Diffraction optical waveguide and near-to-eye display equipment

Abstract

The invention provides a diffraction optical waveguide and a near-to-eye display device. The diffraction optical waveguide comprises a waveguide substrate, and the surface of the waveguide substrate comprises a grating structure area and a non-grating structure area; the grating structure region at least comprises a coupling-in region and a coupling-out region; a plurality of discrete out-coupling grating blocks are arranged in the out-coupling area, and a first auxiliary structure is arranged on the surface of the side, away from the human eyes, of each out-coupling grating block. The first auxiliary structure is used for preventing ambient light from entering the out-coupling grating block to generate diffraction, and is used for preventing image light from entering an external environment along a direction deviating from human eyes to generate leakage; a plurality of discrete second auxiliary structures are arranged in the non-grating structure area, and the change trend of the transmittance of the grating structure area and the non-grating structure area in the visible light wave band is consistent. According to the scheme provided by the invention, the unexpected light leakage and rainbow problems can be improved and even eliminated, and the naked eye observability of the grating structure can be weakened.

Description

[0001] This application is a divisional application. The original patent application was entitled "A Diffractive Waveguide and Near-Eye Display Device", patent number: 2025115082750, and the application date was October 22, 2025. Technical Field

[0002] This application relates to the field of optical technology, and in particular to a diffractive waveguide and near-eye display device. Background Technology

[0003] Augmented reality is a technology that blends the real world with virtual information. Augmented reality display systems typically include micro-projectors and optical displays. The micro-projectors provide virtual display content for the augmented reality display system, which is then projected onto the viewer's eyes through the optical displays. The optical displays are usually transparent optical components, so that users can also see the real world through the optical displays at the same time.

[0004] However, light leakage and rainbow effects caused by ambient light hinder the improvement of waveguide performance. Current technologies have proposed some solutions to improve light leakage and rainbow effects. However, these solutions may make the grating region of the diffractive waveguide more obvious and the grating structure more visible to the naked eye, affecting the appearance of the diffractive waveguide and the user's acceptance and experience. Therefore, developing a diffractive waveguide that can effectively hide the grating structure and reduce its visual observability has become a key technical focus that needs to be addressed by those skilled in the art. Summary of the Invention

[0005] This application provides a diffractive waveguide and a near-eye display device that can improve or even eliminate unwanted light leakage and rainbow problems, and also reduce the visual observability of the grating structure.

[0006] A diffractive waveguide includes: a waveguide substrate, the surface of which includes a grating structure region and a non-grating structure region; the grating structure region includes at least an insertion region and an exit region; a plurality of discrete exit grating blocks are disposed in the exit region, and a first auxiliary structure is disposed on the surface of the exit grating block away from the human eye, the first auxiliary structure being used to block ambient light from entering the exit grating block to generate diffraction, and to block image light from entering the external environment in a direction away from the human eye to generate leakage; a plurality of discrete second auxiliary structures are disposed in the non-grating structure region, and the transmittance of the grating structure region and the non-grating structure region exhibits the same trend in the visible light band.

[0007] In practice, the coupling region may further include several first auxiliary structures directly disposed on the surface of the waveguide substrate between the coupling grating blocks, and the arrangement of the first auxiliary structures in the coupling region is the same as the arrangement of the second auxiliary structures in the non-grating structure region; or, the coupling region may also be provided with several discrete second auxiliary structures, and the overall arrangement of the first auxiliary structures and the second auxiliary structures in the coupling region is the same as the arrangement of the second auxiliary structures in the non-grating structure region.

[0008] In practice, the number of the first auxiliary structures directly disposed on the surface of the waveguide substrate within the coupling region gradually decreases in the direction of image light propagation; the number of the coupling grating blocks within the coupling region gradually increases in the direction of image light propagation; or, the number of the second auxiliary structures within the coupling region gradually decreases in the direction of image light propagation; and the number of the coupling grating blocks within the coupling region gradually increases in the direction of image light propagation.

[0009] In practice, the coupled grating block includes multiple grating units, the size of the coupled grating block gradually increases along the direction of image light propagation, and the size of the coupled grating block is greater than the grating period of the grating unit but does not exceed 2 mm.

