Light guide and ar display device for blocking light from a dilated pupil region

Abstract

The application discloses a light waveguide and an AR display device for blocking light from an expansion pupil area. The light waveguide comprises a waveguide plate, an entrance pupil area, an expansion pupil area, an exit pupil area and a light blocking element. The entrance pupil area is used for coupling light into the light waveguide. The expansion pupil area is used for expanding the light for the first time and turning the light to the exit pupil area. The exit pupil area is used for expanding the light for the second time and coupling the light out of the light waveguide. The light blocking element is used for blocking the light directly propagating from the entrance pupil area to the exit pupil area, blocking the light from the expansion pupil area out of the light waveguide, and not blocking the light directly propagating from the entrance pupil area to the expansion pupil area. The AR display device comprises the light waveguide and an oblique incidence light source. Therefore, the light directly propagating from the entrance pupil area to the exit pupil area is blocked by the light blocking element in the light waveguide, the problem of light leakage imaging in the expansion pupil area is solved, the imaging phenomenon of the expansion pupil area and the exit pupil area is avoided, and the use experience of the AR device is improved.

Description

Technical Field

[0001] This invention relates to the field of optical waveguide technology, and in particular to an optical waveguide that blocks light emanating from the pupil expansion region and an AR display device. Background Technology

[0002] Augmented Reality (AR) is a technology that enhances a user's perception of the real world by using information provided by a computer system. It overlays computer-generated virtual objects, scenes, or system prompts onto the real scene, thereby enhancing reality.

[0003] Modern AR devices primarily utilize diffractive waveguides for light transmission. A diffractive waveguide consists of diffraction gratings placed on a transparent medium (such as glass). Light emitted from a projector enters the waveguide through the coupled-in grating region, undergoes total internal reflection within the waveguide, and finally reaches the coupled-out grating region. From there, it exits and is transmitted to the viewer's eye. The light propagating within the coupled-in, extended, and coupled-out grating regions forms a closed loop in wave vector space, meaning that regardless of where the light enters the waveguide, it can always pass through this closed loop to exit at another region. Under normal circumstances, the expanded pupil region and the exit pupil region are visible to the human eye. The expanded pupil region does not produce light for imaging. However, in AR diffraction waveguide devices, light emitted from the light engine at a certain field of view enters the waveguide through the entrance pupil grating, undergoes total internal reflection, and reaches the expanded pupil region. However, not all of this light from the entrance pupil to the expanded pupil region actually enters the expanded pupil. Due to changes in the incident angle or the size of the field of view, some light propagates directly from the entrance pupil to the exit pupil, while the light reaching the exit pupil continues to propagate to the expanded pupil. This causes some light from the obliquely incident light source to exit and form an image in the expanded pupil region, resulting in the human eye seeing two images, thus degrading the AR device's user experience. Therefore, existing AR devices need to be improved to avoid this phenomenon and enhance the user experience. Summary of the Invention

[0004] In view of this, the present invention addresses the deficiencies of the existing technology, and its main objective is to provide an optical waveguide and AR display device that blocks light emanating from the pupil expansion area. By setting a light-blocking element in the optical waveguide, it blocks the light from the entrance pupil area directly to the exit pupil area, thus solving the problem of light leakage imaging in the pupil expansion area of ​​the optical waveguide, avoiding the phenomenon of imaging in both the pupil expansion and exit pupil areas, and improving the user experience of the AR device.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: An optical waveguide for blocking light emanating from a pupil expansion region includes a waveguide plate and an entrance pupil region, a pupil expansion region, an exit pupil region, and a light-blocking element formed on the waveguide plate. The entrance pupil region is used to couple light into the optical waveguide. The pupil dilation area is used to initially expand and redirect light rays to the exit pupil area; The exit pupil region is used to further expand the light rays and couple them out of the optical waveguide; The light-blocking element is located in the optical path from the entrance pupil area to the exit pupil area. It is used to block light from directly propagating from the entrance pupil area to the exit pupil area and then turning to the dilated pupil area for imaging, without blocking light from directly propagating from the entrance pupil area to the dilated pupil area.

[0006] As a preferred embodiment: the entrance pupil region, the dilation pupil region, and the exit pupil region all employ diffraction gratings, with different grating directions in each region, and the sum of the grating period and direction vector of the grating vector in the three regions equal to 0.

