Diffraction optical waveguide device and AR display equipment
By setting two transition grating sub-regions in the optical waveguide device and adjusting the grating depth and area ratio, the problem of high processing complexity in the prior art is solved, achieving uniformity of light efficiency and brightness, and reducing costs.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- LENS TECHNOLOGY CO LTD
- Filing Date
- 2026-02-12
- Publication Date
- 2026-05-08
AI Technical Summary
The transition region of existing optical waveguide devices is divided into multiple sub-regions, which leads to problems such as high processing complexity, low yield, and high cost.
A diffractive waveguide device is used, and the transition region is set with only two sub-regions: the first transition grating sub-region and the second transition grating sub-region. The grating depth of the first transition grating sub-region is smaller than that of the second transition grating sub-region, and the area ratio is controlled between 5.2 and 8. The design of grating depth and area ensures light efficiency and uniformity.
The process steps were simplified, the processing difficulty was reduced, the robustness and processing yield were improved, and the luminous efficacy and brightness uniformity were ensured.
Smart Images
Figure CN121995574A_ABST
Abstract
Description
Technical Field
[0001] This application belongs to the field of display device technology, specifically relating to a diffractive waveguide device and an AR display device. Background Technology
[0002] With the rapid development of modern portable wearable electronic devices, augmented reality (AR) technology has shown broad application prospects in fields such as industry, education, outdoor activities, entertainment, and travel, and has received widespread attention and is gradually being applied in real-world scenarios.
[0003] As a key optical component in AR devices, the uniformity of the coupled brightness of the optical waveguide directly affects the user experience. To achieve better brightness uniformity, existing designs typically divide the transition region of the optical waveguide into multiple (usually more than two) sub-regions, and use different parameter settings for each sub-region. However, this multi-region design also significantly increases the complexity of fabrication, places higher demands on process precision and manufacturing yield, and thus increases manufacturing costs.
[0004] Therefore, how to simplify the structural design and reduce the manufacturing difficulty as much as possible while ensuring the optical performance such as the uniformity of the light output has become a key problem that urgently needs to be solved in this field. Summary of the Invention
[0005] The purpose of this application is to provide a diffractive optical waveguide device and an AR display device to solve the problems of high processing complexity, low yield and high cost in existing optical waveguides where the transition region is divided into multiple sub-regions.
[0006] To achieve the above objectives, the first aspect of this application provides a diffractive optical waveguide device, including an optical waveguide substrate and a coupling-in region, a transition region and a coupling-out region disposed on the optical waveguide substrate. The transition region is composed of a first transition grating sub-region and a second transition grating sub-region, and the second transition grating sub-region is disposed on the side of the first transition grating region away from the coupling-in region.
[0007] Wherein, the grating depth in the first transition grating sub-region is less than the grating depth in the second transition grating sub-region, the area of the first transition grating sub-region is greater than the area of the second transition grating sub-region, and the area ratio of the first transition grating sub-region to the second transition grating sub-region ranges from 5.2 to 8.
[0008] As a further improvement to the above technical solution: In some implementations, the area of the first transition grating sub-region is defined as α, and the area of the second transition grating sub-region is defined as β, where 6 7.
[0009] In some embodiments, the turning region has a long bottom edge, a first narrow side edge, and a second narrow side edge. The long bottom edge is close to the coupling out region, the first narrow side edge is located at one end of the long bottom edge close to the coupling in region and intersects the long bottom edge at point A, and the second narrow side edge is located at one end of the long bottom edge away from the coupling in region. The first and second fold grating sub-regions are separated by a partition boundary line. The partition boundary line intersects the second narrow side at point C. The angle between the line connecting points A and C and the coupling grating vector of the coupling region is 5° to 5.5°. The direction of the coupling grating vector is perpendicular to the grating lines in the coupling region.
[0010] In some embodiments, a partition boundary line is provided between the first transition grating sub-region and the second transition grating sub-region, and the extension direction of the partition boundary line is parallel to the grating line direction in both the first transition grating sub-region and the second transition grating sub-region.
[0011] In some embodiments, the grating ridge width in the first fold grating sub-region is the same as the grating ridge width in the second fold grating sub-region; And / or, the grating period in the first transition grating sub-region is consistent with the grating period in the second transition grating sub-region; And / or, the grating duty cycles of the first transition grating sub-region and the second transition grating sub-region are the same.
