Optical waveguide and display device

Abstract

The invention discloses an optical waveguide and a display device, the optical waveguide is provided with an entrance pupil area and an exit pupil area, the exit pupil area comprises a first exit pupil sub-area and a second exit pupil sub-area, the first exit pupil sub-area is provided with a first grating, the second exit pupil sub-area is provided with a second grating, and the direction of the first grating is different from that of the second grating; input light is diffracted into first conduction light through the pupil entrance area, and part of the first conduction light is diffracted by the first pupil exit sub-area, then is emitted to the second pupil exit sub-area, and is diffracted by the second pupil exit sub-area to form first output light. Part of the first conduction light is emitted to the first pupil exit sub-region after being diffracted by the second pupil exit sub-region, and then is diffracted by the first pupil exit sub-region to form second output light. The first grating direction of the first pupil exit sub-region is different from the second grating direction of the second pupil exit sub-region, so that pupil expansion can be performed on the pupil exit region in two dimensions, the size of a display image is increased, and meanwhile, the size of the display equipment can be reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of optical waveguides, and in particular to an optical waveguide and a display device. Background Art

[0002] As a key component in optical devices, optical waveguides play a vital role in display devices such as AR (Augmented Reality) and VR (Virtual Reality). In these display devices, optical waveguides are not only responsible for efficiently guiding the light emitted by the optical machine to the exit pupil area near the user's eyes, but also for achieving precise control and optimization of light through their internal structure, so that users can see clear images.

[0003] At present, most mainstream optical waveguides on the market adopt a three-section structure, which consists of an entrance pupil area, an expansion pupil area, and an exit pupil area. The entrance pupil area is responsible for coupling the input light into the optical waveguide, and the expansion pupil area expands the light inside the optical waveguide through a grating to cover a larger field of view. The exit pupil area is responsible for guiding the light passing through the expansion pupil area out of the optical waveguide and finally passing it to the user's eyes. Although this three-section structure can effectively expand the field of view, since each area needs to occupy a certain space, the volume of the entire optical waveguide device is large, which is not conducive to the lightweight and miniaturized design of AR / VR display devices. In order to solve this problem, a two-section optical waveguide has also appeared on the market. The two-section optical waveguide omits the expansion pupil area and only includes the entrance pupil area and the exit pupil area, which can significantly reduce the overall area of ​​the optical waveguide.

[0004] However, the existing two-segment optical waveguide can only expand the pupil in one dimension, resulting in a smaller displayed image and a larger display device. Summary of the invention

[0005] In view of the shortcomings of the prior art, the present application provides an optical waveguide and a display device. By having an exit pupil area including a first exit pupil sub-area and a second exit pupil sub-area, and a first grating direction of the first exit pupil sub-area and a second grating direction of the second exit pupil sub-area being different, the exit pupil area can be expanded in two dimensions, thereby increasing the size of the displayed image and reducing the volume of the display device at the same time.

[0006] To solve the above problems, the present invention provides the following technical solutions:

[0007] In a first aspect, an embodiment of the present application provides an optical waveguide, wherein an entrance pupil area and an exit pupil area are provided on the optical waveguide, wherein the exit pupil area includes a first exit pupil sub-area and a second exit pupil sub-area, wherein the first exit pupil sub-area is provided with a first grating, and the second exit pupil sub-area is provided with a second grating, and a first grating direction of the first exit pupil sub-area is different from a second grating direction of the second exit pupil sub-area;

[0008] The input light is diffracted by the entrance pupil area to form the first transmission light, part of the first transmission light is diffracted by the first exit pupil sub-area and then emitted to the second exit pupil sub-area, and then diffracted by the second exit pupil sub-area to form the first output light; part of the first transmission light is diffracted by the second exit pupil sub-area and then emitted to the first exit pupil sub-area, and then diffracted by the first exit pupil sub-area to form the second output light.

[0009] In some embodiments, the position of the first exit pupil sub-area and the position of the second exit pupil sub-area are symmetrical about a center line axis of the exit pupil area.

[0010] In some embodiments, the center line of the entrance pupil area is determined by the center point of the entrance pupil area and the propagation direction of the first transmitted light, and the center line of the entrance pupil area is on the same straight line as the center line of the exit pupil area.

[0011] In some embodiments, the grating direction of the first grating and the grating direction of the second grating are symmetrical about the center line of the exit pupil area.

