Diffractive optical waveguide and near-eye display device

Abstract

The application provides a diffraction optical waveguide and a near-eye display device, 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 a coupling-in region and a coupling-out region; a plurality of discrete coupling-out grating blocks are arranged in the coupling-out region, a first auxiliary structure is arranged on a surface of the coupling-out grating block far away from a human eye, the first auxiliary structure is used for blocking ambient light from entering the coupling-out grating block to generate diffraction, and is used for blocking image light from entering an 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 a change trend of transmittance of the grating structure region and the non-grating structure region in a visible light wave band is consistent. The scheme provided by the application can improve or even eliminate the problem of undesirable light leakage and rainbow, and can also weaken the visibility of the grating structure.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of optical technology, in particular to a diffractive optical waveguide and a near-eye display device. BACKGROUND

[0002] Augmented reality is a technology that combines the real world and virtual information, and 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 to project 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.

[0003] However, the problem of light leakage and the problem of rainbow caused by ambient light hinder the improvement of the performance of the waveguide. The current technology proposes some solutions to improve the problems of light leakage and rainbow. However, these solutions may make the grating area of the diffractive optical waveguide more obvious, and the grating structure more visible to the naked eye, which affects the appearance of the diffractive optical waveguide and the acceptance and use experience of the diffractive optical waveguide by users. Therefore, it is an urgent technical focus for those skilled in the art to develop a diffractive optical waveguide that can effectively hide the grating structure and weaken the visibility of the grating structure to the naked eye. SUMMARY

[0004] The embodiments of the present application provide a diffractive optical waveguide and a near-eye display device, which can improve or even eliminate the problems of undesirable light leakage and rainbow, and weaken the visibility of the grating structure to the naked eye.

[0005] A diffractive optical waveguide, comprising: a waveguide substrate, a surface of the waveguide substrate comprising a grating structure area and a non-grating structure area; the grating structure area comprising at least a coupling-in area and a coupling-out area; a plurality of discrete coupling-out grating blocks are arranged in the coupling-out area, a first auxiliary structure is arranged on the surface of the coupling-out grating block away from the human eye, the first auxiliary structure is used to block ambient light from entering the coupling-out grating block to produce diffraction, and is used to block image light from entering the external environment in the direction away from the human eye to produce 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 waveband is basically consistent.

[0006] In an embodiment, the first auxiliary structure directly arranged on the surface of the waveguide substrate in the out-coupling region further comprises a plurality of structures arranged in the same manner as the second auxiliary structure in the non-grating structure region; or the first auxiliary structure and the second auxiliary structure in the out-coupling region are arranged in the same manner as the second auxiliary structure in the non-grating structure region.

[0007] In an embodiment, the number of the first auxiliary structure directly arranged on the surface of the waveguide substrate in the out-coupling region gradually decreases along the direction of the image light propagation; or the number of the out-coupling grating block in the out-coupling region gradually increases along the direction of the image light propagation; or the number of the second auxiliary structure in the out-coupling region gradually decreases along the direction of the image light propagation; or the number of the out-coupling grating block in the out-coupling region gradually increases along the direction of the image light propagation.

[0008] In an embodiment, the out-coupling grating block comprises a plurality of grating units, and the size of the out-coupling grating block gradually increases along the direction of the 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 2 mm.

[0009] In an embodiment, the first auxiliary structure comprises at least a double-layer structure, and the double-layer structure comprises, in sequence along the direction away from the out-coupling grating block, a high-reflectivity metal film layer and a high-absorption material film layer; and the second auxiliary structure comprises at least the high-absorption material film layer.

[0010] In an embodiment, 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; and the period of the sub-wavelength periodic array is less than the grating period of the out-coupling grating block.

[0011] In an embodiment, the spacing between the out-coupling grating blocks is in the range of 0.3 mm to 4 mm.

