Diffractive optical waveguide and near-eye display device

Abstract

This invention provides a diffractive waveguide and a near-eye display device. The diffractive waveguide includes a waveguide substrate, which includes at least one grating region and at least one extinction grating-sensitive region surrounding the grating region. The extinction grating-sensitive region includes multiple extinction grating-sensitive sub-regions, each of which is provided with a micro / nano structure. The structural parameters of the micro / nano structures within different extinction grating-sensitive sub-regions are different, and the difference in transmittance between any two adjacent extinction grating-sensitive sub-regions is less than a target value. This invention improves visual effect by setting an extinction grating-sensitive region around the grating region and incorporating micro / nano structures within it, thereby significantly reducing the grating sensitivity at the region boundaries.

Description

Technical Field

[0001] This utility model relates to the field of diffractive waveguide technology, and in particular to a diffractive waveguide and near-eye display device. Background Technology

[0002] Diffractive waveguide lenses alter the path of light through one or more gratings, ultimately directing the image into the eye. Because a diffractive waveguide includes both grating and non-grating regions, the diffraction effect of the grating region reduces its transmittance, resulting in a significant difference in transmittance compared to the non-grating region. In actual use, this difference in transmittance between the grating and non-grating regions manifests as abrupt changes in transmittance at the edges of the grating region, creating a grating-like sensation. Prolonged wear can cause a foreign body sensation in the eye. Utility Model Content

[0003] This invention provides a diffractive waveguide and a near-eye display device. By setting an anti-grating region around the grating area and setting micro-nano structures in the anti-grating region, the grating effect at the boundary of the region is greatly reduced, thereby improving the visual effect.

[0004] According to one aspect of the present invention, a diffractive waveguide is provided, comprising a waveguide substrate, the waveguide substrate comprising at least one grating region and at least one extinction grating region disposed around the grating region;

[0005] The extinction grating sensing region includes multiple extinction grating sensing sub-regions, each of which is provided with a micro-nano structure. The structural parameters of the micro-nano structures in different extinction grating sensing sub-regions are different, and the difference in transmittance between any two adjacent extinction grating sensing sub-regions is less than the target value.

[0006] Optionally, the plurality of extinction grating sensor regions include at least a first extinction grating sensor region and a second extinction grating sensor region. The grating region includes a grating with constant transmittance. The first extinction grating sensor region is disposed around the grating region, and the second extinction grating sensor region is disposed around the first extinction grating sensor region. The first extinction grating sensor region has a first width, and the second extinction grating sensor region has a second width.

[0007] Optionally, the grating region includes a gradient grating with gradually changing transmittance, and the extinction grating-sensitive region includes at least a first extinction grating-sensitive region surrounding the gradient grating. The gradient grating includes at least a first edge region and a second edge region with different transmittance and constant transmittance. The first extinction grating-sensitive region includes a first sub-region and a second sub-region with different structural parameters of the micro / nano structure. The first sub-region is arranged adjacent to the first edge region, and the second sub-region is arranged adjacent to the second edge region.

[0008] Optionally, the light transmittance of the first edge region is less than that of the second edge region. The number of extinction grating-sensor sub-regions in the extinction grating-sensor region adjacent to the first edge region is m1, and the number of extinction grating-sensor sub-regions in the extinction grating-sensor region adjacent to the second edge region is m2, where m1>m2, and both m1 and m2 are positive integers.

[0009] Optionally, the widths of the first sub-region and the second sub-region are different.

[0010] Optionally, the gradient grating further includes a third edge region with a gradient in transmittance, and the first extinction grating sensing region further includes a third sub-region with a gradient in the structural parameters of the micro / nano structure, the third sub-region being disposed adjacent to the third edge region.

[0011] Optionally, the extinction grating sensing region is arranged around the grating region, and the transmittance of multiple extinction grating sensing sub-regions with micro-nano structures increases in the direction from the grating region outward toward the extinction grating sensing region.

[0012] Optionally, the width of the extinction grating sensing sub-region satisfies:

[0013] ;

[0014] in, L represents the distance between the human eye and the grating, θ represents the smallest field of view that the human eye can distinguish, λ represents the wavelength of light, and D represents the diameter of the human eye pupil.