[0012] In some embodiments, the grating duty cycle of the first transition grating sub-region and the second transition grating sub-region is 40% to 50%.
[0013] In some embodiments, the grating depth in the first transition grating sub-region is h1, and the grating depth in the second transition grating sub-region is h2; Among them, h1:h2=1:(1.307~1.545). And / or, the grating depth of the first transition grating sub-region is in the range of 55nm~65nm, and the grating depth of the second transition grating sub-region is in the range of 70nm~101nm.
[0014] In some embodiments, the grating depth in the first transition grating sub-region is h1, the grating depth in the second transition grating sub-region is h2, the grating ridge width of the first or second transition grating sub-region is d, and the grating period of the first or second transition grating sub-region is p. Among them, the following condition is met: 1.9 2.16, and / or, 0.9 1.1.
[0015] In some embodiments, the coupling region is provided with a plurality of continuous coupling grating sub-partitions along a direction away from the turning region; The area of the coupled grating sub-partition closest to the transition region is larger than the area of the other coupled grating sub-partitions.
[0016] To achieve the above objectives, a second aspect of this application provides an AR display device, including a diffractive waveguide device according to the first aspect described above.
[0017] Compared to existing technologies, the diffractive waveguide device and AR display device provided in this application have at least the following advantages: The diffractive waveguide device provided in this application has only two sub-regions in the transition region: the first transition grating sub-region and the second transition grating sub-region. The use of fewer sub-regions simplifies the process steps and reduces processing errors, thereby improving robustness and processing yield.
[0018] Furthermore, the grating depth is strongly correlated with diffraction efficiency. If the grating depth of the first transition grating sub-region is greater than that of the second transition grating sub-region, it will cause some areas of the field of view to be darker. This is because the light in some corners of the field of view is diffracted by the pupil expansion of the second transition grating sub-region (a smaller grating depth corresponds to lower diffraction efficiency). Therefore, in this embodiment, by designing the depth of the first transition grating sub-region to be smaller than that of the second transition grating sub-region, the first transition grating sub-region located in the main light propagation area of the transition region has a lower grating diffraction efficiency, thereby reducing light loss when it reaches the second transition grating sub-region. At the same time, the area of the first transition grating sub-region in the two partitions of the transition region is designed to be larger than that of the second transition grating sub-region, and the area ratio is controlled between 5.2 and 8. This allows for adjustment by setting a larger area ratio for the first transition grating sub-region, ensuring the stability of the diffraction efficiency distribution in the first transition grating sub-region, thereby ensuring the overall light efficiency and uniformity of the transition region. It also gives the first transition grating sub-region better processing advantages and yield, thereby reducing the overall processing difficulty.
[0019] Other features and advantages of the embodiments of this application will be described in detail in the following detailed description section. Attached Figure Description
[0020] The accompanying drawings are provided to further illustrate the embodiments of this application and form part of the specification. They are used together with the following detailed description to explain the embodiments of this application, but do not constitute a limitation on the embodiments of this application. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without any inventive effort. In the drawings: Figure 1A schematic diagram of the structure of a diffractive waveguide device provided in an embodiment of this application; Figure 2 for Figure 1 A magnified schematic diagram of the transition region in the diffractive waveguide device shown. Figure 3 A schematic diagram of the structure of the first transition grating sub-region and the second transition grating sub-region in the transition region provided in the embodiments of this application, showing the grating depth and related parameters. Figure 4 For based on , Simulation diagrams of different brightness uniformity after combining the transition region related to the ratio in the range of 5.2~8 and close to the lower limit with the coupling region that satisfies the K-domain vector closure, and the brightness display has been uniformly normalized. Figure 5 For based on , Simulation diagrams of different brightness uniformity after combining the transition region with the upper limit value in the range of 5.2~8 and the coupling region that satisfies the K-domain vector closure, and the brightness display has been uniformly normalized. Figure 6 For based on , Simulation diagrams of different brightness uniformity after combining the transition region related to the lower limit value when the ratio is outside the range of 5.2~8 with the coupling region that satisfies the K-domain vector closure, and the brightness display has been uniformly normalized. Figure 7 For based on , Simulation diagrams of different brightness uniformity after combining the transition region related to the upper limit value of the ratio outside the range of 5.2~8 with the coupling region that satisfies the K-domain vector closure, and the brightness display has been uniformly normalized.