[0010] In practice, the first auxiliary structure includes at least a double-layer structure, consisting of a high-reflectivity metal film layer and a high-absorptivity material film layer in sequence along the direction away from the coupling grating block; the second auxiliary structure includes at least the high-absorptivity material film layer.

[0011] In practice, a subwavelength periodic array is provided across the entire surface of the waveguide substrate; or, a subwavelength periodic array is provided on the side of the first auxiliary structure and the second auxiliary structure away from the waveguide substrate; wherein the period of the subwavelength periodic array is less than the grating period of the coupling grating block.

[0012] In practice, the spacing between the coupled grating blocks can range from 0.3 mm to 4 mm.

[0013] A diffractive waveguide includes: a waveguide substrate, the surface of which includes a grating structure region and a non-grating structure region, the grating structure region including at least an insertion region and an exit region; a plurality of discrete exit grating blocks disposed in the exit region; a protective sheet, the protective sheet being stacked on the side of the waveguide substrate away from the human eye, the surface of the protective sheet having a first auxiliary structure disposed in the orthographic projection region of the exit grating blocks; the first auxiliary structure is used to block ambient light from entering the exit grating blocks to generate diffraction, and to block image light from entering the external environment in a direction away from the human eye to generate leakage; the surface of the protective sheet having a plurality of discrete second auxiliary structures disposed in the orthographic projection region of the non-grating structure region, the transmittance of the grating structure region and the non-grating structure region exhibiting the same trend in the visible light band.

[0014] In an implementable manner, the protective sheet surface may further include a plurality of first auxiliary structures between the orthographic projection areas of the coupled grating blocks, wherein the arrangement of the first auxiliary structures in the coupled area is the same as the arrangement of the second auxiliary structures in the non-grating structure area; or, a plurality of discrete second auxiliary structures may be provided between the orthographic projection areas of the coupled grating blocks on the protective sheet surface, wherein the overall arrangement of the first auxiliary structures and the second auxiliary structures in the coupled area is the same as the arrangement of the second auxiliary structures in the non-grating structure area.

[0015] A near-eye display device includes: a projection optical engine and a diffractive waveguide as described in any of the preceding claims.

[0016] The diffractive waveguide provided in this application has several advantages. First, it incorporates auxiliary structures on the grating structure to block ambient light from entering and causing diffraction, and also prevents image light from leaking into the environment in a direction away from the human eye, effectively improving light leakage and rainbow effects. Second, it uses a small-area, segmented arrangement of the grating structure to reduce the blocking effect of the auxiliary structures on ambient light. The human eye can still receive sufficient ambient light through the areas of the diffractive waveguide without auxiliary structures, ensuring effective intake of ambient light while minimizing its impact on real-world observation. Third, the entire waveguide surface is covered with auxiliary structures, with the grating structure partially hidden beneath them. This results in a uniform or consistent transmittance across the entire waveguide, making it impossible to visually determine the exact location of the grating and reducing its observability. The near-eye display device provided in this application, including the aforementioned diffractive waveguide, possesses all the advantages of such a waveguide. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 A schematic diagram of a diffractive waveguide provided in one embodiment of this application;

[0019] Figure 2 A schematic diagram of a diffractive waveguide provided in another embodiment of this application;

[0020] Figure 3 A schematic diagram of a diffractive waveguide provided in another embodiment of this application;

[0021] Figure 4 A schematic diagram of a diffractive waveguide provided in another embodiment of this application;

[0022] Figure 5 A schematic diagram of a diffractive waveguide provided in another embodiment of this application;

[0023] Figure 6 A schematic diagram of a diffractive waveguide provided in another embodiment of this application;

[0024] Figure 7 A schematic diagram of a diffractive waveguide provided in another embodiment of this application;

[0025] Attached image labels:

[0026] 110, waveguide substrate; 120, coupling region; 130, transition region; 140, coupling out region;

[0027] 1100: Structure A; 1200: Structure B. Detailed Implementation

[0028] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0029] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0030] It should be noted that the terms "consistent trend of transmittance" and "same arrangement" in this application do not require absolute consistency or identicalness in a mathematical sense. They can be implemented as basically consistent or basically identical, as long as they are within the range allowed by the performance indicators. For example, the transmittance of the grating structure region and the non-grating structure region in the visible light band is consistent. Complete consistency of transmittance is not required. The difference between the average transmittance of the grating structure region and the average transmittance of the non-grating structure region in the visible light band in the visible light band is less than or equal to a preset value, such as 8%, 5%, 3%, etc.

