Binocular waveguide, design method of binocular waveguide and AR glasses

Abstract

The invention relates to the technical field of AR display, in particular to a binocular waveguide, a design method of the binocular waveguide and AR glasses, the binocular waveguide comprises a waveguide substrate, and two exit pupil areas are symmetrically distributed on the waveguide substrate; and a coupling-in grating, a first diffraction element, a second diffraction element, a first coupling-out grating and a second coupling-out grating, the coupling-in grating is arranged on the waveguide substrate, and the first diffraction element and the first coupling-out grating are respectively arranged in one exit pupil area. The second diffraction element and the second coupling-out grating are respectively arranged in the other exit pupil area, and incident light can be respectively transmitted to the first diffraction element and the second diffraction element after being coupled into the waveguide substrate through the coupling-in grating. The application has the effect of improving the wearing experience of the AR equipment.

Description

Technical Field

[0001] This application relates to the field of AR display technology, and in particular to a binocular waveguide, a design method for a binocular waveguide, and AR glasses. Background Technology

[0002] Augmented Reality (AR) technology is a technology that integrates virtual information with the real world. Its core lies in overlaying virtual images onto real-world scenes using display devices, providing users with an enhanced visual experience. AR display systems typically utilize microdisplays to project images onto the user's eyes via an optical system, allowing the user to still clearly see the real world. This technology has broad application prospects in education, industry, healthcare, entertainment, and many other fields.

[0003] In AR display systems, optical waveguide technology is one of the key technologies for achieving thin, light, and highly transparent displays. Optical waveguides introduce images from a microdisplay into the waveguide through optical coupling and then couple the images out to the human eye through a specific structure. Currently, optical waveguides on the market are mainly divided into two categories: geometric array waveguides and diffractive waveguides. Diffractive waveguides are further subdivided into volume holographic waveguides and surface relief grating waveguides. The essence of these diffractive waveguides is to couple incident light into the waveguide using the principle of grating diffraction and to achieve image transmission and coupling out through a specific grating structure.

[0004] In related technologies, diffractive waveguide structures are mostly single-input, single-output waveguide structures, meaning one entrance pupil region corresponds to one exit pupil region. This design implies that each entrance pupil region requires an independent input light source, and the image output from each exit pupil region can only reach a single eye. To enable both eyes to see the same image simultaneously, two corresponding monocular waveguide structures are needed to output images to each eye, thus requiring two input light sources. In AR glasses devices, this binocular display architecture typically places the two input light sources at the temples. Furthermore, when sensors, cameras, or other functional devices need to be added to the AR glasses device, due to space limitations, these additional devices often have to be placed in other areas.

[0005] Regarding the aforementioned technologies: the use of two input light sources increases the size and weight of the device, which in turn reduces the wearing experience of the AR device. Summary of the Invention

[0006] To improve the wearing experience of AR devices, this application provides a binocular waveguide, a design method for the binocular waveguide, and AR glasses.

[0007] Firstly, this application provides a binocular waveguide, which adopts the following technical solution: A binocular waveguide, comprising: Waveguide substrate, wherein two exit pupil regions are symmetrically distributed on the waveguide substrate; and The waveguide includes an input grating, a first diffraction element, a second diffraction element, a first output grating, and a second output grating. The input grating is disposed on the waveguide substrate. The first diffraction element and the first output grating are respectively disposed in one exit pupil region, and the second diffraction element and the second output grating are respectively disposed in another exit pupil region. After incident light is coupled into the waveguide substrate through the input grating, it can be transmitted to the first diffraction element and the second diffraction element, respectively.

[0008] By adopting the above technical solution, two exit pupil regions are symmetrically distributed on the waveguide substrate. When incident light is coupled into the waveguide substrate through the coupling grating, since the first diffraction element and the first output grating are in one exit pupil region, and the second diffraction element and the second output grating are in another exit pupil region, the light will be transmitted to the first diffraction element and the second diffraction element respectively. The first diffraction element can propagate the coupled light to the first output grating, and the second diffraction element can propagate the coupled light to the second output grating. Finally, the light is output through the first output grating and the second output grating, thereby realizing the output of images from the two exit pupil regions and achieving the effect of single input and dual output. Only one input light source is needed to allow the output images of the two exit pupil regions to reach both eyes at the same time. This avoids the situation in related technologies where the binocular display architecture using a combination of two single-input single-output waveguide structures requires two input light sources. This reduces the number of light sources, which is beneficial to reducing the size and weight of the device, and thus improving the wearing experience of the AR device.

[0009] Optionally, the coupling grating is disposed on the central axis of the waveguide substrate, the first diffraction element includes a first bend grating, the second diffraction element includes a second bend grating, and the first bend grating and the second bend grating are respectively disposed in the two exit pupil regions; Starting from the coupling grating, the coupling grating, the first turning grating and the first coupling out grating are distributed counterclockwise, and the coupling grating, the second turning grating and the second coupling out grating are distributed clockwise.