[0021] Explanation of reference numerals in the attached figures 100. Optical waveguide substrate; 200. Coupling region; 300, Transition zone; 301, Long base edge; 302, First narrow side edge; 303, Second narrow side edge; 304, Partition boundary line; 310, First transition raster sub-region; 320, Second transition raster sub-region; 400, Coupling Region. Detailed Implementation
[0022] The specific embodiments of this application will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit this application.
[0023] The present application will now be described in detail with reference to the accompanying drawings and exemplary embodiments.
[0024] On the one hand, please refer to Figures 1 to 7 This embodiment provides a diffractive waveguide device that can be used in display devices, such as AR display devices.
[0025] AR: Augmented Reality is a technology that cleverly integrates virtual information with the real world. Through various technologies such as multimedia, 3D modeling, real-time tracking and registration, intelligent interaction, and sensing, virtual information such as computer-generated text, images, 3D models, music, and videos are simulated and applied to the real world, thereby achieving "enhancement" of the real world.
[0026] Exit pupil: An effective optical area in which a detector or eye can normally receive a complete image from any position within the area.
[0027] FOV: This refers to the visual area in which a user can see virtual content on an AR display device. It can also be interpreted as the distance from the user to a fixed point in space and the angle formed by the left and right fields of view of that point.
[0028] Please see Figure 1 , Figure 2 and Figure 3 The diffractive waveguide device provided in this application includes: an optical waveguide substrate 100 and a coupling-in region 200, a transition region 300, and a coupling-out region 400 disposed on the optical waveguide substrate 100. Among them, the coupling-in region 200, the transition region 300, and the coupling-out region 400 are all grating regions.
[0029] In this embodiment, the transition region 300 and the coupling out region 400 are arranged on one side of the coupling in region 200 in the first direction, and the transition region 300 and the coupling out region 400 are arranged at intervals along the second direction, with the coupling out region 400 located on one side of the transition region 300. The first direction and the second direction intersect. In this embodiment, as... Figure 1 The perspective shown is illustrated by arrow X for the first direction and arrow Y for the second direction.
[0030] Optionally, the first direction is perpendicular to the second direction, and the turning region 300 and the coupling out region 400 are arranged on at least one side of the coupling in region 200, for example: the left and / or right side. Figure 1 The diagram illustrates that the transition region 300 and the coupling region 400 are arranged to the right of the coupling region 200, and the coupling region 400 is located below the transition region 300. It should be understood that the arrangement of the coupling region 200, the transition region 300, and the coupling region 400 in this embodiment is merely an example and should not be construed as limiting the scope of protection of this application.
[0031] The transition region 300 consists of a first transition grating sub-region 310 and a second transition grating sub-region 320. That is, in this embodiment, the transition region 300 has only two partitions (the first transition grating sub-region 310 and the second transition grating sub-region 320). The second transition grating sub-region 320 is located on the side of the first transition grating sub-region 310 away from the coupling region 200. The grating depth in the first transition grating sub-region 310 is less than the grating depth in the second transition grating sub-region 320, the area of the first transition grating sub-region 310 is greater than the area of the second transition grating sub-region 320, and the area ratio of the first transition grating sub-region 310 to the second transition grating sub-region 320 ranges from 5.2 to 8.
[0032] It is understood that the diffractive waveguide device provided in this embodiment only sets two sub-regions in the transition region 300: the first transition grating sub-region 310 and the second transition grating sub-region 320. The design of fewer sub-regions makes the process steps and difficulty simpler, reduces processing errors, thereby improving robustness (which can be understood as tolerance stability, that is, its performance is relatively good within the tolerance range) and improving the processing yield.
