Diffraction optical structures and optical display devices

Abstract

Conventional one-dimensional gratings modulate diffraction efficiency by adjusting parameters such as line width, depth, and sidewall angle, but they struggle to meet the requirements for overall efficiency and uniformity of the diffractive optical structure. [Solution] Disclosed are a diffractive optical structure and an optical display device, wherein the diffractive optical structure includes a substrate and a lattice structure installed on the substrate, the lattice structure includes a plurality of lattice units periodically tiled on the surface of the substrate along a first direction and a second direction, the lattice structure has a first lattice modulation direction and a second lattice modulation direction, the first lattice modulation direction is perpendicular to the first direction, and the amount of lattice modulation in the first lattice modulation direction is △E, where △E = 1 / (P3*sinθ), where P3 is the period of the second direction of the lattice structure and θ is the angle between the first direction and the second direction, and the light rays of the lattice structure undergo diffraction behavior only in the first lattice modulation direction and not in the second lattice modulation direction.

Description

Technical Field

[0001] This application belongs to the technical field of augmented reality (AR). Specifically, this application relates to diffractive optical structures and optical display devices.

Background Art

[0002] Augmented Reality (AR) technology, as a new human-machine interaction method, shows great application potential in fields such as education, entertainment, and industry. As one of the mainstream technical solutions to realize AR technology, the diffractive optical structure uses the total reflection effect of a transparent substrate to non-destructively conduct an image to the wearer's eyes, realizing the superposition and fusion of the real world and the virtual image. In the diffractive optical structure, the grating plays an important role and is used to control the processes of light coupling, propagation, and output coupling. The conventional one-dimensional grating modulates the diffraction efficiency of the grating by adjusting parameters such as line width, depth, and sidewall angle. However, it is limited by the difficulty and maturity of the existing processes. This modulation method is often costly and has limited effectiveness, and it is difficult to meet the high requirements for the overall efficiency and uniformity of the diffractive optical structure.

Summary of the Invention

Problems to be Solved by the Invention

[0003] The object of this application is to provide technical solutions for diffractive optical structures and optical display devices.

Means for Solving the Problems

[0004] According to a first aspect of this application, this application provides a diffractive optical structure including a substrate and a grating structure disposed on the substrate. The grating structure includes a plurality of grating units periodically tiled on the surface of the substrate along a first direction and a second direction. The grid structure has a first grid modulation direction and a second grid modulation direction, the first grid modulation direction is perpendicular to the first direction, and the amount of grid modulation in the first grid modulation direction is △E, where △E = 1 / (P3*sinθ), where P3 is the period of the second direction of the grid structure, and θ is the angle between the first direction and the second direction. Light rays incident on the lattice structure undergo diffraction behavior only in the first lattice modulation direction and do not undergo diffraction behavior in the second lattice modulation direction.

[0005] Selectively, the period of the lattice structure in the first direction is P2, and P2 <P3である。

[0006] Selectively, the angle θ between the first direction and the second direction is 0 < θ ≤ 90°.

[0007] Selectively, the diffractive optical structure includes an input coupled grating, an output coupled grating, and a refractive grating. At least one of the input coupled grid, the output coupled grid, and the refractive grid includes at least a portion of the grid structure.

[0008] Selectively, at least a portion of the refractive grating is the grating structure, or The input coupling grid and the refractive grid are the grid structure, or The input coupled grid, a portion of the output coupled grid, and the refractive grid are the grid structure.

[0009] Selectively, the period P2 in the first direction of the lattice structure is < 300 nm, and the light ray undergoes primary diffraction behavior only in the first lattice modulation direction after diffraction of the lattice structure, and does not undergo diffraction behavior in the second lattice modulation direction.

[0010] Selectively, the input coupling grating employs the grating structure, and when the grating structure satisfies the following conditions, light rays incident in the FOV in at least some directions do not undergo diffraction behavior in the second grating modulation direction after being modulated by the grating structure. JPEG2026070474000002.jpg2473 Here, JPEG2026070474000003.jpg98 is the grid modulation amount at any point within the FOV of the grid structure, n2 is the refractive index of the substrate, JPEG2026070474000004.jpg1916 represents the second grid modulation direction.

[0011] Selectively, the input coupling grating employs the grating structure, and when the grating structure satisfies the following conditions, light rays incident in the FOV in at least some directions are modulated by the grating structure and then undergo primary diffraction only in the first grating modulation direction. JPEG2026070474000005.jpg24109 Here, JPEG2026070474000006.jpg88 is the grid modulation amount at any point within the FOV of the grid structure, n2 is the refractive index of the substrate, JPEG2026070474000007.jpg2016 is the first grid modulation direction, JPEG2026070474000008.jpg1915 represents the second grid modulation direction.

[0012] Selectively, the refractive grating or the output coupling grating employs the grating structure, and the grating structure satisfies the following conditions, so that light rays incident within the FOV or in at least some directions do not undergo diffraction behavior in the second grating modulation direction after being modulated by the grating structure. JPEG2026070474000009.jpg2487 Here, JPEG2026070474000010.jpg109 is the grid modulation amount at any point within the FOV of the grid structure, JPEG2026070474000011.jpg99 is the grid modulation amount of the input coupled grid, n2 is the refractive index of the substrate, JPEG2026070474000012.jpg1915 represents the second grid modulation direction.

[0013] Selectively, the refractive grating or the output coupling grating employs the grating structure, and the grating structure satisfies the following conditions, so that light rays incident in the FOV in at least some directions are modulated by the grating structure and then undergo primary diffraction only in the first grating modulation direction. JPEG2026070474000013.jpg22115 Here, JPEG2026070474000014.jpg99 is the grid modulation amount at any point within the FOV of the grid structure, JPEG2026070474000015.jpg910 is the grid modulation amount of the input coupled grid, n2 is the refractive index of the substrate, JPEG2026070474000016.jpg1915 is the first grid modulation direction, JPEG2026070474000017.jpg1714 represents the second grid modulation direction.