[0010] By adopting the above technical solution, the coupling grating is placed on the central axis of the waveguide substrate, and the first and second bend gratings are respectively placed in the two exit pupil regions. This arrangement ensures that, starting from the coupling grating, the coupling grating, the first bend grating, and the first exit grating are distributed counterclockwise, while the coupling grating, the second bend grating, and the second exit grating are distributed clockwise. Therefore, when incident light is coupled into the waveguide substrate through the coupling grating, it can be efficiently transmitted to the first and second bend gratings respectively. Since the two bend gratings are symmetrically placed in the exit pupil region, and the optical path is symmetrically distributed clockwise and counterclockwise, this ensures that the images output from the two exit pupil regions have high symmetry and consistency. Simultaneously, because the gratings in the two exit pupil regions are symmetrically placed, the output signals originate from the same signal source, allowing for direct binocular fusion of the images received by the human eye, achieving a good visual experience. Furthermore, this arrangement effectively utilizes waveguide space, improving the waveguide's utilization efficiency.

[0011] Optionally, the first diffraction element includes a first folding grating, and the second diffraction element includes a reflective film and a second folding grating. The coupling-in grating, the first folding grating, and the first coupling-out grating are respectively disposed in one of the exit pupil regions, and the second folding grating, the second coupling-out grating, and the reflective film are respectively disposed in another of the exit pupil regions. The coupling-in grating, the first folding grating, and the first coupling-out grating are distributed counterclockwise, and the reflective film, the second folding grating, and the second coupling-out grating are distributed clockwise.

[0012] By adopting the above technical solution, the coupling grating, the first deflection grating, and the first output grating are distributed in one exit pupil region in a counterclockwise direction, while the reflective film, the second deflection grating, and the second output grating are distributed in another exit pupil region in a clockwise direction. This arrangement allows the incident light, after being coupled into the waveguide substrate by the coupling grating, to be effectively transmitted to the first deflection grating and the reflective film, respectively. The reflective film can change the light propagation path, working with the second deflection grating to expand the pupil and transmit the light; the first deflection grating also performs the corresponding pupil expansion and transmission function. Subsequently, the light is diffracted out of the waveguide from the first and second output gratings to form an image, achieving a single-input dual-output effect. Only one input light source is needed for both eyes to receive the image simultaneously, avoiding the use of two input light sources and reducing the number of light sources and related components in the device. Moreover, placing the coupling grating on one side of the exit pupil region instead of in the middle avoids structural protrusions on the forehead, effectively improving the interference problem on the forehead when the overall structure is wrapped, thereby improving the user's wearing experience.

[0013] Optionally, the first diffraction element includes a first array beam-splitting film, and the second diffraction element includes a reflective film and a second array beam-splitting film. The coupling grating, the first array beam-splitting film, and the first coupling grating are respectively disposed in one of the exit pupil regions, and the second array beam-splitting film, the second coupling grating, and the reflective film are respectively disposed in another of the exit pupil regions. The coupling grating, the first array beam-splitting film, and the first coupling grating are arranged counterclockwise, and the reflective film, the second array beam-splitting film, and the second coupling grating are arranged clockwise.

[0014] By adopting the above technical solution, after the incident light is coupled into the waveguide substrate through the coupling grating, the first and second array beam-splitting films can split and guide the light, enabling more effective processing and distribution of the light. This results in a more uniform distribution of light in the two exit pupil regions, improving exit pupil uniformity and thus enhancing the waveguide's optical efficiency. Furthermore, the reflective film alters the light propagation path, working in conjunction with the array beam-splitting films to ensure accurate image output from both exit pupil regions, ultimately achieving better imaging results. This layout enables single-input dual-output, requiring only one input light source to simultaneously deliver images from both exit pupil regions to both eyes, reducing the number of input light sources and mitigating the increased size and weight associated with multiple light sources. Moreover, placing the coupling grating on one side of the exit pupil region instead of the center avoids structural protrusions on the forehead, effectively improving interference with the forehead when the device is wrapped, thereby enhancing the user's wearing experience.

[0015] Secondly, this application provides a binocular waveguide that employs the following technical solution: A binocular waveguide, comprising: Waveguide substrate, wherein two exit pupil regions are symmetrically distributed on the waveguide substrate; and The waveguide includes an input grating, a first output grating, and a second output grating. The input grating is disposed on the central axis of the waveguide substrate. The first output grating and the second output grating are respectively disposed in the two exit pupil regions. The first output grating and the second output grating are both formed by combining three volume holographic gratings with different grating vector directions.

[0016] By adopting the above technical solution, two exit pupil regions are symmetrically distributed on the waveguide substrate, and the coupling grating is set on the central axis of the waveguide substrate. This allows the incident light to be rationally distributed to the two exit pupil regions after coupling into the waveguide substrate. The first and second coupling gratings are located in the two exit pupil regions respectively, and both are formed by combining three volume holographic gratings with different grating vector directions. The volume holographic gratings with different grating vector directions can perform multi-angle and multi-mode diffraction processing on the light, thereby improving the light energy utilization rate, reducing light energy loss, enhancing image brightness and clarity, and making the image output from the two exit pupil regions have higher quality and uniformity. This provides a better visual experience for the human eye and achieves a high-quality binocular imaging effect.