[0012] In some embodiments, the width of the first exit pupil sub-area gradually increases along the propagation direction of the first transmitted light, and the width of the second exit pupil sub-area gradually increases along the propagation direction of the first transmitted light.

[0013] In some embodiments, the first exit pupil sub-area and the second exit pupil sub-area are both right-angled trapezoidal areas, and the right-angle waist of the first exit pupil sub-area coincides with the right-angle waist of the second exit pupil sub-area and is the center line of the entrance pupil area.

[0014] In some embodiments, an area of ​​the first exit pupil sub-region is different from an area of ​​the second exit pupil sub-region.

[0015] In some embodiments, the optical waveguide includes one entrance pupil region and two exit pupil regions.

[0016] In some embodiments, the optical waveguide includes two entrance pupil areas and one exit pupil area, the two entrance pupil areas are symmetrically arranged on both sides of the exit pupil area, and the center lines of the two entrance pupil areas coincide with each other.

[0017] In a second aspect, an embodiment of the present application provides a display device, comprising an optical machine and an optical waveguide as described in the first aspect, wherein the optical machine is used to project input light into an entrance pupil area.

[0018] The present application provides an optical waveguide and a display device. The present application has an exit pupil area including a first exit pupil sub-area and a second exit pupil sub-area, and a first grating direction of the first exit pupil sub-area and a second grating direction of the second exit pupil sub-area are different. The exit pupil area can be expanded in two dimensions, thereby increasing the size of the displayed image and reducing the volume of the display device at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic structural diagram of a first implementation mode of an optical waveguide provided in an embodiment of the present application.

[0020] Figure 2 It is a schematic structural diagram of a second implementation of the optical waveguide provided in an embodiment of the present application.

[0021] Figure 3 It is a schematic structural diagram of a third implementation mode of the optical waveguide provided in an embodiment of the present application.

[0022] Figure 4 It is a schematic structural diagram of a fourth implementation mode of an optical waveguide provided in an embodiment of the present application.

[0023] Figure 5 It is a schematic structural diagram of the fifth implementation mode of the optical waveguide provided in the embodiment of the present application.

[0024] Figure 6 It is a schematic structural diagram of a sixth implementation mode of the optical waveguide provided in an embodiment of the present application. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0026] In addition, 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. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0027] The terms such as "symmetry" or "axisymmetry" mentioned in the technical solution of the present invention are intended to describe an ideal state, and it may be difficult to achieve absolute symmetry in actual operation. Here, it is particularly noted that the terms such as "symmetry" or "axisymmetry" refer to an object or structure that is as close to a symmetrical state as possible in terms of shape, size, performance, etc. within the scope that can be achieved by those skilled in the art. In practical applications, due to the limitations of manufacturing processes, material properties and other factors, absolute symmetry cannot be achieved. The terms such as "symmetry" or "axisymmetry" mentioned in the technical solution of the present invention refer to being as close to a symmetrical state as possible, so as to achieve the predetermined technical effects and performance requirements.

[0028] The present application provides an optical waveguide and a display device. By having an exit pupil area including a first exit pupil sub-area and a second exit pupil sub-area, and a first grating direction of the first exit pupil sub-area and a second grating direction of the second exit pupil sub-area being different, the exit pupil area can be expanded in two dimensions, thereby increasing the size of a displayed image and reducing the volume of the display device at the same time.

[0029] The optical waveguide provided by the present application will be described in detail below with reference to the accompanying drawings.

[0030] See also Figure 1 , Figure 1 It is a schematic structural diagram of a first implementation mode of an optical waveguide provided in an embodiment of the present application. Figure 1 The line segments in the entrance pupil region 10, the first exit pupil sub-region 21 and the second exit pupil sub-region 22 all represent gratings. Figure 1 As shown, in some embodiments, an entrance pupil region 10 and an exit pupil region 20 are provided on the optical waveguide 1, and the exit pupil region 20 includes a first exit pupil sub-region 21 and a second exit pupil sub-region 22. The first exit pupil sub-region 21 is provided with a first grating, and the second exit pupil sub-region 22 is provided with a second grating, and the first grating direction of the first exit pupil sub-region 21 is different from the second grating direction of the second exit pupil sub-region 22. The input light is diffracted into the first transmission light after passing through the entrance pupil region 10, and part of the first transmission light is diffracted by the first exit pupil sub-region 21 and then emitted to the second exit pupil sub-region 22, and then diffracted by the second exit pupil sub-region 22 to form the first output light; part of the first transmission light is diffracted by the second exit pupil sub-region 22 and then emitted to the first exit pupil sub-region 21, and then diffracted by the first exit pupil sub-region 21 to form the second output light. In this way, the exit pupil region can be expanded in two dimensions, thereby increasing the size of the displayed image, and at the same time reducing the volume of the display device.

