Diffraction optical waveguide, preparation method thereof and head-mounted display equipment

Abstract

The invention discloses a diffractive optical waveguide and a preparation method thereof, and a head-mounted display device, and relates to the technical field of augmented reality, and the preparation method of the diffractive optical waveguide comprises the steps: obtaining a target eye box range adaptive to a target crowd; according to the human eye parameters of each user group in the target group, splitting the target eye box range to obtain sub-eye box ranges adapted to each user group; diffractive optical waveguides adapted to the user groups are prepared based on the sub-eye box ranges, and the area of a coupled-out grating in each diffractive optical waveguide is smaller than the area of a coupled-out grating of an optical waveguide designed for covering the target eye box range. The optical efficiency and uniformity of the diffractive optical waveguide can be ensured, and the diffractive optical waveguide is prevented from generating obvious rainbow lines, so that the use experience of a user is improved.

Description

Technical Field

[0001] This application relates to the field of augmented reality technology, and in particular to a diffractive waveguide and its fabrication method, and a head-mounted display device. Background Technology

[0002] Diffractive waveguides are one of the mainstream technologies for realizing augmented reality. The basic principle is that the image projected by the optomechanical system is coupled into the waveguide substrate through a coupling grating, and then transmitted within the waveguide substrate through total internal reflection. Finally, it is coupled out through a coupling grating and enters the human eye to form an image.

[0003] Currently, in order to obtain a larger eyebox to accommodate different users' interpupillary distances, nose bridge heights, and eye movement ranges, diffractive waveguides typically require a large coupling grating area. However, a large coupling grating area makes it difficult to improve the optical efficiency and uniformity of the diffractive waveguide and easily produces noticeable rainbow patterns, affecting the user experience. Summary of the Invention

[0004] The main purpose of this application is to provide a diffractive waveguide and its fabrication method, as well as a head-mounted display device, which aims to ensure the optical efficiency and uniformity of the diffractive waveguide and avoid the generation of obvious rainbow patterns in the diffractive waveguide, so as to improve the user experience.

[0005] This application provides a method for fabricating a diffractive optical waveguide, the method comprising:

[0006] Obtain the target eye box range suitable for the target audience; Based on the human eye parameters of each user group in the target population, the target eye box range is divided to obtain the sub-eye box range adapted to each user group; Based on the range of each sub-eyebox, a diffractive optical waveguide adapted to each user group is prepared, wherein the area of ​​the coupling grating in each diffractive optical waveguide is smaller than the area of ​​the coupling grating of the optical waveguide designed to cover the range of the target eyebox.

[0007] In one embodiment, the human eye parameters include pupillary distance and / or bridge of the nose height; The step of dividing the target eye box range according to the human eye parameters of each user group in the target population to obtain a sub-eye box range suitable for each user group includes: Based on the pupillary distance of each user group, the target eye box range is divided into multiple sub-eye box ranges along the horizontal direction to adapt to the pupillary distance of different user groups; And / or, based on the nose bridge height of each of the user groups, the target eye box range is divided into multiple sub-eye box ranges in the vertical direction to adapt to the nose bridge height of different user groups.

[0008] In one embodiment, when the diffractive waveguide includes an input grating and an output grating, the step of fabricating a diffractive waveguide adapted to each of the user groups based on the range of each of the sub-eyeboxes includes: Based on the preset mapping relationship between the eyebox range and the coupling grating design parameters, the coupling grating design parameters corresponding to each of the sub-eyebox ranges are obtained. The coupling grating design parameters include the layout position of the coupling grating on the waveguide substrate, the shape of the coupling grating, and the geometric dimensions. Based on the design parameters of the coupling grating corresponding to the range of each sub-eyebox, each diffractive waveguide containing the coupling grating is fabricated; Among them, the coupling gratings in the corresponding diffraction waveguides of two adjacent sub-eyeboxes have overlapping areas in terms of layout.

[0009] In one embodiment, the method further includes: For two adjacent sub-eyebox ranges in the horizontal direction, obtain the pupil diameter of the user group associated with the two sub-eyebox ranges; Based on the pupil diameters of the two user groups, determine the layout position of the coupling grating in the diffraction waveguide corresponding to the range of the two sub-eye boxes, and the width of the overlapping area in the horizontal direction. Wherein, the width is greater than the average of the two pupil diameters.

[0010] In one embodiment, the method further includes: For two adjacent sub-eyebox ranges in the vertical direction, obtain the pupil diameter of the user group associated with the two sub-eyebox ranges; Based on the pupil diameters of the two user groups, determine the layout position of the coupling grating in the diffraction waveguide corresponding to the range of the two sub-eye boxes, and the height of the overlapping area in the vertical direction. Wherein, the height is greater than the average of the two pupil diameters.