[0017] Secondly, this application provides a design method for a binocular waveguide, employing the following technical solution: A method for designing a binocular waveguide includes the following steps: A waveguide substrate is provided, on which two symmetrically distributed exit pupil regions are defined; The positions of the first and second coupling gratings on the waveguide substrate are determined so that the first and second coupling gratings are respectively disposed in the exit pupil region and are symmetrically arranged. Provide a first diffraction element and a second diffraction element; The position of the coupling grating is determined to be on the central axis of the waveguide substrate. The first diffraction element includes a first bend grating, and the second diffraction element includes a second bend grating. The positions of the first bend grating and the second bend grating are determined based on the positions of the coupling grating, the first output grating, and the second output grating; or The position of the coupling grating is determined to be within one of the exit pupil regions. The first diffraction element includes a first folding grating, and the second diffraction element includes a reflective film and a second folding grating. The positions of the first folding grating and the second folding grating are determined based on the positions of the coupling grating, the first exiting grating, and the second exiting grating. The reflective film is symmetrically arranged with respect to the coupling grating; or The position of the coupling grating is determined to be located in one of the exit pupil regions. The first diffraction element includes a first array beam splitter, and the second diffraction element includes a reflective film and a second array beam splitter. The positions of the first array beam splitter and the second array beam splitter are determined according to the positions of the coupling grating, the first output grating, and the second output grating. The reflective film is symmetrically arranged with the coupling grating.

[0018] Optionally, determining the positions of the first and second bend gratings, or determining the positions of the first and second array beam-splitting films, based on the positions of the input grating, the first output grating, and the second output grating, includes the following steps: A rectangular coordinate system is established with the center of the coupled grating as the origin O, with the horizontal direction as the X-axis and the vertical direction as the Y-axis; The positions of the first and second coupling gratings are determined based on the dimensions of the first and second coupling gratings and the distance between the centers of the first and second coupling gratings. The vertices of the first transition grating are determined using calculation formulas, and the coupling efficiency of the coupling grating is determined in each state corresponding to a set of coordinates; and The position coordinates corresponding to the maximum coupling efficiency are determined as the position coordinates of each vertex of the first folding grating.

[0019] Optionally, the horizontal and vertical coordinates of the four vertices of the first angular grating are set to F(1,1), F(1,2); F(2,1), F(2,2); F(3,1), F(3,2); and F(4,1), F(4,2), respectively. Then the formula for calculating the position coordinates of each vertex of the first angular grating is as follows: (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) Among them, a x a yLet a1 and a2 be the horizontal and vertical propagation angles of light coupled into the waveguide substrate by the input grating, respectively; let a1 and a2 be the half-field angles in the horizontal and vertical directions, respectively; let λ and Λ be the grating exposure wavelength and grating period, respectively; let inx and iny be the center coordinates of the input grating; let outx and outy be the center coordinates of the output grating; let inw and inh be the width and height of the input grating; and let outw and outh be the width and height of the output grating. The width and height of the output grating are calculated from the exit pupil distance d, the half-field angles in the horizontal and vertical directions a1 and a2, and the exit pupil dimensions Ex and Ey in the horizontal and vertical directions, respectively. The specific calculation formula is as follows: ; .

[0020] Thirdly, this application provides a design method for a binocular waveguide, employing the following technical solution: A method for designing a binocular waveguide includes the following steps: A waveguide substrate is provided, on which two symmetrically distributed exit pupil regions are defined; The position of the coupling grating is determined so that the coupling grating is located on the central axis of the waveguide substrate; The positions of the first and second coupling gratings on the waveguide substrate are determined so that the first and second coupling gratings are respectively disposed in the exit pupil region and are symmetrically arranged. Furthermore, both the first and second coupling gratings are formed by combining three volume holographic gratings with different grating vector directions. The formula for calculating the grating vectors of the three volume holographic gratings is as follows: The grating vectors of the three gratings are set as follows: According to Bragg's formula, we know that: , ; , , ; in, The wavelength in a vacuum. For the grating period, Let be the incident angle of the second beam relative to the holographic plate. Let be the refractive index of the grating medium. It is the angle of refraction.

[0021] Thirdly, this application provides AR glasses, which adopt the following technical solution: An AR glasses comprising a micro-image source and a binocular waveguide as described in any of the above, wherein an image beam emitted by the micro-image source can be coupled into a coupling grating.

[0022] In summary, this application includes at least one of the following beneficial technical effects: 1. By adopting a single-input dual-output waveguide structure, only one input light source is needed to enable the output images of the two exit pupil regions to reach both eyes simultaneously, reducing the size and weight of the device and thus improving the wearing experience of AR devices; 2. The reflective film allows the coupling grating to be placed on one side of the exit pupil area instead of in the middle, thus avoiding structural protrusions on the forehead and effectively improving the interference problem on the forehead when the whole structure is wrapped, thereby improving the user's wearing experience. 3. The first and second coupling gratings are formed by combining three volume holographic gratings with different grating vector directions. This enables multi-angle and multi-mode diffraction processing of light, thereby improving light energy utilization, reducing light energy loss, enhancing image brightness and clarity, and making the images output from the two exit pupil regions have higher quality and uniformity. This provides a better visual experience for the human eye and achieves high-quality binocular imaging. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the overall structure of a binocular waveguide in Embodiment 1 of this application.