[0031] According to one aspect of this application, a diffractive waveguide is provided, comprising: a waveguide substrate, the surface of which includes a grating structure region and a non-grating structure region; the grating structure region includes at least an insertion region and an extraction region; a plurality of discrete extraction grating blocks are disposed in the extraction region, and a first auxiliary structure is disposed on the surface of the extraction grating blocks away from the human eye, the first auxiliary structure being used to block ambient light from entering the extraction grating blocks to generate diffraction, and to block image light from entering the external environment in a direction away from the human eye to generate leakage; a plurality of discrete second auxiliary structures are disposed in the non-grating structure region, and the transmittance variation trends of the grating structure region and the non-grating structure region in the visible light band are basically the same.

[0032] It is understandable that light rays, after being diffracted by a grating structure, have transmission and reflection orders with opposite transmission directions. Therefore, at the grating coupling point, on the one hand, there is a leakage problem caused by image light rays being diffracted and transmitted away from the human eye, and on the other hand, there is a rainbow problem caused by ambient light rays being diffracted and transmitted towards the human eye. Moreover, the human eye can distinguish between grating structure regions and non-grating structure regions based on the difference in reflected light or transmitted light between grating structure regions and non-grating structure regions in the visible light band, thus allowing the naked eye to observe the existence of the grating structure.

[0033] In this application, the grating structure region is the area on the waveguide substrate surface where the grating structure is located, and the remaining area on the waveguide substrate surface other than the grating structure region is the non-grating structure region. The grating structure region may include multiple functional regions, such as coupling-in regions, transition regions, and coupling-out regions. It should be noted that the grating structure within the functional region in this application is not a continuous structure, but rather a discretely distributed grating block; the area of ​​each functional region is the continuous region that can completely cover the grating block that implements the function.

[0034] The first auxiliary structure and the second auxiliary structure can have the same or different structures. The first auxiliary structure is placed on the coupling grating block to mitigate leakage and rainbow problems caused by diffraction. The second auxiliary structure is used to blend in with the first auxiliary structure, resulting in the same or similar optical effects, thus hiding the coupling grating block beneath the first auxiliary structure. In this way, when the first and second auxiliary structures are almost indistinguishable to the naked eye, the specific location of the coupling grating structure becomes unknown, thereby weakening the visual observability of the grating structure.

[0035] In practice, the coupling grating blocks can be arranged regularly or randomly, and the arrangement of the second auxiliary structure is basically the same as that of the coupling grating blocks, so as to achieve the merging of the second auxiliary structure and the first auxiliary structure. The size and spacing of the coupling grating blocks can be fixed or variable. In practice, the size of the coupling grating blocks gradually increases along the direction of light transmission, which can modulate the distribution of diffraction efficiency, thereby optimizing the uniformity of the diffraction waveguide. Alternatively, the spacing between the coupling grating blocks can gradually decrease along the direction of light transmission, which can also modulate the distribution of diffraction efficiency, thereby optimizing the uniformity of the diffraction waveguide.