[0011] In one embodiment, when the diffractive waveguide includes an input grating, an output grating, and a transition grating, the step of fabricating a diffractive waveguide adapted to each of the user groups based on the range of each of the sub-eyeboxes includes: Based on the preset mapping relationship between the eyebox range and the coupling grating design parameters, the coupling grating design parameters corresponding to each of the sub-eyebox ranges are obtained. The coupling grating design parameters include the layout position of the coupling grating on the waveguide substrate, the shape of the coupling grating, and the geometric dimensions. For any sub-eyebox range, based on the sub-eyebox range and the corresponding output grating design parameters, the light propagation path between the input grating and the output grating corresponding to the sub-eyebox range is determined; Based on the light propagation path, the design parameters of the transition grating corresponding to the sub-eye box range are determined. The design parameters of the transition grating include the layout position of the transition grating on the waveguide substrate, the shape of the transition grating, and its geometric dimensions. Based on the design parameters of the coupling grating and the transition grating corresponding to the sub-eyebox range, the diffractive waveguide comprising the coupling grating and the transition grating is fabricated. Among them, the coupling gratings in the corresponding diffraction waveguides of two adjacent sub-eyeboxes have overlapping areas in terms of layout position, and the turning gratings in the corresponding diffraction waveguides also have overlapping areas in terms of layout position.

[0012] In addition, to achieve the above objectives, this application also provides a diffractive optical waveguide, which is prepared by the diffractive optical waveguide preparation method described above.

[0013] In one embodiment, the area of ​​the coupling grating in the diffractive waveguide is greater than 64 square millimeters and less than 225 square millimeters.

[0014] In one embodiment, the area of ​​the coupling grating in the diffractive waveguide is greater than 64 square millimeters and less than three-quarters of the area of ​​the coupling grating of the waveguide designed to cover the target eye box area.

[0015] In addition, to achieve the above objectives, this application also provides a head-mounted display device, which includes a device body and a diffractive waveguide as described above, wherein the diffractive waveguide is disposed on the device body.

[0016] This application provides a method for fabricating a diffractive optical waveguide, comprising: obtaining a target eye box range adapted to a target population; dividing the target eye box range according to the human eye parameters of each user group in the target population to obtain sub-eye box ranges adapted to each user group; and fabricating a diffractive optical waveguide adapted to each user group based on each sub-eye box range, wherein the area of ​​the coupling grating in each diffractive optical waveguide is smaller than the area of ​​the coupling grating of the optical waveguide designed to cover the target eye box range.

[0017] Therefore, the technical solution provided in this application, by targeting each user group within the target population and utilizing their respective human eye parameters, divides the target eye box range into their respective suitable sub-eye box ranges, and accordingly prepares diffractive waveguides adapted to each sub-eye box range. Furthermore, the area of ​​the coupling grating in each prepared diffractive waveguide is smaller than the size required to fit the complete target eye box range, thereby significantly reducing the actual working area of ​​the coupling grating on each prepared diffractive waveguide. This ensures that the prepared diffractive waveguides not only adapt to the corresponding user group but also possess high optical efficiency and light emission uniformity, and significantly suppress rainbow patterns caused by excessively large grating areas, thus improving the user experience.

[0018] In summary, the technical solution provided in this application can ensure the optical efficiency and uniformity of the diffractive waveguide and avoid the generation of obvious rainbow patterns in the diffractive waveguide, thereby improving the user experience. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0020] Figure 1 A schematic flowchart illustrating the fabrication method of the diffractive optical waveguide provided in the first embodiment of this application; Figure 2 A schematic diagram illustrating the principle of horizontally dividing the target eye box area according to the first embodiment of this application; Figure 3 A schematic diagram illustrating the vertical division of the target eye box area according to the first embodiment of this application; Figure 4 A schematic diagram illustrating the principle of dividing the target eye box area along the horizontal and vertical directions, as provided in the first embodiment of this application; Figure 5 A diagram showing the relationship between the region where rainbow patterns are generated and the grating area, provided in the first embodiment of this application; Figure 6 The diagram shows the structure of the diffractive waveguide designed for the target eye box range and the diffractive waveguide designed for the sub-eye box range, as provided in the first embodiment of this application.

[0021] The purpose, features, and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0022] It should be understood that the specific embodiments described herein are merely illustrative of the technical solutions of this application and are not intended to limit this application.