[0012] A diffractive optical waveguide, 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 a coupling-in region and a coupling-out region; a plurality of discrete coupling-out grating blocks are arranged in the coupling-out region; a protective sheet is stacked on a side of the waveguide substrate away from a human eye, a first auxiliary structure is arranged in a projection area of the coupling-out grating blocks on a surface of the protective sheet; the first auxiliary structure is used to block ambient light from entering the coupling-out 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; a plurality of discrete second auxiliary structures are arranged in a projection area of the non-grating structure region on the surface of the protective sheet, and the grating structure region and the non-grating structure region have substantially consistent trends in transmittance in the visible light band.

[0013] In an implementation, the projection area of the coupling-out grating blocks on the surface of the protective sheet further comprises a plurality of the first auxiliary structures, and the arrangement of the first auxiliary structures in the coupling-out region is substantially the same as the arrangement of the second auxiliary structures in the non-grating structure region; or, the projection area of the coupling-out grating blocks on the surface of the protective sheet is provided with a plurality of discrete second auxiliary structures, and the overall arrangement of the first auxiliary structures and the second auxiliary structures in the coupling-out region is substantially the same as the arrangement of the second auxiliary structures in the non-grating structure region.

[0014] A near-eye display device, comprising: a projection light machine and the diffractive optical waveguide according to any one of the preceding embodiments.

[0015] The diffractive optical waveguide provided by the present application has the following advantages: on the one hand, auxiliary structures are arranged on the grating structure, which blocks ambient light from entering the grating structure to produce diffraction, and blocks image light from entering the external environment in a direction away from the human eye to produce leakage, thereby effectively improving the light leakage and rainbow problems; on the other hand, the grating structure is arranged in a small-area partitioning manner to weaken the blocking effect of the auxiliary structures on ambient light, so that the human eye can still fully receive ambient light through the region of the diffractive optical waveguide where no auxiliary structure is arranged, thereby ensuring effective intake of ambient light and minimizing the impact on observation of the real world; on the other hand, auxiliary structures are arranged on the entire surface of the waveguide, and the grating structure is hidden under part of the auxiliary structures, so that the transmittance of the entire waveguide is consistent or has a consistent trend, and the specific position of the grating structure cannot be determined by the naked eye, thereby weakening the naked-eye observability of the grating structure. The near-eye display device provided by the present application comprises the aforementioned diffractive optical waveguide, and also has the advantages of the aforementioned diffractive optical waveguide. BRIEF DESCRIPTION OF DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings needed in the embodiment description. Obviously, the drawings in the following description only show some embodiments of the present application, and for those skilled in the art, other drawings can be obtained without creative labor based on these drawings.

[0017] Figure 1 The schematic diagram of the diffractive optical waveguide provided by an embodiment of the present application is shown in the following figure.

[0018] Figure 2 The schematic diagram of the diffractive optical waveguide provided by another embodiment of the present application is shown in the following figure.

[0019] Figure 3 The schematic diagram of the diffractive optical waveguide provided by another embodiment of the present application is shown in the following figure.

[0020] Figure 4 The schematic diagram of the diffractive optical waveguide provided by another embodiment of the present application is shown in the following figure.

[0021] Figure 5 The schematic diagram of the diffractive optical waveguide provided by another embodiment of the present application is shown in the following figure.

[0022] Figure 6 The schematic diagram of the diffractive optical waveguide provided by another embodiment of the present application is shown in the following figure.

[0023] Figure 7 The schematic diagram of the diffractive optical waveguide provided by another embodiment of the present application is shown in the following figure.

[0024] The figure identification is as follows:

[0025] 110, waveguide substrate; 120, coupling-in region; 130, turning region; 140, coupling-out region;

[0026] 1100: A structure; 1200: B structure. DETAILED DESCRIPTION

[0027] In order to make the person skilled in the art better understand the present application, the following will combine 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 some of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should be within the scope of protection of the present application.