[0036] Furthermore, the transmittance trends of the grating structure region and the non-grating structure region in the visible light band are basically the same, covering both scenarios where transmittance changes and does not change. When the transmittance does not change, the transmittance trend is unchanged, meaning the transmittance of the grating structure region and the non-grating structure region in the visible light band is basically the same, which also means the transmittance of the entire diffractive waveguide surface is basically the same. Thus, the human eye cannot observe a specific grating region. In this scenario, since the first auxiliary structure is set on the coupling grating block, the size of the first auxiliary structure is the same as the size of the coupling grating block; the second auxiliary structure needs to be consistent with the first auxiliary structure, so the size of the second auxiliary structure is the same as the size of the first auxiliary structure, and the arrangement of the second auxiliary structure should also be basically the same as the arrangement of the coupling grating block. It should be noted that this application does not require complete consistency of transmittance; the difference between the average transmittance of the grating structure region and the average transmittance of the non-grating structure region in the visible light band is less than or equal to a preset value, such as 8%, 5%, 3%, etc. Furthermore, when transmittance changes, the trend includes both the overall direction of change and a regular pattern. In this case, the transmittance change trend is uniform across the entire diffractive waveguide surface. Thus, specific grating areas cannot be observed with the naked eye. Even if regional changes are observed, they are specifically designed regional changes that bring additional effects (such as a fashionable regional distribution display effect), rather than regional changes between grating structure areas and non-grating structure areas. The size and spacing of the coupling grating blocks affect the transmittance of the diffractive waveguide surface.

[0037] For example, refer to Figures 1-4 What the naked eye observes is an array of first and second auxiliary structures forming the entire surface of the diffractive waveguide. Variations in the size and spacing of the coupling grating blocks (first / second auxiliary structures) can create waveguides with different transmittance or different transmittance trends. (Comparison) Figure 1 and Figure 2 It can be seen that the size and spacing of the coupling grating blocks are different, and the transmittance of the entire diffractive waveguide surface is consistent, but the transmittance of different waveguide sheets varies. (Comparison) Figure 1 and Figure 3 As can be seen, the coupling grating blocks can be randomly or regularly distributed. Of course, in other embodiments, the size and spacing of the coupling grating blocks can vary. (See reference...) Figure 4 The surface of a diffractive waveguide can be customized with a transmittance distribution to achieve a customized display effect. Figure 4 The display effect shown is for illustrative purposes only.

[0038] In practice, the first auxiliary structure includes at least a double-layer structure, consisting of a high-reflectivity metal film and a high-absorptivity material film layer in sequence along the direction away from the coupling grating block; the second auxiliary structure includes at least a high-absorptivity material film layer.

[0039] For example, the high-reflectivity metal film can be a silver film or an aluminum film, etc. The high-absorptivity material film can be a blackened film, etc. Specifically, the high-reflectivity metal film can reflect the leakage order of image light back into the diffraction waveguide for reuse, thereby improving the coupling efficiency of the diffraction waveguide. The high-absorptivity material film can absorb ambient light to alleviate the rainbow problem, and also reduce surface reflection of the diffraction waveguide to avoid glare. When the outermost structures (the structures closest to the human eye) of the first and second auxiliary structures are the same, the first and second auxiliary structures are almost indistinguishable to the naked eye. Of course, the first and second auxiliary structures can also include more structural layers.

[0040] In practice, a subwavelength periodic array is provided over the entire surface of the waveguide substrate; or, a subwavelength periodic array is provided on the side of the first auxiliary structure and the second auxiliary structure away from the waveguide substrate; wherein the period of the subwavelength periodic array is less than the grating period of the coupled grating block.

[0041] Specifically, the subwavelength periodic array can cause destructive interference of reflected light when ambient light is incident on it, thereby reducing the reflectivity of the waveguide surface and minimizing unwanted surface reflections. Since periodic structures can diffract light, adding a subwavelength periodic array to the waveguide substrate surface may affect the original image light transmission within the waveguide substrate. In this embodiment, the period of the subwavelength periodic array is limited to be less than the grating period of any grating structure within the grating structure region, which can mitigate this effect to some extent.

[0042] In the above embodiments, the example of a coupling-out grating block within the coupling-out region is used for illustration. It can be understood that in some embodiments, the grating structure region of the diffractive waveguide also includes a transition region. Similarly, a plurality of discrete transition grating blocks can be disposed within the transition region, and a first auxiliary structure is disposed on the surface of the transition grating block away from the human eye. Regarding the arrangement of the grating blocks and auxiliary structures, the following illustration uses an example where the diffractive waveguide simultaneously includes a coupling-in region, a transition region, and a coupling-out region.