[0014] Selectively, the output coupling grating employs the grating structure, and if the grating structure satisfies at least one of the following conditions, then light rays incident in the FOV in at least some directions do not undergo diffraction behavior in the second grating modulation direction after being modulated by the grating structure. JPEG2026070474000018.jpg67100 Here, JPEG2026070474000019.jpg98 is the grid modulation amount at any point within the FOV of the grid structure, JPEG2026070474000020.jpg1010 is the grid modulation amount of the input coupled grid, JPEG2026070474000021.jpg1012 is the grid modulation amount of the refractive grating, TIFF2026070474000022.tif79 is the lattice modulation amount of the output coupling grating, n2 is the refractive index of the substrate, JPEG2026070474000023.jpg1815 is the first lattice modulation direction, JPEG2026070474000024.jpg1815 is the second lattice modulation direction.

[0015] Optionally, the output coupling grating adopts the lattice structure, and when the lattice structure satisfies at least one of the following conditions, the light rays in at least some directions incident within the FOV range are modulated by the lattice structure and then generate only first-order diffraction in the first lattice modulation direction, JPEG2026070474000025.jpg64137 Here, JPEG2026070474000026.jpg99 is the lattice modulation amount at any point within the FOV of the lattice structure, JPEG2026070474000027.jpg1111 is the lattice modulation amount of the input coupling grating, JPEG2026070474000028.jpg1112 is the lattice modulation amount of the refractive grating, TIFF2026070474000029.tif89 is the lattice modulation amount of the output coupling grating, n2 is the refractive index of the substrate, JPEG2026070474000030.jpg1815 is the first lattice modulation direction, JPEG2026070474000031.jpg1814 is the second lattice modulation direction.

[0016] Optionally, the lattice unit is a columnar structure installed on the surface of the substrate, and the line width occupancy ratio of the lattice unit in the first direction is DC, where 0 < DC < 1.

[0017] Selectively, the grid unit is a perforated structure installed on the surface of the substrate, and the line width occupancy ratio of the grid unit in the first direction is DC, 0 <DC<1である。

[0018] Selectively, the grid unit includes one or more sub-grids.

[0019] Selectively, the diffractive optical structure is an optical waveguide device.

[0020] According to a second aspect of the present application, an embodiment of the present application provides an optical display device, the optical display device is Image source and, This includes the diffractive optical structure described in the first embodiment. [Effects of the Invention]

[0021] One beneficial effect of the embodiment of the present application is as follows: This invention innovatively proposes a specially designed lattice structure to address the challenges of existing diffractive optics technologies, such as low modulation efficiency, high process costs, and difficulty in comprehensively optimizing overall efficiency and uniformity of one-dimensional lattices. The lattice structure design in this invention maintains the diffraction mode of the one-dimensional lattice while eliminating the complex modulation requirements for lattice depth and sidewall angle. By relying on existing low-cost and mature mass production processes and flexibly adjusting key parameters on the one-dimensional side of a two-dimensional lattice, it enables free modulation of the lattice diffraction efficiency over a wide range. The technical solution provided by this invention significantly improves the overall optical efficiency and uniformity of diffractive optics structures, including brightness, color, and eyebox uniformity, providing a better optical design option for augmented reality display technology.

[0022] Other features and advantages of the present invention will become apparent by describing in detail, with reference to the drawings, exemplary embodiments of the present invention. [Brief explanation of the drawing]

[0023] The drawings incorporated into the specification and constituting part of the specification are used to illustrate embodiments of the present application and to explain the principles of the present application together with their descriptions. [Figure 1] This is one of the schematic diagrams of the diffractive optical structure according to the embodiment of the present invention. [Figure 2] This is a schematic diagram of the diffractive optical structure according to the embodiment of the present invention. [Figure 3] This is a schematic diagram of the diffractive optical structure according to the embodiment of the present invention. [Figure 4] This is the fourth schematic diagram of the diffractive optical structure according to the embodiment of the present invention. [Figure 5] This is a schematic diagram of a typical one-dimensional lattice structure. [Figure 6] This is a schematic diagram of a typical two-dimensional lattice structure. [Figure 7] This is one of the schematic diagrams of a lattice structure according to an embodiment of the present invention. [Figure 8] This is a conventional K-vector diagram of a one-dimensional grid. [Figure 9] This is one of the K vector diagrams of a lattice structure according to an embodiment of the present application. [Figure 10] This is the second vector diagram of the lattice structure according to the embodiment of the present application. [Figure 11] This is a schematic diagram of the lattice structure according to the embodiment of the present invention. [Figure 12] This is a schematic diagram of the lattice structure according to the embodiment of the present invention. [Figure 13] This is the fourth schematic diagram of the lattice structure according to the embodiment of the present invention. [Figure 14] This is a side view of a lattice structure according to an embodiment of the present invention. [Figure 15] This is a side view of the lattice structure according to an embodiment of the present invention. [Figure 16] This is a side view of the lattice structure according to the embodiment of the present application. [Figure 17] This is the fourth side view of the lattice structure according to the embodiment of the present application. [Figure 18] Figure 15 is a plan view of the grid structure shown. [Figure 19]This is a schematic diagram of the lattice structure according to the embodiment of the present invention. [Figure 20] This is a schematic diagram of the lattice structure according to the embodiment of the present invention. [Figure 21] Figure 20 shows the diffraction efficiency diagram of the lattice structure. [Figure 22] This is the fourth schematic diagram of the lattice structure according to the embodiment of the present invention. [Figure 23] Figure 22 shows the diffraction efficiency diagram of the lattice structure. [Figure 24] This is a diffraction efficiency diagram within the field of view of a conventional one-dimensional lattice. [Figure 25] This is a diffraction efficiency diagram within the field of view of the lattice structure according to the present invention. [Figure 26] This is a diffraction efficiency diagram within the field of view for a different lattice structure according to the present invention. [Modes for carrying out the invention]

[0024] Now, various exemplary embodiments of the present application will be described in detail with reference to the attached drawings. It should be noted that the relative arrangements of the components and steps, numerical formulas, and numerical values ​​described in these embodiments do not limit the scope of the present application unless otherwise specified.

