A test system and method for a diffractive optical waveguide
By combining a spherical light source module and a fixed camera, a correction mapping relationship is constructed, which solves the accuracy problem of brightness uniformity testing of diffractive waveguides, realizes the real performance evaluation of diffractive waveguides under different incident angles, and improves the visual experience and quality inspection capabilities of AR displays.
Patent Information
- Application Number
- CN202610529715.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-04-21
- Publication Date
- 2026-06-09
Smart Images
Figure CN122171172A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of optical testing technology, and in particular to a testing system and method for diffractive waveguides. Background Technology
[0002] The core requirement of augmented reality (AR) display technology is to achieve a natural integration of virtual information with the real world. Diffractive waveguides, as an indispensable core optical component in AR near-eye display devices, undertake the crucial functions of transmitting, coupling, and projecting virtual light signals. Simultaneously, the high transparency of diffractive waveguides ensures that users can clearly observe the real world. The optical performance of diffractive waveguides directly determines the clarity, brightness consistency, and immersive experience of AR displays, making their accurate testing crucial.
[0003] Diffractive waveguides possess numerous optical parameters, with uniformity being a core indicator. Its quality directly impacts the stability and visual comfort of AR displays. While traditional flat panel display industries have relatively mature testing methods for brightness uniformity, these methods typically involve meter-level viewing distances and limited field of view. This is severely mismatched with the centimeter-level short viewing distances and wide field of view requirements of near-eye display devices integrated with diffractive waveguides. Directly applying traditional flat panel display testing methods will result in test results that fail to accurately reflect the application performance of diffractive waveguides, especially during rapid quality inspection in mass production, where the measured uniformity differs even more significantly from actual performance.
[0004] Therefore, accurately reflecting the optical performance of diffractive waveguides still faces technical challenges. Summary of the Invention
[0005] This invention provides a testing system and method for diffractive waveguides, used to characterize the brightness uniformity of diffractive waveguides, reflecting the image brightness perceived by the human eye, especially the uniformity of brightness displayed by diffractive waveguides at different incident angles, providing a testing basis for the performance characterization of diffractive waveguides.
[0006] This invention provides a testing system for diffractive optical waveguides, comprising: An image acquisition device, fixedly positioned at a preset location and maintaining a constant orientation, is used to receive and record the emitted light signal from a spherical light source module or a diffractive waveguide under test. The spherical light source module includes at least one light-emitting unit arranged on a spherical surface. Each light-emitting unit corresponds to a different incident light direction. Selective illumination of light-emitting units at different or all locations simulates light incident at different angles onto the image acquisition device. A control processing module is electrically connected to both the image acquisition device and the spherical light source module. In calibration mode, the control processing module is configured to: activate light-emitting units located at different spatial positions in the spherical light source module, triggering the image acquisition signal in each activation state. The acquisition device captures calibration images and simultaneously records the spatial orientation information of the currently activated light-emitting units; based on the grayscale response values of specific pixel positions in each calibration image and the spatial orientation information of the corresponding light-emitting units, a correction mapping relationship between pixel grayscale values and standard grayscale values is constructed within the entire field of view; in test mode, the control processing module is configured to: trigger the image acquisition device to capture a complete test image of the diffractive waveguide under test in a single capture; retrieve the corresponding correction coefficients in the correction mapping relationship according to the position index of each pixel in the complete test image to perform grayscale correction and generate compensated grayscale distribution data; evaluate the display performance of the diffractive waveguide based on the consistency of the compensated grayscale distribution data.
[0007] Furthermore, the spatial distribution of each light-emitting unit in the spherical light source module is configured such that: on the sphere formed with the optical center of the image acquisition device as the center and the exit pupil distance of the diffraction waveguide as the radius, the arrangement position of each light-emitting unit covers the complete field of view of the diffraction waveguide.
[0008] Furthermore, the specific configuration for the control processing module to construct the correction mapping relationship includes: For each of the calibration images, determine the pixel coordinates of the light-emitting unit imaged on the photosensitive surface of the image acquisition device; Extract the grayscale response values at each pixel coordinate position and filter out the peak grayscale value among all grayscale response values; Calculate the ratio C(i,j) of the grayscale response value to the peak grayscale value at each pixel coordinate position, use the ratio C(i,j) as the correction coefficient for that pixel coordinate position, and establish a mapping table between pixel coordinates and correction coefficients.