[0031] It can be understood that the input light enters the entrance pupil area along a direction perpendicular to the plane where the entrance pupil area 10 is located. The first output light and the second output light are emitted from the exit pupil area 20 along a direction perpendicular to the plane where the exit pupil area 20 is located, and then form a display image at the human eye. The relative position of the entrance pupil area 10 and the exit pupil area 20 is not limited to Figure 1 In the case shown, the entrance pupil area 10 can be located at any position such as the left side, right side, top side or bottom side of the exit pupil area 20, as long as the input light can pass through the entrance pupil area 10 and the exit pupil area 20 to form a display image.

[0032] Optionally, the first grating and the second grating are both one-dimensional gratings. One-dimensional gratings have higher diffraction efficiency and lower production difficulty in terms of process.

[0033] Furthermore, the first grating and the second grating are both arranged on the same surface of the optical waveguide.

[0034] See also Figure 2 , Figure 2 Schematic diagram of the structure of the second embodiment of the optical waveguide provided in the embodiment of the present application. Figure 2 As shown, in some embodiments, the first exit pupil sub-area 21 and the second exit pupil sub-area 22 may not fit together, and / or the grating direction of the first exit pupil sub-area 21 and the grating direction of the second exit pupil sub-area 22 may be staggered (i.e., not axisymmetric). In this case, the first grating and the second grating are both one-dimensional gratings. Compared with the manner in which the first exit pupil sub-area and the second exit pupil sub-area are strictly fitted together or the grating directions of the two exit pupil sub-areas are strictly symmetrical, this embodiment has a lower production difficulty in terms of process, and the imaging effect does not change significantly.

[0035] Optionally, the first grating direction and the second grating direction are not perpendicular to the grating direction of the entrance pupil region. This is because the propagation direction of light after passing through the grating is perpendicular to the grating direction. If one of the first grating direction and the second grating direction is perpendicular to the grating direction of the entrance pupil region, the light cannot be diffracted between the first exit pupil sub-region and the second exit pupil sub-region to form an image.

[0036] Optionally, the angle between the first grating direction and the second grating direction ranges from 30 degrees to 150 degrees, for example, 30 degrees, 45 degrees, 90 degrees, 120 degrees, 135 degrees or 150 degrees.

[0037] In some embodiments, the position of the first exit pupil sub-area 21 and the position of the second exit pupil sub-area 22 are symmetrical about the center line of the exit pupil area 20. In this way, the area of ​​the display area corresponding to the first exit pupil sub-area in the displayed image is the same as the area of ​​the display area corresponding to the second exit pupil sub-area in the displayed image, which can avoid the screen ratio of the displayed image not meeting the preset ratio.

[0038] like Figure 1 As shown, optionally, the center line of the exit pupil area 20 is formed by connecting a common endpoint point A and another common endpoint point B of the first exit pupil sub-area 21 and the second exit pupil sub-area 22.

[0039] like Figure 1 As shown, in some embodiments, the grating direction of the first grating and the grating direction of the second grating are symmetrical about the center line of the exit pupil area 20.

[0040] Furthermore, the position of the first exit pupil sub-area 21 and the position of the second exit pupil sub-area 22 are symmetrical about the center line of the exit pupil area 20, and the grating direction of the first grating and the grating direction of the second grating are symmetrical about the center line of the exit pupil area 20. In this way, it is possible to further avoid that the screen ratio of the displayed image does not meet the preset ratio, and improve the brightness uniformity of the displayed image.

[0041] Optionally, the optical parameters of the first grating are the same as the optical parameters of the second grating. The optical parameters include parameters such as grating depth and grating period. In this way, it is possible to further avoid the screen ratio of the displayed image not meeting the preset ratio, and further improve the brightness uniformity of the displayed image.

[0042] In some embodiments, the center line of the entrance pupil area is determined by the center point of the entrance pupil area and the propagation direction of the first guided light. The center point of the entrance pupil area is the center point of the geometric figure of the entrance pupil area. Specifically, the center point of the entrance pupil area is a point on the center line of the entrance pupil area, and a straight line parallel to the propagation direction of the first guided light is determined as the center line of the entrance pupil area.

