Two-dimensional coupling-out grating, diffraction optical waveguide and near-to-eye display equipment

Abstract

The invention discloses a two-dimensional coupling-out grating, a diffraction optical waveguide and a near-to-eye display device. The two-dimensional coupling-out grating comprises a plurality of grating structure units which are arranged in an array mode. The section graph of the grating structure unit is formed by overlapping two first graphs and at least one second graph, and the section graph is formed by cutting a plane of the surface of the substrate where the parallel two-dimensional coupled grating is located; the centers of the two first patterns are spaced by a preset distance and are located on the same straight line, and the two first patterns are at least partially overlapped; the center of the second graph coincides with the center of the graph formed by the two first graphs, the second graph is a symmetrical graph, and a preset included angle is formed between the symmetry axis and the straight line. Through the above structure, the problem that exit pupil uniformity and view field uniformity of an existing two-dimensional coupling-out grating are poor is solved, the energy utilization rate of the diffraction optical waveguide is improved, the display effect of the diffraction optical waveguide is improved, and then the experience feeling of a user is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of diffractive optical waveguides, and in particular to a two-dimensional output grating, a diffractive optical waveguide, and a near-eye display device. Background Art

[0002] Augmented reality is a technology that combines the real world and virtual information. An augmented reality display system usually includes a micro-projector and an optical display screen. The micro-projector provides virtual display content for the augmented reality display system, which is projected into the human eye through the optical display screen. The optical display screen is usually a transparent optical component, so that the user can also see the real world through the optical display screen at the same time.

[0003] A diffractive optical waveguide is a way to implement an optical display screen. Figure 1 FIG. is a schematic structural diagram of a diffractive optical waveguide provided in the related art. Figure 2 FIG. is a schematic structural diagram of the basic diffraction order of a two-dimensional grating provided in the related art. Refer to Figure 1 and Figure 2 As shown, 101 is an input grating, 102 is an output grating, 103 is the light ray that is coupled into the waveguide by the input grating, and 104 is the observation area of the human eye, that is, the eyebox, which can also be called the eyebox. Specifically, the input grating 101 couples the image light rays of the light engine into the diffractive optical waveguide, and after total internal reflection, it is transmitted to the output grating 102. After being turned, pupil-expanded, and coupled out by the output grating 102, it is incident into the eyebox, so that the human eye can see the display screen. It can be seen from Figure 2 that the output grating 102 has 6 basic diffraction orders. Since the output grating 102 has different diffraction orders, the light can be diffracted, so that the light rays can be transmitted in different directions and finally coupled out from the output grating 102. However, the existing two-dimensional gratings still have problems that need to be solved urgently, such as improving the pupil uniformity and energy utilization rate. Summary of the Invention

[0004] The present invention provides a two-dimensional output grating, a diffractive optical waveguide, and a near-eye display device to solve the defects existing in the prior art, improve the pupil uniformity and the field of view uniformity, improve the energy utilization rate of the diffractive optical waveguide, enhance the display effect of the diffractive optical waveguide, and further enhance the user experience.

[0005] In a first aspect, the present invention provides a two-dimensional output grating, which includes a plurality of grating structure units arranged in an array;

[0006] The cross-sectional pattern of the grating structure unit is formed by the intersection of two first patterns and at least one second pattern, and the cross-sectional pattern is cut by a plane parallel to the surface of the substrate where the two-dimensional output grating is located;

[0007] The centers of two first figures are separated by a preset distance and located on the same straight line, and the two first figures at least partially overlap;

[0008] The center of the second figure coincides with the center of the figure formed by the two first figures. The second figure is a symmetric figure and its axis of symmetry forms a preset angle with the straight line.

[0009] Optionally, the first figure is a first ellipse, the second figure is a second ellipse, the two first ellipses are the same and their major axes are located on the straight line, and the included angle between the extending direction of the major axis of the second ellipse and the extending direction of the major axis of the first ellipse is the preset angle.

[0010] Optionally, the preset angle is θ, and 0 < |θ| < 180°.

[0011] Optionally, the value range of the preset distance is 0 to 400 nm.