[0009] Furthermore, in test mode, the specific configuration for grayscale correction by the control processing module includes: For each pixel location in the complete test image, obtain its original measured grayscale value; The corresponding correction coefficient is obtained by querying the mapping table based on the coordinate index of the pixel position. The original measured grayscale value is processed by the correction coefficient to obtain the compensated grayscale value at the pixel position.
[0010] Furthermore, evaluating the display performance of the diffractive waveguide includes: calculating a brightness uniformity index based on the maximum, minimum, and average values in the compensated grayscale distribution data. The brightness uniformity index is used to characterize the display brightness uniformity of the diffractive waveguide at different incident angles.
[0011] Furthermore, the optical axis of the image acquisition device coincides with the optical central axis of the diffractive waveguide, and the photosensitive surface of the image acquisition device is parallel to the light-emitting surface of the diffractive waveguide.
[0012] The spherical light source module includes: The light source substrate has a spherical structure. At least one light-emitting unit is attached to the outer surface of the light source substrate; The driving circuit, connected to the control processing module, is used to illuminate the light-emitting unit at a specified position according to the received control command.
[0013] The evaluation of the display performance of the diffractive waveguide includes: calculating a brightness uniformity index based on the maximum, minimum and average values in the compensated grayscale distribution data. The brightness uniformity index is used to characterize the display brightness uniformity of the diffractive waveguide at different incident angles.
[0014] Furthermore, the optical axis of the image acquisition device coincides with the optical central axis of the diffractive waveguide, and the photosensitive surface of the image acquisition device is parallel to the light-emitting surface of the diffractive waveguide.
[0015] Meanwhile, this invention claims protection for a testing method for diffractive optical waveguides, based on the aforementioned testing system for diffractive optical waveguides, characterized by including a calibration stage and a testing stage: During the calibration phase, the following steps are performed: The position and orientation of the image acquisition device are fixed, and the image acquisition device maintains a constant posture during the calibration process; The spherical light source module is controlled to illuminate the light-emitting units located in different spatial positions or all of them. In each illumination state, the image acquisition device is triggered to capture the calibration image and simultaneously record the spatial orientation information of the currently illuminated light-emitting unit. Based on the grayscale response value of a specific pixel location in each calibration image and the spatial orientation information of the corresponding light-emitting unit, a correction mapping relationship between pixel grayscale values and standard grayscale values is constructed within the entire field of view. During the testing phase, the following steps are performed: Place the diffractive waveguide under test at the test position, so that the optical center of the diffractive waveguide coincides with the position of the spherical light source module; The image acquisition device is triggered to capture a complete test image of the diffractive waveguide in a single operation. Based on the position index of each pixel in the complete test image, the corresponding correction coefficient in the correction mapping relationship is retrieved to perform grayscale correction and generate compensated grayscale distribution data. The display performance of the diffractive waveguide is evaluated based on the uniformity of the compensated grayscale distribution data.
[0016] Based on the above embodiments, grayscale correction generates compensated grayscale distribution data, which includes the following details: The compensated grayscale distribution data, G, is obtained according to the following formula. 补偿 =G i / C(i,j), where the uniformity of the compensated grayscale distribution data represents the brightness uniformity of the diffracted waveguide; where G 补偿 G represents the compensated grayscale value. i Let C(i,j) represent the grayscale value in the test image, and let C(i,j) represent the correction coefficient for pixel (i,j) in the calibration image.
[0017] In the foregoing embodiments, the lighting sequence of the light-emitting units in the spherical light source module is either to light up all light-emitting units or to light up any light-emitting unit in a specific time sequence.
[0018] Furthermore, the brightness uniformity of the diffracted waveguide is evaluated, including: based on the compensated grayscale distribution data G 补偿 The brightness uniformity index is calculated using the maximum, minimum, and average values in the range.