[0033] Furthermore, the grating depth is strongly correlated with diffraction efficiency. If the grating depth of the first transition grating sub-region 310 is greater than that of the second transition grating sub-region 320, it will cause some areas of the field of view to be darker. This is because the light in some corners of the field of view is diffracted by the pupil expansion of the second transition grating sub-region 320 (the grating depth is small, and the corresponding diffraction efficiency is low). Therefore, in this embodiment, by designing the depth of the first transition grating sub-region 310 to be less than the depth of the second transition grating sub-region 320, the first transition grating sub-region 310, located in the main light propagation area of the transition region 300, has a lower grating diffraction efficiency, thereby reducing light loss when it reaches the second transition grating sub-region 320. Simultaneously, the area of the first transition grating sub-region 310 is designed to be larger than the area of the second transition grating sub-region 320, with the area ratio controlled between 5.2 and 8. This allows for adjustment of the grating diffraction efficiency by setting a larger area ratio for the first transition grating sub-region 310, ensuring the stability of the diffraction efficiency distribution within the first transition grating sub-region 310, thus ensuring the overall light efficiency and uniformity of the transition region 300. Furthermore, this also gives the first transition grating sub-region 310 better processing advantages and yield, thereby reducing the overall processing difficulty.
[0034] It should be noted that if the area ratio is too large, the area of the second transition grating sub-region 320, which has a greater grating depth, will be compressed, thereby reducing the overall diffraction efficiency of the second transition grating sub-region 320, which is detrimental to uniformity and efficiency, or may result in a waste of processing area. If the area ratio is too small, the area of the first transition grating sub-region 310, which has higher diffraction efficiency, will be relatively small, and the diffraction enhancement area of some large FOV rays will be brought forward. Although this will bring an overall increase in light efficiency, the increase in local efficiency may easily lead to a deterioration in uniformity. Therefore, designing the area of the first transition grating sub-region 310 to be larger than the area of the second transition grating sub-region 320 and controlling the area ratio between 5.2 and 8 is a comprehensive and optimal balance design based on light efficiency, uniformity, and mass production feasibility.
[0035] In this embodiment, the area of the first transition grating sub-region 310 is defined as α, and the area of the second transition grating sub-region 320 is defined as β, wherein 6 7. In this way, while ensuring the uniformity of the coupled brightness, it is beneficial to reduce the process and manufacturing steps. It is understood that a smaller grating depth has better processing advantages and yield. Therefore, the grating depth design of the first transition grating sub-region 310 in this application is smaller, while the area design is larger. Satisfying the relationship formula is beneficial for the area with a lower grating depth to have a larger area, thereby reducing the overall processing difficulty.
[0036] To better understand the solution of this application, the following examples illustrate the concept: Please see Figures 4 to 5 ,in, Figure 4 and Figure 5 All are based on the above. , Simulation images showing different brightness uniformity after combining the transition zone 300 with a ratio in the range of 5.2 to 8 with the coupling zone 400 that satisfies K-domain vector closure, and the brightness display has undergone uniform normalization processing. Figure 4 The simulation diagram shows the area of the first transition grating sub-region 310 corresponding to the coupling region 400 (e.g., a structure with multiple sub-regions within the coupling region 400, described below). The area is 189 square millimeters, with the second transition grating sub-region having an area of 320. It is 33.8 square millimeters; of which Figure 5 The simulation combination has with Figure 4 The same coupling region 400 corresponds to the area of the first transition grating sub-region 310. The area is 243 square millimeters, with the second transition grating sub-region having an area of 320. It is 33.8 square millimeters; it can be seen that, Figure 4 and Figure 5The differences in overall brightness and uniformity are small, meaning that the efficiency distribution of light transmission within the 300° transition zone and after pupil dilation is reasonable.
[0037] Please refer to the following: Figures 6 to 7 ,like Figures 6 to 7 for , Simulation diagrams showing the different brightness uniformity after combining the transition zone 300 (with a ratio outside the range of 5.2 to 8) with different coupling zones 400 that satisfy K-domain vector closure, and the brightness display has undergone uniform normalization processing. Figure 6 The simulation combination has with Figure 4 The same coupling region 400 corresponds to the area of the first transition grating sub-region 310. The area is 180.6 square millimeters, with the second transition grating sub-region having an area of 320. The area is 42 square millimeters. This shows that the area of the second transition grating sub-region 320, which has high diffraction efficiency, is... While the overall light effect was improved, the uniformity of brightness was actually reduced due to the darker upper corners of the image.
[0038] Figure 7 The simulation combination has with Figure 4 The same coupling region 400 corresponds to the area of the first transition grating sub-region 310. The area is 250.8 square millimeters, with the second transition grating sub-region having an area of 320. It is 26 square millimeters. Referring to the attached figure, it can be seen that the area of the first transition grating sub-region 310, which has relatively low diffraction efficiency, is... Under its influence, the overall light effect is reduced, making the picture darker, but the brightness uniformity is less affected.
