Optical waveguide preparation method, optical waveguide and optical waveguide display system

Abstract

The invention provides an optical waveguide preparation method, an optical waveguide and an optical waveguide display system, and relates to the technical field of optical waveguides, a brightness uniformity index is determined through the diffraction efficiency product of two initial diffraction optical elements at the same diffraction angle, and the brightness uniformity index is determined by taking the brightness uniformity index reaching a preset threshold as a target. And adjusting at least one of the first placement parameter, the first element parameter and the first medium parameter, and / or adjusting at least one of the second placement parameter, the second element parameter and the second medium parameter to obtain a first target diffractive optical element and a second target diffractive optical element, so that the optical waveguide can have the performance of high display brightness uniformity. Through the matching between the diffraction efficiency of the coupling input device and the diffraction efficiency of the coupling output device, the purpose of improving the display brightness uniformity of the optical waveguide is achieved, the coupling output device does not need to be integrated by using a plurality of diffractive optical elements, the preparation difficulty of the optical waveguide is reduced, the processing technology requirement is reduced, and the hardware cost is saved.

Description

Technical Field

[0001] The present invention relates to the technical field of optical waveguides, and in particular to an optical waveguide preparation method, an optical waveguide and an optical waveguide display system. Background Art

[0002] Optical waveguide display technology is a hot topic in the field of augmented reality. By using diffractive optical elements as the input and output couplers of optical waveguides, efficient transmission of micro-image source beams and efficient transmission of external real scene beams can be achieved simultaneously. Figure 1 As shown in FIG. 1 , since the diffraction angle bandwidth of the diffractive optical element usually has the characteristics of high diffraction efficiency at the center angle and low diffraction efficiency at the edge angles on both sides, and the coupler input and coupler output are usually arranged to be axially symmetrically distributed, the image beam will be unevenly diffracted twice, resulting in a large difference in the total efficiency of the diffraction of beams at different angles, resulting in a large difference in the brightness of beams at different angles. Therefore, the optical waveguide display system often faces the problem of uneven display brightness.

[0003] In order to improve the brightness uniformity of the display, multiple diffractive optical elements can be stacked, multiplexed, time-sharing controlled, etc., and concentrated into the output coupler, and the light beam transmitted in the optical waveguide can be diffracted as much as possible by multiple diffractive optical elements to improve the brightness uniformity of the display. However, this method of integrating multiple diffractive optical elements requires a higher processing technology, otherwise it will face stray light or more complex brightness uniformity problems. Summary of the invention

[0004] The present invention provides an optical waveguide preparation method, an optical waveguide and an optical waveguide display system, which are used to solve the defects existing in the related art.

[0005] The present invention provides a method for preparing an optical waveguide, comprising: Acquiring a first diffraction efficiency curve of a first initial diffractive optical element and a second diffraction efficiency curve of a second initial diffractive optical element; With the goal of achieving a preset threshold value for the brightness uniformity index of the first initial diffractive optical element and the second initial diffractive optical element, at least one of a first placement parameter, a first element parameter, and a first medium parameter of the first initial diffractive optical element is adjusted, and / or at least one of a second placement parameter, a second element parameter, and a second medium parameter of the second initial diffractive optical element is adjusted to obtain a first target diffractive optical element and a second target diffractive optical element; Using the first target diffractive optical element as an input coupler, using the second target diffractive optical element as an output coupler, and preparing an optical waveguide based on the input coupler, the output coupler and an optical waveguide body; The brightness uniformity index is determined based on the product of the diffraction efficiencies of the first initial diffractive optical element and the second initial diffractive optical element at the same diffraction angle.

[0006] According to a method for preparing an optical waveguide provided by the present invention, the method takes the brightness uniformity index of the first initial diffractive optical element and the second initial diffractive optical element reaching a preset threshold as a goal, adjusts at least one of a first placement parameter, a first element parameter and a first medium parameter of the first initial diffractive optical element, and / or adjusts at least one of a second placement parameter, a second element parameter and a second medium parameter of the second initial diffractive optical element, to obtain a first target diffractive optical element and a second target diffractive optical element, comprising: If the first diffraction efficiency curve partially overlaps with the second diffraction efficiency curve, then calculating the diffraction efficiency product of the first initial diffraction optical element and the second initial diffraction optical element at the same diffraction angle, and calculating the brightness uniformity index based on the diffraction efficiency product; Continuously adjust at least one of the first placement parameter, the first element parameter and the first medium parameter, and / or continuously adjust at least one of the second placement parameter, the second element parameter and the second medium parameter until the brightness uniformity index reaches the preset threshold, thereby obtaining the first target diffractive optical element and the second target diffractive optical element.