[0023] To better understand the technical solution of this application, a detailed description will be provided below in conjunction with the accompanying drawings and specific implementation methods.

[0024] Diffractive waveguides are one of the mainstream technologies for realizing augmented reality. The basic principle is that the image projected by the optomechanical system is coupled into the waveguide substrate through a coupling grating, and then transmitted within the waveguide substrate through total internal reflection. Finally, it is coupled out through a coupling grating and enters the human eye to form an image.

[0025] Currently, in order to obtain a larger eyebox to accommodate different users' interpupillary distances, nose bridge heights, and eye movement ranges, diffractive waveguides typically require a large coupling grating area. However, a large coupling grating area makes it difficult to improve the optical efficiency and uniformity of the diffractive waveguide and easily produces noticeable rainbow patterns, affecting the user experience.

[0026] Based on this, this application provides a method for fabricating a diffractive optical waveguide, comprising: obtaining a target eye box range adapted to a target population; dividing the target eye box range according to the human eye parameters of each user group in the target population to obtain sub-eye box ranges adapted to each user group; and fabricating a diffractive optical waveguide adapted to each user group based on each sub-eye box range, wherein the area of ​​the coupling grating in each diffractive optical waveguide is smaller than the area of ​​the coupling grating of the optical waveguide designed to cover the target eye box range.

[0027] Therefore, the technical solution provided in this application, by targeting each user group within the target population and utilizing their respective human eye parameters, divides the target eye box range into their respective suitable sub-eye box ranges, and accordingly prepares diffractive waveguides adapted to each sub-eye box range. Furthermore, the area of ​​the coupling grating in each prepared diffractive waveguide is smaller than the size required to fit the complete target eye box range, thereby significantly reducing the actual working area of ​​the coupling grating on each prepared diffractive waveguide. This ensures that the prepared diffractive waveguides not only adapt to the corresponding user group but also possess high optical efficiency and light emission uniformity, and significantly suppress rainbow patterns caused by excessively large grating areas, thus improving the user experience.

[0028] In summary, the technical solution provided in this application can ensure the optical efficiency and uniformity of the diffractive waveguide and avoid the generation of obvious rainbow patterns in the diffractive waveguide, thereby improving the user experience.

[0029] This application presents a method for fabricating a diffractive optical waveguide according to the first embodiment. Please refer to [link / reference]. Figure 1 The fabrication method of the diffractive optical waveguide may include steps S10~S30: Step S10: Obtain the target eye box range suitable for the target audience; It should be noted that the target audience refers to a set of potential users with common usage scenarios or physiological characteristics, such as all possible wearers of a specific head-mounted display device, users in Asia, etc. This embodiment does not specifically limit this. The target eye box range refers to the maximum spatial area required to ensure that the pupils of all individuals in the target audience can receive a complete display image under different usage states (such as eye movement, minor adjustments to the wearing position).

[0030] When obtaining the target eye box range suitable for the target population, statistical data (such as minimum, maximum, and average values) of key human eye parameters (such as pupillary distance, nasal bridge height, and orbital depth) of the target population can be determined through demographic data or product positioning. Then, using the optomechanical parameters of the head-mounted display device (such as field of view and exit pupil distance) and ergonomic requirements (such as permissible eye movement range), optical geometric calculations are used to map the statistical data of the key human eye parameters of the target population to the target eye box range. Alternatively, mature products or general optical design specifications designed for similar target populations in the industry can be referenced to determine the target eye box range suitable for the target population. This embodiment does not specifically limit the implementation method of step S10.

[0031] Step S20: Based on the human eye parameters of each user group in the target population, the target eye box range is divided to obtain the sub-eye box range adapted to each user group. It should be noted that the user group refers to a subset of the target population that has more similar physiological characteristics, further subdivided based on one or more human eye parameters (such as a specific range of pupillary distance or nose bridge height). For example, a subset of users with a pupillary distance of 62mm to 64mm. The sub-eyebox range refers to an eyebox range specifically adapted to a particular user group, separated from the target eyebox range. Each sub-eyebox range is smaller than the target eyebox range. Human eye parameters refer to key geometric and physical quantities used to describe the physiological characteristics of the user group's eyes and their interaction with the optical system when wearing a head-mounted display device. These parameters may include, but are not limited to, pupillary distance, nose bridge height, and / or pupil diameter. This embodiment does not specifically limit these parameters. Specifically, pupillary distance refers to the horizontal distance between the centers of the user's pupils; nose bridge height refers to the vertical distance or height difference from the nose bridge support point (the position of the nose pads on glasses) to the center of the pupil or a specific eye reference point when the user is wearing a head-mounted display device; and pupil diameter refers to the opening size of the human pupil under specific lighting conditions.

