related art, respectively; Figure 2 Figures (d), (e) and (f) are schematic diagrams of the structure, shooting architecture and FOV of the dual-angle VHOE in the related art, respectively.

[0013] Figure 3 Figures (a), (b) and (c) are schematic diagrams of the propagation of light at different incident angles in a display device with an optical waveguide having a multi-angle VHOE in the related art.

[0014] Figure 4 Figures (a), (b) and (c) are schematic diagrams of light propagation at different incident angles in a display device according to an embodiment of the present application.

[0015] Figure 5 Figures (a), (b) and (c) are schematic diagrams of the incident angle, spectral flux and reconstructed wavelength of the first region, the second region and the third region in the optical waveguide of an embodiment of the present application.

[0016] Figure 6Figures (a) and (b) are schematic diagrams of the eye box sizes of an optical waveguide in the related art and an optical waveguide in an embodiment of the present application, respectively.

[0017] Description of the main component symbols: display device-100, 100'; optical machine-10, 10'; optical waveguide-20, 20', 1, 2; substrate-21, 21'; coupling element-22, 22'; coupling element-23, 23'; coupling area-A; first area-A1; second area-A2; third area-A3; light within the first incident angle range-L1; light within the second incident angle range-L2; light within the third incident angle range-L3; blue light-B; green light-G; red light-R; eye-E; eye box-EB, EB'; single-angle VHOE-3; dual-angle VHOE-4; reference light-Lr, Lr1, Lr2; signal light-Ls, Ls1, Ls2; image-IMG1, IMG2, IMG3.

[0018] The following specific implementation methods will further illustrate the present application in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0019] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the embodiments of the present application, and cannot be understood as limiting the present application.

[0020] In the description of the embodiments of the present application, the terms "thickness", "up", "down", "inside", "outside", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the implementation methods of the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they should not be understood as limitations on the present application.

[0021] In the description of the embodiments of the present application, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features.

[0022] In the description of the embodiments of the present application, unless otherwise specified, “plurality” means two or more than two.

[0023] In the description of the embodiments of the present application, unless otherwise specified, the term "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be the internal connection between two elements or the interaction relationship between two elements.

[0024] For those skilled in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0025] Figure 1 Figures (a) and (b) are schematic diagrams of the structures of a single-chip optical waveguide and a multi-chip optical waveguide in the related art, respectively. Figure 1 As shown in Figure (a), the optical waveguide 1 is a monolithic optical waveguide, and the red light R, green light G, and blue light B enter the human eye E after passing through the optical waveguide 1. Since the optical waveguide 1 is a monolithic optical waveguide or a single-layer optical waveguide, its entire eye box has unevenness, and the FOV of the optical waveguide 1 is very small. In order to improve the FOV of the optical waveguide 1, one way is to use Figure 1 The multi-chip optical waveguide shown in Figure (b) is improved by stacking two or even three waveguides.

[0026] like Figure 1 As shown in Figure (b), the optical waveguide 2 is composed of three stacked optical waveguides. The red light R, green light G, and blue light B are transmitted through one optical waveguide in the optical waveguide 2 and finally enter the human eye E. Figure 1 As can be seen from Figures (a) and (b) in the figure: although this method can increase the FOV of the optical waveguide, the thickness of the optical waveguide 2 is increased, thereby resulting in the thickness of the display device (such as AR glasses) using the optical waveguide 2 cannot be reduced.

[0027] Figure 2 Figures (a), (b) and (c) are schematic diagrams of the structure, shooting architecture and FOV of a single-angle volume holographic optical element (VHOE) in the related art. Figure 2 As shown in Figures (a), (b) and (c), the single-angle VHOE3 is formed by single-angle exposure. The single-angle exposure method uses two lights (reference light Lr and signal light Ls) for interference, but because VHOE has high selectivity for angles, the FOV of the single-angle VHOE3 obtained when shooting at a single angle is very small (assuming it is 9°). Figure 2 Figures (d), (e) and (f) are schematic diagrams of the structure, shooting architecture and FOV of dual-angle VHOE in the related art. Figure 2As shown in (d), (e) and (f) in the figure, another way is to increase the FOV through multi-angle multiplexing (Multiplexing) (also known as multi-angle multiplexing). Figure 2 The dual-angle VHOE4 is formed by dual-angle exposure. The dual-angle multiplexing exposure method is to interfere with four lights (reference light Lr1, reference light Lr2, signal light Ls1 and signal light Ls2) in groups of two, which can increase the FOV to ±10°.