[0024] Figure 2 This is a schematic diagram of the structure of the micro-image source and the binocular waveguide in the embodiments of this application.

[0025] Figure 3 This is a schematic diagram of the overall structure of a binocular waveguide in Embodiment 2 of this application.

[0026] Figure 4 This is a schematic diagram of the overall structure of a binocular waveguide in Embodiment 3 of this application.

[0027] Figure 5 This is a schematic diagram of the overall structure of a binocular waveguide in Embodiment 4 of this application.

[0028] Explanation of reference numerals in the attached figures: 1. Waveguide substrate; 11. Exit pupil region; 2. Coupled-in grating; 3. First diffraction element; 31. First transition grating; 32. First array beam splitter; 4. Second diffraction element; 41. Second transition grating; 42. Reflective film; 43. Second array beam splitter; 5. First coupling-out grating; 6. Second coupling-out grating; 7. Micro-image source. Detailed Implementation

[0029] The following is in conjunction with the appendix Figure 1-5This application will be described in further detail.

[0030] This application discloses a binocular waveguide.

[0031] It should be noted that, in the description of this invention, the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0032] Example 1: Refer to Figure 1 and Figure 2 A binocular waveguide includes a waveguide substrate 1, a coupling grating 2, a first diffraction element 3, a second diffraction element 4, a first output grating 5, and a second output grating 6. Two exit pupil regions 11 are symmetrically distributed on the waveguide substrate 1. The coupling grating 2 is disposed on the waveguide substrate 1. The first diffraction element 3 and the first output grating 5 are respectively disposed in one exit pupil region 11, and the second diffraction element 4 and the second output grating 6 are respectively disposed in the other exit pupil region 11. After incident light is coupled into the waveguide substrate 1 through the coupling grating 2, it can be transmitted to the first diffraction element 3 and the second diffraction element 4 respectively. This achieves the effect that the output images of the two exit pupil regions 11 can simultaneously reach both eyes using only one input light source, thereby reducing the size and weight of the device and improving the wearing experience of the AR device.

[0033] The coupling grating 2 is disposed on the central axis of the waveguide substrate 1 and located slightly above vertically. In this embodiment, the coupling grating 2 includes two grating vector-symmetric reflective polarizer holographic gratings, which are stacked together, thereby enabling the coupling grating 2 to efficiently couple incident light into the waveguide substrate 1 and direct the light to the first diffraction element 3 and the second diffraction element 4.

[0034] The first diffraction element 3 includes a first transition grating 31, and the second diffraction element 4 includes a second transition grating 41. The first transition grating 31 and the second transition grating 41 are respectively disposed in two exit pupil regions 11, and are symmetrically distributed about the coupling grating 2. In this embodiment, both the first transition grating 31 and the second transition grating 41 are reflective volume holographic gratings, and the grating vector directions of the first transition grating 31 and the second transition grating 41 are opposite, thereby helping to change the propagation direction of light within the waveguide substrate 1 and achieving pupil-expanding transmission.

[0035] The first output grating 5 is located below the first transition grating 31, and the second output grating 6 is located below the second transition grating 41. Starting from the input grating 2, the input grating 2, the first transition grating 31 and the first output grating 5 are distributed counterclockwise, and the input grating 2, the second transition grating 41 and the second output grating 6 are distributed clockwise.

[0036] Both the first output grating 5 and the second output grating 6 are reflective polarizer holographic gratings, so that the first output grating 5 and the second output grating 6 can diffract light out of the waveguide and finally form an image for human eyes to receive.

[0037] In this embodiment, the first turning grating 31 and the first coupling grating 5 are partially overlapped, which ensures that each grating functions normally and saves space on the waveguide substrate 1, making the entire binocular waveguide structure more compact.

[0038] The implementation principle of this embodiment is as follows: When the light emitted from the micro-image source 7 is collimated and amplified by the collimating optical system, it first diffracts through the coupling grating 2 into the waveguide substrate 1. Then, the light is transmitted in two directions to the first transition grating 31 and the second transition grating 41 on both sides, respectively. These gratings then expand the pupil and diffract to the corresponding first output grating 5 and second output grating 6. Finally, the first output grating 5 and the second output grating 6 diffract to form the waveguide image. Since the output signal originates from the same signal source, the images received by the human eye can be directly fused together.

[0039] In this embodiment, by employing a single-input dual-output waveguide structure, binocular imaging can be achieved with only one input light source. Compared to the traditional dual-input dual-output structure, this significantly reduces the number of light sources required by the device, thereby reducing its size and weight. Furthermore, through a reasonable grating layout and design, it ensures that the images received by the human eyes can be directly fused, improving imaging quality and the user's visual experience. This represents a significant improvement over existing AR glasses waveguide technology.

[0040] Example 2: Refer to Figure 2 and Figure 3 The difference between this embodiment and embodiment 1 is that the second diffraction element 4 includes a reflective film 42 and a second folding grating 41.