[0032] In one feasible implementation, the human eye parameters may include pupil distance and / or nose bridge height. Step S20 may include: dividing the target eye box range into multiple sub-eye box ranges in the horizontal direction based on the pupil distance of each user group to adapt to the pupil distance of different user groups; and / or, dividing the target eye box range into multiple sub-eye box ranges in the vertical direction based on the nose bridge height of each user group to adapt to the nose bridge height of different user groups.

[0033] When dividing the target eye box area into multiple sub-eye box areas horizontally based on the pupillary distance of each user group, the number of sub-eye box areas required for the target eye box area to be divided, as well as the horizontal span of the division, can be determined using the pupillary distance of each user group. During the division process, to ensure a good experience for users at the boundaries of adjacent pupillary distance intervals, adjacent sub-eye box areas can be kept to overlap horizontally. Furthermore, considering that the number of people with different pupillary distances approximates a normal distribution, it is preferable to divide the horizontally into an odd number of sub-eye box areas. This ensures that the middle sub-eye box area corresponds to the pupillary distance of the most people and is centrally located.

[0034] Similarly, when dividing the target eye box area into multiple sub-eye box areas vertically based on the nose bridge height of each user group, the number of sub-eye box areas needed to be obtained from the target eye box area, as well as the vertical span during division, can be determined using the nose bridge height of each user group. During the division process, to ensure a good experience for users at the boundaries of adjacent nose bridge height ranges, adjacent sub-eye box areas can be made to overlap to a certain extent vertically.

[0035] For example, to help understand the sub-eyebox ranges obtained by using horizontal segmentation, vertical segmentation, and simultaneous horizontal and vertical segmentation, specifically: Please refer to Figure 2 The target eye box area can be divided into sub-eye box areas A1, A2, and A3 by splitting the target eye box area horizontally. Please refer to Figure 3 The target eye box area can be divided vertically into sub-eye box area B1, sub-eye box area B2 and sub-eye box area B3; Please refer to Figure 4 At the same time, the target eye box area can be divided into sub-eye box areas C1~C9 by splitting it along the horizontal and vertical directions.

[0036] It should be noted that the above examples are only for the purpose of assisting in understanding this application and do not constitute a limitation on the fabrication method of the diffractive waveguide of this application.

[0037] Step S30: Based on the range of each sub-eye box, prepare diffractive waveguides adapted to each user group, wherein the area of ​​the coupling grating in each diffractive waveguide is smaller than the area of ​​the coupling grating of the waveguide designed to cover the target eye box range.

[0038] Understandably, because the area of ​​the coupling grating of the diffractive waveguide fabricated using the sub-eyebox area is smaller than the area of ​​the coupling grating of the waveguide designed to cover the target eyebox area, the area that can produce rainbow patterns can be significantly reduced or even eliminated in actual use, thereby improving the user experience. See [link to relevant documentation] for details. Figure 5 ,Depend on Figure 5 It can be seen that as the area of ​​the coupling grating decreases, the area in which it can produce rainbow patterns will also be greatly reduced.

[0039] In one feasible implementation, when the diffractive waveguide includes an input grating and an output grating, step S30 may include steps S31-S32: Step S31: Based on the preset mapping relationship between the eye box range and the coupling grating design parameters, obtain the coupling grating design parameters corresponding to each sub-eye box range. The coupling grating design parameters include the layout position of the coupling grating on the waveguide substrate, the shape of the coupling grating, and the geometric dimensions. Step S32: Based on the design parameters of the coupling grating corresponding to the range of each sub-eyebox, fabricate each diffraction waveguide containing the coupling grating; Among them, the coupling gratings in the corresponding diffraction waveguides of two adjacent sub-eyeboxes have overlapping areas in terms of layout.

[0040] It should be noted that the mapping relationship between the eyebox range and the coupling grating design parameters refers to the correspondence established through preliminary optical design, simulation, and verification. This correspondence describes the relationship between the eyebox range and the key attributes of the coupling grating required to achieve that eyebox range. The mapping relationship can be recorded using databases, function models, or other methods; this embodiment does not impose specific limitations on it. The shapes of the coupling gratings corresponding to each sub-eyebox range can be the same or different; this embodiment does not impose specific limitations on this. The shape of the coupling grating corresponding to each sub-eyebox range can be quadrilateral, chamfered rectangle, oval, etc., and can be flexibly set according to the specific sub-eyebox range; this embodiment does not impose specific limitations on this.