[0025] In the following description, at least one exemplary embodiment is for illustrative purposes only and is not in any way intended to limit the present application or its application or use.

[0026] Techniques, methods, and apparatus known to those skilled in the art will not be discussed in detail, but where appropriate, such techniques, methods, and apparatus should be considered part of the specification.

[0027] In all the examples presented and discussed herein, any specific values ​​should be interpreted as merely illustrative and not limiting. Therefore, other examples of the illustrative embodiments may have different values.

[0028] It should be noted that similar symbols and letters indicate the same items in the following drawings, and therefore, if an item is defined in one drawing, there is no need to discuss it further in subsequent drawings.

[0029] In the following, the diffractive optical structure and optical display device according to the embodiment of this application will be described in detail with reference to the attached drawings.

[0030] Based on one embodiment of the present invention, a diffractive optical structure is provided, referring to Figures 1 to 4, the diffractive optical structure includes a substrate 1 and a lattice structure 5 installed on the substrate 1, referring to Figure 7, the lattice structure 5 includes a plurality of lattice units 51 periodically tiled on the surface of the substrate 1 along a first direction and a second direction, the lattice structure 5 has a first lattice modulation direction and a second lattice modulation direction, the first lattice modulation direction is perpendicular to the first direction, and the amount of lattice modulation in the first lattice modulation direction is △E, where △E = 1 / (P3*sinθ), where P3 is the period of the lattice structure 5 in the second direction, and θ is the angle between the first direction and the second direction, and the light rays of the lattice structure undergo diffraction behavior only in the first lattice modulation direction and not in the second lattice modulation direction.

[0031] In the above embodiment, the occurrence of diffraction behavior in the second lattice modulation direction means that the diffraction behavior in the second lattice modulation direction is suppressed or minimized.

[0032] The diffractive optical structure according to the embodiment of the present application is, for example, a diffractive optical waveguide device, where the lattice structure 5 can be used as one or at least one of the input coupling lattice 2, output coupling lattice 3, and refractive lattice 4 on the diffractive optical waveguide device, as shown in Figures 1 to 4, and is not limited thereto in the present application.

[0033] In augmented reality (AR) technology, diffractive optical waveguide devices are crucial optical assemblies for image transmission and display. Currently, one-dimensional gratings are widely used in diffractive optical waveguide devices, modulating diffraction efficiency by adjusting parameters such as linewidth, depth, and sidewall angle. However, such modulation methods are limited by process difficulty and cost, and adjusting depth and sidewall angle in particular is often difficult or costly. Furthermore, improvement in diffraction efficiency through linewidth adjustment alone is limited and affects the overall efficiency and uniformity of the optical waveguide device.

[0034] To overcome the above-mentioned defects, the embodiments of the present invention provide a specially designed lattice structure 5, which is similar to a two-dimensional lattice in terms of optical structure design, but similar to a one-dimensional lattice in terms of diffraction performance.

[0035] Referring to Figure 5, which shows the structure of a typical one-dimensional lattice, multiple lattice units are arranged in the same direction with a period P1.

[0036] Referring to Figure 6, which shows the structure of a typical two-dimensional lattice, as can be seen from Figure 6, multiple lattice units are arranged periodically along two different directions, with the period in one direction being P2 and the period in the other direction being P3. Here, the direction of period P2 is perpendicular to the direction of period P1 of the one-dimensional lattice in Figure 5, and simultaneously, period P3 is repeatedly introduced in any other direction, i.e., a typical two-dimensional lattice structure.

[0037] Referring to Figure 7, the lattice structure in this application maintains the one-dimensional lattice diffraction mode while introducing a periodic tile-like arrangement in a second direction, forming a novel lattice unit layout design, as shown in Figure 7. Such a lattice design according to this application does not require complex modulation of the depth or sidewall angle of the lattice units, and by adjusting the parameters in the second direction (e.g., period, linewidth), more flexible and effective modulation of the lattice diffraction efficiency of the lattice structure can be achieved.

[0038] The lattice structure according to this invention, as shown in Figure 7, maintains one-dimensional diffraction characteristics while simultaneously adjusting parameters in a second direction, such as period P3 and linewidth, to achieve modulation of the lattice diffraction efficiency. This modulation method does not rely on the adjustment of depth or sidewall angle, which are difficult processes, and utilizes mature, low-cost processes, thereby significantly improving the overall efficiency of the diffractive optical structure as well as the uniformity of brightness, color, and eyebox.

[0039] Compared to the high costs associated with adjusting the depth and sidewall angle of conventional one-dimensional lattices (see Figure 7), this invention reduces process difficulty and cost by adjusting more controllable parameters such as the period P3 in the second direction. Such high-performance lattice structures can be more easily produced and applied on a large scale.

[0040] According to the above-described embodiment of the present application, light rays incident on the lattice structure undergo effective diffraction behavior only in the first lattice modulation direction, while diffraction behavior in the second lattice modulation direction is suppressed or minimized. Such characteristics help reduce stray light and unwanted diffraction effects, thereby improving image quality and clarity.

[0041] In summary, the lattice structure according to the embodiment of this application demonstrates remarkable technical advantages in improving the overall efficiency and uniformity of the diffractive optical structure, while also reducing process costs, enhancing design flexibility and practicality, and providing a new solution for the development of optical display technologies such as augmented reality.