[0007] As a preferred embodiment: the waveguide plate has a light-blocking area for setting light-blocking elements, the light-blocking area being formed by a first edge line, a second edge line, a third edge line, and a fourth edge line; wherein, the first edge line is the outermost ray from the entrance pupil area through the expansion pupil area to the exit pupil area; the second edge line is the outermost ray from the expansion pupil area to the exit pupil area and on the side closest to the entrance pupil area; the third edge line is the ray with the largest vector direction angle after entering the optical waveguide from the entrance pupil area; and the fourth edge line is the boundary of the entrance pupil area between the intersection points of the first edge line, the third edge line, and the entrance pupil area.

[0008] As a preferred embodiment, the lower edge of the light-blocking element may extend beyond the third side line.

[0009] As a preferred embodiment, the light-blocking element is a textured surface formed by cutting the waveguide plate, so that light from the entrance pupil region to the exit pupil region is scattered by these textured surfaces and does not directly enter the exit pupil region.

[0010] As a preferred embodiment, the light-blocking element has a hollow structure with light-absorbing material at its edges, thereby cutting off the light propagation path from the entrance pupil area to the exit pupil area.

[0011] As a preferred embodiment, the light-blocking element is a light-absorbing material attached to the surface of the waveguide plate that can directly absorb light from the entrance pupil region to the exit pupil region.

[0012] As a preferred embodiment, the light-blocking element is a diffraction grating, which deflects the light rays from the entrance pupil region to the exit pupil region in other directions before they are emitted out of the optical waveguide.

[0013] An AR display device includes the aforementioned optical waveguide and an obliquely incident light source, wherein the central ray of the obliquely incident light source forms an angle with the perpendicular line from the center of the surface of the entrance pupil region of the optical waveguide.

[0014] As a preferred embodiment, the obliquely incident light source is monochromatic light or colored light.

[0015] Compared with existing technologies, this invention has significant advantages and beneficial effects. Specifically, as shown in the above technical solution, by setting a light-blocking element in the optical waveguide to block the light directly from the entrance pupil area to the exit pupil area, light cannot re-enter the dilated pupil area from the exit pupil area, thus preventing light from exiting the dilated pupil area and forming an image. Simultaneously, the light-blocking element does not block the light directly transmitted from the entrance pupil area to the dilated pupil area. Therefore, the problem of light leakage imaging in the dilated pupil area of ​​the optical waveguide is solved, avoiding the phenomenon of imaging in both the dilated pupil and exit pupil areas, and improving the user experience of AR devices.

[0016] To more clearly illustrate the structural features and effects of the present invention, a detailed description is provided below in conjunction with the accompanying drawings and specific embodiments. Attached Figure Description

[0017] Figure 1 A schematic diagram of light emission from the pupil area of ​​a traditional AR display device; Figure 2 A schematic diagram of the light path in which a light-blocking element is used in the AR display device of the present invention to block the light emitted from the pupil expansion area; Figure 3 This is a schematic diagram defining the location of the light-blocking element of the present invention; Figure 4 This is a schematic diagram of the wave vector principle of the optical waveguide of the present invention, showing the oblique light entering the entrance pupil, expanding the pupil, and finally exiting the pupil. Figure 5 A schematic diagram of the wave vector principle of a traditional optical waveguide, showing the oblique light rays entering the entrance pupil, exiting the pupil, and finally expanding the pupil. Figure 6 This is a schematic diagram of the wave vector principle for two types of imaging when tilted light enters the waveguide according to the present invention. Figure 7 This is a schematic diagram of the optical path when the light-blocking element of the present invention has a cut texture; Figure 8 This is a schematic diagram of the optical path when the light-blocking element of the present invention has a hollow structure; Figure 9 This is a schematic diagram of the optical path when the light-blocking element of this invention is black ink; Figure 10 This is a schematic diagram of the optical path when the light-blocking element of this invention is a diffraction grating; Figure 11 This is a schematic diagram showing the location of the light-blocking element when the exit pupil area of ​​the present invention is not rectangular; Figure 12 This is a schematic diagram showing the location of the light-blocking element when the present invention has a double pupil expansion region; Figure 13 This is a schematic diagram showing the location of the light-blocking element when the present invention has a double pupil expansion region and an exit pupil region.