[0028] Figure 3 Figures (a), (b) and (c) are schematic diagrams of the propagation of light at different incident angles in a display device with an optical waveguide having a multi-angle VHOE in the related art.

[0029] Figure 3 In the embodiment, the display device 100' comprises an optical engine 10' and an optical waveguide 20'. The optical waveguide 20' is located at the light output side of the optical engine 10'. The optical engine 10' is used to project image light to the optical waveguide 20'.

[0030] The optical waveguide 20' includes a substrate 21', an in-coupling element 22' and an out-coupling element 23'. The in-coupling element 22' and the out-coupling element 23' are both arranged on the substrate 21' and are both gratings. The out-coupling element 23' is a multi-angle VHOE, which adopts a multi-angle multiplexing method, and generally the same multiplexing method is used in the entire out-coupling area. When light travels in the optical waveguide 20' to the out-coupling area, light at various angles will be coupled out by the out-coupling element 23', but light at some angles will not be able to effectively enter the human eye.

[0031] Specifically, Figure 3 Figures (a), (b) and (c) in the figure respectively represent the paths of light with different incident angles in the optical waveguide 20'.

[0032] like Figure 3 As shown in Figures (a), (b) and (c), light with different incident angles (such as light L1 within the first incident angle range, light L2 within the second incident angle range, and light L3 within the third incident angle range) at the same position of the outcoupling element 23' will all emit light, but some of the light coupled out of the outcoupling element 23' does not enter the human eye, and that light will be wasted. If the position of the eyes is moved, although the image can be seen, the image IMG2 and the image IMG3 are incomplete, so they are not considered to be within the range of the eye box EB. The eye box is defined as the range in which a complete image (such as image IMG1) can be seen.

[0033] Figure 4 Figures (a), (b) and (c) in the figure are schematic diagrams of light propagation at different incident angles in a display device according to an embodiment of the present application. Figure 4As shown, the display device 100 includes an optical engine 10 and an optical waveguide 20. The optical waveguide 20 is located at the light output side of the optical engine 10. The optical waveguide 20 is used to receive the light projected by the optical engine 10.

[0034] In some embodiments, the optical engine 10 may be any one of, but not limited to, an organic light emitting diode display, a micro inorganic light emitting diode display, a liquid crystal display, a silicon-based liquid crystal display, a digital micromirror device, and a laser beam scanner.

[0035] Specifically, the optical waveguide 20 includes a substrate 21, an incoupling element 22, and an outcoupling element 23. The incoupling element 22 is disposed on the substrate 21, and is used to couple light of different incident angles into the substrate 21. The outcoupling element 23 is disposed on the substrate 21. The outcoupling element 23 has a plurality of outcoupling regions A. The plurality of outcoupling regions A are configured to selectively outcouple light according to the incident angle.

[0036] The multiple outcoupling regions A include a first region A1, a second region A2 and a third region A3 which are sequentially arranged along the propagation direction of light.

[0037] The first area A1 is configured to selectively couple out the light L1 within a first incident angle range and limit the coupling out of the light L2 within a second incident angle range.

[0038] The second area A2 is configured to couple out light L1 within a first incident angle range and light L2 within a second incident angle range.

[0039] The third region A3 is configured to selectively couple out the light L2 within the second incident angle range and limit the coupling out of the light L1 within the first incident angle range. The first incident angle range and the second incident angle range partially overlap.

[0040] The optical waveguide 20 of the embodiment of the present application can effectively expand the eye box by selectively coupling out light at different angles through different coupling-out regions A. Compared with single-angle coupling, multi-angle multiplexing can cover a wider angle range.

[0041] In addition, conventional multi-angle multiplexing uses the same multiplexing method in the entire outcoupling area, causing some light to be outcoupled in inappropriate areas and unable to enter the human eye, resulting in waste. The optical waveguide 20 of the embodiment of the present application controls the light of a specific angle to be outcoupled in a specific area by partitioning the outcoupling element 23. Compared with conventional multi-angle multiplexing, the optical waveguide 20 of the embodiment of the present application can avoid unnecessary light outcoupling, reduce light waste, and thus improve light utilization.