[0012] Optionally, at least one of the major axis dimension of the first ellipse, the minor axis dimension of the first ellipse, the major axis dimension of the second ellipse, the minor axis dimension of the second ellipse, the preset distance, and the preset angle of the grating structure units at different positions in the two-dimensional output grating is different, so that the diffraction efficiency of the (-1, 0) diffraction order and the (0, -1) diffraction order at different positions in the two-dimensional output grating or the diffraction efficiency ratio of the (0, -1) diffraction order and the (-1, -1) diffraction order at different positions is different.

[0013] Optionally, the height or depth range of the grating structure in the direction perpendicular to the plane of the substrate is 0 to 500 nm.

[0014] Optionally, the length range of the major axis of the first ellipse is 50 to 800 nm, and / or the length range of the minor axis of the first ellipse is 50 to 460 nm.

[0015] Optionally, the length range of the major axis of the second ellipse is 50 to 1000 nm, and / or the length range of the minor axis of the second ellipse is 50 to 400 nm.

[0016] In a second aspect, the present invention provides a diffractive optical waveguide, including: a substrate, an input grating, and the above two-dimensional output grating, and the input grating and the two-dimensional output grating are disposed on the surface of the waveguide substrate.

[0017] In a third aspect, the present invention provides a near-eye display device, including a projection optical machine and the above diffractive optical waveguide, and the projection optical machine is used to emit virtual image light rays.

[0018] In the technical solution of the present invention, the cross-sectional pattern of the grating structure unit of the two-dimensional output grating is an asymmetric pattern formed by the overlap of two first patterns and at least one second pattern. By changing the dimensions of each of the first pattern and the second pattern, and / or the relative positional relationship between the second pattern and the first pattern, and the relative positional relationship between the two first patterns, the diffraction efficiency ratio of each diffraction order of the two-dimensional output grating can be adjusted, and the diffraction efficiency of the required orders in different regions of the two-dimensional output grating can be improved, so that more light energy is more evenly expanded and coupled out in the waveguide, making the pupil uniformity and the field-of-view uniformity of the waveguide better and at the same time improving the energy utilization rate. Description of the Drawings

[0019] Figure 1 FIG. is a schematic structural diagram of a diffractive optical waveguide provided in the related art;

[0020] Figure 2 FIG. is a schematic structural diagram of the basic diffraction order of a two-dimensional grating provided in the related art;

[0021] Figure 3 FIG. is a schematic structural diagram of a two-dimensional output grating provided in an embodiment of the present invention;

[0022] Figures 4 - 7 FIG. is a schematic cross-sectional structure diagram of four grating structure units provided in an embodiment of the present invention;

[0023] Figure 8 FIG. is a schematic structural diagram of a specific two-dimensional output grating provided in an embodiment of the present invention;

[0024] Figure 9 FIG. is a schematic structural diagram of a grating with columnar protrusions provided in an embodiment of the present invention;

[0025] Figure 10 FIG. is a schematic structural diagram of a grating with columnar pits provided in an embodiment of the present invention;

[0026] Figure 11 FIG. is a graph showing the variation of the diffraction efficiency with the incident angle provided in an embodiment of the present invention;

[0027] Figure 12 FIG. is another graph showing the variation of the diffraction efficiency with the incident angle provided in an embodiment of the present invention;

[0028] Figure 13 FIG. is yet another graph showing the variation of the diffraction efficiency with the incident angle provided in an embodiment of the present invention;

[0029] Figure 14 FIG. is a schematic structural diagram of a diffractive optical waveguide provided in an embodiment of the present invention. Detailed Embodiments

[0030] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It can be understood that the specific embodiments described herein are only for explaining the present invention, rather than limiting the present invention. Additionally, it should be noted that for the sake of description, only the parts related to the present invention rather than all the structures are shown in the drawings.

[0031] The terms used in the embodiments of the present invention are only for the purpose of describing specific embodiments, and are not intended to limit the present invention. It should be noted that the orientation terms such as "upper", "lower", "left", and "right" described in the embodiments of the present invention are described from the angles shown in the drawings, and should not be construed as limiting the embodiments of the present invention. In addition, in the context, it should also be understood that when it is mentioned that an element is formed "on" or "under" another element, it can not only be directly formed "on" or "under" another element, but also be indirectly formed "on" or "under" another element through an intermediate element. The terms "first", "second", etc. are only for descriptive purposes and do not indicate any order, quantity, or importance, but are only used to distinguish different components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0032] The term "including" and its variants used in the present invention are open-ended, that is, "including but not limited to". The term "based on" means "at least partially based on". The term "an embodiment" means "at least one embodiment".