[0039] In some embodiments, the area ratio of the first transition grating sub-region 310 to the second transition grating sub-region 320 Alternatively, the area ratios can be 6.12, 6.15, 6.17, 6.20, 6.24, 6.28, 6.31, 6.35, 6.39, 6.45, 6.48, 6.52, 6.55, 6.58, 6.61, 6.68, 6.7, 6.72, 6.77, 6.83, 6.86, 6.88, 6.90, 6.96, or 6.99, etc. It should be understood that the above-mentioned area ratios of the first transition grating sub-region 310 and the second transition grating sub-region 320 are merely illustrative examples and should not be construed as limiting the scope of protection of this application.
[0040] Please see Figure 1 and Figure 2It should be noted that the first transition grating sub-region 310 and the second transition grating sub-region 320 have partition edge lines at their junctions. There will be a very small gap between the two partition edge lines. Since the width of the gap is very small and will not have a significant impact on the subsequent angle data, in this embodiment, the gap is uniformly defined as the partition boundary line 304, or it can be understood as the line parallel to the grating line on either side of the gap is the partition boundary line 304.
[0041] Specifically, in this embodiment, the transition region 300 is designed as a polygonal structure, wherein the transition region 300 has a long base 301, a first narrow side 302, and a second narrow side 303. The long base 301 is close to the coupling out region 400. The first narrow side 302 is located at the end of the long base 301 close to the coupling in region 200 and intersects the long base 301 at point A. The second narrow side 303 is located at the end of the long base 301 away from the coupling in region 200 and intersects the long base 301 at point B. A partition boundary line 304 is provided between the first transition grating sub-region 310 and the second transition grating sub-region 320. The partition boundary line 304 intersects the second narrow side 303 at point C. The angle between the line connecting points A and C and the coupling grating vector of the coupling in region 200 is 5°~5.5°. The direction of the coupling grating vector is perpendicular to the grating lines within the coupling in region 200.
[0042] It is understood that, in this embodiment, the use of an angle of 5° to 5.5° is beneficial for limiting the partitioning position of the first transition grating sub-region 310 and the second transition grating sub-region 320, ensuring that the large FOV light rays are appropriately modulated in efficiency when the pupil is expanded in the second transition grating sub-region 320 of the transition region 300, thereby achieving a reasonable distribution of the efficiency of the large FOV light rays on the pupil expansion path, and thus improving the brightness uniformity and light efficiency of the image corners.
[0043] Optionally, the angle between the line connecting points AC and the coupling grating vector of the coupling area 200 can also be selected as 5.12°, 5.14°, 5.18°, 5.2°, 5.24°, 5.26°, 5.29°, 5.31°, 5.32°, 5.37°, 5.39°, 5.41°, 5.44°, 5.45°, 5.47°, or 5.49°. It should be understood that the above-described angle design between the line connecting points AC and the coupling grating vector of the coupling area 200 is merely illustrative and should not be construed as limiting the scope of protection of this application.
[0044] It should be noted that the intersection point C on the partition boundary line 304 is set on the second narrow side 303, which can further adjust the area of the second transition grating sub-region 320, so that the transition region meets the diffraction efficiency while the appearance of the transition region is uniform.
[0045] In some embodiments, when the long base 301 is a straight line, the line connecting points A and B is the long base 301. The angle between the line connecting points A and B and the coupled grating vector in the coupled region 200 is between -5° and 5°. Thus, setting the angle range of -5° to 5° ensures that the far-light side region of the transition region 300 (the second transition grating sub-region 320) does not excessively encroach on the position of the output region 400, ensuring that the Eyebox region formed by the output region 400 is in a properly centered position. Otherwise, if the Eyebox is squeezed and moves downwards, it will deviate from the normal human eye viewing area.
[0046] In some embodiments, the line connecting points A and B is parallel to the coupled grating vector in the coupled region 200, such that the angle between the line connecting points A and C and the line connecting points A and B is 5° to 5.5° (e.g., Figure 2 As shown in the figure, this can effectively reduce manufacturing difficulty and further ensure that the Eyebox area formed by the coupling area 400 is in a suitable central position.