[0041] The insertion grating 2, the first deflection grating 31, and the first output grating 5 are respectively disposed in one exit pupil region 11, and the second deflection grating 41, the second output grating 6, and the reflective film 42 are respectively disposed in another exit pupil region 11. The insertion grating 2, the first deflection grating 31, and the first output grating 5 are distributed counterclockwise, and the reflective film 42, the second deflection grating 41, and the second output grating 6 are distributed clockwise.

[0042] The reflective film 42 and the coupling grating 2 are mirror-symmetrical about the central axis of the waveguide substrate 1, which facilitates the symmetry of the light propagation path and improves the consistency of imaging. In this embodiment, the reflective film 42 is usually made of a metal or dielectric material with high reflectivity, so that light can be reflected to the second deflection grating 41 by the reflective film 42, thereby realizing the propagation of light and imaging.

[0043] The implementation principle of Example 2 is as follows: When light is emitted from the micro-image source 7, it is collimated and amplified by the collimating optical system, enters the waveguide substrate 1 through the coupling grating 2, and then passes through the first deflection grating 31 for deflection and pupil expansion transmission, reaching the first coupling grating 5 and diffracting out the waveguide image. At the same time, some light passes through the waveguide substrate 1 to reach the reflective film 42, is reflected by the reflective film 42, is processed by the second deflection grating 41, and is finally diffracted out by the second coupling grating 6 to form the waveguide image.

[0044] This embodiment alters the light propagation path by incorporating a reflective film 42, effectively avoiding excessive structures in the waveguide's center. This allows the coupling grating 2 to be positioned on one side of the exit pupil region 11 instead of in the middle, thus significantly reducing interference from the overall structure on the user's forehead and improving the wearing experience. Furthermore, through a well-designed grating layout and the reflective film 42, the single-input dual-output function is still maintained, achieving excellent binocular imaging.

[0045] Example 3: Reference Figure 2 and Figure 4 The difference between this embodiment and embodiment 1 is that the first diffraction element 3 includes a first array beam splitting film 32, and the second diffraction element 4 includes a reflective film 42 and a second array beam splitting film 43.

[0046] The input grating 2, the first array beam splitter 32, and the first output grating 5 are respectively disposed in one exit pupil region 11, and the second array beam splitter 43, the second output grating 6, and the reflective film 42 are respectively disposed in another exit pupil region 11. The input grating 2, the first array beam splitter 32, and the first output grating 5 are distributed counterclockwise, and the reflective film 42, the second array beam splitter 43, and the second output grating 6 are distributed clockwise.

[0047] The first array beam splitter 32 and the second array beam splitter 43 are array structures composed of multiple beam splitting units. They can split and guide light, so that the light propagates more uniformly in the waveguide, thereby improving the light efficiency and exit pupil uniformity.

[0048] The reflective film 42 is mirror-symmetrical to the coupling grating 2 about the central axis of the waveguide substrate 1, and is used to reflect light to the second array beam splitter 43, thereby realizing the propagation and imaging of light.

[0049] The implementation principle of Example 3 is as follows: When the light emitted from the micro-image source 7 is collimated and amplified by the collimating optical system, it enters the waveguide substrate 1 through the coupling grating 2. The first array beam splitter 32 splits and guides the light, making it propagate more uniformly to the first output grating 5 and diffract out the waveguide image. At the same time, some light passes through the waveguide substrate 1 to reach the reflective film 42, is reflected, and then processed by the second array beam splitter 43, and finally diffracted out by the second output grating 6 to form the waveguide image.

[0050] This embodiment uses an array beam-splitting film instead of a traditional deflection grating, which better controls the propagation and distribution of light, improves light efficiency and exit pupil uniformity, resulting in clearer and more stable imaging. Combined with the reflective film 42, it effectively reduces interference from the overall structure's wrapping around the forehead, enhancing the user experience.

[0051] Example 4: Reference Figure 2 and Figure 5 The difference between this embodiment and embodiment 1 is that the first diffraction element 3 and the second diffraction element 4 are not provided.

[0052] The first and second output gratings 5 ​​and 6 are respectively disposed in the two exit pupil regions 11 and are symmetrically arranged about the input grating 2. Both the first and second output gratings 5 ​​and 6 are formed by stacking three volume holographic gratings with different grating vector directions. In this embodiment, the volume holographic grating is a reflective polarization volume holographic grating, which can effectively diffract and process light, achieving a simpler structure, higher grating diffraction efficiency, and better image quality.

[0053] The implementation principle of Example 4 is as follows: When working, the light emitted by the micro-image source 7 is collimated and amplified by the collimating optical system, then diffracted into the waveguide through the coupling grating 2, and then transmitted in two directions to the first coupling grating 5 and the second coupling grating 6 on both sides respectively. The composite holographic grating in the two coupling gratings then diffracts the light out of the waveguide to form an image, which is finally received by the human eye.

[0054] This embodiment simplifies the waveguide structure and improves the diffraction efficiency of the grating by using three volume holographic gratings with different grating vector directions to form a coupling grating, resulting in a significant improvement in image quality. This structural design provides a new solution for waveguide technology in AR glasses and has better application prospects.