[0028] It is to be understood that the terms "first", "second", and the like, used in the description and the claims of the present application as well as the above description of the drawings merely refer to different categories and do not imply a specific order or chronology thereof. It is to be understood that the data thus used can be interchanged, where appropriate, so that the embodiments of the present application described herein can be carried out in other than the order shown or described herein. Furthermore, the terms "comprising", "having", and any variations thereof are intended to cover a non-exclusive inclusion, for example, a process, method, system, product, or apparatus that comprises a list of steps or units can not necessarily be limited to those steps or units that are clearly listed, but can include other not clearly listed steps or units that are inherent to such process, method, product, or apparatus.

[0029] According to an aspect of the present application, a diffractive optical waveguide is provided, 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 a coupling-in region and a coupling-out region; a plurality of discrete coupling-out grating blocks are arranged in the coupling-out region, a first auxiliary structure is arranged on a surface of the coupling-out grating blocks away from a human eye, the first auxiliary structure is used to block ambient light from entering the coupling-out grating blocks to cause diffraction, and is used to block image light from entering an external environment in a direction away from the human eye to cause 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 have substantially consistent variation trends of transmittance in a visible light waveband.

[0030] It can be understood that there are transmission orders and reflection orders in opposite directions due to the diffraction of light by the grating structure, so that at the coupling-out grating, on the one hand, there is a leakage problem caused by the transmission of image light away from the human eye after diffraction, and on the other hand, there is a rainbow problem caused by the transmission of ambient light toward the human eye after diffraction; and the human eye can distinguish the grating structure region and the non-grating structure region based on the difference between the reflected light in the grating structure region and the non-grating structure region in the visible light waveband or the difference between the transmitted light in the grating structure region and the non-grating structure region, so that the existence of the grating structure is observed by the naked eye.

[0031] In the present application, the grating structure region is a region where the grating structure on the surface of the waveguide substrate is located, and the remaining region of the surface of the waveguide substrate except the grating structure region is the non-grating structure region; the grating structure region can comprise a plurality of functional regions, such as a coupling-in region, a turning region, a coupling-out region, etc. It should be noted that the grating structure in the functional region in the present application is not a whole continuous structure, but a discrete grating block; the range of each functional region is a continuous region that can cover all the grating blocks that can realize the function.

[0032] The first auxiliary structure and the second auxiliary structure can have the same structure or different structures. The first auxiliary structure is arranged on the out-coupling grating block to alleviate the leakage problem and the rainbow problem caused by diffraction. The second auxiliary structure is used to mix with the first auxiliary structure, so that the optical structures caused by the two auxiliary structures are the same or similar, and the out-coupling grating block under the first auxiliary structure is hidden. In this way, when the first auxiliary structure and the second auxiliary structure cannot be distinguished by the naked eye, the specific position of the out-coupling grating structure cannot be known, and the naked-eye observability of the grating structure is weakened.

[0033] In an embodiment, the out-coupling grating blocks can be regularly arranged or randomly arranged, and the arrangement mode of the second auxiliary structure is basically consistent with the arrangement mode of the out-coupling grating blocks, so as to mix the first auxiliary structure and the second auxiliary structure. The size and the interval of the out-coupling grating blocks can be fixed or variable. In an embodiment, the size of the out-coupling grating blocks gradually increases along the direction of light transmission, so that the distribution of diffraction efficiency is modulated, and the uniformity of the diffractive optical waveguide is optimized. In another embodiment, the interval between the out-coupling grating blocks gradually decreases along the direction of light transmission, so that the distribution of diffraction efficiency is modulated, and the uniformity of the diffractive optical waveguide is optimized.