[0018] Explanation of reference numerals in the attached diagram: 10: Optical waveguide; 11: Entrance pupil area; 21: Pupil expansion area; 31: Exit pupil area; 40: Light blocking element; 41: Light blocking area; 411: First edge; 412: Second edge; 413: Third edge; 414: Fourth edge; 50: Obliquely incident light source; 60: Light ray; 70: Cut edge; SUB1: Waveguide plate. Detailed Implementation

[0019] The present invention is as follows Figures 1 to 13 As shown, an optical waveguide and AR display device that block light emanating from the pupil expansion region are disclosed, wherein: The optical waveguide 10 includes a waveguide plate SUB1 and an entrance pupil region 11, a dilation pupil region 21, an exit pupil region 31, and a light-blocking element 40 formed on the waveguide plate SUB1. The entrance pupil region 11 is used to couple light into the optical waveguide 10. The dilation pupil region 21 is used to expand the light for the first time and deflect it to the exit pupil region 31. The exit pupil region 31 is used to expand the light for the second time and couple it out of the optical waveguide 10. The light-blocking element 40 is located between the entrance pupil region 11 and the exit pupil region 31. It is used to block the light from directly propagating from the entrance pupil region 11 to the exit pupil region 31 and deflecting it to the dilation pupil region 21 for imaging, but does not block the light from directly propagating from the entrance pupil region 11 to the dilation pupil region 21.

[0020] The waveguide plate SUB1 has a light-blocking region 41 for setting the light-blocking element 40. The light-blocking region 41 is formed by a first edge line 411, a second edge line 412, a third edge line 413, and a fourth edge line 414. The first edge line 411 is the outermost ray from the entrance pupil region 11 through the dilation pupil region 21 to the exit pupil region 31. The second edge line 412 is the outermost ray from the dilation pupil region 21 to the exit pupil region 31 and close to the side of the entrance pupil region 11. The third edge line 413 is the ray with the largest vector direction angle after entering the optical waveguide from the entrance pupil region 11. The fourth edge line 414 is the boundary of the entrance pupil region between the two intersection points of the first edge line 411, the third edge line 413, and the entrance pupil region 11.

[0021] like Figure 3 As shown, the pupil expansion region 21 is an irregular quadrilateral with four vertices a, b, c, and d. Vertices a and c are closer to the entrance pupil region 11, while vertices b and d are farther away. The exit pupil region 31 is a rectangle with four vertices e, f, g, and h. Vertices e and f are closer to the pupil expansion region 21, while vertices g and h are farther away. The pupil expansion region 21 and the exit pupil region 31 are spaced apart from each other. Therefore, light rays that enter the pupil region 11 at a slightly downward angle propagate through the optical waveguide 10 from the entrance pupil region 11, and some light rays will directly pass through the gap between the pupil expansion region 21 and the exit pupil region 31 to enter the exit pupil region 31.

[0022] Based on the light path entering the optical waveguide 10 after passing through the entrance pupil region 11, the placement position of the light-blocking element 40 is determined. Specifically, it is determined by the outermost edge light ray jcf from the entrance pupil region 11 through the dilation pupil region 21 to the exit pupil region 31 (the extension of the line connecting the upper right vertex of the exit pupil region 31 and the lower left vertex of the dilation pupil region 21 intersects with the entrance pupil region 11; the line connecting the upper right vertex of the exit pupil region 31, the lower left vertex of the dilation pupil region 21, and the intersection point constitutes the upper boundary of the area where the light-blocking element 40 is placed), the outermost edge light ray cg that is close to the entrance pupil region 11 and propagates from the dilation pupil region 21 to the exit pupil region 31 (the line connecting the lower left vertex of the dilation pupil region 21 and the lower left vertex of the exit pupil region 31 constitutes the right boundary of the area where the light-blocking element 40 is placed), and the .... Figure 6 The corresponding light ray ik with the largest vector direction angle after entering the optical waveguide 10 from the entrance pupil region 11 (determined by the FOV of the input light and the incident angle) is point i, which is the tangent point between line ik and the entrance pupil region 11. The area enclosed by the three lines jcf, cg, and ik and the boundary of the entrance pupil region 11 is the light-blocking region 41, in which a light-blocking element 40 can be set. The light-blocking element 40 cannot extend upward beyond the first side line 411 (line jcf); cannot extend to the right beyond the second side line 412 (line cg); is separated from the entrance pupil region 11 to the left and does not extend beyond the third side line (line ij); and can extend downward beyond the third side line 413 (line ik, in fact, the lower edge of the light-blocking element 40 can extend slightly beyond the third side line 413). This can block the light entering the optical waveguide 10 from the entrance pupil region 11 from directly reaching the exit pupil region 31, and will not cause light to emerge from the pupil expansion region 21 for imaging.