[0043] For example, refer to Figure 5The waveguide substrate 110 of the diffractive waveguide includes a coupling region 120, a transition region 130, and a coupling out region 140. It can be seen that structure A 1100 is disposed within the transition region 130 and the coupling out region 140, and structure B 1200 is disposed within the non-grating structure region. Structure A 1100 is a stacked first auxiliary structure and a grating block (a transition grating block or a coupling out grating block), and structure B 1200 is a second auxiliary structure. It should be noted that in this figure, structures A and B are shown as different symbols to indicate that they are different components, but this does not imply that they are differently visible to the human eye in a real-world scenario; that is, the human eye can hardly distinguish between these two structures.

[0044] In practice, the coupling region may also include several first auxiliary structures directly disposed on the surface of the waveguide substrate between the coupling grating blocks. The arrangement of the first auxiliary structures in the coupling region is basically the same as the arrangement of the second auxiliary structures in the non-grating structure region. Alternatively, several discrete second auxiliary structures may also be disposed in the coupling region. The overall arrangement of the first and second auxiliary structures in the coupling region is basically the same as the arrangement of the second auxiliary structures in the non-grating structure region.

[0045] Specifically, in some embodiments, in order to modulate the distribution of diffraction efficiency in the coupling region, the coupling grating blocks are non-uniformly distributed, with the density of the coupling grating blocks gradually increasing along the direction of light transmission. In this case, a first auxiliary structure or a second auxiliary structure can be directly disposed on the waveguide substrate surface between the coupling grating blocks in the coupling region. This allows for a more harmonious arrangement of the first auxiliary structure, or the arrangement of the first and second auxiliary structures, within the coupling region, thereby improving the user's overall visual experience.

[0046] In practice, the number of first auxiliary structures directly disposed on the surface of the waveguide substrate within the coupling region gradually decreases in the direction of image light propagation; the number of coupling grating blocks within the coupling region gradually increases in the direction of image light propagation; or, the number of second auxiliary structures within the coupling region gradually decreases in the direction of image light propagation; and the number of coupling grating blocks within the coupling region gradually increases in the direction of image light propagation.

[0047] For example, refer to Figure 6 The waveguide substrate 110 of the diffractive waveguide includes a coupling region 120, a transition region 130, and a coupling out region 140. It can be seen that the number of A-structures 1100 in the transition region 130 near the coupling region 120 is less than the number of A-structures 1100 in the transition region 130 far from the coupling region 120, and the number of A-structures 1100 in the coupling out region 140 near the transition region 130 is less than the number of A-structures 1100 in the coupling out region 140 far from the transition region 130.

[0048] In practice, the coupled grating block includes multiple grating units, the size of the coupled grating block gradually increases along the direction of image light propagation, and the size of the coupled grating block is greater than the grating period of the grating unit but does not exceed 2 mm.

[0049] Specifically, this application addresses light leakage and rainbow issues by adding auxiliary structures to the grating structure. However, these auxiliary structures can affect the user's observation of the real world. Therefore, a small-area, segmented layout of the grating structure is necessary to reduce the obstruction of ambient light by the auxiliary structures, allowing the human eye to still receive sufficient ambient light through the area of ​​the diffraction waveguide without auxiliary structures. When using a small-area, segmented layout for the grating structure, each grating block can include multiple grating units. The size of the grating block should be larger than the grating period of the grating units to avoid affecting the imaging path of the image light within the diffraction waveguide. The size of the grating block gradually increases along the direction of image light propagation; a larger diffraction area results in greater diffraction efficiency, which helps optimize the uniformity of the diffraction waveguide. The size of the grating block should not be too large, as this would affect the user's observation of the real world. The size of the grating block should generally not exceed 2 mm. The size variation method and range of the grating block also apply to transition grating blocks in transition regions and coupling grating blocks in coupling regions.

[0050] For example, refer to Figure 7 The waveguide substrate 110 of the diffractive waveguide includes a coupling region 120, a transition region 130, and a coupling out region 140. It can be seen that the size of structure A 1100 in the transition region 130 near the coupling region 120 is smaller than the size of structure A 1100 in the transition region 130 away from the coupling region 120, and the size of structure A 1100 in the coupling out region 140 near the transition region 130 is smaller than the size of structure A 1100 in the coupling out region 140 away from the transition region 130.