[0007] According to a method for preparing an optical waveguide provided by the present invention, the method takes the brightness uniformity index of the first initial diffractive optical element and the second initial diffractive optical element reaching a preset threshold as a goal, adjusts at least one of a first placement parameter, a first element parameter and a first medium parameter of the first initial diffractive optical element, and / or adjusts at least one of a second placement parameter, a second element parameter and a second medium parameter of the second initial diffractive optical element to obtain a first target diffractive optical element and a second target diffractive optical element, and further includes: If the first diffraction efficiency curve does not overlap with the second diffraction efficiency curve, continuously adjust at least one of the first placement parameter, the first element parameter and the first medium parameter, and / or continuously adjust at least one of the second placement parameter, the second element parameter and the second medium parameter to make the first diffraction efficiency curve partially overlap with the second diffraction efficiency curve.

[0008] According to a method for preparing an optical waveguide provided by the present invention, the brightness uniformity index is calculated based on the following steps: Calculating the diffraction efficiency product of the first initial diffractive optical element and the second initial diffractive optical element at the same diffraction angle; Determining the brightness uniformity index based on the standard deviation or range normalized index of the diffraction efficiency product at each diffraction angle; The range normalization index is determined based on the maximum and minimum values ​​of the product of the diffraction efficiencies at each diffraction angle.

[0009] According to a method for preparing an optical waveguide provided by the present invention, the minimum angle between the diffracted light beam of the coupler and the surface normal of the optical waveguide body is greater than or equal to the arcsine value of the reciprocal of the refractive index of the optical waveguide body.

[0010] According to a method for preparing an optical waveguide provided by the present invention, the first initial diffractive optical element and the second initial diffractive optical element are volume holographic optical elements or metasurface optical elements.

[0011] According to a method for preparing an optical waveguide provided by the present invention, the first initial diffractive optical element and the second initial diffractive optical element are reflective optical elements or transmissive optical elements.

[0012] According to a method for preparing an optical waveguide provided by the present invention, the first initial diffractive optical element and the second initial diffractive optical element are both gratings; The first element parameter and the second element parameter both include the fringe spacing and fringe direction of the grating; The first medium parameter and the second medium parameter both include a refractive index and a thickness.

[0013] The present invention also provides an optical waveguide, comprising: an optical waveguide body, an input coupler and an output coupler; The optical waveguide is obtained based on the above optical waveguide preparation method.

[0014] The present invention also provides an optical waveguide display system, characterized in that it comprises: an image source, a collimator and the optical waveguide mentioned above; The image source is used to generate an image light beam; The collimator is used to collimate the image light beam to obtain an incident light beam of the optical waveguide; The optical waveguide is used to receive the incident light beam and obtain an output light beam after total reflection transmission.

[0015] The optical waveguide preparation method, optical waveguide and optical waveguide display system provided by the present invention determine the brightness uniformity index by multiplying the diffraction efficiency of the first initial diffractive optical element and the second initial diffractive optical element at the same diffraction angle, and take the brightness uniformity index reaching a preset threshold as the goal, adjust at least one of the first placement parameter, the first element parameter and the first medium parameter of the first initial diffractive optical element, and / or adjust at least one of the second placement parameter, the second element parameter and the second medium parameter of the second initial diffractive optical element, so as to obtain a first target diffractive optical element that can be used as an input coupler and a second target diffractive optical element that can be used as an output coupler, so that the prepared optical waveguide has the performance of high display brightness uniformity. In this method, the purpose of improving the display brightness uniformity of the optical waveguide is achieved by matching the diffraction efficiency between the input coupler and the output coupler, and it is not necessary to use multiple diffractive optical elements to integrate the output coupler, which can not only reduce the difficulty of preparing the optical waveguide, reduce the processing requirements, but also save hardware costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the present invention or related technologies, the drawings required for use in the embodiments or related technical descriptions are briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 It is a schematic diagram of the diffraction efficiency curves of the existing coupler input and coupler output in a coordinate system.