[0042] Referring to Figures 8 to 10, Figure 8 shows a K vector diagram of a typical one-dimensional lattice. Figures 9 and 10 are both K vector diagrams of lattice structure 5 according to an embodiment of the present application. Compared to Figure 8, Figure 9 shows that the length of λ / P3·sinθ is basically the same as λ / P1 in Figure 8, indicating that the lattice structure of the present application undergoes lattice modulation in the P2 direction and produces diffraction behavior. Figure 9 also shows four diagonal lines, which are four diagonal lines extending from the four vertices of the rectangular dashed frame in the figure, and these four diagonal lines are offset from the outermost circle, indicating that there is no diffraction behavior in another dimension of the lattice structure 5. The difference between Figure 10 and Figure 9 is that the lattice structure 5 does not directly modulate the incident light ray; that is, the lattice structure 5 is not applied to the input coupling lattice of the diffractive optical structure. Instead, the light ray is modulated before being incident on the lattice structure 5 and modulated. It can also be seen that the eight diagonal lines in Figure 10 are shifted from the outermost circle, which indicates that diffraction does not exist in another dimension of the lattice structure 5.

[0043] In some examples of the present application, referring to Figure 7, the period of the lattice structure 5 in the first direction is P2, and P2 <P3である。

[0044] Based on the diffractive optical structure according to the embodiment of the present invention, the lattice structure 5 here has a periodic difference in two directions.

[0045] In lattice design, period is a crucial parameter that directly affects the diffraction properties of the lattice.

[0046] In the diffractive optical structure according to the embodiment of the present application, the lattice structure has two lattice modulation directions: a first lattice modulation direction and a second lattice modulation direction. Here, the first lattice modulation direction is the direction in which normal diffraction operation is desired, and the second lattice modulation direction is an ineffective direction in which light rays do not undergo diffraction behavior. The first lattice modulation direction is influenced by the period P2 of the first direction, and the second lattice modulation direction is influenced by the period P3 of the second direction.

[0047] The lattice structure of the present invention, having a period P2 in the first direction smaller than the period P3 in the second direction, can produce a stronger diffraction or interference effect in the first direction because a denser period means more interaction between lattice lines and light.

[0048] The specific analysis of the diffraction performance of the lattice structure of this application is as follows: Light rays incident on the lattice structure exhibit significant diffraction behavior only in the first lattice modulation direction (related to P2), while diffraction in the second lattice modulation direction (related to P3) is suppressed or minimized. Such a design helps to achieve more precise and efficient optical control.

[0049] Specifically, the lattice structure according to the embodiment of the present invention can enhance diffraction efficiency, specifically, the period P2 in the first direction makes the diffraction of light rays in that direction stronger and more effective, which is advantageous for the transmission efficiency of optical energy in the input coupling, output coupling, or refraction processes of optical waveguide devices. The lattice structure according to the embodiment of the present invention can also optimize optical performance, specifically, the period P3 in the second direction effectively suppresses diffraction in unexpected directions, reduces stray light and energy loss, and improves image clarity and contrast. By optimizing the periods in both directions, the scheme of the present invention improves the brightness, color, and surface uniformity of the diffractive optical structure, such as the eyebox, by achieving fine control of lattice diffraction efficiency while maintaining the fundamental diffraction characteristics of the one-dimensional lattice.

[0050] In some examples of this application, referring to Figures 7 and 20, the angle θ between the first direction and the second direction is 0 < θ ≤ 90°.

[0051] The lattice structure 5 has a period P2 in a first direction and a period P3 in a second direction, and forms a constant angle θ between the first and second directions. The design of this angle θ allows the lattice structure to be flexibly positioned in a plane, thereby adapting to the requirements of different optical systems. By adjusting the value of this angle θ, the diffraction intensity in different directions of the lattice structure 5 can be controlled to some extent, optimizing the propagation path of light rays.

[0052] When the angle θ is within the above range, the diffraction in the two directions of the lattice structure exhibits different characteristics. The first direction (direction of period P2) governs the main diffraction effect, while the second direction (direction of period P3) can be used for fine-tuning or suppressing diffraction.

[0053] Furthermore, setting the angle θ increases the design flexibility of the lattice structure, allowing for flexible adjustment of the lattice layout and parameters according to specific application scenarios and performance requirements, thereby achieving optimal optical effects.

[0054] Based on the range of the angle θ between the first direction and the second direction as described in the examples of this application, precise control of the diffraction direction can be achieved. Specifically, by rationally adjusting the θ value within this range, the diffraction direction of the grating can be precisely controlled so that light rays propagate along a predetermined path. Furthermore, a rational design of the angle θ helps to balance the diffraction effects of the two directions, reduce unwanted diffraction losses, and improve image clarity. Optimization of the angle θ can improve the overall efficiency of the diffractive optical structure by allowing the grating structure to more effectively input-couple light rays to the diffractive optical structure or output-couple them from it.

[0055] In summary, the setting range of the angle θ between the first and second directions in the example of this application (0 < θ ≤ 90°) is a design choice that offers high flexibility and optimization space. This ensures the basic diffraction characteristics of the lattice while simultaneously enabling fine control of optical performance by adjusting the angle θ, thereby improving the overall efficiency and optical performance of the diffractive optical structure.

[0056] In some examples of the present application, referring to Figures 1 to 4, the diffractive optical structure includes an input coupled grating 2, an output coupled grating 3, and a refractive grating 4, wherein at least one of the input coupled grating 2, the output coupled grating 3, and the refractive grating 4 comprises at least a portion of the grating structure.

[0057] The diffractive optical structure according to the embodiment of the present invention, as shown in Figures 1 to 4, has an input coupling grating 2, an output coupling grating 3, and a refractive grating 4 integrated on the substrate 1, and these functional gratings play a crucial role in the diffractive optical structure.

[0058] Specifically, the input coupling grid 2 effectively couples light rays projected from an external light source into the substrate 1, the output coupling grid 3 couples the light rays from the substrate 1 to the wearer / user's eyes, and the refractive grid 4 is located in the optical path between the input coupling grid 2 and the output coupling grid 3 and is used to change the direction of light ray propagation and achieve pupil dilation or redirection of the image.