[0033] It should be noted that the concepts such as "first", "second", etc. mentioned in the present invention are only used to distinguish the corresponding contents, and are not used to limit the order or the interdependent relationship.

[0034] It should be noted that the modifications of "one" and "multiple" mentioned in the present invention are illustrative rather than restrictive. Those skilled in the art should understand that unless otherwise clearly specified in the context, it should be understood as "one or more".

[0035] Figure 3 It is a schematic structural diagram of a two-dimensional output grating provided for the embodiments of the present invention. Figures 4 - 7 It is a schematic cross-sectional structural diagram of four grating structure units provided for the embodiments of the present invention. Refer to Figures 3 to 7As shown, the two-dimensional output grating 5 includes a plurality of grating structure units 2 arranged in an array; the cross-sectional pattern of the grating structure unit 2 is formed by the overlap of two first patterns 23 and at least one second pattern 24, and the cross-sectional pattern is cut by a plane parallel to the surface of the substrate 1 where the two-dimensional output grating 5 is located; the centers of the two first patterns 23 are separated by a preset distance and are located on the same straight line, and the two first patterns 23 at least partially overlap; the center of the second pattern 24 coincides with the center of the pattern formed by the two first patterns 23, and the second pattern 24 is a symmetric pattern and the axis of symmetry forms a preset angle with the straight line.

[0036] Specifically, Figures 4 to 7 only several schematic diagrams of the structure of the grating structure unit 2 are provided exemplarily. Refer to Figure 4 , Figure 6 and Figure 7 , the cross-sectional pattern of the grating structure unit 2 is formed by the overlap of two first patterns 23 and one second pattern 24; refer to Figure 5 , the cross-sectional pattern of the grating structure unit 2 is formed by the overlap of two first patterns 23 and two second patterns 24. Among them, Figure 3 the shape of the first pattern 23 in Figures 5 to 7 is a rhombus shape, Figure 4 , Figure 5 and Figure 7 the shape of the first pattern 23 shown in Figure 6 is an oval shape, the two first patterns 23 partially overlap, and the shape of the second pattern 24 is an oval shape. In addition, the positional relationship between the two first patterns 23 can be arranged horizontally or vertically; among them,

[0037] In the technical solution of the embodiment of the present invention, the cross-sectional pattern of the grating structure unit of the two-dimensional output grating is an asymmetric pattern formed by the overlap of two first patterns and at least one second pattern. By changing the dimensions of the first pattern and the second pattern, and / or, the relative positional relationship between the second pattern and the first pattern, and the relative positional relationship between the two first patterns, the diffraction efficiency ratio of each diffraction order of the two-dimensional output grating can be adjusted, and the diffraction efficiency of the required order in different regions of the two-dimensional output grating can be improved, so that more light energy is more evenly expanded and coupled out in the waveguide, making the pupil uniformity and field of view uniformity of the waveguide better and at the same time improving the energy utilization rate.

[0038] As an optional embodiment, Figure 8 is a schematic diagram of the structure of a specific two-dimensional output grating provided by the embodiment of the present invention. Refer toFigure 8 As shown, the first figure 23 is the first ellipse 21, and the second figure 24 is the second ellipse 22. The two first ellipses 21 are the same and their major axes are located on a straight line. The extension direction of the major axis of the second ellipse 22 forms a preset angle with the extension direction of the major axis of the first ellipse 21.

[0039] Optionally, continue to refer to Figure 8 , the preset angle is θ, and 0 < |θ| < 180°.

[0040] Specifically, the extension direction of the major axis a2 of the second ellipse 22 forms a preset angle θ with the extension direction of the major axis a1 of the first ellipse 21, where 0 < |θ| < 180°, indicating that the preset angle θ is an acute angle, a right angle, or an obtuse angle. The two second ellipses 22 provided on the grating structure unit 2 intersect or are perpendicular to the first ellipse 21. It can be understood that when the two first ellipses 21 and the second ellipse 22 are perpendicular, θ is 90° at this time. In addition, the situation where the two first ellipses 21 and the second ellipse 22 intersect includes that the second ellipse 22 tilts to the right and tilts to the left. When the second ellipse 22 tilts to the right, θ represents the angle between the extension direction of the major axis a1 of the first ellipse 21 to the right and the extension direction of the major axis a2 of the second ellipse 22, and θ is an acute angle at this time; when the second ellipse 22 tilts to the left, θ is an obtuse angle at this time. In this way, when light is transmitted in the grating structure unit 2, the light beam can be propagated in the required direction in the required manner at each position, so that when the finally emitted light is incident on the human eye, the uniformity is better, the diffraction efficiency is higher, and the display effect of the object seen by the human eye is better.