[0015] Optionally, the micro / nano structure includes a grating, and the structural parameters include at least one of the following: grating duty cycle, grating height, and grating shape.

[0016] Optionally, the grating has a duty cycle of 20-80% and a grating height of 10nm-300nm.

[0017] Optionally, it may also include an anti-reflection grating region surrounding the anti-reflection grating region, wherein the anti-reflection grating region is provided with an anti-reflection grating.

[0018] Optionally, the transmittance of the anti-reflection grating is greater than or equal to 99%, and the period d1 of the anti-reflection grating satisfies:

[0019] ;

[0020] Where λ represents the wavelength of light and n represents the refractive index of the diffracting waveguide substrate.

[0021] According to another aspect of the present invention, a near-eye display device is provided, comprising any of the diffractive waveguides described above.

[0022] The diffractive waveguide provided in this embodiment includes a waveguide substrate, which includes at least one grating region and at least one extinction grating-sensitive region surrounding the grating region. By setting the extinction grating-sensitive region around the grating region, the extinction grating-sensitive region includes multiple extinction grating-sensitive sub-regions, each of which is provided with a micro / nano structure. The structural parameters of the micro / nano structures in different extinction grating-sensitive sub-regions are different, so that the difference in transmittance between any two adjacent extinction grating-sensitive sub-regions is less than the target value, thereby eliminating the abrupt change in transmittance at the edge of the grating region, reducing the foreign body sensation during long-term wear, improving the visual effect, and enhancing the user experience.

[0023] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of this utility model, nor is it intended to limit the scope of this utility model. Other features of this utility model will become readily apparent from the following description. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a top view schematic diagram of a diffractive optical waveguide in the prior art;

[0026] Figure 2 For along Figure 1 Transmittance curves of different regions along the a-a' section line;

[0027] Figure 3 This is a top view schematic diagram of another diffractive waveguide in the prior art;

[0028] Figure 4 For along Figure 3 Transmittance curves for different regions along the b-b' section line;

[0029] Figure 5 A top view of a diffractive waveguide provided for an embodiment of this utility model;

[0030] Figure 6 This is a schematic diagram showing the relationship between the grating duty cycle and transmittance.

[0031] Figure 7 This is a schematic diagram showing the relationship between grating height and transmittance.

[0032] Figure 8 A top view schematic diagram of another diffractive waveguide provided in an embodiment of this utility model;

[0033] Figure 9 A top view schematic diagram of another diffractive waveguide provided in an embodiment of this utility model;

[0034] Figure 10 A top view schematic diagram of another diffractive waveguide provided in an embodiment of this utility model;

[0035] Figure 11 This is a schematic diagram of the transmittance curve of a diffractive waveguide. Detailed Implementation

[0036] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present invention.

[0037] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this utility model 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 the utility model 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.

[0038] Due to its function of diffraction, the diffraction grating region of a diffraction waveguide diffracts light. When facing ambient light, the diffraction grating will diffract the light, causing its transmittance to decrease. As a result, the edge of the grating region cannot be ignored, and there is a grating effect.

[0039] For non-gradient gratings, the overall transmittance of the grating area is low, and the grating effect is quite pronounced at the edges of the entire grating area. For example, Figure 1 This is a top view schematic diagram of a diffractive waveguide in the prior art, for reference. Figure 1 The diffractive waveguide includes a grating region 1 and a non-grating region 2. The grating region 1 includes a non-gradient grating. The transmittance of each region of the non-gradient grating is constant and less than that of the non-grating region 2. Therefore, the grating region 1 has a strong grating effect around its perimeter. Figure 2 For along Figure 1 Transmittance curves of different regions along the a-a' section line (see reference). Figure 2 Because the light transmittance of the grating area is less than that of the non-grating area, there is a strong grating effect at the boundary between the grating area and the non-grating area, which affects the visual effect.