[0051] In practice, the spacing between the coupled grating blocks can range from 0.3 mm to 4 mm.

[0052] Specifically, the spacing between the coupled grating blocks should not be too small, as this will affect the user's observation of the real world. The spacing between the coupled grating blocks should generally be greater than 0.3 mm. The spacing between the coupled grating blocks should also not be too large. To avoid situations where virtual content cannot be viewed from certain areas within the viewing window, the spacing between the coupled grating blocks should be smaller than the diameter of the human pupil, and should generally be less than 4 mm.

[0053] In the above embodiments, the first auxiliary structure and the second auxiliary structure are disposed on the waveguide substrate, or directly disposed on the surface of the waveguide substrate, or disposed on the grating block on the surface of the waveguide substrate. According to another aspect of this application, the first auxiliary structure and the second auxiliary structure can also be disposed on a protective sheet.

[0054] A diffractive waveguide includes: a waveguide substrate, the surface of which includes a grating structure region and a non-grating structure region, the grating structure region including at least an insertion region and an exit region; a plurality of discrete exit grating blocks disposed in the exit region; a protective sheet, which is stacked on the side of the waveguide substrate away from the human eye, and a first auxiliary structure disposed in the orthographic projection region of the exit grating blocks on the surface of the protective sheet; the first auxiliary structure is used to block ambient light from entering the exit grating blocks to generate diffraction, and to block image light from entering the external environment in a direction away from the human eye to generate leakage; a plurality of discrete second auxiliary structures are disposed in the orthographic projection region of the non-grating structure region on the surface of the protective sheet, and the transmittance variation trends of the grating structure region and the non-grating structure region in the visible light band are basically the same.

[0055] In an implementable manner, the orthographic projection areas of the grating blocks on the surface of the protective sheet may also include several first auxiliary structures, the arrangement of the first auxiliary structures in the coupling area being basically the same as the arrangement of the second auxiliary structures in the non-grating structure area; or, several discrete second auxiliary structures may be provided between the orthographic projection areas of the grating blocks on the surface of the protective sheet, the overall arrangement of the first and second auxiliary structures in the coupling area being basically the same as the arrangement of the second auxiliary structures in the non-grating structure area.

[0056] It is understood that the specific implementation methods (such as parameter settings, arrangement settings, etc.) of the first auxiliary structure and the second auxiliary structure in the foregoing embodiments when they are disposed on the waveguide substrate are also applicable to the scenario where the first auxiliary structure and the second auxiliary structure are disposed on the protective sheet.

[0057] According to one aspect of this application, a near-eye display device is also provided, comprising: a projection optical engine and a diffractive waveguide as described in any of the preceding claims. The projection optical engine is used to emit image light. The near-eye display device can specifically be implemented as an augmented reality eye or an augmented reality helmet, etc. The near-eye display device provided by this application includes the aforementioned diffractive waveguide, and therefore possesses the advantages of the aforementioned diffractive waveguide.

[0058] The specific embodiments described above do not constitute a limitation on the scope of protection of this application. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A diffractive optical waveguide, characterized by, Comprising: a waveguide substrate, a surface of the waveguide substrate comprising a grating structure region and a non-grating structure region; the grating structure region comprising at least an in-coupling region and an out-coupling region; a plurality of discrete out-coupling grating blocks are arranged in the out-coupling region, a first auxiliary structure is arranged on a surface of the out-coupling grating blocks away from a human eye, the first auxiliary structure is used to block ambient light from entering the out-coupling grating blocks to generate diffraction, and is used to block image light from entering the external environment in a direction away from the human eye to generate leakage; a plurality of discrete second auxiliary structures are arranged in the non-grating structure region, and the grating structure region and the non-grating structure region are consistent in the change trend of the transmittance in the visible light wave band; wherein, the surface of the waveguide substrate is provided with a sub-wavelength periodic array; or, the side of the first auxiliary structure and the second auxiliary structure away from the waveguide substrate is provided with a sub-wavelength periodic array; the period of the sub-wavelength periodic array is smaller than the grating period of the out-coupling grating block.