[0047] Furthermore, the extension direction of the partition boundary line 304 between the first transition grating sub-region 310 and the second transition grating sub-region 320 is parallel to the direction of the grating lines in both the first transition grating sub-region 310 and the second transition grating sub-region 320. That is to say, the direction of the grating lines in the first transition grating sub-region 310 and the second transition grating sub-region 320 is consistent, which effectively reduces processing difficulty and improves product yield.
[0048] Please refer to the following: Figure 3 The grating ridge width in the first transition grating sub-region 310 is the same as the grating ridge width in the second transition grating sub-region 320; this can reduce some manufacturing process steps and improve processing efficiency. In this embodiment, the grating ridge width of the first transition grating sub-region 310 and the second transition grating sub-region 320 is indicated by d.
[0049] In some embodiments, the grating period in the first transition grating sub-region 310 is consistent with the grating period in the second transition grating sub-region 320; this can also reduce some manufacturing process steps and improve processing efficiency. In this embodiment, the grating periods of the first transition grating sub-region 310 and the second transition grating sub-region 320 are indicated by p.
[0050] In some embodiments, the grating duty cycles of the first transition grating sub-region 310 and the second transition grating sub-region 320 are the same. The grating duty cycle is the ratio of the grating ridge width to the grating period.
[0051] In some embodiments, the grating duty cycle of the first transition grating sub-region 310 and the second transition grating sub-region 320 is 40% to 50%. This setting has two advantages: firstly, from a manufacturing perspective, a duty cycle close to 50% is the most manufacturable, meaning that when the grating ridge width and grating groove width are similar in one grating cycle, it has excellent manufacturability; secondly, the duty cycle range used in this embodiment has a moderate impact on the grating diffraction efficiency, so that the overall diffraction efficiency of the region can be further precisely controlled by adjusting the grating region size and grating depth.
[0052] Optionally, the grating duty cycle of the first transition grating sub-region 310 and the second transition grating sub-region 320 may also be selected as 41%, 42.4%, 43%, 44.5%, 45%, 45.7%, 46%, 46.2%, 46.8%, 47.1%, 47.6%, 48%, 48.6%, 48.7%, or 48.9%. It should be understood that the above selection of grating duty cycle is only for illustrative purposes and should not be construed as limiting the scope of protection of this application.
[0053] The grating depth in the first transition grating sub-region 310 is h1, and the grating depth in the second transition grating sub-region 320 is h2; wherein, h1:h2 = 1:(1.307~1.545). For example, based on the above ratio, in an AR display device, the grating depth of the first transition grating sub-region 310 is designed to be in the range of 55nm~65nm, and the grating depth of the second transition grating sub-region 320 is designed to be in the range of 70nm~101nm. The reason for adopting this design is that as light propagates in the optical waveguide substrate 100, the grating depth of each partition of the transition region 300 increases smoothly, making the phase matching of light at the transition pupil smoother, avoiding scattering loss caused by abrupt changes. Moreover, as the grating depth increases, the diffraction efficiency gradually converges and tends to stabilize, and the light field gradually adapts to greater phase modulation when entering each sub-region, thereby improving the overall diffraction efficiency.
[0054] Optionally, the grating depth ratio h1:h2 of the first transition grating sub-region 310 and the second transition grating sub-region 320 is 1:(1.35~1.45) to further enhance the above-mentioned objective. It should be noted that the grating depth of the first transition grating sub-region 310 in the transition region 300 is in the range of 55nm~65nm, and the grating depth of the first transition grating sub-region 310 in the transition region 300 is in the range of 74nm~95nm, and h1:h2=1:(1.35~1.45). Controlling h1:h2 within the range of 1.35~1.45 makes it easier to precisely control the process, resulting in better uniformity, reasonable energy modulation in the partitions, and uniform brightness in the field of view, thus satisfying the visual experience.
[0055] In this embodiment, the grating ridge widths and grating periods in the first turning grating sub-region 310 and the second turning grating sub-region 320 are both set to be the same. In this way, the grating duty cycles corresponding to the first turning grating sub-region 310 and the second turning grating sub-region 320 are also the same. Thus, the turning region 300 adopts a grating design of "constant duty cycle + stepped transition and increasing grating depth", precisely regulating the propagation and energy distribution of light, compensating for light transmission loss, making the energy distribution in each region uniform, avoiding excessive darkness at the far end, and thus improving the overall brightness and color uniformity.