[0018] Figure 2 It is a schematic flow chart of the optical waveguide preparation method provided by the present invention.

[0019] Figure 3 It is a schematic diagram of the first diffraction efficiency curve, the second diffraction efficiency curve and the display brightness curve provided by the present invention in a coordinate system.

[0020] Figure 4 It is a schematic diagram of a diffraction efficiency curve of a first target diffractive optical element, a diffraction efficiency curve of a second target diffractive optical element and a display brightness curve provided by the present invention in a coordinate system.

[0021] Figure 5 It is a schematic diagram of the structure of the optical waveguide provided by the present invention.

[0022] Figure 6 This is one of the structural schematic diagrams of the optical waveguide display system provided by the present invention.

[0023] Figure 7This is the second structural schematic diagram of the optical waveguide display system provided by the present invention.

[0024] Figure 8 It is a structural schematic diagram of the electronic device provided by the present invention. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] In the prior art, multiple diffractive optical elements are stacked, multiplexed, time-sharing controlled, etc., and concentrated into a coupler output device, and the light beam transmitted in the optical waveguide is diffracted as much as possible by multiple diffractive optical elements to improve the brightness uniformity of the display. This requires a high processing technology and increases the processing cost. To this end, an optical waveguide preparation method is provided in an embodiment of the present invention.

[0027] Figure 2 FIG. 1 is a schematic diagram of a process for preparing an optical waveguide according to an embodiment of the present invention. Figure 2 As shown, the method includes: S1, acquiring a first diffraction efficiency curve of a first initial diffractive optical element and a second diffraction efficiency curve of a second initial diffractive optical element; S2, with the goal of achieving a preset threshold value for the brightness uniformity index of the first initial diffractive optical element and the second initial diffractive optical element, adjusting at least one of a first placement parameter, a first element parameter, and a first medium parameter of the first initial diffractive optical element, and / or adjusting at least one of a second placement parameter, a second element parameter, and a second medium parameter of the second initial diffractive optical element, to obtain a first target diffractive optical element and a second target diffractive optical element; S3, using the first target diffractive optical element as an input coupler, using the second target diffractive optical element as an output coupler, and preparing an optical waveguide based on the input coupler, the output coupler and the optical waveguide body; The brightness uniformity index is determined based on the product of the diffraction efficiencies of the first initial diffractive optical element and the second initial diffractive optical element at the same diffraction angle.

[0028] Specifically, the optical waveguide preparation method provided in the embodiment of the present invention first performs step S1, selects a first initial diffractive optical element and a second initial diffractive optical element, and the first initial diffractive optical element and the second initial diffractive optical element can both be one of a grating, a binary optical element (Binary Optics), a holographic optical element (Holographic Optical Element), a diffractive optical element with a phase-controlled surface that changes smoothly (Kinoform), a metasurface optical element, and a diffractive lens.

[0029] When selecting the first initial diffractive optical element and the second initial diffractive optical element, the diffraction efficiency range, diffraction angle range, element parameters, and medium parameters can be considered. The element parameters may include parameters such as the grating stripe spacing and stripe direction, which can be selected according to specific application requirements. The medium parameters refer to the material parameters of the first initial diffractive optical element and the second initial diffractive optical element. For example, if the first initial diffractive optical element and the second initial diffractive optical element are both volume holographic optical elements, the medium parameters may be relevant parameters of the holographic recording medium.

[0030] Thereafter, the diffraction efficiencies of the first initial diffractive optical element and the second initial diffractive optical element at different diffraction angles may be calculated respectively to determine a first diffraction efficiency curve of the first initial diffractive optical element and a second diffraction efficiency curve of the second initial diffractive optical element.

[0031] The first diffraction efficiency curve is a curve showing that the diffraction efficiency of the first initial diffraction optical element varies with different diffraction angles, and the second diffraction efficiency curve is a curve showing that the diffraction efficiency of the second initial diffraction optical element varies with different diffraction angles.