[0055] This application also discloses a design method for a binocular waveguide.

[0056] Reference Figure 1 and Figure 2 A design method for a binocular waveguide includes the following steps: S1. A waveguide substrate 1 is provided, and two symmetrically distributed exit pupil regions 11 are defined on the waveguide substrate 1. In this step, the approximate location and size range of the exit pupil regions 11 need to be determined based on the overall design requirements of the AR glasses and the visual characteristics of the human eye. Optical simulation software or experimental testing methods can be used to ensure the rationality and accuracy of the exit pupil regions 11.

[0057] S2, determine the positions of the first coupling grating 5 and the second coupling grating 6 on the waveguide substrate 1, so that the first coupling grating 5 and the second coupling grating 6 are respectively set in the exit pupil region 11 and symmetrically arranged.

[0058] S3, a first diffraction element 3 and a second diffraction element 4 are provided. In this embodiment, the first diffraction element 3 includes a first folding grating 31, and the second diffraction element 4 includes a second folding grating 41.

[0059] S4, determine the position of the coupling grating 2 so that the coupling grating 2 is located on the central axis of the waveguide substrate 1, and determine the positions of the first deflection grating 31 and the second deflection grating 41 according to the positions of the coupling grating 2, the first deflection grating 5 and the second deflection grating 6.

[0060] S41, establish a rectangular coordinate system with the center of the coupled grating 2 as the origin O, with the horizontal direction as the X-axis and the vertical direction as the Y-axis; determine the positions of the first coupled grating 5 and the second coupled grating 6 according to the size of the first coupled grating 5, the size of the second coupled grating 6, and the distance between the center of the first coupled grating 5 and the center of the second coupled grating 6.

[0061] In this embodiment, based on the design consideration of an average distance between the two pupils of an adult, the center distance between the first output grating 5 and the second output grating 6 is set to 64mm, and the vertical distance between the center of the input grating 2 and the center of the output grating is in the range of 11.5-14.5, with the specific values ​​adapted to the lens frame design.

[0062] S42, using calculation formulas to determine each vertex of the first turning grating 31, and the coupling efficiency of the coupling grating 2 in each state corresponding to each set of coordinates.

[0063] Specifically, the horizontal and vertical coordinates of the four vertices of the first angular grating 31 are set as F(1,1), F(1,2); F(2,1), F(2,2); F(3,1), F(3,2); and F(4,1), F(4,2), respectively. The formula for calculating the position coordinates of each vertex of the first angular grating 31 is as follows: First, calculate the horizontal and vertical propagation angles α of the light rays coupled from the coupling grating 2 into the waveguide substrate 1. x and a y .

[0064] (1) (2) Next, calculate the coefficient matrices A, B, and C.

[0065] (3) (4) (5) Finally, the position coordinates of each vertex of the first angular grating 31 are calculated.

[0066] (6) (7) (8) (9) (10) (11) (12) (13) Where a1 and a2 are the half-field angles in the horizontal and vertical directions, respectively. λ and Λ are the grating exposure wavelength and grating period, respectively. inx and iny are the center coordinates of the coupled grating 2, outx and outy are the center coordinates of the coupled grating 2, inw and inh are the width and height of the coupled grating 2, and outw and outh are the width and height of the coupled grating 2.

[0067] Furthermore, the width and height of the coupling grating are calculated from the exit pupil distance d, the half-field angles a1 and a2 in the horizontal and vertical directions, and the exit pupil sizes Ex and Ey in the horizontal and vertical directions. The specific calculation formulas are as follows: ; .

[0068] Since the rectangular coordinate system is established with the midpoint of the coupled grating 2 as the origin, the center coordinates (inx, iny) of the coupled grating 2 are (0,0).

[0069] S5. Calculate the coupling efficiency for each set of position coordinates using VirtualLab (optical modeling platform) simulation software. Determine the position coordinates corresponding to the maximum coupling efficiency as the position coordinates of each vertex of the first deflection grating 31.

[0070] Furthermore, since the second transition grating 41 is symmetrically arranged with the first transition grating 31, the position coordinates of each vertex of the second transition grating 41 can also be determined after the position coordinates of the first transition grating 31 are determined. Having determined the position coordinates of the first transition grating 31 and the second transition grating 41, the dimensions of the first transition grating 31 can be designed by connecting each point of the first transition grating 31 with straight lines. The actual size of the first transition grating 31 must not be smaller than the size of the quadrilateral formed by connecting the straight lines; that is, the actual size of the first transition grating 31 must not be smaller than the theoretical size of the designed first transition grating 31, in order to maximize the utilization of light.

[0071] It should be noted that the calculation method described in this embodiment is mainly used to calculate the coordinates of the first folding grating 31 and the second folding grating 41 in Embodiment 1 and Embodiment 2, and can also be used to calculate the coordinates of the first array beam splitter 32 and the second array beam splitter 43 in Embodiment 3.

[0072] This application also discloses a design method for a binocular waveguide.