[0041] Implementably, at least one of the major axis a1 dimension of the first ellipse 21, the minor axis b1 dimension of the first ellipse 21, the major axis a2 dimension of the second ellipse 22, the minor axis b2 dimension of the second ellipse 22, the preset distance S, and the preset angle θ of the grating structure units 2 at different positions in the two-dimensional output grating 5 is different, so that the diffraction efficiency ratios of different diffraction orders at different positions in the two-dimensional output grating 5 are different, so as to improve the diffraction efficiency of effectively using different diffraction orders at different positions in the two-dimensional output grating 5 respectively, thereby improving the pupil uniformity and the field of view uniformity.

[0042] Exemplarily, continue to refer to Figure 8 As shown, at least one of the major axis a1 dimension of the first ellipse 21, the minor axis b1 dimension of the first ellipse 21, the major axis a2 dimension of the second ellipse 22, the minor axis b2 dimension of the second ellipse 22, the preset distance S, and the preset angle θ of the grating structure units 2 at different positions in the two-dimensional output grating 5 is different, so that the diffraction efficiencies of the (-1,0) diffraction order and the (0,-1) diffraction order at different positions in the two-dimensional output grating 5 or the diffraction efficiency ratios of the (0,-1) diffraction order and the (-1,-1) diffraction order at different positions are different.

[0043] Optionally, Figure 9 FIG. is a schematic diagram of a grating structure with columnar protrusions provided by an embodiment of the present invention, Figure 10 FIG. is a schematic diagram of a grating structure with columnar pits provided by an embodiment of the present invention. Refer to Figure 9 and Figure 10 As shown, the grating structure unit 2 is a columnar protrusion or a columnar pit.

[0044] Optionally, the height or depth range of the grating structure unit 2 in the direction perpendicular to the plane of the substrate 1 is 0 to 500 nm.

[0045] Among them, the height or depth of the grating structure unit 2 in the direction perpendicular to the plane of the substrate 1 is greater than 0 and less than or equal to 500 nm. For example, it can be 70 nm, 100 nm, 200 nm, 300 nm, etc. The embodiment of the present invention does not limit the specific numerical relationship.

[0046] Optionally, the length range of the major axis of the first ellipse 21 is 50 to 800 nm, and / or the length range of the minor axis of the first ellipse 21 is 50 to 460 nm. In this case, the numerical range includes the boundary values.

[0047] Among them, refer to Figure 8 The major axis of the first ellipse 21 is a1. The length range of the major axis of the first ellipse 21, that is, the value of the length range of a1, is between 50 nm and 800 nm. For example, it can be 50 nm, 100 nm, 300 nm, 500 nm, 800 nm, etc. The embodiment of the present invention does not limit the specific numerical relationship. In addition, the value of the length range of the minor axis of the first ellipse 21 is between 50 nm and 460 nm. For example, it can be 50 nm, 150 nm, 200 nm, 350 nm, 460 nm, etc. The embodiment of the present invention does not limit the specific numerical relationship.

[0048] Optionally, the value range of the preset distance is 0 to 400 nm.

[0049] Among them, refer to Figure 8 The preset distance is S. The value range of the preset distance, that is, the value range of S, is greater than 0 and less than or equal to 400 nm. For example, it can be 50 nm, 150 nm, 200 nm, 300 nm, 400 nm, etc. The embodiment of the present invention does not limit the specific numerical relationship.

[0050] Optionally, the length range of the major axis of the second ellipse 22 is 50 to 1000 nm, and / or the length range of the minor axis of the second ellipse 22 is 50 to 400 nm. In this case, the numerical range includes the boundary values.