[0034] In addition, the change trend of the transmittance of the grating structure region and the non-grating structure region in the visible light band is basically consistent, covering two scenarios of transmittance change and no change. When the transmittance does not change, the change trend of the transmittance is no change, and the transmittance of the grating structure region and the non-grating structure region in the visible light band is basically consistent, and the transmittance of the entire surface of the diffractive optical waveguide is also basically consistent. In this way, the human eye cannot observe the specific grating region by the naked eye. In this scenario, since the first auxiliary structure is arranged on the out-coupling grating block, the size of the first auxiliary structure is consistent with the size of the out-coupling grating block. The second auxiliary structure needs to be mixed with the first auxiliary structure, so the size of the second auxiliary structure is consistent with the size of the first auxiliary structure, and the arrangement mode of the second auxiliary structure should also be basically consistent with the arrangement mode of the out-coupling grating blocks. It should be noted that the application does not require complete consistency of the transmittance. The difference between the average transmittance of the grating structure region in the visible light band 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. In addition, when the transmittance changes, the change trend includes the overall change direction and the regular trend. At this time, the change trend of the transmittance of the entire surface of the diffractive optical waveguide is uniform, so the human eye cannot observe the specific grating region by the naked eye. Even if the region change can be observed, it is not the region change between the grating structure region and the non-grating structure region. The change of the size and the interval of the out-coupling grating blocks affects the transmittance of the surface of the diffractive optical waveguide.

[0035] For example, referring to FIG. 1, the diffractive optical waveguide includes a grating structure region and a non-grating structure region. The grating structure region includes a plurality of out-coupling grating blocks and a plurality of first auxiliary structures arranged on the out-coupling grating blocks. The non-grating structure region is arranged around the grating structure region. The second auxiliary structure is arranged on the non-grating structure region. Figures 1-4The human eye can observe that the entire diffraction light waveguide surface is an array formed by the first auxiliary structure and the second auxiliary structure. By changing the size and spacing of the out-coupling grating blocks (the first auxiliary structure / second auxiliary structure), waveguides with different transmittances or different transmittance variation trends can be achieved. As shown in Figure 1 and Figure 2 It can be seen that the size and spacing of the out-coupling grating blocks are different, the transmittance of the entire diffraction light waveguide surface is consistent, and the transmittance of different waveguide pieces is different. As shown in Figure 1 and Figure 3 It can be seen that the out-coupling grating blocks can be randomly distributed or regularly distributed. Of course, in other embodiments, the size and spacing of the out-coupling grating blocks can be changed. Referring to Figure 4 , the diffraction light waveguide surface can have a self-defined transmittance distribution to achieve a self-defined display effect, Figure 4 The display effect is only an example.

[0036] In an implementation, the first auxiliary structure includes at least a double-layer structure, and the double-layer structure includes, in sequence along a direction away from the out-coupling grating block, a high-reflectivity metal film layer and a high-absorptivity material film layer; and the second auxiliary structure includes at least a high-absorptivity material film layer.

[0037] For example, the high-reflectivity metal film layer can be a silver film or an aluminum film, etc. The high-absorptivity material film layer can be implemented as a blackened film, etc. Specifically, the high-reflectivity metal film layer can reflect the leakage orders of the image light back into the diffraction light waveguide for reuse, which can improve the out-coupling efficiency of the diffraction light waveguide. On the one hand, the high-absorptivity material film layer can absorb ambient light to alleviate the rainbow problem, and on the other hand, the high-absorptivity material film layer can also reduce the surface reflection of the diffraction light waveguide to avoid forming "glare". When the outermost structure (the structure closest to the human eye) of the first auxiliary structure and the second auxiliary structure is the same, the first auxiliary structure and the second auxiliary structure are almost indistinguishable to the human eye. Of course, the first auxiliary structure and the second auxiliary structure can also include more structure layers.

[0038] In an implementation, the entire 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; wherein the period of the sub-wavelength periodic array is less than the grating period of the out-coupling grating block.

[0039] Specifically, the sub-wavelength periodic array can cause the reflected light formed when ambient light is incident thereon to interfere destructively, which can reduce the surface reflectivity of the waveguide and reduce the undesired surface reflection. Since the periodic structure can diffract light, when the sub-wavelength periodic array is added to the surface of the waveguide substrate, it is possible to affect the transmission of the original image light in the waveguide substrate. In this embodiment, the period of the sub-wavelength periodic array is limited to be less than the grating period of any grating structure in the grating structure region, which can weaken the influence to some extent.