[0073] Reference Figure 5 A design method for a binocular waveguide includes the following steps: A waveguide substrate 1 is provided, and two symmetrically distributed exit pupil regions 11 are defined on the waveguide substrate 1; Determine the position of the coupling grating 2 so that it is located on the central axis of the waveguide substrate 1; The positions of the first coupling grating 5 and the second coupling grating 6 on the waveguide substrate 1 are determined so that the first coupling grating 5 and the second coupling grating 6 are respectively set in the exit pupil region 11 and are symmetrically arranged; Furthermore, both the first coupling grating 5 and the second coupling grating 6 are formed by stacking three volume holographic gratings with different grating vector directions. Specifically, reflective polarization volume holographic gratings can be used. The formulas for calculating the grating vectors of the three volume holographic gratings are as follows: The grating vectors of the three gratings are set as follows: According to Bragg's formula, we know that: , ; , , ; in, The wavelength in a vacuum. For the grating period, Let be the incident angle of the second beam relative to the holographic plate. Let be the refractive index of the grating medium. It is the angle of refraction.

[0074] The above calculations can obtain the grating vectors of the three volume holographic gratings that make up the first coupling grating 5 and the second coupling grating 6, which makes it easier to manufacture the first coupling grating 5 and the second coupling grating 6 that meet the requirements, so as to ensure high-quality binocular imaging effect.

[0075] This application also discloses an AR glasses embodiment.

[0076] Reference Figure 2 An AR glasses system includes a micro-image source 7 and the binocular waveguide described above. The micro-image source 7 is positioned directly opposite the coupling grating 2, allowing the image beam emitted from the micro-image source 7 to be coupled into the coupling grating 2. In one specific embodiment, the image light emitted from the micro-image source 7 is perpendicularly coupled into the coupling grating 2.

[0077] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A binocular waveguide, characterized in that, include: Waveguide substrate (1), on which two exit pupil regions (11) are symmetrically distributed. as well as The waveguide substrate (1) is equipped with an input grating (2), a first diffraction element (3), a second diffraction element (4), a first output grating (5), and a second output grating (6). The input grating (2) is disposed on the waveguide substrate (1). The first diffraction element (3) and the first output grating (5) are respectively disposed in one of the exit pupil regions (11). The second diffraction element (4) and the second output grating (6) are respectively disposed in another exit pupil region (11). After the incident light is coupled into the waveguide substrate (1) through the input grating (2), it can be transmitted to the first diffraction element (3) and the second diffraction element (4) respectively.

2. The binocular waveguide according to claim 1, characterized in that: The coupling grating (2) is disposed on the central axis of the waveguide substrate (1). The first diffraction element (3) includes a first bend grating (31), and the second diffraction element (4) includes a second bend grating (41). The first bend grating (31) and the second bend grating (41) are respectively disposed in the two exit pupil regions (11). Starting from the coupling grating (2), the coupling grating (2), the first turning grating (31) and the first coupling grating (5) are distributed counterclockwise, and the coupling grating (2), the second turning grating (41) and the second coupling grating (6) are distributed clockwise.

3. The binocular waveguide according to claim 1, characterized in that: The first diffraction element (3) includes a first folding grating (31), and the second diffraction element (4) includes a reflective film (42) and a second folding grating (41). The coupling-in grating (2), the first folding grating (31) and the first coupling-out grating (5) are respectively disposed in one of the exit pupil regions (11), and the second folding grating (41), the second coupling-out grating (6) and the reflective film (42) are respectively disposed in another of the exit pupil regions (11). The coupling-in grating (2), the first folding grating (31) and the first coupling-out grating (5) are distributed counterclockwise, and the reflective film (42), the second folding grating (41) and the second coupling-out grating (6) are distributed clockwise.

4. The binocular waveguide according to claim 1, characterized in that: The first diffraction element (3) includes a first array beam splitter (32), and the second diffraction element (4) includes a reflective film (42) and a second array beam splitter (43). The coupling grating (2), the first array beam splitter (32) and the first coupling grating (5) are respectively disposed in one exit pupil region (11), and the second array beam splitter (43), the second coupling grating (6) and the reflective film (42) are respectively disposed in another exit pupil region (11). The coupling grating (2), the first array beam splitter (32) and the first coupling grating (5) are distributed counterclockwise, and the reflective film (42), the second array beam splitter (43) and the second coupling grating (6) are distributed clockwise.

5. A binocular waveguide, characterized in that, include: Waveguide substrate (1), on which two exit pupil regions (11) are symmetrically distributed. as well as The waveguide substrate (1) has an input grating (2), a first output grating (5), and a second output grating (6). The input grating (2) is disposed on the central axis of the waveguide substrate (1). The first output grating (5) and the second output grating (6) are respectively disposed in the two exit pupil regions (11). The first output grating (5) and the second output grating (6) are both formed by combining three volume holographic gratings with different grating vector directions.