[0051] Among them, refer to Figure 8, the major axis of the second ellipse 22 is a2. The length range of the major axis of the second ellipse 22, that is, the numerical value of the length range of a2, is between 50 nm and 1000 nm. For example, it can be 50 nm, 200 nm, 500 nm, 800 nm, 1000 nm, etc. The embodiments of the present invention do not limit the specific numerical relationship. In addition, the numerical value of the length range of the minor axis of the second ellipse 22 is between 50 nm and 400 nm. For example, it can be 50 nm, 150 nm, 200 nm, 300 nm, 400 nm, etc. The embodiments of the present invention do not limit the specific numerical relationship.

[0052] In an alternative embodiment, Figure 11 is a graph showing the variation of the diffraction efficiency with the incident angle provided by the embodiment of the present invention. Referring to Figure 8 and Figure 11 as shown, this figure shows a two-dimensional grating structure composed of grating structure units with a cross-sectional shape as shown in Figure 8 The figure shows the trend of the (-1,0) diffraction order and the (0,-1) diffraction order changing with the incident angle when other parameters are fixed and a2 takes different values. It can be seen from this figure that when a2 increases, the diffraction efficiency of the (-1,0) diffraction order decreases, and the diffraction efficiency of the (0,-1) diffraction order increases. In this way, the major axis size of the second ellipse in the two-dimensional output grating region where the (0,-1) diffraction order needs to be utilized can be larger than the major axis size of the second ellipse in the two-dimensional output grating region where the (-1,0) diffraction order needs to be utilized.

[0053] In an alternative embodiment, Figure 12 is another graph showing the variation of the diffraction efficiency with the incident angle provided by the embodiment of the present invention. Referring to Figure 8 and Figure 12 as shown, this figure shows a two-dimensional grating structure composed of grating structure units with a cross-sectional shape as shown in Figure 8 The figure shows the trend of the (-1,0) diffraction order and the (0,-1) diffraction order changing with the incident angle when other parameters are fixed and θ takes different values. It can be seen from this figure that when θ increases, the diffraction efficiency of the (-1,0) diffraction order decreases, and the diffraction efficiency of the (0,-1) diffraction order increases. In this way, the included angle between the first ellipse and the second ellipse in the two-dimensional output grating region where the (0,-1) diffraction order needs to be utilized can be larger than the included angle between the first ellipse and the second ellipse in the two-dimensional output grating region where the (-1,0) diffraction order needs to be utilized.

[0054] In an alternative embodiment, Figure 13 is yet another graph showing the variation of the diffraction efficiency with the incident angle provided by the embodiment of the present invention. Referring to Figure 8 and Figure 13 as shown, this figure shows a two-dimensional grating structure composed of grating structure units with a cross-sectional shape as shown in Figure 8The trend diagram of the (-1,1) diffraction order and the (0,-1) diffraction order changing with the incident angle when the two-dimensional grating structure composed of the shown grating structure units has different S values and other parameters are fixed. It can be seen from this diagram that as S increases, the efficiency of the (0,-1) diffraction order can be greatly changed while the efficiency of the (-1,-1) diffraction order is basically unchanged. In this way, in the two-dimensional output grating region where the (-1,-1) diffraction order needs to be utilized but the utilization of the (0,-1) diffraction order is different, the distance between the two first ellipses is modulated to modulate the efficiency of the (0,-1) diffraction order.

[0055] It should be noted that for the two-dimensional output grating, the requirements for pupil expansion and output at different positions are different, and the effectively utilized diffraction orders are also different. For example, for the area below the eyebox, the mainly utilized diffraction order is (-1,0), for the area above the eyebox, the mainly utilized diffraction order is (0,-1), and for the area on the horizontal line of the eyebox area, the diffraction orders of (0,-1), (-1,-1), and (-1,0) will all be utilized. Combining Figures 11 - 13 , for the two-dimensional output grating provided by the present application, when changing the dimensions of each item in the first pattern and / or the second pattern, and / or, the relative positional relationship between the second pattern and the first pattern, and / or, the relative positional relationship between the two first patterns, it can indeed effectively change the diffraction efficiency ratio between different diffraction orders of the two-dimensional output grating. In this way, by changing these parameters of the grating structure unit, the diffraction efficiency ratios of the diffraction orders at different positions in the two-dimensional output grating can be made different, so as to respectively improve the diffraction efficiency of the effectively utilized diffraction orders at different positions in the two-dimensional output grating, thereby effectively improving the pupil uniformity of the two-dimensional output grating and also improving the diffraction efficiency.