[0041] When obtaining the coupling grating design parameters corresponding to each sub-eyebox range based on the preset mapping relationship between the eyebox range and the coupling grating design parameters, when using a database to record the mapping relationship between the eyebox range and the coupling grating design parameters, each sub-eyebox range can be used as an index to search for the corresponding coupling grating design parameters in the database. When using a function model to record the mapping relationship between the eyebox range and the coupling grating design parameters, each sub-eyebox range can be used as model input to determine the coupling grating design parameters corresponding to each sub-eyebox range. This embodiment does not specifically limit the implementation method of step S31.

[0042] This embodiment utilizes the mapping relationship between the eyebox range and the coupling grating design parameters to obtain the coupling grating design parameters corresponding to each sub-eyebox range. Based on this, each diffractive waveguide containing the coupling grating is fabricated. This ensures that the layout, shape, and geometry of the coupling grating designed for each sub-eyebox range are precisely constrained within an optimal range that matches that sub-eyebox range. This allows for the direct customization of dedicated coupling gratings with more compact physical structures and better optical performance for each user group. Furthermore, by limiting the coupling gratings on waveguides fabricated for adjacent sub-eyebox ranges to have overlapping areas, seamless compatibility between diffractive waveguide products of different specifications can be achieved, providing users near parameter boundaries with a continuous and uninterrupted visual experience.

[0043] Furthermore, in one feasible implementation, for two adjacent sub-eyebox ranges in the horizontal direction, the pupil diameter of the user group associated with the two sub-eyebox ranges is obtained; based on the pupil diameter of the two user groups, the layout position of the coupling grating in the diffraction waveguide corresponding to the two sub-eyebox ranges is determined, and the width of the overlapping area in the horizontal direction is determined; wherein, the width is greater than the average value of the two pupil diameters.

[0044] This embodiment limits the layout of the coupling gratings in the diffraction waveguides of two adjacent sub-eyeboxes in the horizontal direction. The width of the overlapping area in the horizontal direction needs to be greater than the average pupil diameter of the user group associated with the two sub-eyeboxes. This ensures that when the user's pupillary distance falls exactly at the boundary of the two sub-eyeboxes, the pupil still has enough space to move in the horizontal direction and can always be covered by the overlapping area. This avoids problems such as loss of field of view, image edge cropping, or sharp decrease in brightness caused by the pupil completely moving out of the effective coupling area.

[0045] In another feasible implementation, for two adjacent sub-eyebox ranges in the vertical direction, the pupil diameter of the user group associated with the two sub-eyebox ranges is obtained; based on the pupil diameter of the two user groups, the layout position of the coupling grating in the diffraction waveguide corresponding to the two sub-eyebox ranges is determined, and the height of the overlapping area in the vertical direction is determined; wherein, the height is greater than the average value of the two pupil diameters.

[0046] This embodiment limits the layout of the coupling gratings in the diffraction waveguides of two adjacent sub-eyeboxes in the vertical direction. The width of the overlapping area in the vertical direction needs to be greater than the average pupil diameter of the user group associated with the two sub-eyeboxes. This ensures that when the user's nose bridge height falls exactly at the boundary of the two sub-eyeboxes, the pupil still has enough room to move in the vertical direction and can always be covered by the overlapping area. This avoids problems such as loss of field of view, image edge cropping, or sharp decrease in brightness caused by the pupil completely moving out of the effective coupling area.

[0047] In another feasible implementation, when the diffractive waveguide includes a coupling grating, a coupling grating, and a transition grating, step S30 may include steps S33-S36: Step S33: Based on the preset mapping relationship between the eyebox range and the coupling grating design parameters, obtain the coupling grating design parameters corresponding to each sub-eyebox range. The coupling grating design parameters include the layout position of the coupling grating on the waveguide substrate, the shape of the coupling grating, and the geometric dimensions. Step S34: For any sub-eye box range, based on the sub-eye box range and the corresponding output grating design parameters, determine the light propagation path between the input grating and the output grating corresponding to the sub-eye box range. It should be noted that the light propagation path refers to the theoretical optical path that the image light travels from the input grating into the waveguide substrate, through total internal reflection inside the waveguide substrate, and finally reaches the output grating. It usually includes geometric information such as the direction of light propagation and the positions where total internal reflection occurs on the upper and lower surfaces of the waveguide.