[0032] Figure 3 is a schematic diagram of the first diffraction efficiency curve r1, the second diffraction efficiency curve r2 and the display brightness curve in a coordinate system, and the black solid line is the display brightness curve of the optical waveguide with the first initial diffractive optical element and the second initial diffractive optical element being the coupler input and the coupler output respectively.

[0033] Then, step S2 is performed, and the brightness uniformity index of the first initial diffractive optical element and the second initial diffractive optical element can be determined by multiplying the diffraction efficiency of the first initial diffractive optical element and the second initial diffractive optical element at the same diffraction angle. The diffraction efficiency product of the first initial diffractive optical element and the second initial diffractive optical element at a certain diffraction angle can represent the display brightness value of the output light beam position corresponding to the diffraction angle of the optical waveguide with the first initial diffractive optical element as the input coupler and the second initial diffractive optical element as the output coupler. The brightness uniformity index can be determined by multiplying the diffraction efficiency at each diffraction angle.

[0034] Thereafter, with the brightness uniformity index reaching a preset threshold as the goal, at least one of the first placement parameter, the first element parameter, and the first medium parameter of the first initial diffractive optical element is continuously adjusted, and / or at least one of the second placement parameter, the second element parameter, and the second medium parameter of the second initial diffractive optical element is continuously adjusted, so that the first target diffractive optical element and the second target diffractive optical element can be obtained. The preset threshold can be set as needed, for example, it can be set to 90%, 95%, etc.

[0035] The first placement parameter may include a placement position and a placement angle of the first initial diffractive optical element in the optical waveguide. The placement angle may be an angle between a surface normal of the first initial diffractive optical element and a surface normal of the optical waveguide body.

[0036] The second placement parameter may include a placement position and a placement angle of the second initial diffractive optical element in the optical waveguide. The placement angle may be an angle between a surface normal of the second initial diffractive optical element and a surface normal of the optical waveguide body.

[0037] The first element parameter may be a structural parameter that affects the diffraction efficiency of the first initial diffractive optical element; the second element parameter may be a structural parameter that affects the diffraction efficiency of the second initial diffractive optical element. For example, the first element parameter and the second element parameter may both include parameters such as the grating stripe spacing and stripe direction.

[0038] The first medium parameter may be a material parameter affecting the first initial diffractive optical element, and the second medium parameter may be a material parameter affecting the second initial diffractive optical element. For example, the first medium parameter and the second medium parameter may both include parameters such as refractive index and thickness.

[0039] During adjustment, you can adjust only one or more of the first placement parameter, the first element parameter and the first medium parameter, or only one or more of the second placement parameter, the second element parameter and the second medium parameter. You can also adjust one or more of the first placement parameter, the first element parameter and the first medium parameter, and one or more of the second placement parameter, the second element parameter and the second medium parameter at the same time. As long as the target can be achieved, the first target diffractive optical element and the second target diffractive optical element can be obtained.

[0040] like Figure 4 As shown, it is a schematic diagram of the diffraction efficiency curve r3 of the first target diffractive optical element, the diffraction efficiency curve of the second target diffractive optical element and the display brightness curve in a coordinate system, and the black solid line is the display brightness curve of the optical waveguide where the first target diffractive optical element and the second target diffractive optical element are the coupling input and coupling output respectively.

[0041] Finally, step S3 is performed, wherein the first target diffractive optical element is used as an input coupler, the second target diffractive optical element is used as an output coupler, and the input coupler and the output coupler are assembled with the optical waveguide body to obtain an optical waveguide.

[0042] In the optical waveguide, the coupler is used to receive the incident light beam, which can be a collimated image light beam emitted by the image source. The optical waveguide body is used to transmit the incident light beam through the principle of total reflection. Since both the coupler and the coupler are diffraction optical elements, their diffraction efficiencies for light beams with different incident angles are different. Therefore, the energy of the light beam transmitted in the waveguide is different due to the different incident angles.

[0043] The output coupler is used to output the light beam transmitted by the optical waveguide body to obtain an output light beam. The light beam with weaker energy transmitted by the optical waveguide body is diffracted by the output coupler with higher diffraction efficiency, and the light beam with stronger energy transmitted by the optical waveguide body is diffracted by the output coupler with lower efficiency. Finally, the output light beams at each diffraction angle diffracted by the output coupler have approximately equal energy, showing uniform display brightness.