[0059] In the present invention, a portion or all of the region of at least one functional grating (e.g., input coupling grating 2, output coupling grating 3, or refractive grating 4) on the substrate 1 employs the grating structure 5, and such a structure can significantly improve the diffraction efficiency of the grating and optimize the overall efficiency and uniformity of the diffractive optical structure without increasing process complexity by adjusting parameters such as line width, groove width, and period in the one-dimensional direction.

[0060] To optimize the lattice structure 5, the entire diffractive optical structure can more effectively utilize light energy in the input coupling, output coupling, and refraction processes of light rays, reducing energy loss and improving image brightness, color uniformity, and eyebox uniformity.

[0061] The optimized lattice structure significantly improves diffraction efficiency in the input coupling, output coupling, and refraction processes of light rays, thereby increasing the overall utilization rate of light energy and making the diffractive optical structure brighter and clearer when displayed.

[0062] In the diffractive optical structure according to the embodiment of the present invention, at least one of the input coupling grating 2, output coupling grating 3, and refractive grating 4, at least a portion of the region, employs the grating structure according to the present invention, thereby enhancing imaging quality. This is because optimizing the grating structure reduces stray light and unwanted diffraction loss, improves image sharpness and contrast, and makes the fusion of virtual images and the real world more natural and realistic.

[0063] An efficient diffractive optical structure allows optical waveguide devices to exhibit better uniformity in terms of brightness, color, and eyebox, reducing visual fatigue and discomfort, and improving the overall user experience when using augmented reality devices.

[0064] The design of the diffractive optical structure in this example significantly improves the overall performance and user experience of the diffractive optical structure by integrating an optimized lattice structure 5. Such a design not only improves the utilization rate of optical energy and image quality, but also reduces production costs and process complexity, providing support for the development of augmented reality technology.

[0065] In some examples of the present application, referring to Figures 1 and 2, at least a portion of the refractive grating 4 is the grating structure 5, or referring to Figure 3, the input coupled grating 2 and the refractive grating 4 are the grating structure 5, or referring to Figure 4, the input coupled grating 2, a portion of the output coupled grating 3 and the refractive grating 4 are the grating structure 5.

[0066] In one example, referring to Figure 1, the refractive lattice 4 includes a first region 41 and a second region 42, which are set as the lattice structure 5.

[0067] In one example, referring to Figure 2, the refractive lattice 4 is set as the lattice structure 5 overall.

[0068] In the two methods described above, referring to Figures 1 and 2, a portion or all of the region of the refractive grating 4 employs the grating structure 5. Such a design allows for more effective utilization of the diffraction characteristics of the grating structure when light rays are refracted within the diffractive optical structure, thereby controlling the refraction angle and intensity distribution of the light rays.

[0069] The optimized grating structure 5 reduces energy loss in the light ray refraction process, improves refraction efficiency, and allows images to remain sharp and bright at a wider field of view. By precisely controlling the diffraction behavior of the refraction grating 4, the eyebox uniformity of the diffractive optical structure can be improved, ensuring consistency in image quality at different observation angles.

[0070] In one example, referring to Figure 3, both the input coupling grating 2 and the refractive grating 4 employ a grating structure 5. Such a design not only optimizes the input coupling efficiency of the light rays but also further improves the refractive performance of the internal light rays of the diffractive optical structure.

[0071] By doubly optimizing the input coupling grating 2 and the refractive grating 4, the diffractive optical structure can maintain high overall efficiency in the light conduction and refraction processes, improving image brightness and color uniformity. Optimizing the refractive grating 4 can expand the field of view range of the diffractive optical structure.

[0072] In one example, referring to Figure 4, the input coupling grid 2, a portion of the output coupling grid 3, and the refractive grid 4 constitute the grid structure 5, where the output coupling grid 3 includes a first region 31, a second region 32, and a third region 33, and the second region 32 is located between the first region 31 and the third region 33, and the second region 32 is the grid structure 5. Such a comprehensive optimization design ensures that the diffractive optical structure exhibits optimal performance in all processes of input coupling, conduction, refraction, and output coupling of light rays.

[0073] By optimizing the input coupling grid 2, output coupling grid 3, and refractive grid 4 in all directions, the diffractive optical structure is significantly improved in terms of brightness, color uniformity, eyebox uniformity, and viewing angle. An efficient diffractive optical structure makes augmented reality displays clearer, more natural, and more comfortable, greatly enhancing the user's visual experience.

[0074] Based on the examples described above, this invention improves the performance of a diffractive optical structure by flexibly applying the lattice structure 5 to different functional lattice portions of the diffractive optical structure. Whether the refractive grating is optimized alone, the input coupling grating and the refractive grating are optimized simultaneously, or the input coupling, output coupling, and refractive grating are optimized comprehensively, the efficiency, uniformity, and user experience of the diffractive optical structure can be improved to different degrees.

[0075] In some examples of the present invention, the period P2 in the first direction of the lattice structure 5 is < 300 nm, and the light ray undergoes primary diffraction action only in the first lattice modulation direction after diffraction of the lattice structure 5, and does not undergo diffraction action in the second lattice modulation direction.

[0076] The diffractive optical structure according to the present invention, where the lattice structure 5 satisfies the following specific optical relations: the first lattice modulation direction is perpendicular to the first direction, the amount of lattice modulation on the first lattice modulation direction is △E, and △E = 1 / (P3*sinθ), and further satisfies the conditions in this example of the present invention, namely, the constraint on the period P2 of the first direction of the lattice structure 5. In this way, the lattice structure 5 can completely ensure that only one direction is the lattice modulation direction for normal diffraction operation, and the other direction is an invalid direction.

[0077] Furthermore, the period P2 in the first direction of the lattice structure 5 is < 250 nm.

[0078] Furthermore, the period P2 in the first direction of the lattice structure 5 is < 200 nm.