[0048] When determining the light propagation path between the input and output gratings corresponding to the sub-eyebox range based on the sub-eyebox range and the corresponding output grating design parameters, the starting point can be the preset input grating position, and the ending point can be the output grating layout position determined in step S33. Using geometric optics or a waveguide-based propagation model, the light propagation path that satisfies the total internal reflection condition and effectively guides light from the starting point to the ending point can be calculated. Alternatively, using the preset input grating period, the output grating period determined in step S33, and the incident angle of the incident beam, the diffraction angles of the beam at the input and output gratings 0 are calculated using the grating diffraction equation shown in Equation 1 below. This is then combined with geometric optics for ray tracing calculations to determine the light propagation path.

[0049] Formula 1; in, The angle of incidence, For diffraction angle, Let be the refractive index on the incident side. λ is the refractive index on the diffraction side, m is the diffraction order, and λ is the wavelength of the incident beam. The period is the grating period.

[0050] Step S35: Determine the design parameters of the transition grating corresponding to the sub-eye box range based on the light propagation path. The design parameters of the transition grating include the layout position of the transition grating on the waveguide substrate, the shape of the transition grating, and its geometric dimensions. It should be noted that the shape of the turning grating corresponding to each sub-eye box range can be the same or different, and this embodiment does not make specific limitations on this.

[0051] When determining the design parameters of the transition grating corresponding to the sub-eye box range based on the light propagation path, the light propagation path can first be analyzed and located on the waveguide substrate plane. By analyzing the spatial distribution of all principal rays and boundary rays pointing from the coupling region to the corresponding coupling region, a minimum continuous region that can completely cover the light propagation path can be determined. This region is the initial layout position of the transition grating. Then, based on the initial layout position of the transition grating, the grating parameters can be designed and optimized to determine the design parameters of the transition grating corresponding to the sub-eye box range.

[0052] Step S36: Based on the design parameters of the coupling grating and the transition grating corresponding to the sub-eye box range, fabricate a diffractive waveguide containing the coupling grating and the transition grating. Among them, the coupling gratings in the corresponding diffraction waveguides of two adjacent sub-eyeboxes have overlapping areas in terms of layout position, and the turning gratings in the corresponding diffraction waveguides also have overlapping areas in terms of layout position.

[0053] Similarly, for two adjacent sub-eyeboxes in the horizontal direction, the width of the overlapping region of the corresponding diffraction waveguides in the horizontal direction must also be greater than the average pupil diameter of the user group associated with the two sub-eyeboxes. For two adjacent sub-eyeboxes in the vertical direction, the width of the overlapping region of the corresponding diffraction waveguides in the vertical direction must also be greater than the average pupil diameter of the user group associated with the two sub-eyeboxes.

[0054] For example, please refer to Figure 6 Assuming the target eyebox area is horizontally divided into sub-eyebox area A and sub-eyebox area B along the vertical direction, the grating of the diffraction waveguide designed for sub-eyebox area A can be specifically referred to as the diffraction waveguide M2 ​​in the figure, compared with the diffraction waveguide M1 designed for the target eyebox area in the figure. The grating of the diffraction waveguide designed for sub-eyebox area B can be specifically referred to as the diffraction waveguide M3 in the figure.

[0055] This embodiment utilizes the range of each sub-eyebox and collaboratively designs the coupling grating and the transition grating. This ensures that all internal optical functional units (i.e., coupling grating, transition grating, and coupling grating) of the diffractive waveguide designed for each sub-eyebox range are optimized holistically to achieve high-performance adaptation for that specific eyebox range. Not only is efficiency and uniformity improved by reducing the area of ​​the coupling grating, and rainbow patterns suppressed, but the optimization of the transition grating also ensures efficient utilization and precise guidance of light energy during its propagation within the waveguide, thereby achieving performance improvement at a more complete optical path level. Simultaneously, limiting the overlap between the coupling grating and the transition grating allows for a deeper interweaving and complementarity in the optical functions of diffractive waveguide products manufactured for adjacent groups, providing users near parameter boundaries with a continuous and uninterrupted visual experience.

[0056] The above are only two feasible implementation methods of step S30 provided in this embodiment. This embodiment does not specifically limit the specific implementation method of step S30.

[0057] Based on the above, this embodiment provides a method for fabricating a diffractive optical waveguide, including: obtaining a target eye box range suitable for a target population; dividing the target eye box range according to the human eye parameters of each user group in the target population to obtain sub-eye box ranges suitable for each user group; and fabricating a diffractive optical waveguide suitable for each user group based on each sub-eye box range, wherein the area of ​​the coupling grating in each diffractive optical waveguide is smaller than the area of ​​the coupling grating of the optical waveguide designed to cover the target eye box range.