[0040] In the above embodiments, the out-coupling grating blocks in the out-coupling region are taken as an example for description. It can be understood that, in some embodiments, the grating structure region of the diffractive optical waveguide also includes a turning region, and similarly, a plurality of discrete turning grating blocks can also be arranged in the turning region, and the first auxiliary structures are arranged on the side surface away from the human eye of the turning grating blocks. Regarding the arrangement of the grating blocks and the auxiliary structures, the following takes the diffractive optical waveguide including the in-coupling region, the turning region and the out-coupling region as an example for description.

[0041] Exemplarily, referring to Figure 5 , the waveguide substrate 110 of the diffractive optical waveguide includes the in-coupling region 120, the turning region 130 and the out-coupling region 140. It can be seen that the A structure 1100 is arranged in the turning region 130 and the out-coupling region 140, and the B structure 1200 is arranged in the non-grating structure region. The A structure 1100 is the first auxiliary structure and the grating block (the turning grating block or the out-coupling grating block) stacked together, and the B structure 1200 is the second auxiliary structure. It should be noted that, in this figure, the A structure and the B structure are displayed as different legends to indicate that they are different elements, but it does not mean that the visibility to the human eye is different in the actual scene, that is, the two structures can hardly be distinguished by the naked eye observation of the human eye.

[0042] Exemplarily, a plurality of first auxiliary structures are arranged directly on the surface of the waveguide substrate between the out-coupling grating blocks in the out-coupling region, and the arrangement mode of the first auxiliary structures in the out-coupling region is basically the same as the arrangement mode of the second auxiliary structures in the non-grating structure region; or a plurality of discrete second auxiliary structures are arranged in the out-coupling region, and the overall arrangement mode of the first auxiliary structures and the second auxiliary structures in the out-coupling region is basically the same as the arrangement mode of the second auxiliary structures in the non-grating structure region.

[0043] Specifically, in some embodiments, in order to modulate the distribution of the diffraction efficiency of the out-coupling region, the out-coupling grating blocks are unevenly distributed, and the density of the out-coupling grating blocks gradually increases along the direction of light transmission. At this time, the first auxiliary structures or the second auxiliary structures can be arranged directly on the surface of the waveguide substrate between the out-coupling grating blocks in the out-coupling region, so that the arrangement of the first auxiliary structures or the arrangement of the first auxiliary structures and the second auxiliary structures in the out-coupling region is more harmonious, and the comprehensive visual experience of the user is improved.

[0044] In an embodiment, the number of the first auxiliary structures directly arranged on the surface of the waveguide substrate in the out-coupling region gradually decreases in the direction along which the image light propagates; the number of the out-coupling grating blocks in the out-coupling region gradually increases in the direction along which the image light propagates; or, the number of the second auxiliary structures in the out-coupling region gradually decreases in the direction along which the image light propagates; the number of the out-coupling grating blocks in the out-coupling region gradually increases in the direction along which the image light propagates.

[0045] For example, referring to Figure 6 , the waveguide substrate 110 of the diffractive optical waveguide includes the in-coupling region 120, the turning region 130 and the out-coupling region 140. It can be seen that the number of the A structure 1100 in the region close to the in-coupling region 120 of the turning region 130 is less than the number of the A structure 1100 in the region away from the in-coupling region 120 of the turning region 130, and the number of the A structure 1100 in the region close to the turning region 130 of the out-coupling region 140 is less than the number of the A structure 1100 in the region away from the turning region 130 of the out-coupling region 140.

[0046] In an embodiment, the out-coupling grating block includes a plurality of grating units, the size of the out-coupling grating block gradually increases in the direction along which the image light propagates, and the size of the out-coupling grating block is greater than the grating period of the grating unit and does not exceed 2 mm.