[0056] Based on the same inventive concept, the embodiment of the present invention also provides a diffractive optical waveguide, Figure 14 which is a schematic structural diagram of a diffractive optical waveguide provided by an embodiment of the present invention. Referring to Figure 14 as shown, the diffractive optical waveguide includes: a substrate 1, an input grating 3, and the above two-dimensional output grating 5. The input grating 31 and the two-dimensional output grating 5 are arranged on the surface of the waveguide substrate 1. Having the technical features of the two-dimensional output grating provided by the embodiment of the present invention, it can achieve the same beneficial effects as the two-dimensional output grating provided by the embodiment of the present invention. The same parts are referred to the above description and will not be repeated here.

[0057] Based on the same inventive concept, an embodiment of the present invention further provides a near-eye display device, including a projection optical engine and the above-mentioned diffractive optical waveguide, and the projection optical engine is configured to emit virtual image light rays. With the technical features of the diffractive optical waveguide provided by the embodiment of the present invention, the same beneficial effects as those of the diffractive optical waveguide provided by the embodiment of the present invention can be achieved. The same parts are referred to the above description and will not be repeated here.

[0058] Exemplarily, the near-eye display device may include AR glasses and XR glasses.

[0059] Note that the above is only a preferred embodiment of the present invention and the applied technical principles. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein. Various obvious changes, re-adjustments, combinations with each other and substitutions can be made by those skilled in the art without departing from the protection scope of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments only. Without departing from the inventive concept of the present invention, more other equivalent embodiments may be included, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A two-dimensional output grating, characterized in that, It includes a plurality of grating structure units arranged in an array; The cross-sectional pattern of the grating structure unit is formed by the overlap of two first patterns and at least one second pattern, and the cross-sectional pattern is formed by a plane parallel to the surface of the substrate where the two-dimensional output grating is located; The centers of the two first patterns are separated by a preset distance and are located on the same straight line, and the two first patterns at least partially overlap; The center of the second pattern coincides with the center of the pattern formed by the two first patterns. The second pattern is a symmetric pattern and the axis of symmetry forms a preset angle with the straight line.

2. The two-dimensional output grating according to claim 1, wherein The first pattern is a first ellipse, the second pattern is a second ellipse, the two first ellipses are the same and the major axis is located on the straight line, and the included angle between the extension direction of the major axis of the second ellipse and the extension direction of the major axis of the first ellipse is the preset angle.

3. The two-dimensional output grating according to claim 1, wherein The preset angle is θ, 0 < |θ| < 180°; 4. The two-dimensional output grating according to claim 1, wherein The value range of the preset distance is 0 to 400 nm; 5. The two-dimensional output grating according to claim 1, wherein The height or depth range of the grating structure unit in the direction perpendicular to the plane of the substrate is 0 to 500 nm; 6. The two-dimensional output grating according to claim 2, wherein, At least one of the major axis dimension of the first ellipse, the minor axis dimension of the first ellipse, the major axis dimension of the second ellipse, the minor axis dimension of the second ellipse, the preset distance, and the preset angle of the grating structure units at different positions in the two-dimensional output grating is different, so that the diffraction efficiency of the (-1, 0) diffraction order and the (0, -1) diffraction order at different positions in the two-dimensional output grating, or the diffraction efficiency ratio of the (0, -1) diffraction order and the (-1, -1) diffraction order at different positions is different.

7. The two-dimensional output grating according to claim 6, wherein, The length range of the major axis of the first ellipse is 50 to 800 nm, and / or the length range of the minor axis of the first ellipse is 50 to 460 nm; 8. The two-dimensional output grating according to claim 6, wherein The length range of the major axis of the second ellipse is 50 to 1000 nm, and / or the length range of the minor axis of the second ellipse is 50 to 400 nm; 9. A diffractive optical waveguide, characterized in that, It includes: A substrate, an input grating, and the two-dimensional output grating according to any one of claims 1-8, wherein the input grating and the two-dimensional output grating are disposed on the surface of the waveguide substrate; 10. A near-eye display device, characterized in that, It includes a projection optical machine and the diffraction optical waveguide according to claim 9, and the projection optical machine is used to emit virtual image light rays.

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