[0040] For gradient gratings, the transmittance of the grating region gradually increases from low to high. The grating effect is relatively mild in the high-transmittance areas and more pronounced in the low-transmittance areas. For example, Figure 3 This is a top view schematic diagram of another diffractive waveguide in the prior art, for reference. Figure 3 The diffractive waveguide includes a grating region 1 and a non-grating region 2, wherein the grating region 1 includes a gradient grating. Figure 3 The diagram schematically shows that the transmittance of grating region 1 gradually decreases from left to right. The non-grating area to the left of grating region 1 has a slight grating effect, while the non-grating area to the right of grating region 1 has a severe grating effect. Figure 4 For along Figure 3 Transmittance curves for different regions along the b-b' section line (see reference). Figure 4 Because the light transmittance of the grating area is less than that of the non-grating area, there is a grating effect at the boundary between the grating area and the non-grating area, and the grating effect on the right side is stronger than that on the left side, which affects the visual effect.

[0041] To address the aforementioned issues, this utility model provides a diffractive waveguide comprising a waveguide substrate. The waveguide substrate includes at least one grating region and at least one extinction grating sensing region surrounding the grating region. The extinction grating sensing region comprises multiple extinction grating sensing sub-regions, each of which is provided with a micro / nano structure. The structural parameters of the micro / nano structures within different extinction grating sensing sub-regions are different, and the difference in transmittance between any two adjacent extinction grating sensing sub-regions is less than a target value.

[0042] For example, Figure 5 A top view schematic diagram of a diffractive waveguide provided for an embodiment of this utility model, with reference to... Figure 5 Taking a grating region as an example, the diffractive waveguide includes a grating region 10 and an extinction grating-sensitive region 20 surrounding the grating region 10; wherein, the extinction grating-sensitive region 20 includes multiple extinction grating-sensitive sub-regions 21 ( Figure 5 The diagram schematically shows three extinction grating-sensitive regions 21, which are not intended to limit the embodiments of this utility model. Each extinction grating-sensitive region 21 is provided with a corresponding micro / nano structure. Figure 5 (Not shown) The structural parameters of the micro-nano structures in different extinction grating sensor regions 21 are different, and the difference in transmittance between any two adjacent extinction grating sensor regions 21 is less than the target value.

[0043] The grating region 10 may include functional grating regions such as an input grating region, a transition grating region, and an output grating region. In specific implementations, the input grating region is usually corresponding to the optomechanical system but is invisible to the human eye. Therefore, a matting grating-sensitivity region may not be set around the input grating region, but a matting grating-sensitivity region may be set around the transition grating region and / or the output grating region. In specific implementations, the target value can be set according to actual conditions. For example, depending on the differences between the environment and the individual, the target value can be selected between 1% and 5%. For instance, the same person may be able to distinguish a 1% difference in transmittance in a bright environment and only a 5% difference in transmittance in a dark environment. In this embodiment, 1% is taken as the distinguishable transmittance difference, i.e., the target value can be set to 1%. The transmittance difference between any two adjacent matting grating-sensitivity sub-regions is designed to be less than 1%, replacing the boundary of a strong grating-sensitivity region with multiple long-distance boundaries without grating-sensitivity. The human eye will not perceive any foreign object sensation, thereby improving the visual effect and enhancing the user experience.

[0044] Optionally, the micro / nano structure includes a grating, and the structural parameters include at least one of the following: grating duty cycle, grating height, and grating shape.

[0045] When a grating is used in a micro / nano structure, the grating transmittance can be adjusted in the following ways:

[0046] 1. Adjust the grating duty cycle design at the same grating height. The grating duty cycle can be modulated from 20% to 80% to obtain the expected transmittance. Figure 6 This is a schematic diagram showing the relationship between the grating duty cycle and transmittance. Figure 6 It allows for designs with different light transmittance.

[0047] 2. Adjust the grating height design under the same grating duty cycle. The grating height can be modulated from 10nm to 300nm to obtain the expected transmittance. Figure 7 This is a schematic diagram showing the relationship between grating height and transmittance. Figure 7 It is also possible to achieve designs with different light transmittance.

[0048] 3. The grating duty cycle and grating height can be modulated simultaneously. The optional grating duty cycle is 20~80% and the grating height is 10nm~300nm.

[0049] 4. Under the same grating height and grating duty cycle, the shape of the grating can be adjusted by means of: changing the projection pattern, such as changing from a diamond grating to an elliptical grating, or a straight grating to a blazed grating; and designing the projection pattern with cutouts.