6. A method for designing a binocular waveguide, used to design a binocular waveguide as described in any one of claims 1-4, characterized in that, Includes the following steps: A waveguide substrate (1) is provided, and two symmetrically distributed exit pupil regions (11) are defined on the waveguide substrate (1). The positions of the first coupling grating (5) and the second coupling grating (6) on the waveguide substrate (1) are determined so that the first coupling grating (5) and the second coupling grating (6) are respectively disposed in the exit pupil region (11) and symmetrically disposed; Provide a first diffraction element (3) and a second diffraction element (4); The position of the coupling grating (2) is determined to be on the central axis of the waveguide substrate (1). The first diffraction element (3) includes a first bend grating (31), and the second diffraction element (4) includes a second bend grating (41). The positions of the first bend grating (31) and the second bend grating (41) are determined according to the positions of the coupling grating (2), the first coupling grating (5), and the second coupling grating (6); or The position of the coupling grating (2) is determined to be located in one of the exit pupil regions (11). The first diffraction element (3) includes a first folding grating (31), and the second diffraction element (4) includes a reflective film (42) and a second folding grating (41). The positions of the first folding grating (31) and the second folding grating (41) are determined according to the positions of the coupling grating (2), the first exiting grating (5), and the second exiting grating (6). The reflective film (42) is symmetrically arranged with respect to the coupling grating (2); or The position of the coupling grating (2) is determined to be located in one of the exit pupil regions (11). The first diffraction element (3) includes a first array beam splitter (32), and the second diffraction element (4) includes a reflective film (42) and a second array beam splitter (43). The positions of the first array beam splitter (32) and the second array beam splitter (43) are determined according to the positions of the coupling grating (2), the first output grating (5), and the second output grating (6). The reflective film (42) is symmetrically arranged with the coupling grating (2).

7. The design method for a binocular waveguide according to claim 6, characterized in that: The positions of the first transition grating (31) and the second transition grating (41), or the positions of the first array beam splitter (32) and the second array beam splitter (43), are determined based on the positions of the coupling-in grating (2), the first coupling-out grating (5), and the second coupling-out grating (6), including the following steps: A rectangular coordinate system is established with the center of the coupled grating (2) as the origin O, with the horizontal direction as the X-axis and the vertical direction as the Y-axis; The positions of the first coupling grating (5) and the second coupling grating (6) are determined based on the size of the first coupling grating (5), the size of the second coupling grating (6), and the distance between the center of the first coupling grating (5) and the center of the second coupling grating (6); The vertices of the first transition grating (31) are determined using calculation formulas, and the coupling efficiency of the coupling grating (2) is determined in each state corresponding to a set of coordinates; and The position coordinates corresponding to the maximum coupling efficiency are determined as the position coordinates of each vertex of the first folding grating (31).

8. The design method for a binocular waveguide according to claim 7, characterized in that: Let the horizontal and vertical coordinates of the four vertices of the first angular grating (31) be F(1,1), F(1,2); F(2,1), F(2,2); F(3,1), F(3,2); and F(4,1), F(4,2), respectively. Then the formula for calculating the position coordinates of each vertex of the first angular grating (31) is as follows: ；（1） ；（2） ；（3） ；（4） ；（5） ；（6） ；（7） ；（8） ；（9） ；（10） ；（11） ；（12） ；（13） Among them, a x a y Let a1 and a2 be the horizontal and vertical propagation angles of light coupled from the coupling grating (2) into the waveguide substrate (1), respectively. Let a1 and a2 be the half-field angles in the horizontal and vertical directions, respectively. Let λ and Λ be the grating exposure wavelength and grating period, respectively. Let inx and iny be the center coordinates of the coupling grating (2), and outx and outy be the center coordinates of the coupling grating. Let inw and inh be the width and height of the coupling grating (2), and outw and outh be the width and height of the coupling grating. The width and height of the coupling grating are calculated from the exit pupil distance d, the half-field angles in the horizontal and vertical directions a1 and a2, and the exit pupil sizes Ex and Ey in the horizontal and vertical directions. The specific calculation formula is as follows: ； 。 9. A design method for a binocular waveguide, used to design the binocular waveguide as described in claim 5, characterized in that, Includes the following steps: A waveguide substrate (1) is provided, and two symmetrically distributed exit pupil regions (11) are defined on the waveguide substrate (1). Determine the position of the coupling grating (2) so that the coupling grating (2) is located on the central axis of the waveguide substrate (1); The positions of the first coupling grating (5) and the second coupling grating (6) on the waveguide substrate (1) are determined so that the first coupling grating (5) and the second coupling grating (6) are respectively disposed in the exit pupil region (11) and symmetrically disposed; Furthermore, both the first coupling grating (5) and the second coupling grating (6) are formed by combining three volume holographic gratings with different grating vector directions. The formula for calculating the grating vectors of the three volume holographic gratings is as follows: The grating vectors of the three gratings are set as follows: According to Bragg's formula, we know that: ， ； ； ； ； in, The wavelength in a vacuum. For the grating period, Let be the incident angle of the second beam relative to the holographic plate. Let be the refractive index of the grating medium. It is the angle of refraction.

10. An AR glasses, characterized in that, Includes a micro-image source (7) and a binocular waveguide as described in any one of claims 1-5, wherein the image beam emitted by the micro-image source (7) can be coupled into a coupling grating (2).

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