[0042] In addition, the optical waveguide 20 of the embodiment of the present application achieves the expansion of the eye box and the improvement of light utilization by optimizing the structural design of the outcoupling zone without increasing the number of layers of the waveguide sheet, and thus does not increase the thickness of the optical waveguide 20.

[0043] In some embodiments, the third area A3 is further configured to selectively couple out light L3 within a third incident angle range, and the third incident angle range partially overlaps with the second incident angle range. Thus, by coupling out light L3 within the third incident angle range in the third area A3, the eye box can be further expanded and light utilization can be improved.

[0044] Specifically, Figure 4 Figures (a), (b) and (c) are schematic diagrams of optical paths after the light L1 within the first incident angle range, the light L2 within the second incident angle range and the light L3 within the third incident angle range are incident on the optical waveguide 20 .

[0045] like Figure 4 As shown in (a), (b) and (c) in the figure, corresponding to the first area A1, the light L1 within the first incident angle range is coupled out, and the light L2 within the second incident angle range and the light L3 within the third incident angle range are restricted from being coupled out or are not coupled out.

[0046] Corresponding to the second area A2, the light L1 within the first incident angle range and the light L2 within the second incident angle range are both coupled out, and the light L3 within the third incident angle range is restricted from being coupled out or is not coupled out.

[0047] Corresponding to the third area A3, the light L2 within the second incident angle range and the light L3 within the third incident angle range are both coupled out, and the light L1 within the first incident angle range has been almost completely coupled out in the first area A1 and the second area A2. Therefore, the light L1 within the first incident angle range will basically not be transmitted to the third area A3 and cause waste.

[0048] In some embodiments, the partitioning arrangement of the outcoupling element 23 is not only designed for the incident angle, but also allows different efficiencies in each outcoupling area A. The purpose is to allow light to be almost coupled out at a specific position without continuing to be transmitted backwards and causing waste.

[0049] In some embodiments, the outcoupling element 23 is a volume holographic grating, the first area A1 includes at least one group of grating arrays, the second area A2 includes at least two groups of grating arrays, and the third area A3 includes at least one group of grating arrays, each grating array includes at least two grating stripes, and different groups of grating arrays in each outcoupling area A have different angular selectivities, so as to diffraction couple out light in different incident angle ranges.

[0050] Therefore, the coupling-out element 23 of the embodiment of the present application adopts a volume holographic grating, and uses its diffraction characteristics to achieve selective coupling-out of light. The angle selectivity of each area is controlled by the number of grating arrays, and the structure is simple and easy to implement.

[0051] Figure 5 Figures (a), (b) and (c) are schematic diagrams of the incident angle, spectral flux and reconstructed wavelength of the first region, the second region and the third region in the optical waveguide of an embodiment of the present application. Specifically, in the schematic diagram of the incident angle, spectral flux and reconstructed wavelength, the horizontal axis is the reconstructed wavelength, and the vertical axis is the incident angle and spectral flux, respectively. The distribution of grayscale represents the size of the spectral flux, or the diffraction efficiency. The brighter the grayscale, the higher the diffraction efficiency.

[0052] like Figure 5 As shown in Figure (a), corresponding to the first area, a set of grating arrays is used to couple out light in a first incident angle range (such as light with an incident angle range of approximately -10° to 0° with an efficiency greater than 0.8).

[0053] like Figure 5 As shown in Figure (b), corresponding to the second area, two sets of grating arrays are used to couple out the light in the first incident angle range (such as light with an incident angle range of approximately -10° to 0° and an efficiency greater than 0.8) and the light in the second incident angle range (such as light with an incident angle range of approximately -5° to 4° and an efficiency greater than 0.8).

[0054] like Figure 5 As shown in Figure (c), corresponding to the third area, two sets of grating arrays are used to couple out the light in the second incident angle range (such as light with an incident angle range of about -5° to 4° and an efficiency greater than 0.8) and the light in the third incident angle range (such as light with an incident angle range of about 2° to 10° and an efficiency greater than 0.8).

[0055] In some embodiments, in each outcoupling region A, the number of grating arrays is no more than 10 groups (e.g., 1 group, 2 groups, 3 groups, 4 groups, 5 groups, 6 groups, 7 groups, 8 groups, 9 groups, 10 groups, etc.). Thus, by limiting the number of grating arrays in each outcoupling region, efficiency dispersion caused by an excessive number of gratings is avoided, thereby ensuring the diffraction efficiency of the outcoupling element.