[0019] In this application, during the calibration phase, by activating the light-emitting units located at different or all positions in the spherical light source module, the image acquisition device is triggered to capture calibration images and synchronously record the spatial orientation information of the currently activated light-emitting units in each activation state; based on the grayscale response value of a specific pixel position in each calibration image and the spatial orientation information of the corresponding light-emitting unit, a correction mapping relationship between pixel grayscale values and standard grayscale values within the entire field of view is constructed. In test mode, the image acquisition device is triggered to capture a complete test image of the diffractive waveguide under test in a single capture; the corresponding correction coefficients in the correction mapping relationship are retrieved according to the position index of each pixel in the complete test image to perform grayscale correction and generate compensated grayscale distribution data; the display performance of the diffractive waveguide is evaluated based on the uniformity of the compensated grayscale distribution data.
[0020] The testing system and method of this application can accurately reflect the true performance of diffractive waveguides under different incident angles of light sources during calibration, obtain the true image brightness scene perceived by the human eye, and determine the grayscale compensation correction coefficients at different angles, thereby determining the uniformity of the display brightness of the diffractive waveguide under different incident angles, providing an accurate testing means for characterizing the true performance of diffractive waveguides.
[0021] Meanwhile, the image acquisition device in this application is fixedly set in a preset position and maintains a constant posture. Its position remains unchanged during calibration or testing. By lighting up light sources at different positions, the mechanical errors and focusing misalignment problems caused by traditional driving structures can be avoided, thereby improving the stability and accuracy of diffractive waveguide testing and better meeting the testing requirements.
[0022] During the calibration and testing phases, the image acquisition device is fixed in a preset position and maintains a constant attitude to ensure that the geometric relationship of the image acquisition device is stable and reliable during the testing of the diffractive waveguide. On the one hand, this avoids the introduction of additional errors due to pose drift. On the other hand, and more importantly, it ensures that the true optical characteristics of the diffractive waveguide are accurately captured to restore the real optical scene and provide a stable and reproducible data basis for subsequent full-view brightness uniformity analysis.
[0023] The diffractive waveguide testing system and method provided by this invention uses a spherical light source module to simulate incident light conditions at multiple angles. Calibration is completed by fixing the camera and light source, which can be lit separately at multiple angles. This effectively compensates for the optical defects of the camera itself, accurately characterizes the brightness performance of the diffractive waveguide at different incident angles, and accurately obtains the compensation relationship between the brightness uniformity reference surface and the grayscale information of the actual image of the diffractive waveguide. This is closer to the real visual experience of the human eye for near-eye display devices, so as to achieve accurate characterization of the brightness distribution and brightness uniformity of the diffractive waveguide. This calibration process provides a reliable testing method for the design optimization and quality inspection of diffractive waveguides. Attached Figure Description
[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0025] Figure 1 A schematic diagram of a test system for a diffractive waveguide provided by the present invention; Figure 2 This is a schematic diagram of the calibration stage of a test system or method for a diffractive optical waveguide provided by the present invention. Detailed Implementation
[0026] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.
[0027] This application provides a testing system for diffractive waveguides, used to characterize the optical performance of diffractive waveguides, especially their uniformity, to accurately reflect the true performance of diffractive waveguides under different incident angles of light sources, and to obtain the true image brightness perceived by the human eye, especially the uniformity of the brightness displayed by the diffractive waveguide under different incident angles, thus providing an accurate testing method for characterizing the true performance of diffractive waveguides.
[0028] This invention provides a testing system for diffractive optical waveguides, such as... Figures 1-2 The above includes: Image acquisition device 10, spherical light source module 20 and control processing module 30; The image acquisition device 10 is fixedly set at a preset position and maintains a constant posture. It is used to receive and record the outgoing light signal of the spherical light source module 20 or the diffractive waveguide under test. The image acquisition device 10 includes a high dynamic range camera, the photosensitive surface of which is positioned facing the object under test. The optical axis of the image acquisition device 10 coincides with the optical central axis of the diffractive waveguide under test, and the photosensitive surface is parallel to the light-emitting surface of the diffractive waveguide.