[0056] Specifically, the grating depth in the first turning grating sub-region 310 is h1, the grating depth in the second turning grating sub-region 320 is h2, the grating ridge widths of the first turning grating sub-region 310 and the second turning grating sub-region 320 are both d, and the grating periods of the first turning grating sub-region 310 and the second turning grating sub-region 320 are both p. Among them, the grating parameters of the first turning grating sub-region 310 and the second turning grating sub-region 320 have the following relationship: 1.9 2.16, and h1 < h2.
[0057] It can be understood that since the aspect ratio (grating ridge width divided by grating depth) in the grating topography has a direct impact on the processing error and difficulty, the smaller the aspect ratio, the narrower and longer the grating column, the higher the processing difficulty and the easier to break, and the larger the aspect ratio, the shallower and thicker the grating column, the smaller the processing difficulty but the too low diffraction efficiency. Therefore, it is usually necessary to consider both the manufacturability of the grating and the appropriate diffraction efficiency at the same time. Combining the above duty cycle in the range of 40% - 50%, satisfying the relationship between the grating ridge width and depth in the above formula can make the aspect ratio have a good processing condition while having an appropriate diffraction efficiency when it is greater than 1.
[0058] In addition, h1 < h2. Considering that the second turning grating sub-region 320 requires a larger grating depth to ensure sufficient diffraction efficiency for some marginal field angles, so as to ensure the brightness uniformity of the overall field of view.
[0059] Furthermore, the limitation of the above formula is also beneficial to balance and limit the grating size in the two sub-regions of the turning region 300, making the grating have better processability.
[0060] Further, there is also a limiting relationship between the grating parameters in the turning region 300: 0.9 1.1. It is understandable that since the first transition grating sub-region 310 and the second transition grating sub-region 320 have the same grating ridge width, when the relationship is satisfied, the difference between the two grating depths h1 and h2 can be kept at a small level, that is, the grating depth step between the partitions of the transition region 300 is kept at a small level, so that the difference in diffraction efficiency is not too large, avoiding the overall appearance difference of the transition region 300 being too obvious, while further ensuring the diffraction efficiency and uniformity of the second transition grating sub-region 320.
[0061] In some embodiments, the coupling region 400 is provided with a plurality of consecutive coupling grating sub-sections along the direction away from the transition region 300; wherein the area of the coupling grating sub-sections near the transition region 300 is larger than the area of other coupling grating sub-sections. Thus, by setting multiple consecutive coupling grating sub-sections, brightness and uniformity are improved. Furthermore, the area of the coupling grating sub-sections near the transition grating region is larger than the area of other coupling grating sub-sections, resulting in a decreasing trend in the area of the coupling grating sub-sections. This is beneficial for improving the distribution of incident light energy in the coupling grating sub-sections far from the transition grating region, avoiding insufficient light energy in certain areas of the eyepiece, thereby further ensuring brightness and uniformity.
[0062] Furthermore, the coupling area 400 is configured with three sub-partitions. Compared to using more consecutive partitions (three or more), it is implemented with fewer and limited partitions, reducing the processing difficulty. The three sub-partitions of the coupling area 400 are, in order, the first coupling raster sub-partition, the second coupling raster sub-partition, and the third coupling raster sub-partition, moving away from the turning area 300. That is to say, the first coupling raster sub-partition is located near the turning area 300.
[0063] It should be noted that if the area ratio of the first coupling grating sub-section to the adjacent second coupling grating sub-section is too small, the control capability of the first coupling grating sub-section near the transition region 300 will be weak, which is not conducive to improving uniformity. If the ratio is too large, the control of the coupled light energy of each sub-section in the coupling region 400 will easily become unbalanced, resulting in poor luminous efficiency and uniformity. To solve the above problems, in this embodiment, the area ratio of the first coupling grating sub-section to the adjacent second coupling grating sub-section can be set to 2.7 to 3.2, which can effectively solve the above problems.
[0064] In some embodiments, the area ratio of the second and third coupled grating sub-partitions is 0.75 to 1.1, and this ratio range can better play a role in energy distribution.
[0065] Optionally, the area ratio of the second and third coupled-out grating sub-sections is 1:1 to further enhance the energy distribution effect.