[0050] The optical waveguide capable of eliminating grating-induced diffraction provided in this embodiment can be designed through the following steps:

[0051] S1. Determine the initial structure of the diffractive waveguide, and determine the transmittance of the grating region and the non-grating region of the diffractive waveguide based on the initial structure.

[0052] In this step, by determining the initial structure of the diffractive waveguide, the transmittance of each region of the diffractive waveguide can be obtained, for example, for Figure 1 The structure shown has a constant transmittance in the grating region. Figure 3 The structure shown has a gradually changing transmittance in the grating region.

[0053] S2. Set at least a portion of the non-grating region adjacent to the grating region as the grating-sensing region, and set micro-nano structures in the grating-sensing region according to the transmittance of the non-grating region and the transmittance difference between the grating region and the non-grating region.

[0054] The extinction grating sensing region includes multiple extinction grating sensing sub-regions. The structural parameters of the micro-nano structures in different extinction grating sub-regions are different, and the difference in transmittance between any two adjacent extinction grating sensing sub-regions is less than the target value.

[0055] Specifically, S2 includes:

[0056] S21. Based on the transmittance of the non-grating region and the transmittance difference between the grating region and the non-grating region, determine the structural parameters of the first micro-nano structure set in the first extinction grating sensing sub-region on the side of the extinction grating sensing region close to the grating region, and ensure that the transmittance difference between the first extinction grating sensing sub-region and the grating region is less than the target value after the first micro-nano structure is set.

[0057] S22. Set the first micro-nano structure in the first extinction grating sensor region.

[0058] S23. Based on the transmittance difference between the first extinction grating sensor region and the non-grating region and the transmittance of the non-grating region, determine the structural parameters of the second micro / nano structure set in the second extinction grating sensor region on the side of the extinction grating sensor region close to the first extinction grating sensor region, so that the transmittance difference between the second extinction grating sensor region and the first extinction grating sensor region is less than the target value after the second micro / nano structure is set.

[0059] S24. A second micro / nano structure is set in the second extinction grating sensor region.

[0060] S25. Continue to set micro-nano structures with corresponding structural parameters in the extinction grating-sensor region outside the second extinction grating-sensor region in the same way until the transmittance difference between any two adjacent extinction grating-sensor regions is less than the target value, thereby eliminating the grating sensation.

[0061] Through the above steps, the region is divided outward from the grating area (i.e., the eyebox field of view grating area) according to a certain pattern. The micro-nano structure (grating) parameters are designed for each region from the inside out, so that the grating effect at the boundary of the region is greatly reduced. The design satisfies the following formula:

[0062] (1)

[0063] (2)

[0064] (3)

[0065] In formula (1), L represents the distance between the human eye and the grating, θ is the smallest resolvable field of view for the human eye, and d represents the resolvable grating width for the human eye when the grating is L away from the human eye. Preferably, λ represents the wavelength of light, and D represents the diameter of the human eye pupil, which commonly ranges from 2mm to 4mm. When θ is less than this range, d is less than the length that the human eye can distinguish.

[0066] Formula (2) is the formula for calculating transmittance without a grating. When light is incident from a medium with a refractive index of n1 to a medium with a refractive index of n2, reflection will occur at the interface, which will reduce the transmittance.

[0067] Formula (3) is the method for calculating the number of regions, T max T represents the transmittance at the location without a grating. min This indicates the lowest transmittance at the location where the grating is located. This represents the difference in light transmittance that the human eye can distinguish. Due to differences in environment and individual circumstances, this value typically ranges from 1% to 5%, similar to how a person can distinguish differences in transmittance in a bright environment. Materials that, in low-light environments, can only distinguish differences in transmittance. The material. In this embodiment, 1% is used as the distinguishable transmittance difference.

[0068] When satisfied , At that time, the edge of the grating with a strong grating effect will be replaced by multiple grating areas with a weak grating effect. Since the human eye has a small focusing range, only one grating boundary with a weak grating effect can be seen at the same time. This design can slightly reduce the grating effect.