[0044] The output light beam is received by a receiving object such as a human eye, forming a display image with uniform brightness.

[0045] In the optical waveguide preparation method provided in the embodiment of the present invention, the brightness uniformity index is determined by multiplying the diffraction efficiency of the first initial diffractive optical element and the second initial diffractive optical element at the same diffraction angle, and the brightness uniformity index reaches a preset threshold as the goal, and at least one of the first placement parameter, the first element parameter and the first medium parameter of the first initial diffractive optical element is adjusted, and / or at least one of the second placement parameter, the second element parameter and the second medium parameter of the second initial diffractive optical element is adjusted to obtain a first target diffractive optical element that can be used as an input coupler and a second target diffractive optical element that can be used as an output coupler, so that the prepared optical waveguide has the performance of high display brightness uniformity. In this method, the purpose of improving the display brightness uniformity of the optical waveguide is achieved by matching the diffraction efficiency of the input coupler and the output coupler, and it is not necessary to use multiple diffractive optical elements to integrate the output coupler, which can not only reduce the difficulty of preparing the optical waveguide, reduce the processing requirements, but also save hardware costs.

[0046] On the basis of the above-mentioned embodiment, in the optical waveguide manufacturing method in the embodiment of the present invention, the brightness uniformity index of the first initial diffractive optical element and the second initial diffractive optical element reaches a preset threshold as a goal, at least one of the first placement parameter, the first element parameter and the first medium parameter of the first initial diffractive optical element is adjusted, and / or at least one of the second placement parameter, the second element parameter and the second medium parameter of the second initial diffractive optical element is adjusted to obtain the first target diffractive optical element and the second target diffractive optical element, including: If the first diffraction efficiency curve partially overlaps with the second diffraction efficiency curve, then calculating the diffraction efficiency product of the first initial diffraction optical element and the second initial diffraction optical element at the same diffraction angle, and calculating the brightness uniformity index based on the diffraction efficiency product; Continuously adjust at least one of the first placement parameter, the first element parameter and the first medium parameter, and / or continuously adjust at least one of the second placement parameter, the second element parameter and the second medium parameter until the brightness uniformity index reaches the preset threshold, thereby obtaining the first target diffractive optical element and the second target diffractive optical element.

[0047] Specifically, during adjustment, in order to reduce the amount of calculation, it is possible to first determine whether the first diffraction efficiency curve overlaps with the second diffraction efficiency curve. If they partially overlap, the brightness uniformity index can be directly calculated, and the calculated brightness uniformity index can be compared with a preset threshold to continuously adjust the relevant parameters.

[0048] On the basis of the above-mentioned embodiment, the optical waveguide manufacturing method in the embodiment of the present invention, taking the brightness uniformity index of the first initial diffractive optical element and the second initial diffractive optical element reaching a preset threshold as a goal, adjusting at least one of the first placement parameter, the first element parameter and the first medium parameter of the first initial diffractive optical element, and / or adjusting at least one of the second placement parameter, the second element parameter and the second medium parameter of the second initial diffractive optical element to obtain the first target diffractive optical element and the second target diffractive optical element, further comprises: If the first diffraction efficiency curve does not overlap with the second diffraction efficiency curve, adjust at least one of the first placement parameter, the first element parameter and the first medium parameter, and / or continuously adjust at least one of the second placement parameter, the second element parameter and the second medium parameter to make the first diffraction efficiency curve partially overlap with the second diffraction efficiency curve.

[0049] Specifically, during adjustment, if the first diffraction efficiency curve does not overlap with the second diffraction efficiency curve, the brightness uniformity index cannot be directly calculated. At this time, it is necessary to first adjust at least one of the first placement parameter, the first element parameter, and the first medium parameter, and / or continuously adjust at least one of the second placement parameter, the second element parameter, and the second medium parameter, so that the first diffraction efficiency curve partially overlaps with the second diffraction efficiency curve. Thereafter, the brightness uniformity index is calculated, and the relevant parameters are continuously adjusted by comparing the calculated brightness uniformity index with the preset threshold.