[0079] In one specific example of the present invention, the input coupling grid 2 employs the grid structure 5, and when the grid structure 5 satisfies the following conditions, light rays incident in the FOV in at least some directions do not undergo diffraction behavior in the second grid modulation direction after being modulated by the grid structure 5. JPEG2026070474000032.jpg2883 Here, JPEG2026070474000033.jpg98 is the grid modulation amount at any point within the FOV of the grid structure 5. n2 is the refractive index of the substrate 1, JPEG2026070474000034.jpg2621 represents the second grid modulation direction.

[0080] In one specific example of the present invention, the input coupled grating 2 employs the grating structure 5, and when the grating structure 5 satisfies the following conditions, light rays incident in the FOV in at least some directions undergo primary diffraction only in the first grating modulation direction after being modulated by the grating structure 5. JPEG2026070474000035.jpg26120 Here, JPEG2026070474000036.jpg88 is the grid modulation amount at any point within the FOV of the grid structure 5. n2 is the refractive index of the substrate 1, JPEG2026070474000037.jpg2621 is the first grid modulation direction, JPEG2026070474000038.jpg2621 represents the second grid modulation direction.

[0081] In one specific example of the present application, the refractive grating 4 or the output coupling grating 3 employs the grating structure 5, and when the grating structure 5 satisfies the following conditions, light rays incident in the FOV in at least some directions do not undergo diffraction behavior in the second grating modulation direction after being modulated by the grating structure 5. JPEG2026070474000039.jpg2899 Here, JPEG2026070474000040.jpg109 is the grid modulation amount at any point within the FOV of the grid structure 5. JPEG2026070474000041.jpg99 is the grid modulation amount of the input coupled grid 2, n2 is the refractive index of the substrate 1, JPEG2026070474000042.jpg2520 represents the second grid modulation direction.

[0082] In one specific example of the present application, the refractive grating 4 or the output coupling grating 3 employs the grating structure 5, and when the grating structure 5 satisfies the following conditions, light rays incident in the FOV in at least some directions undergo primary diffraction only in the first grating modulation direction after being modulated by the grating structure 5. JPEG2026070474000043.jpg26136 Here, JPEG2026070474000044.jpg99 is the grid modulation amount at any point within the FOV of the grid structure 5. JPEG2026070474000045.jpg910 is the grid modulation amount of the input coupled grid 2, n2 is the refractive index of the substrate 1, JPEG2026070474000046.jpg2621 is the first grid modulation direction, JPEG2026070474000047.jpg2319 represents the second grid modulation direction.

[0083] In one specific example of the present invention, the output coupling grating 3 employs the grating structure, and when the grating structure 5 satisfies at least one of the following conditions, light rays incident in at least some directions within the FOV do not undergo diffraction behavior in the second grating modulation direction after being modulated by the grating structure 5. JPEG2026070474000048.jpg78117 Here, JPEG2026070474000049.jpg98 is the grid modulation amount at any point within the FOV of the grid structure 5. JPEG2026070474000050.jpg1010 is the grid modulation amount of the input coupled grid 2, JPEG2026070474000051.jpg1012 is the grid modulation amount of the refractive grid 4, TIFF2026070474000052.tif79 is the grid modulation amount of the output coupled grid 3, n2 is the refractive index of the substrate 1, JPEG2026070474000053.jpg2621 is the first grid modulation direction, JPEG2026070474000054.jpg2419 represents the second grid modulation direction.

[0084] In one specific example of the present application, the output coupling grating 3 employs the grating structure, and when the grating structure 5 satisfies at least one of the following conditions, light rays incident in the FOV range in all directions or at least some directions undergo primary diffraction only in the first grating modulation direction after being modulated by the grating structure 5. JPEG2026070474000055.jpg69146 Here, JPEG2026070474000056.jpg99 is the grid modulation amount at any point within the FOV of the grid structure 5. JPEG2026070474000057.jpg1111 is the grid modulation amount of the input coupled grid 2, JPEG2026070474000058.jpg1112 is the grid modulation amount of the refractive grid 4, TIFF2026070474000059.tif79 is the grid modulation amount of the output coupled grid 3, n2 is the refractive index of the substrate 1, JPEG2026070474000060.jpg2621 is the first grid modulation direction, JPEG2026070474000061.jpg2319 is the second grating modulation direction.

[0085] In addition, when any one of the conditions of the above six specific examples is not fully satisfied, in order to realize the modulation effect of optical efficiency and uniformity, the diffraction efficiency perpendicular to the second direction (the direction of period P3) of the grating structure can be suppressed by the optimization means. Here, such a method can achieve a relatively low k4 diffraction efficiency.

[0086] The grating structure 5 of the present application is not limited to the shape of the repeated grating unit 51 here, and the grating unit 51 may have any shape.

[0087] For example, referring to FIGS. 11 to 13, the grating unit 51 may be a polygon, a curved-sided shape, or a combination and connection of a plurality of units at any rotation angle.

[0088] In some examples of the present application, referring to FIGS. 14 to 17, the grating unit 51 is a columnar structure installed on the surface of the substrate 1, and the line width occupancy ratio of the grating unit 51 in the first direction (the direction of period P2) is DC, where 0 < DC < 1. Refer to FIGS. 20 and 22.

[0089] Referring to FIGS. 14 to 17, from a side viewing angle, the shape of the grating unit 51 is not limited either, and it may be a vertical columnar shape, an inclined columnar shape, a columnar shape with a taper angle, or various forms such as a curved surface columnar shape. In addition, these columnar structures can rotate at an arbitrary angle φ around the z-axis within the xy plane (refer to FIG. 17), providing extremely high design flexibility.

[0090] Line width occupancy ratio DC: This is an important parameter that determines the ratio of the width of the grating unit 51 in the first direction to the entire period.

[0091] Referring to Figure 20, the diffraction efficiency of the grating unit 51 can be effectively adjusted by adjusting the linewidth occupancy DC in the first direction (the direction of period P2), as shown in Figure 21. This is because the change in linewidth occupancy directly affects the diffraction of light waves by the grating, thereby allowing for finer control of light in a specific direction.