[0069] When satisfied , At this time, the human eye cannot perceive the width of the area. The optimization of the grating effect is to optimize the sudden decrease in transmittance into a continuous decrease over a certain distance, thereby reducing the sharpness of the grating effect and reducing the foreign object sensation perceived by the human eye.

[0070] When satisfied , At this point, the human eye cannot perceive the difference in light transmittance at the boundary of the area. The optimization at this point is to replace the boundary with a strong grating effect with multiple intersections of a longer distance without a grating effect, so that the human eye will not feel the foreign object.

[0071] When satisfied , At this time, the human eye cannot perceive the width of the area, nor can it perceive the difference in light transmittance at the boundary of the area, thus ensuring the elimination of the foreign object sensation in two dimensions.

[0072] In one embodiment, the grating parameters can be gradually varied from the grating area outwards, and the grating period is consistent with the grating period of the functional area, so that the grating appears as a whole and the transmittance difference between any two points is <<1%, which is imperceptible to the human eye.

[0073] Continue to refer to Figure 5 Optionally, the plurality of extinction grating sensor regions include at least a first extinction grating sensor region 21a and a second extinction grating sensor region 21b. The grating region 10 includes a grating with constant transmittance. The first extinction grating sensor region 21a is disposed around the grating region 10, and the second extinction grating sensor region 21b is disposed around the first extinction grating sensor region 21a. The first extinction grating sensor region 21a has a first width a1, and the second extinction grating sensor region 21b has a second width a2.

[0074] In this embodiment, the grating region 10 includes a grating with constant transmittance. The transmittance difference around the grating is the same, that is, the grating sense is the same. Therefore, multiple grating sense sub-regions can be uniformly designed, for example, a1=a2. In other embodiments, different widths of different grating sense sub-regions can also be designed. For example, from the inside to the outside, the width of the grating sense sub-regions gradually decreases or gradually increases. In specific implementation, it can be designed according to the actual situation, as long as the effect of grating sense can be achieved.

[0075] Figure 8 A top view schematic diagram of another diffractive waveguide provided in an embodiment of this utility model, with reference to... Figure 8 Optionally, the grating region 10 includes a gradient grating with gradually changing transmittance. The extinction grating sensing region includes at least a first extinction grating sensing region 210 surrounding the gradient grating. The gradient grating includes at least a first edge region 101 and a second edge region 102 with different transmittance and constant transmittance. The first extinction grating sensing region 210 includes a first sub-region 211 and a second sub-region 212 with different structural parameters of the micro / nano structure. The first sub-region 211 is arranged adjacent to the first edge region 101, and the second sub-region 212 is arranged adjacent to the second edge region 102.

[0076] Understandably, when the grating region 10 contains a gradient grating with gradually changing transmittance, for example, the right edge (first edge region 101) has lower transmittance and a stronger grating effect, while the left edge (second edge region 102) has higher transmittance and a weaker grating effect. Therefore, when designing the matte grating effect sub-region, [the following applies]. Figure 5 Since the uniformly designed extinction grating-sensitive sub-regions differ, it is necessary to separately set a first sub-region 211 and a second sub-region 212 with different structural parameters of the micro-nano structure in the first extinction grating-sensitive sub-region 210 to achieve grating-sensitivity elimination in different regions. The design method is similar to that of the aforementioned embodiments. Optionally, the widths of the first sub-region 211 and the second sub-region 212 are different, and their specific widths can be selected according to actual conditions. This embodiment of the present invention does not limit this.

[0077] Continue to refer to Figure 8 Optionally, the gradient grating also includes a third edge region 103 with a gradient in transmittance, and the first extinction grating sensing region 210 also includes a third sub-region 213 with a gradient in the structural parameters of the micro-nano structure, and the third sub-region 213 is arranged adjacent to the third edge region 103.

[0078] The transmittance of the third edge region 103 is gradually changed, meaning that the transmittance is different at different positions. The transmittance of the left end of the third edge region 103 is the same as that of the first edge region 101, and the transmittance of the right end of the third edge region 103 is the same as that of the second edge region 102. In order to eliminate the grating effect around the third edge region 103, the structural parameters of the micro-nano structure in the third sub-region 213 need to be gradually changed, that is, the transmittance of the third sub-region 213 also gradually changes, so as to match the transmittance of the third edge region 103 and achieve the elimination of the grating effect.