[0066] On the other hand, please see Figures 1 to 7This embodiment also provides an AR display device. The AR display device includes the diffractive waveguide device provided according to the above embodiment.
[0067] It should be noted that, in this application, unless otherwise stated, the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" used to indicate orientation or positional relationships are based on the orientation or positional relationships shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.
[0068] In the description of this application, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.
[0069] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between components; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.
[0070] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.
[0071] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.
Claims
1. A diffractive optical waveguide device, characterized in that, It includes an optical waveguide substrate (100) and a coupling region (200), a transition region (300) and a coupling out region (400) disposed on the optical waveguide substrate (100). The transition region (300) is composed of a first transition grating sub-region (310) and a second transition grating sub-region (320). The second transition grating sub-region (320) is disposed on the side of the first transition grating sub-region (310) away from the coupling region (200). Wherein, the grating depth in the first transition grating sub-region (310) is less than the grating depth in the second transition grating sub-region (320), the area of the first transition grating sub-region (310) is greater than the area of the second transition grating sub-region (320), and the area ratio of the first transition grating sub-region (310) to the second transition grating sub-region (320) is in the range of 5.2 to 8.
2. The diffractive waveguide device according to claim 1, characterized in that, Let α be the area of the first transition grating sub-region (310) and β be the area of the second transition grating sub-region (320), where 6 7.
3. The diffractive waveguide device according to claim 1, characterized in that, The transition area (300) has a long bottom edge (301), a first narrow side edge (302), and a second narrow side edge (303). The long bottom edge (301) is close to the coupling area (400). The first narrow side edge (302) is located at one end of the long bottom edge (301) close to the coupling area (200) and intersects the long bottom edge (301) at point A. The second narrow side edge (303) is located at one end of the long bottom edge (301) away from the coupling area (200). The first fold grating sub-region (310) and the second fold grating sub-region (320) are separated by a partition boundary line (304). The partition boundary line (304) intersects the second narrow side (303) at point C. The angle between the line connecting points A and C and the coupling grating vector of the coupling region (200) is 5° to 5.5°. The direction of the coupling grating vector is perpendicular to the grating lines in the coupling region (200).
4. The diffractive waveguide device according to claim 1, characterized in that, The first angular grating sub-region (310) and the second angular grating sub-region (320) have a partition boundary line (304), and the extension direction of the partition boundary line (304) is parallel to the grating line direction in the first angular grating sub-region (310) and the second angular grating sub-region (320).
5. The diffractive waveguide device according to claim 1, characterized in that, The grating ridge width in the first transition grating sub-region (310) is the same as the grating ridge width in the second transition grating sub-region (320); And / or, the grating period in the first transition grating sub-region (310) is consistent with the grating period in the second transition grating sub-region (320); And / or, the grating duty cycles of the first transition grating sub-region (310) and the second transition grating sub-region (320) are the same.
6. The diffractive waveguide device according to claim 1, characterized in that, The grating duty cycle of the first transition grating sub-region (310) and the second transition grating sub-region (320) is 40%~50%.
7. The diffractive waveguide device according to claim 1, characterized in that, The grating depth in the first transition grating sub-region (310) is h1, and the grating depth in the second transition grating sub-region (320) is h2, satisfying: h1:h2=1:(1.307~1.545). And / or, the grating depth of the first transition grating sub-region (310) is in the range of 55nm~65nm, and the grating depth of the second transition grating sub-region (320) is in the range of 70nm~101nm.
8. The diffractive waveguide device according to any one of claims 1 to 7, characterized in that, The grating depth in the first transition grating sub-region (310) is h1, the grating depth in the second transition grating sub-region (320) is h2, the grating ridge width of the first transition grating sub-region (310) or the second transition grating sub-region (320) is d, and the grating period of the first transition grating sub-region (310) or the second transition grating sub-region (320) is p; Among them, the following condition is met: 1.9 2.16, and / or, 0.9 1.
1.
9. The diffractive waveguide device according to claim 1, characterized in that, The coupling region (400) has multiple continuous coupling grating sub-partitions along the direction away from the turning region (300); The area of the coupled grating sub-partition closest to the transition region (300) is larger than the area of the other coupled grating sub-partitions.
10. An AR display device, characterized in that, Includes the diffractive waveguide device according to any one of claims 1-9.