[0043] Optionally, the shape of the entrance pupil area is circular, rectangular, fan-shaped, etc.

[0044] Because the light spot of the output light from the optical machine is generally a circular spot, such as Figure 1 As shown, preferably, the shape of the entrance pupil area 10 is circular. The center point of the entrance pupil area 10 is the center point O of the entrance pupil area 10. At this time, the center line L1 of the entrance pupil area 10 is a straight line where the diameter passes through the point O. In this way, the entrance pupil area can receive as much output light as possible, while reducing the area of ​​the entrance pupil area, thereby reducing the manufacturing cost.

[0045] like Figure 1As shown, in some embodiments, the center line L1 of the entrance pupil area 10 is on the same straight line as the center line of the exit pupil area 20. The center line of the exit pupil area 20 is formed by connecting a common endpoint point A and another common endpoint point B of the first exit pupil sub-area 21 and the second exit pupil sub-area 22. At this time, the grating direction of the entrance pupil area 10 is perpendicular to the center line L1 of the entrance pupil area 10, and the straight line where the propagation direction of the first conductive light is located coincides with the center line L1 of the entrance pupil area 10. In this way, the exit pupil area 20 can receive as much first conductive light as possible, thereby improving the brightness of the displayed image.

[0046] It can be understood that the center line L1 and the center point O of the entrance pupil area 10 are mathematical terms, which are only used to describe the structure of the optical waveguide 1 , and are not structures actually existing on the optical waveguide 1 .

[0047] In some embodiments, the width of the first exit pupil sub-area gradually increases along the propagation direction of the first conducted light, and the width of the second exit pupil sub-area gradually increases along the propagation direction of the first conducted light. Because the energy of the first conducted light gradually decreases along the propagation direction of the first conducted light, in this way, the areas of the first exit pupil sub-area and the second exit pupil sub-area receiving light along the propagation direction of the first conducted light gradually increase, and the received light energy can remain approximately unchanged, thereby improving the brightness uniformity of the displayed image.

[0048] The width of the first exit pupil sub-region at one position refers to the distance between the two intersection points of the first straight line perpendicular to the straight line where the center line of the entrance pupil region is located and the contour line of the first exit pupil sub-region, taken from a point on the center line of the entrance pupil region as the foot of the perpendicular. The width of the second exit pupil sub-region at one position refers to the distance between the two intersection points of the first straight line and the contour line of the second exit pupil sub-region.

[0049] like Figure 1 As shown, in some embodiments, the width of the first exit pupil sub-area 21 at one position is the length of the line segment connecting point A and point C, and the width of the first exit pupil sub-area 21 at another position is the length of the line segment connecting point B and point D. The width of the second exit pupil sub-area 22 at one position is the length of the line segment connecting point A and point E, and the width of the second exit pupil sub-area 22 at another position is the length of the line segment connecting point B and point F.

[0050] like Figure 1As shown, in some embodiments, the first exit pupil sub-area 21 and the second exit pupil sub-area 22 are both right-angled trapezoidal areas, and the right-angle waist of the first exit pupil sub-area 21 coincides with the right-angle waist of the second exit pupil sub-area 22 and is the center line of the entrance pupil area 20. Exemplarily, the first exit pupil sub-area 21 is a right-angled trapezoidal area determined by point A, point B, point D, and point C, and the second exit pupil sub-area 22 is a right-angled trapezoidal area determined by point A, point B, point F, and point E, and the connecting line segment of point A and point B is the right-angle waist of the first exit pupil sub-area 21, the right-angle waist of the second exit pupil sub-area 22, and the center line of the entrance pupil area 20 at the same time.

[0051] In other embodiments, the shape of the entire exit pupil area can be any shape such as a rectangle, a circle, a sector or an irregular shape. The first exit pupil sub-area and the second exit pupil sub-area can also be any shape, which is not limited here.

[0052] See also Figure 3 , Figure 3 is a schematic structural diagram of a third embodiment of the optical waveguide provided in the embodiment of the present application. Figure 3 As shown, in some embodiments, the area of ​​the first exit pupil sub-area 21 is different from the area of ​​the second exit pupil sub-area 22. Optionally, the area of ​​each exit pupil sub-area can be adjusted for the display area corresponding to each exit pupil sub-area in the displayed image. In this way, the display area corresponding to the exit pupil sub-area with a larger area in the displayed image will be larger, which can meet the user's usage needs in application scenarios such as watching short videos.