[0050] On the basis of the above-mentioned embodiment, in the optical waveguide preparation method in the embodiment of the present invention, the brightness uniformity index is calculated based on the following steps: Calculating the diffraction efficiency product of the first initial diffractive optical element and the second initial diffractive optical element at the same diffraction angle; Determining the brightness uniformity index based on the standard deviation or range normalized index of the diffraction efficiency product at each diffraction angle; The range normalization index is determined based on the maximum and minimum values ​​of the product of the diffraction efficiencies at each diffraction angle.

[0051] Specifically, in the embodiment of the present invention, when calculating the brightness uniformity index, the product of the diffraction efficiency of the first initial diffractive optical element and the second initial diffractive optical element at the same diffraction angle may be calculated first, and then the brightness uniformity index may be determined according to the standard deviation or range normalization index of the diffraction efficiency product at each diffraction angle, that is, the standard deviation or range normalization index may be used as the brightness uniformity index.

[0052] The standard deviation calculation formula can be: ; in, is the standard deviation, N is the number of diffraction angles, is the product of the diffraction efficiency at the i-th diffraction angle, It is the average value of the product of the diffraction efficiencies at each diffraction angle within the overlap range.

[0053] The range normalization index calculation formula can be: ; Wherein, RN is the range normalization index, max is the maximum value of the product of the diffraction efficiency at each diffraction angle, and min is the minimum value of the product of the diffraction efficiency at each diffraction angle.

[0054] It can be understood that if the standard deviation is used as a brightness uniformity indicator, the smaller the standard deviation, the higher the brightness uniformity; if the range normalization index is used as a brightness uniformity indicator, the larger the range normalization index, the higher the brightness uniformity.

[0055] In the embodiment of the present invention, the brightness uniformity index is represented by a standard deviation or a range normalization index, which can fully characterize whether the brightness is uniform, and thus the optical waveguide obtained by adjusting the brightness uniformity index to a preset threshold value can have higher brightness uniformity.

[0056] Based on the above embodiment, the minimum angle between the diffracted light beam of the coupler and the surface normal of the optical waveguide body is greater than or equal to the arcsine value of the reciprocal of the refractive index of the optical waveguide body.

[0057] Specifically, the diffracted light beam of the coupler is the light beam obtained by diffracting the incident light beam through the coupler. To ensure that the diffracted light beam can be totally reflected in the optical waveguide body, the minimum angle between the diffracted light beam and the surface normal of the optical waveguide body needs to be greater than or equal to the arc sine value of the inverse of the refractive index of the optical waveguide body. That is: ; Wherein, θ is the minimum angle between the diffracted light beam and the surface normal of the optical waveguide body, and n is the refractive index of the optical waveguide body.

[0058] Based on the above embodiment, the first initial diffractive optical element and the second initial diffractive optical element are volume holographic optical elements or metasurface optical elements.

[0059] Specifically, the first initial diffractive optical element and the second initial diffractive optical element may both be volume holographic optical elements, or both be metasurface optical elements, or one may be a volume holographic optical element and the other may be a metasurface optical element, which is not specifically limited in the embodiment of the present invention.

[0060] Based on the above embodiment, the first initial diffractive optical element and the second initial diffractive optical element are reflective optical elements or transmissive optical elements.

[0061] Specifically, the first initial diffractive optical element and the second initial diffractive optical element may both be reflective optical elements, or both be transmissive optical elements, or one may be a reflective optical element and the other may be a transmissive optical element, which is not specifically limited in the embodiment of the present invention.

[0062] Based on the above embodiment, the first initial diffractive optical element and the second initial diffractive optical element are both gratings; The first element parameter and the second element parameter both include the fringe spacing and fringe direction of the grating; The first medium parameter and the second medium parameter both include a refractive index and a thickness.

[0063] like Figure 5 As shown, based on the above embodiments, an optical waveguide is further provided in the embodiments of the present invention, including an optical waveguide body 104, an input coupler 103 and an output coupler 105. The optical waveguide can be obtained by the optical waveguide preparation method provided in the above embodiments, so that the optical waveguide can have the performance of high display brightness uniformity.