[0029] The spherical light source module 20 includes at least one light-emitting unit 21 arranged on the spherical surface. Each light-emitting unit 21 corresponds to a different light incident direction. By selectively illuminating the light-emitting units 21 at different positions, light can be simulated to be incident on the image acquisition device 10 at different angles. The control processing module 30 is electrically connected to both the image acquisition device 10 and the spherical light source module 20; it is used to control the execution of the calibration and testing processes. The control processing module 30 includes a processor, a memory, and interface circuits, and is capable of executing calibration algorithms, storing correction mapping relationships, and controlling the lighting sequence of the light-emitting units.
[0030] In the calibration mode, the control processing module 30 is configured to: activate the light-emitting units 21 located at different spatial positions in the spherical light source module 20; trigger the image acquisition device 10 to capture calibration images and synchronously record the spatial orientation information of the currently activated light-emitting units in each activation state; and construct a correction mapping relationship between pixel gray values and standard gray values within the entire field of view based on the gray response values of specific pixel positions in each calibration image and the spatial orientation information of the corresponding light-emitting units. In test mode, the control processing module 30 is configured to: trigger the image acquisition device 10 to capture a complete test image of the diffractive waveguide under test in a single capture; retrieve the corresponding correction coefficients in the correction mapping relationship according to the position index of each pixel in the complete test image to perform grayscale correction and generate compensated grayscale distribution data; and evaluate the display performance of the diffractive waveguide based on the consistency of the compensated grayscale distribution data.
[0031] More in detail, such as Figure 2 As shown, during the calibration phase, the control processing module 30 activates the light-emitting units 21 located at different spatial positions in the spherical light source module 20. Each time a light-emitting unit 21 is activated, the image acquisition device 10 is triggered to capture the calibration image and simultaneously record the spatial orientation information (including polar angle and azimuth angle) of the currently activated light-emitting unit 21.
[0032] The spatial distribution of each light-emitting unit 21 in the spherical light source module 20 is configured such that it is on a sphere with the optical center of the image acquisition device 10 as the center and the exit pupil distance of the diffractive waveguide as the radius. The arrangement of each light-emitting unit 21 covers the complete field of view of the diffractive waveguide. It is understood that the distance between the light source and the image acquisition component is set as the exit pupil distance (eye-relief) of the diffractive waveguide to simulate the actual working state of a real diffractive waveguide in a near-eye display device, ensuring that the calibration conditions are consistent with the usage scenario.
[0033] In one embodiment, the angular spacing between adjacent light-emitting units 21 is equal to achieve uniform sampling across the entire field of view. For example, the angular spacing in both the polar direction and the azimuth direction can be set to 5 degrees.
[0034] The control processing module 30 constructs a correction mapping relationship between pixel grayscale values and standard grayscale values across the entire field of view based on the grayscale response values of specific pixel locations in each calibration image and the spatial orientation information of the corresponding light-emitting unit 21. The specific construction process is as follows: First, for each calibration image, the pixel coordinates of the light-emitting unit 21 image on the photosensitive surface of the image acquisition device 10 are determined. Since the light-emitting area of the light-emitting unit 21 is extremely small, approaching a geometric point, its image on the photosensitive surface is a bright spot. The pixel coordinates of this bright spot can be accurately located through image processing algorithms.
[0035] The control processing module 30 controls all or part of the light-emitting units 21 in the spherical light source module 20 to be lit, and collects at least one calibration image at a different position to establish a grayscale response database for each pixel at different incident angles. Then, the grayscale response values at each pixel coordinate position are extracted, and the peak grayscale value among all grayscale response values is selected. This peak grayscale value corresponds to the response of the light-emitting unit 21 when it is facing the optical axis of the image acquisition device 10, and is used as the standard grayscale value.
[0036] Next, the ratio of the grayscale response value to the peak grayscale value at each pixel coordinate position is calculated, and this ratio is used as the correction coefficient for that pixel coordinate position. The formula for calculating the correction coefficient is: C(i,j) = G(i,j) / Gmax, where C(i,j) is the correction coefficient for pixel (i,j), Gmax is the peak grayscale value, and G(i,j) is the grayscale response value of any pixel (i,j).
[0037] Finally, a mapping table between pixel coordinates and correction coefficients is established to form a correction mapping relationship, which is then stored in the memory of the control processing module 30.