[0047] Specifically, the light leakage problem and the rainbow problem are solved in the present application by arranging auxiliary structures on the grating structure, but the auxiliary structures will affect the user's observation of the real world, so a small-area partitioning arrangement method is adopted for the grating structure to weaken the blocking effect of the auxiliary structures on the ambient light, and the human eye can still fully receive the ambient light through the region of the diffractive optical waveguide where no auxiliary structure is arranged. When a small-area partitioning arrangement is adopted for the grating structure, each grating block can include a plurality of grating units, and the size of the grating block should be greater than the grating period of the grating unit, so as not to affect the imaging light path of the image light in the diffractive optical waveguide. The size of the grating block gradually increases in the direction along which the image light propagates, the larger the diffractive area, the greater the diffractive efficiency, which helps to optimize the uniformity of the diffractive optical waveguide. The size of the grating block should not be too large, otherwise it will affect the user's observation of the real world, and the size of the grating block should generally not exceed 2 mm. The size change mode and size value range of the grating block are also applicable to the turning grating block in the turning region and the out-coupling grating block in the out-coupling region.

[0048] For example, referring to Figure 7The waveguide substrate 110 of the diffractive light waveguide includes the in-coupling region 120, the turning region 130 and the out-coupling region 140. It can be seen that the size of the A structure 1100 in the region close to the in-coupling region 120 is smaller than the size of the A structure 1100 in the region away from the in-coupling region 120, and the size of the A structure 1100 in the region close to the out-coupling region 140 is smaller than the size of the A structure 1100 in the region away from the out-coupling region 140.

[0049] In an embodiment, the interval between the out-coupling grating blocks is 0.3mm-4mm.

[0050] Specifically, the interval between the out-coupling grating blocks should not be too small, otherwise it will affect the user's observation of the real world. Generally, the interval between the out-coupling grating blocks should be greater than 0.3mm. The interval between the out-coupling grating blocks should not be too large, otherwise there will be a position in the window where the virtual content cannot be imaged. Therefore, the interval between the out-coupling grating blocks should be less than the pupil diameter of the human eye, and generally less than 4mm.

[0051] In the above embodiments, the first auxiliary structure and the second auxiliary structure are arranged on the waveguide substrate, directly on the surface of the waveguide substrate, or on the grating blocks on the surface of the waveguide substrate. According to another aspect of the present application, the first auxiliary structure and the second auxiliary structure can also be arranged on the protective sheet.

[0052] A diffractive light waveguide includes: a waveguide substrate, the surface of the waveguide substrate including a grating structure region and a non-grating structure region, the grating structure region including at least an in-coupling region and an out-coupling region; a plurality of discrete out-coupling grating blocks arranged in the out-coupling region; a protective sheet, the protective sheet being stacked on the side of the waveguide substrate away from the human eye, and a first auxiliary structure being arranged in the orthographic projection region of the out-coupling grating blocks on the surface of the protective sheet; the first auxiliary structure is 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; a plurality of discrete second auxiliary structures are arranged in the orthographic projection region of the non-grating structure region on the surface of the protective sheet, and the change trend of the transmittance of the grating structure region and the non-grating structure region in the visible light band is basically consistent.

[0053] In an embodiment, a plurality of first auxiliary structures are further arranged between the orthographic projection regions of the out-coupling grating blocks on the surface of the protective sheet, and the arrangement mode of the first auxiliary structures in the out-coupling region is basically the same as the arrangement mode of the second auxiliary structures in the non-grating structure region; or, a plurality of discrete second auxiliary structures are arranged between the orthographic projection regions of the out-coupling grating blocks on the surface of the protective sheet, and the overall arrangement mode of the first auxiliary structures and the second auxiliary structures in the out-coupling region is basically the same as the arrangement mode of the second auxiliary structures in the non-grating structure region.