[0079] Optionally, the transmittance of the first edge region is less than that of the second edge region. The number of extinction grating-sensor regions in the extinction grating-sensor region adjacent to the first edge region is m1, and the number of extinction grating-sensor regions in the extinction grating-sensor region adjacent to the second edge region is m2, where m1>m2, and both m1 and m2 are positive integers.

[0080] When the light transmittance of the first edge region is less than that of the second edge region, the grating effect outside the first edge region is stronger than that of the second edge region. Therefore, to eliminate the grating effect, more grating effect sub-regions need to be set in the grating effect area adjacent to the first edge region, i.e., m1>m2.

[0081] For example, taking m1=3 and m2=1 as an example, Figure 9 This is a top view schematic diagram of another diffractive waveguide provided in an embodiment of the present invention, with reference to... Figure 9The transmittance of the first edge region 101 is less than that of the second edge region 102. The number of grating-sensing sub-regions in the grating-sensing region adjacent to the first edge region 101 is 3, and the number of grating-sensing sub-regions in the grating-sensing region adjacent to the second edge region 102 is 1, so as to achieve grating-sensing elimination with gradient grating.

[0082] In one embodiment, optionally, the extinction grating sensing region is arranged around the grating region, and the transmittance of multiple extinction grating sensing sub-regions with micro-nano structures increases in the direction from the grating region outward toward the extinction grating sensing region.

[0083] Since the transmittance of the grating area is usually less than that of the non-grating area, the transmittance is set to increase gradually from the grating area outward toward the matting grating area, so that the transmittance of the matting grating area changes slowly and achieves a better matting effect.

[0084] In another embodiment, optionally, the width of the extinction grating sensing region satisfies:

[0085] ;

[0086] in, L represents the distance between the human eye and the grating, θ represents the smallest field of view that the human eye can distinguish, λ represents the wavelength of light, and D represents the diameter of the human eye pupil.

[0087] when Since the human eye cannot distinguish the width of each extinction grating sensor region, in this case, the transmittance difference between two adjacent extinction grating sensor regions can be appropriately increased, that is, the transmittance difference requirement is reduced, thus reducing the difficulty of the process.

[0088] Figure 10 This is a top view schematic diagram of another diffractive waveguide provided in an embodiment of the present invention, with reference to... Figure 10 Optionally, the diffractive waveguide may also include an anti-reflection grating region 30 surrounding the anti-reflection grating region 20, wherein the anti-reflection grating region 30 is provided with an anti-reflection grating.

[0089] Optionally, the transmittance of the anti-reflection grating is greater than or equal to 99%, and the period d1 of the anti-reflection grating satisfies:

[0090] ;

[0091] Where λ represents the wavelength of light and n represents the refractive index of the diffracting waveguide substrate.

[0092] Since the highest transmittance achievable in the functional grating region of a diffractive waveguide is approximately equal to the transmittance in the grating-free region, an anti-reflection grating can be added to further enhance transmittance after eliminating grating artifacts in the functional grating region. An anti-reflection grating is placed outside the grating artifact elimination region to improve the transmittance of the waveguide sheet. For example, Figure 11 This is a schematic diagram of the transmittance curve of a diffractive waveguide. After setting an anti-transmittance grating, the transmittance can be increased to 99%.

[0093] The width of the anti-reflective grating area is determined by the width and number of zones, and its width can vary in different directions. When there is no anti-reflective grating area, the light transmittance at the outer edge of the anti-reflective grating area is the same as the light transmittance of the lens. When there is an anti-reflective grating area, the light transmittance of the anti-reflective grating area is the same at the intersection with the anti-reflective grating area.

[0094] The eyebox field of view area is calculated using the following formula:

[0095] ;

[0096] ;

[0097] Where W represents the width of the eyebox field of view grating area in the x-direction, w represents the width of the eyebox in the x-direction, L represents the distance between the human eye and the grating, and FOVx represents the field of view angle in the x-direction. This represents the angle between the image position and the field of view in the horizontal direction. D1 represents the width of the eyebox field of view raster area in the y direction, d2 represents the width of the eyebox in the y direction, and FOVy represents the field of view angle in the y direction. It indicates the angle between the position of the image and the field of view in the vertical direction.