[0064] like Figure 6 As shown, based on the above embodiment, an optical waveguide display system is further provided in an embodiment of the present invention, comprising: an image source 101, a collimator 102 and the optical waveguide provided in the above embodiment.

[0065] The image source 101 is used to generate an image light beam.

[0066] The collimator 102 is used to collimate the image light beam to obtain an incident light beam 201 of the optical waveguide. The incident light beam 201 is a parallel light beam with approximately the same energy.

[0067] The coupler 103 in the optical waveguide is used to receive the incident light beam 201 and diffract the incident light beam 201 to obtain a diffracted light beam 202 . The minimum angle 301 between the diffracted light beam 202 and the surface normal of the optical waveguide body 104 is greater than or equal to the arcsine value of the reciprocal of the refractive index of the optical waveguide body 104 .

[0068] The diffracted light beam 202 is transmitted in the optical waveguide body 104 by total reflection, and is diffracted by the output coupler 105 to obtain an output light beam 203. The output light beam 203 is received by a receiving object 106 such as a human eye, and a display image of the image source 101 is obtained. Since the diffraction efficiency of the input coupler 103 for incident light beams 201 at different angles is different, the energy of the light beam transmitted in the optical waveguide body 104 is different due to different angles.

[0069] Understandably, Figure 6 In the embodiment, the stripe spacings of the gratings of the coupler 103 and the coupler 105 are different, but the stripe directions are axisymmetric about the surface normal of the optical waveguide body 104, so the directions of the incident light beam 201 and the output light beam 203 are also axisymmetric.

[0070] The optical waveguide display system provided in the embodiment of the present invention uses an optical waveguide obtained by the optical waveguide preparation method, and can have the performance of high display brightness uniformity, improve the display image quality, and enhance the user experience.

[0071] like Figure 7 As shown, another optical waveguide display system provided in an embodiment of the present invention is shown. In the optical waveguide display system, the stripe spacings of the gratings of the coupler input 103 and the coupler output 105 are different, and the stripe directions are asymmetric about the surface normal of the optical waveguide body 104, so the directions of the incident light beam 201 and the output light beam 203 are not axially symmetrical.

[0072] like Figure 8 As shown in FIG. 1 , another optical waveguide display system provided in an embodiment of the present invention is shown. In the optical waveguide display system, the diffraction angle ranges of the input coupler 103 and the output coupler 105 are different, that is, the diffraction efficiency curves do not overlap. Therefore, the input coupler 103 is firstly tilted on the surface of the optical waveguide body 104, and the spatial angle of the input coupler 103 is adjusted to achieve partial overlap of the diffraction angle ranges of the input coupler 103 and the output coupler 105, and partial overlap of the diffraction efficiency curves, thereby improving the uniformity of display brightness.

[0073] In summary, the embodiments of the present invention provide a method for preparing an optical waveguide, an optical waveguide, and an optical waveguide display system. By using two commonly used initial diffractive optical elements as the coupling input and coupling output of the optical waveguide, and by matching the coupling input and the coupling output, a display effect with high brightness uniformity is achieved in a relatively simple and low-cost manner.

[0074] The device embodiments described above are merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Ordinary technicians in this field can understand and implement it without paying creative labor.

[0075] Through the description of the above implementation methods, those skilled in the art can clearly understand that each implementation method can be implemented by means of software plus a necessary general hardware platform, and of course, can also be implemented by hardware. Based on this understanding, the above technical solution is essentially or the part that contributes to the relevant technology can be embodied in the form of a software product, and the computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a disk, an optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiment.

[0076] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing an optical waveguide, characterized in that: include: Acquiring a first diffraction efficiency curve of a first initial diffractive optical element and a second diffraction efficiency curve of a second initial diffractive optical element; With the goal of achieving a preset threshold value for the brightness uniformity index of the first initial diffractive optical element and the second initial diffractive optical element, at least one of a first placement parameter, a first element parameter, and a first medium parameter of the first initial diffractive optical element is adjusted, and / or at least one of a second placement parameter, a second element parameter, and a second medium parameter of the second initial diffractive optical element is adjusted to obtain a first target diffractive optical element and a second target diffractive optical element; Using the first target diffractive optical element as an input coupler, using the second target diffractive optical element as an output coupler, and preparing an optical waveguide based on the input coupler, the output coupler and an optical waveguide body; The brightness uniformity index is determined based on the product of the diffraction efficiencies of the first initial diffractive optical element and the second initial diffractive optical element at the same diffraction angle.