[0023] Each region within the optical waveguide 10 employs a diffraction grating. The grating directions in the entrance pupil region 11, the expanded pupil region 21, and the exit pupil region 31 are different. The grating period and direction of the grating vector in the three regions can satisfy the vector sum equal to 0, so light can propagate arbitrarily in the three regions.

[0024] Figure 2 The diagram shows the actual optical path of the light source from the pupil expansion region 21 after the application of the light-blocking element 40. The light-blocking element 40 blocks the light path from the entrance pupil region 11 directly to the exit pupil region 31, but does not affect the original light path from the entrance pupil region 11 directly to the pupil expansion region 21.

[0025] Figure 4 The wave vector diagram is shown for the oblique light rays entering the entrance pupil region 11, the dilation pupil region 21, and finally the exit pupil region 31, which is the wave vector diagram of the waveguide pupil imaging principle. Figure 5 The wave vector diagram of the oblique light entering the entrance pupil region 11, exit pupil region 31, and finally reaching the dilation pupil region 21 is shown, which is the light emission principle diagram of the dilation pupil region 21 (without light blocking elements).

[0026] In the two figures above, the input light IN1 contains all propagating rays within a certain angular range, entering the entrance pupil region 11 in a direction slightly below the center of the optical waveguide. BND1 represents the first boundary used to satisfy the total internal reflection (TIR) ​​criterion in the waveguide plate SUB1. BND2 represents the second boundary of the maximum wave vector in the waveguide plate SUB1; the maximum wave vector can be determined by the refractive index of the waveguide plate SUB1. A ray can waveguide in the waveguide plate SUB1 only if its wave vector is within the region ZONE1 between the first boundary BND1 and the second boundary BND2. If the wave vector of the ray is outside region ZONE1, the light may leak out of the waveguide plate SUB1 or not propagate at all.

[0027] Figure 4 As shown, the incident light IN1 enters the waveguide from region BOX0a (BOX3a) and propagates in the positive ky direction to the right of the grating V11. The wave vector of the propagating light B1a is in region BOX1a. Propagating light B1a in the V21 direction has its wave vector in region BOX2a. Propagating light B2a in the V31 direction has its wave vector in region BOX3a (BOX0a). Finally, the image OUT1 is output at the exit pupil. According to waveguide theory, the paths of the three wave vectors V11, V21, and V31 in this waveguide must be closed loops to ensure the symmetry between the waveguide input and output.

[0028] Figure 5 As shown, the incident light IN1 enters the waveguide from region BOX0b (BOX3b) and propagates in the positive ky direction to the right of the grating V12. The wave vector of the propagating light B1b is in region BOX1b, and its propagation direction is V22, with its wave vector in region BOX2b. The propagating light B2b propagates direction V32, with its wave vector in region BOX3b (BOX0b). Finally, the image OUT2 is output in the pupil expansion region 21. According to waveguide theory, the paths of the three wave vectors V12, V22, and V32 in this waveguide must be closed loops to ensure the symmetry between the input and output of the optical waveguide. Due to the large FOV of the incident light IN1 and the angle of the oblique incident light in region BOX2b, some light rays may fall outside the second boundary BND2, meaning that a portion of the angled light rays will be missing when imaging in the pupil expansion region 21.

[0029] Figure 6 For the wave vector diagrams of two types of imaging when the light rays enter the optical waveguide at an angle, the center i of the wave vector diagram and the direction of any point in region BOX1b represent all the light vector directions of the light rays propagating from the entrance pupil region 11 to the expansion pupil region 21. Then, the line ik connecting the center i of the wave vector diagram and the vertex k of region BOX1b represents the light vector direction with the largest angle after the light rays enter the optical waveguide 10 from the entrance pupil region 11.

[0030] The light-blocking element 40 can be in the following forms: 1. For example Figure 7 As shown, the light-blocking element 40 can be a pattern formed by cutting the surface of the waveguide plate SUB1; specifically, some patterns are cut on the light path from the entrance pupil region 11 to the exit pupil region 31 on the waveguide plate SUB1 by laser cutting, cutting off the total reflection surface, so that when light hits these cutting patterns, it can only be scattered in all directions and become extremely weak light 60 instead of directly entering the exit pupil region 31.