[0092] Based on the example of the present application, the value range of DC is between 0 and 1, and in this way, multiple lattice units 51 can be arranged periodically along two different directions. Referring to Figure 20, when DC=1, the lattice units 51 along the first direction (the direction of period P2) are connected in a stripe pattern, and the final formation is a one-dimensional lattice.

[0093] In this example of the present invention, the efficiency and uniformity of the waveguide can be further improved by precisely controlling the shape of the lattice unit 51 and setting the linewidth occupancy in the periodic direction. This is particularly important for applications requiring high efficiency and uniform light distribution.

[0094] Since the linewidth occupancy of the lattice unit 51 in the first direction is adjustable, an asymmetric lattice structure can be realized (see Figures 25 and 26). Such asymmetry is very useful for certain applications (e.g., increasing or decreasing light intensity in a particular direction).

[0095] Overall, the design of the lattice unit 51 in this example of the present application provides precise control of diffraction efficiency by adjusting the linewidth occupancy DC in the first direction (the direction of period P2), increases design flexibility, improves the efficiency and uniformity of the diffractive optical structure, and enables the realization of an asymmetric lattice structure.

[0096] In some examples of the present application, referring to Figure 19, the grid unit 51 is a perforated structure installed on the surface of the substrate 1, and referring to Figure 22, the line width occupancy of the grid unit 51 in the first direction is DC, 0 <DC<1である。

[0097] Similarly, in the substrate 1, the grid unit 51 is not limited to a columnar structure, but may be replaced with a perforated structure arranged in two dimensions accordingly.

[0098] Specifically, refer to Figures 18 and 19. Figure 18 shows a plan view of a columnar lattice unit 51. Figure 19 replaces the columnar lattice unit 51 in Figure 18 with a perforated structure corresponding to its cross-sectional shape. The perforated lattice unit 51 design further expands the design possibilities. This degree of design freedom allows the lattice unit 51 to meet the needs of multiple complex optical applications.

[0099] Referring to Figure 23, when DC is between 0 and 0.7, the diffraction efficiency of the lattice structure 5 basically tends to increase gradually, and between 0.7 and 1, the diffraction efficiency of the lattice structure 5 decreases slightly.

[0100] In some examples of the present invention, the grid unit 51 includes one or more sub-grids.

[0101] In the present example, referring to Figures 7 and 11-13, the grid unit 51 is designed to include one or more sub-grids. This indicates that each grid unit 51 is not limited to a single shape, but may consist of two or more sub-grids of different shapes, referring to Figure 12.

[0102] Here, by combining sub-grids of different shapes and sizes, as shown in Figure 12, multiple different optical effects can be designed. This makes the grid structure 5 more flexible and adaptable to various application scenarios, and allows the performance of the grid to be adjusted and optimized according to actual needs.

[0103] When the lattice unit 51 includes multiple different sub-grids, each sub-grid has independent diffraction characteristics. By combining them, the diffraction efficiency in different directions of the lattice can be precisely controlled. This helps to realize more complex diffraction modes and meet specific optical needs.

[0104] Manufacturing a single large grid unit with a complex shape can sometimes present significant technical challenges. Breaking down a large grid unit into multiple simpler sub-grids can reduce manufacturing difficulty and improve production efficiency and yield.

[0105] Different sub-lattices can exhibit different response characteristics to light rays of different wavelengths or polarization states. By combining multiple sub-lattices, it is possible to design lattices that are well-adapted to diverse light conditions, thereby expanding the range of applications for the lattice.

[0106] Referring to Figure 24, Figure 24 shows that a typical one-dimensional lattice (you may also refer to the structure shown in Figure 5) provides the ability to adjust symmetry within its field of view (FOV).

[0107] The lattice structure 5 according to the embodiment of the present invention is intended to further optimize the performance of a conventional one-dimensional lattice, and this solution can achieve a significant improvement in diffraction efficiency within the field of view (FOV) range of the lattice structure 5. Furthermore, referring to Figures 25 and 26, the lattice structure 5 of the present invention provides the ability to finely adjust asymmetry within the FOV, thereby achieving higher waveguide efficiency and uniformity.

[0108] Specifically, compared to a conventional one-dimensional lattice design (see Figure 24), it exhibits nearly vertically symmetrical characteristics in the image. However, the improved lattice structure 5 (see Figures 25 and 26) achieves a vertically asymmetric effect, and the diffraction efficiency in the upper right corner region is significantly improved, resulting in a deeper black and demonstrating a significant enhancement of the optical performance in that region.

[0109] Another embodiment of the present application provides an optical display device, which includes an image source and the diffractive optical structure described above.

[0110] Light rays emitted from the image source can be incident on the input coupling grating 2 on the diffractive optical structure.

[0111] Here, the image source is, for example, a projector.

[0112] Here, the diffractive optical structure is, for example, a diffractive optical waveguide.

[0113] The optical display device according to the embodiment of the present application is, for example, an AR smart head-mounted device. Furthermore, the AR smart head-mounted device is, for example, AR smart glasses or an AR smart helmet.

[0114] Specific embodiments of the optical display device of the present invention may refer to each embodiment of the diffractive optical structure described above, and since they have at least all the beneficial effects of the technical solutions of the above embodiments, they will not be described further here.

[0115] The above examples have focused on explaining the differences between each example. While the different optimization features between each example can be combined to form a superior example, as long as they are not contradictory, this will not be repeated here for the sake of brevity.

[0116] While several specific embodiments of this application have been described in detail by example, those skilled in the art should understand that the above examples are for illustrative purposes only and do not limit the scope of this application. Those skilled in the art should also understand that the above embodiments can be modified without departing from the scope and spirit of this application. The scope of this application is limited by the appended claims. [Explanation of Symbols]

[0117] 1. Substrate, 2. Input coupling grid, 3. Output coupling grid, 4. Refraction grid, 5. Grid structure, 51. Grid unit.