[0054] It can be understood that the specific implementation (such as parameter setting, arrangement mode setting, etc.) in the foregoing embodiment about the first auxiliary structure and the second auxiliary structure arranged on the waveguide substrate is also applicable to the scenario that the first auxiliary structure and the second auxiliary structure are arranged on the protective sheet.

[0055] According to an aspect of the present application, a near-eye display device is also provided, which comprises a projection light machine and the diffractive optical waveguide according to any one of the foregoing. The projection light machine is used to emit image light. The near-eye display device can be specifically implemented as an augmented reality eye, an augmented reality helmet, or the like. The near-eye display device provided by the present application comprises the foregoing diffractive optical waveguide, and also has the advantages of the foregoing diffractive optical waveguide.

[0056] The foregoing detailed implementation does not constitute a limitation on the protection scope of the present application. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations, and replacements can be made according to design requirements and other factors. Any modification, equivalent replacement, and improvement within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A diffractive optical waveguide, characterized by, The application relates to a waveguide substrate, which comprises a grating structure region and a non-grating structure region on the surface of the waveguide substrate. The grating structure region comprises at least a coupling-in region and a coupling-out region; a plurality of discrete coupling-out grating blocks are arranged in the coupling-out region; a first auxiliary structure is arranged on the surface of the coupling-out grating block far away from the human eye; the first auxiliary structure is used for blocking ambient light from entering the coupling-out grating block to generate diffraction and for blocking image light from entering the external environment in the direction away from the human eye to generate leakage; A plurality of discrete second auxiliary structures are arranged in the non-grating structure region; the variation trends of the transmittances of the grating structure region and the non-grating structure region in the visible light waveband are consistent; The first auxiliary structure arranged directly on the surface of the waveguide substrate is arranged between the coupling-out grating blocks in the coupling-out region; the arrangement mode of the first auxiliary structure in the coupling-out region is the same as that of the second auxiliary structure in the non-grating structure region; or a plurality of discrete second auxiliary structures are arranged in the coupling-out region; the overall arrangement mode of the first auxiliary structure and the second auxiliary structure in the coupling-out region is the same as that of the second auxiliary structure in the non-grating structure region. The number of the first auxiliary structures arranged directly on the surface of the waveguide substrate in the coupling-out region gradually decreases along the direction of image light propagation; the number of the coupling-out grating blocks in the coupling-out region gradually increases along the direction of image light propagation; or the number of the second auxiliary structures in the coupling-out region gradually decreases along the direction of image light propagation; the number of the coupling-out grating blocks in the coupling-out region gradually increases along the direction of image light propagation.

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

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

4. The diffractive optical waveguide of claim 1, 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; wherein the period of the sub-wavelength periodic array is smaller than the grating period of the coupling-out grating block.

5. The diffractive optical waveguide of claim 4, wherein, The interval between the coupling-out grating blocks ranges from 0.3 mm to 4 mm.

6. The diffractive optical waveguide of claim 1, wherein, The application relates to a waveguide substrate, which comprises a grating structure region and a non-grating structure region on the surface of the waveguide substrate.

7. A diffractive optical waveguide, characterized by The grating structure region comprises at least a coupling-in region and a coupling-out region; a plurality of discrete coupling-out grating blocks are arranged in the coupling-out 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 area, and the variation trends of the transmittances of the grating structure area and the non-grating structure area in the visible light waveband are consistent; The surface of the protection sheet further includes first auxiliary structures between the areas of the normal projection of the out-coupling grating blocks, and the arrangement mode of the first auxiliary structures in the out-coupling area is the same as that of the second auxiliary structures in the non-grating structure area; or, the surface of the protection sheet includes discrete second auxiliary structures between the areas of the normal projection of the out-coupling grating blocks, and the overall arrangement mode of the first auxiliary structures and the second auxiliary structures in the out-coupling area is the same as that of the second auxiliary structures in the non-grating structure area.

8. A near-eye display device, comprising: The near-eye display device includes a projection light machine and the diffractive optical waveguide according to any one of claims 1-7.

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