[0031] 2. For example Figure 8 As shown, the light-blocking element 40 can be a hollow structure on the waveguide plate SUB1; specifically, a small part of the waveguide plate SUB1 is directly cut off by laser cutting, and then a light-absorbing material, such as black ink, is set on the cutting edge 70 of the hollow structure part to directly cut off the propagation path of light from the entrance pupil region 11 to the exit pupil region 31.

[0032] 3. For example Figure 9 As shown, the light-blocking element 40 can be a light-absorbing material attached to the surface of the waveguide plate SUB1, such as black ink, which can directly absorb light from the entrance pupil region 11 to the exit pupil region 31, and has a good blocking effect.

[0033] 4. For example Figure 10 As shown, the light-blocking element 40 can be a diffraction grating, which is set to be consistent with the grating direction of the exit pupil region 31, so as to deflect the light to other directions and then emit it out of the optical waveguide; the diffraction grating can be made small, so that the deflection range and direction of the light will not interfere with the expansion pupil region 21 and the exit pupil region 31.

[0034] This invention applies several different light-blocking elements 40, all of which can block the light emitted from the pupil expansion area 21 to form an image, reduce light leakage in the grating area, and improve the user experience of AR devices; the specific form of the light-blocking element 40 can be selected as needed.

[0035] This invention can be applied to AR display devices, such as an AR display device that blocks light emanating from the pupil expansion region 21, including the aforementioned optical waveguide device and oblique incident light source 50; the oblique incident light source 50 can be monochromatic light or colored light and has a field of view angle; the central ray of the oblique incident light source 50 has a downward angle A with the vertical line of the center of the surface of the entrance pupil region 11, so that the light obliquely enters the entrance pupil region 11.

[0036] It should be noted that the optical waveguide 10 can also be in the following forms; like Figure 11 As shown, the shape of the exit pupil region 31 can also be non-rectangular. Of course, the shape of the pupil dilation region 21 can also be set as needed; the setting method of its light-blocking region 41 is the same as... Figure 3 The corresponding embodiments are the same, and the light-blocking principle is the same.

[0037] like Figure 12 As shown, the entrance pupil region 11 is a two-dimensional grating with two expanding pupil regions 21. The input light IN1 enters the entrance pupil region 11 at a slightly left and lower angle, generating two parts of light that directly enter the exit pupil region 31. Therefore, two light-blocking elements are needed to block the two parts of light that directly enter the exit pupil region 31 from the entrance pupil region 11.

[0038] In this design, the first edge 411 of the first light-blocking area 41 is line jcf; the second edge 412 is line ag; the third edge 413 is line ik (there are two ik lines in the figure, this is the upper ik line); the fourth edge 414 is line ij (between the intersection of lines jcf and ik and the entrance pupil area 11); a light-blocking element 40 is provided in the first light-blocking area 41, and the light-blocking element 40 can be as follows: Figure 7-10 As shown, its lower edge can also extend slightly beyond the third edge 413.

[0039] The first edge 411 of the second light-blocking area 41 is line jcg; the second edge 412 is line af; the third edge 413 is line ik (the ik line located at the bottom in the figure); the fourth edge 414 is line ji (between the intersection of lines jcg and ik and the entrance pupil area 11); a light-blocking element 40 is provided in the first light-blocking area 41, and the light-blocking element 40 can be as follows: Figure 7-10 As shown, its lower edge can also slightly extend beyond the third edge 413. The diagram involves multiple intersection areas, which are marked with black dots for clearer distinction.

[0040] like Figure 13 As shown, the optical waveguide 10 has two symmetrically arranged pupil expansion regions 21 and two exit pupil regions 31. It requires two light-blocking regions 41 to block light rays that directly enter the exit pupil region 31 from the entrance pupil region 11. The first edge 411 of the left light-blocking region 41 is the left line jcf; the second edge 412 is the left line cg; the third edge 413 is the left line ik; and the fourth edge 414 is the left line ij (between the intersections of the left lines jcf and ik with the entrance pupil region 11). A light-blocking element 40 is provided in the left light-blocking region 41. This light-blocking element 40 can be, for example,... Figure 7-10 As shown, its lower edge can also extend slightly beyond the third edge 413.

[0041] The first edge 411 of the light-blocking area 41 on the right side is the right line jcf; the second edge 412 is the right line cg; the third edge 413 is the right line ik; and the fourth edge 414 is the right line ij (between the intersection of the right lines jcf and ik and the entrance pupil area 11). A light-blocking element 40 is provided in the right light-blocking area 41, and the light-blocking element 40 can be as follows: Figure 7-10 As shown, its lower edge can also extend slightly beyond the third edge 413.