[0058] Therefore, the technical solution provided in this embodiment, by targeting each user group within the target population and utilizing their respective human eye parameters, divides the target eye box range into their respective suitable sub-eye box ranges, and accordingly prepares diffractive waveguides adapted to each sub-eye box range. Furthermore, the area of ​​the coupling grating in each prepared diffractive waveguide is smaller than the size required to fit the complete target eye box range, thereby significantly reducing the actual working area of ​​the coupling grating on each prepared diffractive waveguide. This ensures that the prepared diffractive waveguides not only adapt to the corresponding user group but also possess high optical efficiency and light emission uniformity, and significantly suppress rainbow patterns caused by excessively large grating areas, thus improving the user experience.

[0059] In summary, the technical solution provided in this embodiment can ensure the optical efficiency and uniformity of the diffractive waveguide and avoid the generation of obvious rainbow patterns in the diffractive waveguide, thereby improving the user experience.

[0060] Furthermore, this application embodiment also provides a diffractive optical waveguide, which is prepared by the diffractive optical waveguide preparation method described in the above embodiment.

[0061] In one feasible implementation, the area of ​​the coupling grating in the diffractive waveguide is greater than 64 square millimeters and less than 225 square millimeters.

[0062] Understandably, considering that the pupil diameter of a normal adult under natural light is typically between 2 and 5 millimeters, and combining this with the design requirements of diffractive waveguides (e.g., a field of view typically greater than 15° and an eye-box distance generally of 18mm), it is clear that to meet the complete imaging needs of a single interpupillary distance user group, the area of ​​the coupling grating usually needs to be greater than 64 square millimeters. This results in a more comfortable viewing experience for the human eye, a relatively complete light spot, and avoids the decrease in MTF (Modulation Transfer Function) caused by an incomplete light spot, thus ensuring image clarity. On the other hand, setting the upper limit of the coupling grating area to less than 225 square millimeters ensures that the area where the coupling grating produces rainbow patterns is small enough, or even non-existent, thereby improving the user experience.

[0063] In another feasible implementation, the area of ​​the coupling grating in the diffracting waveguide is greater than 64 square millimeters and less than three-quarters of the area of ​​the coupling grating of the waveguide designed to cover the target eyebox range.

[0064] This embodiment sets the upper limit of the area of ​​the coupling grating to be less than three-quarters of the area of ​​the coupling grating of the optical waveguide designed to cover the target eyebox range. This ensures that the fabricated diffractive waveguide adapted to each sub-eyebox range not only achieves a significant improvement in optical performance but also maintains a reasonable adaptation range. Specifically, this upper limit means that the area of ​​the sub-grating is at least 25% smaller than the area of ​​the complete grating (i.e., the coupling grating of the optical waveguide designed to cover the target eyebox range). This improves diffraction efficiency and uniformity, while also limiting the area of ​​rainbow patterns that may occur during diffraction. Furthermore, this upper limit ensures that the grating area is not too small, thus retaining sufficient spatial tolerance to cover the corresponding sub-eyebox range and guaranteeing the reliability of adaptation in actual use.

[0065] It is understood that since the above-mentioned fabrication method of diffractive optical waveguide is used in the diffractive optical waveguide, the embodiment of the diffractive optical waveguide includes all the technical solutions of all embodiments of the above-mentioned fabrication method of diffractive optical waveguide, and the technical effects achieved are exactly the same, so they will not be repeated here.

[0066] In addition, this application embodiment also provides a head-mounted display device, which may include a device body and the diffractive waveguide in the above embodiment, the diffractive waveguide being disposed on the device body.

[0067] It should be noted that head-mounted display devices may include, but are not limited to, head-mounted display devices such as Mixed Reality (MR) devices (e.g., MR glasses or MR helmets), Augmented Reality (AR) devices (e.g., AR glasses or AR helmets), Virtual Reality (VR) devices (e.g., VR glasses or VR helmets), Extended Reality (XR) devices, or some combination thereof.

[0068] It is understood that, since the above-mentioned diffractive waveguide is used in the head-mounted display device, the embodiments of the head-mounted display device include all the technical solutions of all the above-mentioned diffractive waveguide embodiments, and the technical effects achieved are exactly the same, so they will not be repeated here.

[0069] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or system that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or system. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or system that includes that element.

[0070] The sequence numbers of the above embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0071] The above are merely preferred embodiments of this application and do not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent scope of this application.

Claims

1. A method for fabricating a diffractive optical waveguide, characterized in that, The method includes: Obtain the target eye box range suitable for the target audience; Based on the human eye parameters of each user group in the target population, the target eye box range is divided to obtain the sub-eye box range adapted to each user group; Based on the range of each sub-eyebox, a diffractive optical waveguide adapted to each user group is prepared, wherein the area of ​​the coupling grating in each diffractive optical waveguide is smaller than the area of ​​the coupling grating of the optical waveguide designed to cover the range of the target eyebox.