[0053] See also Figure 4 , Figure 4 Schematic diagram of the structure of the fourth embodiment of the optical waveguide provided in the embodiment of the present application. Figure 4 As shown, in some embodiments, the optical waveguide 1 includes an entrance pupil area 10 and two exit pupil areas 20. For the description of the exit pupil area 20, refer to the above content. At this time, the optical waveguide 1 is a binocular waveguide, which has a larger field of view than a monocular waveguide.

[0054] Optionally, two exit pupil areas 20 are symmetrically arranged on both sides of the entrance pupil area 10 .

[0055] Optionally, the grating directions of the two exit pupil regions 20 are also symmetrical.

[0056] Furthermore, the optical parameters of the gratings of the two exit pupil regions 20 are the same.

[0057] Optionally, the angle A1 between the center line L1 of the entrance pupil area 10 and a straight line L2 of the exit pupil area 20 that does not intersect the center line of the exit pupil area 20 is in a range of 20 to 80 degrees. For example, the angle A1 is 20 degrees, 30 degrees, 40 degrees, 50 degrees, 60 degrees, 70 degrees or 80 degrees.

[0058] In some embodiments, the center line of the entrance pupil area coincides with the straight line where the center lines of the two exit pupil areas are located.

[0059] See also Figure 5 , Figure 5 Schematic diagram of the structure of the fifth embodiment of the optical waveguide provided in the embodiment of the present application. Figure 5 As shown, in some embodiments, the exit pupil area 20 may be rectangular, and the first exit pupil sub-area 21 and the second exit pupil sub-area 22 may also be rectangular.

[0060] See also Figure 6 , Figure 6 Schematic diagram of the structure of the sixth embodiment of the optical waveguide provided in the embodiment of the present application. Figure 6 As shown, in some embodiments, the optical waveguide 1 includes two entrance pupil areas 10 and one exit pupil area 20, the two entrance pupil areas 10 are symmetrically arranged on both sides of the exit pupil area 20, and the center lines L1 of the two entrance pupil areas 10 coincide. In this case, the optical waveguide 1 is an integrated optical waveguide.

[0061] Furthermore, the width of a portion of the first exit pupil sub-area 21 close to each entrance pupil area 10 gradually increases along the propagation direction of the first conducted light emitted from the entrance pupil area 10, and the width of a portion of the second exit pupil sub-area 22 close to each entrance pupil area 10 gradually increases along the propagation direction of the first conducted light emitted from the entrance pupil area 10. Because the energy of the first conducted light gradually decreases along the propagation direction of the first conducted light, in this way, the area of ​​the first exit pupil sub-area and the second exit pupil sub-area along the propagation direction of the first conducted light that receives light gradually increases, and the received light energy can remain approximately unchanged, thereby improving the brightness uniformity of the displayed image.

[0062] Furthermore, the width of the first exit pupil sub-area 21 at any two positions of a portion of the area between the two entrance pupil areas 10 is the same, and the width of the second exit pupil sub-area 22 at any two positions of a portion of the area between the two entrance pupil areas 10 is the same. Because the two entrance pupil areas 10 are symmetrically arranged on both sides of the exit pupil area 20, and the propagation directions of the first conductive light on both sides are opposite, the light energy in the middle area of ​​the exit pupil area 20 is roughly equal. In this way, the light energy received by the first exit pupil sub-area and the second exit pupil sub-area along the propagation direction of the first conductive light can be further kept unchanged, thereby further improving the brightness uniformity of the displayed image.

[0063] In summary, the optical waveguide provided in the embodiments of the present application has the following advantages:

[0064] 1. By including a first exit pupil sub-area and a second exit pupil sub-area in the exit pupil area, and a first grating direction of the first exit pupil sub-area and a second grating direction of the second exit pupil sub-area are different, the exit pupil area can be expanded in two dimensions, thereby increasing the size of the displayed image and reducing the volume of the display device at the same time.

[0065] 2. By making the shape of the first exit pupil sub-area and the shape of the second exit pupil sub-area symmetrical about the center line axis of the exit pupil area, the area of ​​the display area corresponding to the first exit pupil sub-area in the displayed image is the same as the area of ​​the display area corresponding to the second exit pupil sub-area in the displayed image, thereby avoiding the picture ratio of the displayed image not meeting the preset ratio.