[0042] The above embodiments are preferred embodiments of the present invention. In actual solutions, the shapes of the pupil dilation region 21 and the exit pupil region 31 can be changed, and the number, symmetrical or asymmetrical distribution of the entrance pupil region 11, the pupil dilation region 21 and the exit pupil region 31 can be set as needed. The setting principle, position and form of the light blocking element 40 are the same as those of the above embodiments, and will not be listed one by one here.

[0043] The key design feature of this invention is that by incorporating a light-blocking element within the optical waveguide, light directly from the entrance pupil region to the exit pupil region is blocked. This prevents light from re-entering the dilated pupil region from the exit pupil region, thus hindering image formation in the dilated pupil region. Simultaneously, the light-blocking element does not obstruct light directly from the entrance pupil region to the dilated pupil region. Therefore, this solves the problem of light leakage in the dilated pupil region of the optical waveguide, avoiding the phenomenon of image formation in both the dilated and exit pupil regions, and improving the user experience of AR devices.

[0044] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the technical scope of the present invention. Therefore, any minor modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. An optical waveguide that blocks light emanating from the pupil expansion region, characterized in that: It includes a waveguide plate and entrance pupil region, dilation pupil region, exit pupil region and light-blocking element formed on the waveguide plate. The entrance pupil region is used to couple light into the optical waveguide. The pupil dilation area is used to initially expand and redirect light rays to the exit pupil area; The exit pupil region is used to further expand the light rays and couple them out of the optical waveguide; The light-blocking element is located in the optical path from the entrance pupil area to the exit pupil area. It is used to block light from directly propagating from the entrance pupil area to the exit pupil area and turning to the dilated pupil area for imaging, but does not block light from directly propagating from the entrance pupil area to the dilated pupil area. The waveguide plate has a light-blocking area for setting light-blocking elements. The light-blocking area is formed by a first edge line, a second edge line, a third edge line, and a fourth edge line. The first edge line is the outermost ray from the entrance pupil area through the dilation pupil area to the exit pupil area. The second edge line is the outermost ray from the dilation pupil area to the exit pupil area and close to the entrance pupil area. The third edge line is the ray with the largest vector direction angle after entering the optical waveguide from the entrance pupil area. The fourth edge line is the boundary of the entrance pupil area between the intersections of the first edge line, the third edge line, and the entrance pupil area.

2. The optical waveguide that blocks light emanating from the pupil expansion region according to claim 1, characterized in that: The entrance pupil region, dilation pupil region, and exit pupil region all employ diffraction gratings. The grating directions in each region are different, and the sum of the grating period and direction vector of the grating vector in the three regions is equal to 0.

3. The optical waveguide that blocks light emanating from the pupil expansion region according to claim 1, characterized in that: The lower edge of the light-blocking element extends beyond the third side line.

4. The optical waveguide that blocks light emanating from the pupil expansion region according to claim 1, characterized in that: The light-blocking element is formed by cutting the texture of the waveguide plate surface, so that the light from the entrance pupil area to the exit pupil area is scattered when it hits these cutting textures, and does not directly enter the exit pupil area.

5. The optical waveguide that blocks light emanating from the pupil expansion region according to claim 1, characterized in that: The light-blocking element has a hollow structure with light-absorbing material on the edges to cut off the light propagation path from the entrance pupil area to the exit pupil area.

6. The optical waveguide that blocks light emanating from the pupil expansion region according to claim 1, characterized in that: The light-blocking element is a light-absorbing material attached to the surface of the waveguide plate that can directly absorb light from the entrance pupil region to the exit pupil region.

7. The optical waveguide that blocks light emanating from the pupil expansion region according to claim 1, characterized in that: The light-blocking element is a diffraction grating, which deflects the light rays from the entrance pupil region to the exit pupil region in other directions, and then emits them outside the optical waveguide.

8. An AR display device, characterized in that: Includes the optical waveguide and obliquely incident light source as described in any one of claims 1-7, wherein the central ray of the obliquely incident light source forms an angle with the perpendicular line from the center of the surface of the entrance pupil region of the optical waveguide.

9. The AR display device according to claim 8, characterized in that: The obliquely incident light source is monochromatic light or colored light.

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