2. The diffractive optical waveguide of claim 1, wherein, The first auxiliary structure directly arranged on the surface of the waveguide substrate between the out-coupling grating blocks in the out-coupling region is arranged in the same manner as the second auxiliary structure in the non-grating structure region; or, a plurality of discrete second auxiliary structures are also arranged in the out-coupling region, and the overall arrangement manner of the first auxiliary structure and the second auxiliary structure in the out-coupling region is the same as that of the second auxiliary structure in the non-grating structure region.

3. The diffractive optical waveguide of claim 2, wherein, The number of the first auxiliary structure directly arranged on the surface of the waveguide substrate in the out-coupling region gradually decreases in the direction of image light propagation; the number of the out-coupling grating blocks in the out-coupling region gradually increases in the direction of image light propagation; or, the number of the second auxiliary structure in the out-coupling region gradually decreases in the direction of image light propagation; the number of the out-coupling grating blocks in the out-coupling region gradually increases in the direction of image light propagation.

4. The diffractive optical waveguide of claim 1, wherein, The out-coupling grating block comprises a plurality of grating units, the size of the out-coupling grating block gradually increases in the direction of image light propagation, and the size of the out-coupling grating block is greater than the grating period of the grating unit and does not exceed 2mm.

5. The diffractive optical waveguide of claim 1, wherein, The first auxiliary structure and the second auxiliary structure are different in structure; the first auxiliary structure comprises at least a double-layer structure, which comprises a high-reflectivity metal film layer and a high-absorbance material film layer in sequence in the direction away from the out-coupling grating block; the second auxiliary structure comprises at least the high-absorbance material film layer; or, the first auxiliary structure and the second auxiliary structure are the same in structure.

6. The diffractive optical waveguide of claim 1, wherein, The spacing between the out-coupling grating blocks gradually decreases in the direction of light transmission.

7. The diffractive optical waveguide of claim 1, wherein, The spacing between the out-coupling grating blocks is in the range of 0.3mm-4mm.

8. A diffractive optical waveguide, characterized by Comprising: a waveguide substrate, a surface of the waveguide substrate comprising a grating structure region and a non-grating structure region, the grating structure region comprising at least an in-coupling region and an out-coupling region; a plurality of discrete out-coupling grating blocks are arranged in the out-coupling region; A protection sheet is stacked on the side of the waveguide substrate away from the human eye, and first auxiliary structures are arranged on the surface of the protection sheet within the area of the normal projection of the out-coupling grating blocks; the first auxiliary structures are used to block ambient light from entering the out-coupling grating blocks to produce diffraction and to block image light from entering the external environment in a direction away from the human eye to produce leakage; second auxiliary structures are arranged on the surface of the protection sheet within the area of the normal projection of the non-grating structure region, and the grating structure region and the non-grating structure region are consistent in the change trend of the transmittance in the visible light waveband. The surface of the protection sheet is provided with a sub-wavelength periodic array; or the side of the first auxiliary structures and the second auxiliary structures away from the protection sheet is provided with a sub-wavelength periodic array; the period of the sub-wavelength periodic array is smaller than the grating period of the out-coupling grating blocks.

9. The diffractive optical waveguide of claim 8, wherein, The surface of the protection sheet further includes first auxiliary structures between the normal projection areas of the out-coupling grating blocks, and the arrangement mode of the first auxiliary structures in the coupling-out region is the same as the arrangement mode of the second auxiliary structures in the non-grating structure region; or the surface of the protection sheet is provided with discrete second auxiliary structures between the normal projection areas of the out-coupling grating blocks, and the overall arrangement mode of the first auxiliary structures and the second auxiliary structures in the coupling-out region is the same as the arrangement mode of the second auxiliary structures in the non-grating structure region.

10. A near-eye display device, comprising: The near-eye display device comprises a projection light machine and the diffractive optical waveguide according to any one of claims 1-9.

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