[0066] 3. By gradually increasing the width of the first exit pupil sub-area along the propagation direction of the first conducted light and gradually increasing the width of the second exit pupil sub-area along the propagation direction of the first conducted light, the areas of the first exit pupil sub-area and the second exit pupil sub-area receiving light along the propagation direction of the first conducted light will gradually increase, and the received light energy can remain roughly unchanged, thereby improving the brightness uniformity of the displayed image.

[0067] The present application also provides a display device, including an optical machine and the optical waveguide as described above, wherein the optical machine is used to project input light to an entrance pupil area.

[0068] Optionally, the display device may be an AR display device or a VR display device.

[0069] In summary, the present application provides an optical waveguide and a display device, wherein an entrance pupil region and an exit pupil region are provided on the optical waveguide, wherein the exit pupil region includes a first exit pupil sub-region and a second exit pupil sub-region, wherein the first exit pupil sub-region is provided with a first grating, wherein the second exit pupil sub-region is provided with a second grating, wherein the first grating direction of the first exit pupil sub-region and the second grating direction of the second exit pupil sub-region are different; wherein the input light is diffracted into a first transmission light after passing through the entrance pupil region, wherein part of the first transmission light is diffracted through the first exit pupil sub-region and then emitted to the second exit pupil sub-region, and then diffracted through the second exit pupil sub-region to form a first output light; wherein part of the first transmission light is diffracted through the second exit pupil sub-region and then emitted to the first exit pupil sub-region, and then diffracted through the first exit pupil sub-region to form a second output light. The present application enables the exit pupil region to be expanded in two dimensions by having the exit pupil region include a first exit pupil sub-region and a second exit pupil sub-region, wherein the first grating direction of the first exit pupil sub-region and the second grating direction of the second exit pupil sub-region are different, thereby increasing the size of the displayed image and reducing the volume of the display device at the same time.

[0070] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. An optical waveguide, characterized in that: The optical waveguide is provided with an entrance pupil area and an exit pupil area, the exit pupil area includes a first exit pupil sub-area and a second exit pupil sub-area, the first exit pupil sub-area is provided with a first grating, the second exit pupil sub-area is provided with a second grating, and the first grating direction of the first exit pupil sub-area is different from the second grating direction of the second exit pupil sub-area; The input light is diffracted by the entrance pupil area to form the first transmission light, part of the first transmission light is diffracted by the first exit pupil sub-area and then emitted to the second exit pupil sub-area, and then diffracted by the second exit pupil sub-area to form the first output light; part of the first transmission light is diffracted by the second exit pupil sub-area and then emitted to the first exit pupil sub-area, and then diffracted by the first exit pupil sub-area to form the second output light.

2. The optical waveguide according to claim 1, characterized in that The position of the first exit pupil sub-area and the position of the second exit pupil sub-area are symmetrical about the center line of the exit pupil area.

3. The optical waveguide according to claim 2, characterized in that The center line of the entrance pupil area is determined by the center point of the entrance pupil area and the propagation direction of the first guided light, and the center line of the entrance pupil area is on the same straight line as the center line of the exit pupil area.

4. The optical waveguide according to claim 1, characterized in that The grating direction of the first grating and the grating direction of the second grating are symmetrical about the center line of the exit pupil area.

5. The optical waveguide according to claim 1, characterized in that The width of the first exit pupil sub-area gradually increases along the propagation direction of the first conducted light, and the width of the second exit pupil sub-area gradually increases along the propagation direction of the first conducted light.

6. The optical waveguide according to claim 5, characterized in that The first exit pupil sub-area and the second exit pupil sub-area are both right-angled trapezoidal areas, and the right-angle waist of the first exit pupil sub-area coincides with the right-angle waist of the second exit pupil sub-area and is the center line of the entrance pupil area.

7. The optical waveguide according to claim 1, characterized in that An area of ​​the first exit pupil sub-region is different from an area of ​​the second exit pupil sub-region.

8. The optical waveguide according to any one of claims 1 to 7, characterized in that: The optical waveguide includes one entrance pupil area and two exit pupil areas.

9. The optical waveguide according to any one of claims 1 to 7, characterized in that: The optical waveguide includes two entrance pupil areas and one exit pupil area, the two entrance pupil areas are symmetrically arranged on both sides of the exit pupil area, and the center lines of the two entrance pupil areas coincide with each other.

10. A display device, characterized in that: The display device comprises an optical engine and the optical waveguide according to any one of claims 1 to 9, wherein the optical engine is used to project input light to an entrance pupil area.

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