[0056] In some embodiments, the spacing between two adjacent grating stripes ranges from 0.1 micrometer to 10 micrometers (e.g., 0.1 micrometer to 0.5 micrometer, 0.5 micrometer to 1 micrometer, 1 micrometer to 5 micrometers, 5 micrometers to 8 micrometers, 8 micrometers to 10 micrometers, etc.). Thus, by limiting the range of the spacing between grating stripes, the diffraction effect of the grating is ensured.

[0057] In some embodiments, the coupling element 23 includes a photosensitive material layer, which includes but is not limited to one of silver halide, optical crystal and photosensitive polymer material. Therefore, the photosensitive material layer is written into the grating by using the above material through the exposure recording process, which is conducive to ensuring the recording quality of the grating.

[0058] In other embodiments, the outcoupling element 23 may also adopt different grating structures, such as a blazed grating, etc., to achieve adjustment of diffraction efficiency and angle selectivity.

[0059] In some embodiments, the refractive index of the substrate 21 ranges from 1.3 to 2.5 (e.g., 1.3 to 1.5, 1.5 to 1.8, 1.8 to 2.0, 2.0 to 2.3, 2.3 to 2.5, etc.). Therefore, the refractive index of the substrate 21 is limited to the above range, which is conducive to ensuring total reflection of light in the substrate 21 of the optical waveguide 20.

[0060] In some embodiments, the material of the substrate 21 may be, but is not limited to, glass or polymethyl methacrylate (PMMA).

[0061] In some embodiments, the light at different incident angles has a single wavelength, for example, the single wavelength may be, but is not limited to, one of red light, green light, or blue light.

[0062] In some embodiments, the light at different incident angles includes at least two different wavelengths. For example, the at least two different wavelengths may be a combination of red light and green light; or a combination of red light and blue light; or a combination of blue light and green light; or a combination of red light, green light and blue light. Thus, the light at different incident angles includes at least two different wavelengths, which is conducive to achieving a better color display effect for a display device using the optical waveguide.

[0063] In other embodiments, the number of the outcoupling areas A may be changed. For example, there are two outcoupling areas A; or there are four outcoupling areas A, or more than four outcoupling areas A, to achieve a wider eye box.

[0064] The optical waveguide 20 of the embodiment of the present application designs the coupling element 23 into a plurality of coupling regions A, each coupling region A has a different angle (multiplexing) design, which is also beneficial to increase the eye box size. Figure 6 Provide explanation.

[0065] Figure 6 Figures (a) and (b) are schematic diagrams of the eye box sizes of an optical waveguide of the related art and an optical waveguide of an embodiment of the present application, respectively. Figure 6 As shown in FIG. 2( a ), in the optical waveguide 20 ′ of the related art, since there is no partition design for the outcoupling element 23 ′, the efficiency of each position of the outcoupling element 23 ′ is the same.

[0066] Figure 6Figure (a) shows, from top to bottom, the energy distribution of light L1 within the first incident angle range after being coupled out by the coupling element 23', the energy distribution of light L2 within the second incident angle range after being coupled out by the coupling element 23', and the energy distribution of light L1 within the first incident angle range and light L2 within the second incident angle range after being coupled out by the coupling element 23' and superimposed.

[0067] Specifically, along the direction of light propagation (ie, the direction indicated by the arrow at the outcoupling element 23 ′), the energy of the light L1 within the first incident angle range gradually decreases. Figure 6 In Figure (a), along the direction of light propagation, each diamond block indicates that the energy of light L1 within the first incident angle range is gradually halved, and the energy of light indicated by the four diamond blocks is approximately 50%, 25%, 12.5%, and 6.25%, respectively.

[0068] akin, Figure 6 In Figure (b), along the direction of light propagation, each diamond block indicates that the energy of light L2 within the second incident angle range is gradually halved, and the energy of light represented by the four diamond blocks is approximately 50%, 25%, 12.5%, and 6.25%, respectively.

[0069] thus, Figure 6 In Figure (c), after the light L1 within the first incident angle range and the light L2 within the second incident angle range coupled out from the coupling element 23' are superimposed, some of the energies are too low (e.g., less than 10%), resulting in unclear images, making the size of the actual eye box EB smaller than the size of the ideal eye box EB'.