2. The optical waveguide preparation method according to claim 1, characterized in that: The method takes the brightness uniformity index of the first initial diffractive optical element and the second initial diffractive optical element reaching a preset threshold as a goal, adjusts at least one of a first placement parameter, a first element parameter, and a first medium parameter of the first initial diffractive optical element, and / or adjusts at least one of a second placement parameter, a second element parameter, and a second medium parameter of the second initial diffractive optical element to obtain a first target diffractive optical element and a second target diffractive optical element, including: If the first diffraction efficiency curve partially overlaps with the second diffraction efficiency curve, then calculating the diffraction efficiency product of the first initial diffraction optical element and the second initial diffraction optical element at the same diffraction angle, and calculating the brightness uniformity index based on the diffraction efficiency product; Continuously adjust at least one of the first placement parameter, the first element parameter and the first medium parameter, and / or continuously adjust at least one of the second placement parameter, the second element parameter and the second medium parameter until the brightness uniformity index reaches the preset threshold, thereby obtaining the first target diffractive optical element and the second target diffractive optical element.

3. The optical waveguide preparation method according to claim 2, characterized in that: The method takes the brightness uniformity index of the first initial diffractive optical element and the second initial diffractive optical element reaching a preset threshold as a goal, adjusts at least one of the first placement parameter, the first element parameter and the first medium parameter of the first initial diffractive optical element, and / or adjusts at least one of the second placement parameter, the second element parameter and the second medium parameter of the second initial diffractive optical element to obtain a first target diffractive optical element and a second target diffractive optical element, and further includes: If the first diffraction efficiency curve does not overlap with the second diffraction efficiency curve, continuously adjust at least one of the first placement parameter, the first element parameter and the first medium parameter, and / or continuously adjust at least one of the second placement parameter, the second element parameter and the second medium parameter to make the first diffraction efficiency curve partially overlap with the second diffraction efficiency curve.

4. The optical waveguide preparation method according to claim 1, characterized in that: The brightness uniformity index is calculated based on the following steps: Calculating the diffraction efficiency product of the first initial diffractive optical element and the second initial diffractive optical element at the same diffraction angle; Determining the brightness uniformity index based on the standard deviation or range normalized index of the diffraction efficiency product at each diffraction angle; The range normalization index is determined based on the maximum and minimum values ​​of the product of the diffraction efficiencies at each diffraction angle.

5. The optical waveguide preparation method according to claim 1, characterized in that: The minimum angle between the diffracted light beam of the coupler and the surface normal of the optical waveguide body is greater than or equal to the arcsine value of the reciprocal of the refractive index of the optical waveguide body.

6. The method for preparing an optical waveguide according to any one of claims 1 to 5, characterized in that: The first initial diffractive optical element and the second initial diffractive optical element are volume holographic optical elements or metasurface optical elements.

7. The method for preparing an optical waveguide according to any one of claims 1 to 5, characterized in that: The first initial diffractive optical element and the second initial diffractive optical element are reflective optical elements or transmissive optical elements.

8. The method for preparing an optical waveguide according to any one of claims 1 to 5, characterized in that: The first initial diffractive optical element and the second initial diffractive optical element are both gratings; The first element parameter and the second element parameter both include the fringe spacing and fringe direction of the grating; The first medium parameter and the second medium parameter both include a refractive index and a thickness.

9. An optical waveguide, characterized in that: include: An optical waveguide body, an input coupler and an output coupler; The optical waveguide is obtained based on the optical waveguide preparation method according to any one of claims 1 to 8.

10. An optical waveguide display system, characterized in that: include: An image source, a collimator, and an optical waveguide as claimed in claim 9; The image source is used to generate an image light beam; The collimator is used to collimate the image light beam to obtain an incident light beam of the optical waveguide; The optical waveguide is used to receive the incident light beam and obtain an output light beam after total reflection transmission.

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