2. The method as described in claim 1, characterized in that, The human eye parameters include pupillary distance and / or bridge of the nose height; The step of dividing the target eye box range according to the human eye parameters of each user group in the target population to obtain a sub-eye box range suitable for each user group includes: Based on the pupillary distance of each user group, the target eye box range is divided into multiple sub-eye box ranges along the horizontal direction to adapt to the pupillary distance of different user groups; And / or, based on the nose bridge height of each of the user groups, the target eye box range is divided into multiple sub-eye box ranges in the vertical direction to adapt to the nose bridge height of different user groups.

3. The method as described in claim 1, characterized in that, In the case where the diffractive waveguide includes an input grating and an output grating, the step of fabricating a diffractive waveguide adapted to each of the user groups based on the range of each of the sub-eyeboxes includes: Based on the preset mapping relationship between the eyebox range and the coupling grating design parameters, the coupling grating design parameters corresponding to each of the sub-eyebox ranges are obtained. The coupling grating design parameters include the layout position of the coupling grating on the waveguide substrate, the shape of the coupling grating, and the geometric dimensions. Based on the design parameters of the coupling grating corresponding to the range of each sub-eyebox, each diffractive waveguide containing the coupling grating is fabricated; Among them, the coupling gratings in the corresponding diffraction waveguides of two adjacent sub-eyeboxes have overlapping areas in terms of layout.

4. The method as described in claim 3, characterized in that, The method further includes: For two adjacent sub-eyebox ranges in the horizontal direction, obtain the pupil diameter of the user group associated with the two sub-eyebox ranges; Based on the pupil diameters of the two user groups, determine the layout position of the coupling grating in the diffraction waveguide corresponding to the range of the two sub-eye boxes, and the width of the overlapping area in the horizontal direction. Wherein, the width is greater than the average of the two pupil diameters.

5. The method as described in claim 3, characterized in that, The method further includes: For two adjacent sub-eyebox ranges in the vertical direction, obtain the pupil diameter of the user group associated with the two sub-eyebox ranges; Based on the pupil diameters of the two user groups, determine the layout position of the coupling grating in the diffraction waveguide corresponding to the range of the two sub-eye boxes, and the height of the overlapping area in the vertical direction. Wherein, the height is greater than the average of the two pupil diameters.

6. The method as described in claim 1, characterized in that, In the case where the diffractive waveguide includes an input grating, an output grating, and a transition grating, the step of fabricating a diffractive waveguide adapted to each of the user groups based on the range of each of the sub-eyeboxes includes: Based on the preset mapping relationship between the eyebox range and the coupling grating design parameters, the coupling grating design parameters corresponding to each of the sub-eyebox ranges are obtained. The coupling grating design parameters include the layout position of the coupling grating on the waveguide substrate, the shape of the coupling grating, and the geometric dimensions. For any sub-eyebox range, based on the sub-eyebox range and the corresponding output grating design parameters, the light propagation path between the input grating and the output grating corresponding to the sub-eyebox range is determined; Based on the light propagation path, the design parameters of the transition grating corresponding to the sub-eye box range are determined. The design parameters of the transition grating include the layout position of the transition grating on the waveguide substrate, the shape of the transition grating, and its geometric dimensions. Based on the design parameters of the coupling grating and the transition grating corresponding to the sub-eyebox range, the diffractive waveguide comprising the coupling grating and the transition grating is fabricated. Among them, the coupling gratings in the corresponding diffraction waveguides of two adjacent sub-eyeboxes have overlapping areas in terms of layout position, and the turning gratings in the corresponding diffraction waveguides also have overlapping areas in terms of layout position.

7. A diffractive optical waveguide, characterized in that, The diffractive waveguide is prepared by the method for preparing a diffractive waveguide as described in any one of claims 1 to 6.

8. The diffractive waveguide as described in claim 7, characterized in that, The area of ​​the coupling grating in the diffractive waveguide is greater than 64 square millimeters and less than 225 square millimeters.

9. The diffractive waveguide as described in claim 7, characterized in that, The area of ​​the coupling grating in the diffractive waveguide is greater than 64 square millimeters and less than three-quarters of the area of ​​the coupling grating of the waveguide designed to cover the target eye box range.

10. A head-mounted display device, characterized in that, The head-mounted display device includes a device body and a diffractive waveguide as described in any one of claims 7 to 9, wherein the diffractive waveguide is disposed on the device body.

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