[0070] However, if Figure 6 As shown in FIG. (b), in the optical waveguide 20 of the embodiment of the present application, since a plurality of coupling regions A are designed for the coupling element 23, different coupling regions A have different coupling efficiencies for light at different incident angles. Among them, the first region A1 will not couple out the light L2 within the second incident angle range, and the third region A3 will not couple out the light L1 within the first incident angle range. And with the control of different efficiencies, the energy of the light L1 within the first incident angle range coupled out from the first region A1 and the two second regions A2 is equivalent (e.g., both are approximately 31.25%); the energy of the light L1 within the first incident angle range coupled out from the two second regions A2 and the third region A3 is equivalent (e.g., both are approximately 31.25%).

[0071] Thus, after the light L1 in the first incident angle range and the light L2 in the second incident angle range coupled out from the coupling element 23 are superimposed, the size of the actual eye box EB is consistent with the size of the ideal eye box EB'. Therefore, the optical waveguide 20 of the embodiment of the present application is conducive to expanding the eye box size and achieving a larger eye box.

[0072] In some embodiments, the display device 100 is a near-eye display device. The near-eye display device can be configured in the form of glasses (such as AR glasses), or in the form of a helmet or goggles, which is not limited here.

[0073] Specifically, the AR glasses (not shown) may include a glasses frame and temples connected to both sides of the glasses frame. The optical engine 10 may be disposed on the glasses frame or on the temples on both sides. The optical waveguide 20 is disposed on the glasses frame and is disposed corresponding to the user's eyes respectively.

[0074] In some embodiments, the display device 100 is a vehicle-mounted display. The vehicle includes a windshield, and the optical waveguide 20 may be disposed inside or on the inner side of the windshield to project the light projected by the optical engine 10 onto the windshield.

[0075] It is understandable that the display device 100 can also be applied to other enhanced display scenarios without being limited to the above.

[0076] The above implementation modes are only used to illustrate the technical solutions of the present application and are not intended to limit the present application. Although the present application has been described in detail with reference to the above preferred implementation modes, a person skilled in the art should understand that the technical solutions of the present application may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present application.

Claims

1. An optical waveguide, characterized in that: include: substrate; A coupling element, disposed on the substrate, for coupling light at different incident angles into the substrate; as well as A coupling element is disposed on the substrate, the coupling element having a plurality of coupling regions, the plurality of coupling regions are configured to selectively couple light according to an incident angle, and the plurality of coupling regions include a first region, a second region, and a third region sequentially arranged along a propagation direction of the light; The first region is configured to selectively couple out light within a first incident angle range and limit coupling out light within a second incident angle range; The second region is configured to couple out light within the first incident angle range and light within the second incident angle range; The third region is configured to selectively couple out light within the second incident angle range and limit coupling out light within the first incident angle range; The first incident angle range and the second incident angle range partially overlap.

2. The optical waveguide according to claim 1, characterized in that The outcoupling element is a volume holographic grating, the first region includes at least one group of grating arrays, the second region includes at least two groups of grating arrays, and the third region includes at least one group of grating arrays, each of the grating arrays includes at least two grating stripes, and different groups of the grating arrays in each of the outcoupling regions have different angular selectivities for diffraction coupling of light in different incident angle ranges.

3. The optical waveguide according to claim 2, characterized in that In each of the outcoupling regions, the number of the grating arrays is no more than 10 groups.

4. The optical waveguide according to claim 2, characterized in that The interval between two adjacent grating stripes ranges from 0.1 microns to 10 microns.

5. The optical waveguide according to claim 2, characterized in that The coupling-out element comprises a photosensitive material layer, and the photosensitive material layer comprises one of silver halide, optical crystal and photosensitive polymer material.

6. The optical waveguide according to any one of claims 1 to 5, characterized in that The refractive index of the substrate ranges from 1.3 to 2.

5.

7. The optical waveguide according to any one of claims 1 to 5, characterized in that The light at different incident angles has a single wavelength; or, the light at different incident angles includes at least two different wavelengths.

8. The optical waveguide according to any one of claims 1 to 5, characterized in that The third region is further configured to selectively couple out light within a third incident angle range, and the third incident angle range partially overlaps with the second incident angle range.

9. A display device, characterized in that: include: Optical machine; as well as The optical waveguide according to any one of claims 1 to 8, wherein the optical waveguide is used to receive light projected by the optical machine.

10. The display device according to claim 9, characterized in that The display device is a near-eye display device; or, the display device is a vehicle-mounted display.

Images