[0098] This utility model embodiment also provides a near-eye display device, including any of the diffractive waveguides provided in the above embodiments.

[0099] Since the near-eye display device provided in this embodiment includes any of the diffractive waveguides provided in the above embodiments, and has the same or corresponding technical effects as the diffractive waveguide, it will not be described in detail here.

[0100] The specific embodiments described above do not constitute a limitation on the scope of protection of this utility model. 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 utility model should be included within the scope of protection of this utility model.

Claims

1. A diffractive optical waveguide, characterized in that, The waveguide substrate includes at least one grating region and at least one grating-sensitive region surrounding the grating region. The extinction grating sensing region includes multiple extinction grating sensing sub-regions, each of which is provided with a micro-nano structure. The structural parameters of the micro-nano structures in different extinction grating sensing sub-regions are different, and the difference in transmittance between any two adjacent extinction grating sensing sub-regions is less than the target value.

2. The diffractive waveguide according to claim 1, characterized in that, The plurality of said extinction grating sensor regions include at least a first extinction grating sensor region and a second extinction grating sensor region. The grating region includes a grating with constant transmittance. The first extinction grating sensor region is disposed around the grating region, and the second extinction grating sensor region is disposed around the first extinction grating sensor region. The first extinction grating sensor region has a first width, and the second extinction grating sensor region has a second width.

3. The diffractive waveguide according to claim 1, characterized in that, The grating region includes a gradient grating with gradually changing transmittance. The extinction grating sensor region includes at least a first extinction grating sensor region surrounding the gradient grating. The gradient grating includes at least a first edge region and a second edge region with different transmittance and constant transmittance. The first extinction grating sensor region includes a first sub-region and a second sub-region with different structural parameters of the micro / nano structure. The first sub-region is adjacent to the first edge region, and the second sub-region is adjacent to the second edge region.

4. The diffractive waveguide according to claim 3, characterized in that, The light transmittance of the first edge region is less than that of the second edge region. The number of extinction grating-sensor sub-regions in the extinction grating-sensor region adjacent to the first edge region is m1, and the number of extinction grating-sensor sub-regions in the extinction grating-sensor region adjacent to the second edge region is m2, where m1>m2, and both m1 and m2 are positive integers.

5. The diffractive waveguide according to claim 3, characterized in that, The widths of the first sub-region and the second sub-region are different.

6. The diffractive waveguide according to claim 3, characterized in that, The gradient grating further includes a third edge region with a gradient in transmittance, and the first extinction grating sensing region further includes a third sub-region with a gradient in the structural parameters of the micro / nano structure, and the third sub-region is arranged adjacent to the third edge region.

7. The diffractive waveguide according to claim 1, characterized in that, The extinction grating sensing region is arranged around the grating region, and the transmittance of multiple extinction grating sensing sub-regions with micro-nano structures increases in the direction from the grating region outward to the extinction grating sensing region.

8. The diffractive waveguide according to claim 1, characterized in that, The width of the extinction grating-sensitive sub-region satisfies: ； in, L represents the distance between the human eye and the grating, θ represents the smallest field of view that the human eye can distinguish, λ represents the wavelength of light, and D represents the diameter of the human pupil.

9. The diffractive waveguide according to claim 1, characterized in that, The micro / nano structure includes a grating, and the structural parameters include at least one of the following: grating duty cycle, grating height, and grating shape.

10. The diffractive waveguide according to claim 9, characterized in that, The grating has a duty cycle of 20-80% and a height of 10nm-300nm.

11. The diffractive waveguide according to claim 1, characterized in that, It also includes an anti-reflection grating region surrounding the anti-reflection grating region, wherein the anti-reflection grating region is provided with an anti-reflection grating.

12. The diffractive waveguide according to claim 11, characterized in that, The transmittance of the anti-reflection grating is greater than or equal to 99%, and the period d1 of the anti-reflection grating satisfies: ； Where λ represents the wavelength of light and n represents the refractive index of the diffracting waveguide substrate.

13. A near-eye display device, characterized in that, Includes the diffractive waveguide as described in any one of claims 1 to 12.

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