Claims

1. A diffractive optical structure comprising a substrate (1) and a lattice structure (5) installed on the substrate (1), The lattice structure (5) includes a plurality of lattice units (51) that are periodically arranged in a tile-like manner on the surface of the substrate (1) along a first direction and a second direction. The grid structure (5) has a first grid modulation direction and a second grid modulation direction, the first grid modulation direction is perpendicular to the first direction, and the amount of grid modulation in the first grid modulation direction is ΔE, where ΔE = 1 / (P ３ *sinθ), where P ３ θ is the period of the lattice structure (5) in the second direction, and θ is the angle between the first direction and the second direction. Light rays incident on the lattice structure undergo diffraction behavior only in the first lattice modulation direction and do not undergo diffraction behavior in the second lattice modulation direction. The diffractive optical structure includes an input coupled grating (2), an output coupled grating (3), and a refractive grating (4). At least one of the input coupled grid (2), the output coupled grid (3), and the refractive grid (4) includes the grid structure, The input coupling grid (2) employs the grid structure (5), and when the grid structure (5) satisfies the following conditions, light rays incident in the FOV in at least some directions do not undergo diffraction behavior in the second grid modulation direction after being modulated by the grid structure (5). Here, This is the grid modulation amount at any point within the FOV of the grid structure (5), n ２ This is the refractive index of the substrate (1), The diffractive optical structure is characterized in that the second lattice modulation direction is described above.

2. The period of the lattice structure (5) in the first direction is P ２ and P ２ <P ３ The diffractive optical structure according to claim 1, characterized in that it is the same as described in claim 1.

3. The diffractive optical structure according to claim 2, characterized in that the angle θ between the first direction and the second direction is 0 < θ ≤ 90°.

4. At least a portion of the refractive grating (4) is the grating structure (5), or The input coupling grid (2) and the refractive grid (4) are the grid structure (5), or The diffractive optical structure according to claim 1, characterized in that the input coupled grating (2), a portion of the output coupled grating (3), and the refractive grating (4) are the grating structure (5).

5. The period of the lattice structure (5) in the first direction is P ２ <300 nm, The diffractive optical structure according to claim 1, characterized in that the light ray undergoes primary diffraction action only in the first lattice modulation direction after diffraction of the lattice structure (5), and does not undergo diffraction action in the second lattice modulation direction.

6. The input coupling grid (2) employs the grid structure (5), When the lattice structure (5) satisfies the following conditions, light rays incident in the FOV in at least some directions undergo primary diffraction only in the first lattice modulation direction after being modulated by the lattice structure (5). Here, This is the grid modulation amount at any point within the FOV of the grid structure (5), n ２ is the refractive index of the substrate (1), This is the first grid modulation direction, The diffractive optical structure according to claim 5, characterized in that is the second lattice modulation direction.

7. The refractive grid (4) or the output coupling grid (3) employs the grid structure (5), When the lattice structure (5) satisfies the following conditions, light rays incident in the FOV in at least some directions do not undergo diffraction behavior in the second lattice modulation direction after being modulated by the lattice structure (5). Here, This is the grid modulation amount at any point within the FOV of the grid structure (5), This is the grid modulation amount of the input coupling grid (2), n ２ This is the refractive index of the substrate (1), The diffractive optical structure according to claim 5, characterized in that is the second lattice modulation direction.

8. The refractive grid (4) or the output coupling grid (3) employs the grid structure (5), When the lattice structure (5) satisfies the following conditions, light rays incident in the FOV in at least some directions undergo primary diffraction only in the first lattice modulation direction after being modulated by the lattice structure (5). Here, This is the grid modulation amount at any point within the FOV of the grid structure (5), This is the grid modulation amount of the input coupling grid (2), n ２ This is the refractive index of the substrate (1), This is the first grid modulation direction, The diffractive optical structure according to claim 5, characterized in that is the second lattice modulation direction.

9. The output coupling grid (3) adopts the grid structure described above. When the lattice structure (5) satisfies at least one of the following conditions, light rays incident in the FOV in at least some directions do not undergo diffraction behavior in the second lattice modulation direction after being modulated by the lattice structure (5). Here, This is the grid modulation amount at any point within the FOV of the grid structure (5), This is the grid modulation amount of the input coupling grid (2), This is the amount of grid modulation of the refractive grid (4), This is the grid modulation amount of the output coupling grid (3), n ２ This is the refractive index of the substrate (1), This is the first grid modulation direction, The diffractive optical structure according to claim 5, characterized in that is the second lattice modulation direction.

10. The output coupling grid (3) adopts the grid structure described above. When the lattice structure (5) satisfies at least one of the following conditions, light rays incident in the FOV range in at least some directions undergo primary diffraction only in the first lattice modulation direction after being modulated by the lattice structure (5). Here, This is the grid modulation amount at any point within the FOV of the grid structure (5), This is the grid modulation amount of the input coupling grid (2), This is the amount of grid modulation of the refractive grid (4), This is the grid modulation amount of the output coupling grid (3), n ２ This is the refractive index of the substrate (1), This is the first grid modulation direction, The diffractive optical structure according to claim 5, characterized in that is the second lattice modulation direction.

11. The grid unit (51) is a columnar structure installed on the surface of the substrate (1), The line width occupancy ratio of the grid unit (51) in the first direction is DC, The diffractive optical structure according to claim 1, characterized in that 0 < DC < 1.

12. The grid unit (51) is a perforated structure installed on the surface of the substrate (1), The line width occupancy ratio of the grid unit (51) in the first direction is DC, The diffractive optical structure according to claim 1, characterized in that 0 < DC < 1.

13. The diffractive optical structure according to claim 1, characterized in that the lattice unit (51) includes one or more sublattices.

14. The diffractive optical structure according to claim 5 is characterized in that the diffractive optical structure is an optical waveguide device.

15. An optical display device, Image source and, An optical display device characterized by comprising a diffractive optical structure according to any one of claims 1 to 14.

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