[0038] The spherical light source module 20 includes: The light source substrate has a spherical structure. At least one light-emitting unit 21 is attached to the outer surface of the light source substrate and arranged in an array. Each light-emitting unit 21 can be a light-emitting diode (LED) or a laser diode (LD), and its emission wavelength corresponds to the operating wavelength of the diffractive waveguide under test. For a colored diffractive waveguide, red, green, and blue light-emitting units can be arranged separately to test the performance of the diffractive waveguide at different wavelengths.
[0039] The driving circuit, connected to the control processing module, is used to illuminate the light-emitting unit at a specified position according to the received control command.
[0040] The lighting sequence of the light-emitting units in the spherical light source module can be either all light-emitting units or any light-emitting units lit in a specific time sequence. Depending on different test requirements, it is possible to select to light up all light-emitting units 21 or to light up only a portion of the light-emitting units 21.
[0041] It is known that when all the light-emitting units 21 are lit, the image acquisition device 10 still acquires a multi-angle superimposed image formed by light-emitting units at different angles. The gray values of different light-emitting units at different positions can still be obtained through this superimposed image. At this time, an image separation algorithm is needed to extract the independent response corresponding to each light-emitting unit, so as to obtain the gray correction coefficient. When lit in sequence, the single response image of each light-emitting unit at a specific moment is accurately captured through the time synchronization mechanism.
[0042] This application, by controlling the illumination of all or part of the light-emitting units 21 in the spherical light source module 20, can flexibly simulate illumination conditions with different incident angles and light intensity distributions, thereby accurately reproducing the variable optical environment faced by the diffractive waveguide in actual use; and by establishing a mapping table between pixel coordinates and correction coefficients through correction coefficients, a correction mapping relationship is formed to evaluate the display performance of the diffractive waveguide, which is close to the real use scenario of the diffractive waveguide and significantly improves the accuracy of the test.
[0043] During the calibration process, the corresponding light-emitting unit combination can be selected and lit according to different actual lighting scenarios, and multiple sets of calibration images can be collected simultaneously to control the density of sampling points and use different optical requirements.
[0044] Furthermore, the testing phase includes the following steps: Step S11: Replace the spherical light source module 20 with a diffractive waveguide, and make the distance between it and the image acquisition component equal to the exit pupil distance of the diffractive waveguide; In detail, the spherical light source module 20 is removed, and the geometric center of the diffraction waveguide is aligned with the initial position of the spherical light source module 20; at the same time, the orientation of the image acquisition device 10 remains constant.
[0045] The field of view of the diffractive waveguide is limited to -180° to 180°.
[0046] Step S12: Trigger the image acquisition device 10 to capture a complete test image of the diffractive waveguide in a single capture; and obtain a grayscale image based on the specific position information and grayscale value of each pixel on the complete test image; Step S13: Based on the position index of each pixel in the complete test image, retrieve the corresponding correction coefficient in the correction mapping relationship to perform grayscale correction and generate compensated grayscale distribution data; In detail, grayscale correction generates compensated grayscale distribution data, including the following: The compensated grayscale distribution data, G, is obtained according to the following formula. 补偿 =G i / C(i,j), where the uniformity of the compensated grayscale distribution data represents the brightness uniformity of the diffracted waveguide; where G补偿 G represents the compensated grayscale value. i Let C(i,j) represent the grayscale value in the test image, and let C(i,j) represent the correction coefficient for pixel (i,j) in the calibration image.
[0047] Step S14: Evaluate the display performance of the diffractive waveguide based on the uniformity of the compensated grayscale distribution data. Specifically, evaluating the brightness uniformity of the diffractive waveguide based on the uniformity includes: based on the compensated grayscale distribution data G... 补偿 The brightness uniformity index is calculated using the maximum, minimum, and average values in the range.
[0048] Specifically, the control processing module 30 controls the diffraction waveguide to display the required test image, and acquires the test image by triggering the image acquisition device 10, and obtains the relationship diagram of position and gray value based on the specific position information and gray value of each pixel in the test image; Based on the relationship diagram of the complete test image, the correction coefficient corresponding to the corresponding position in the correction mapping relationship is obtained, and the gray value in the test image is compensated and corrected. The compensation calculation formula is: G 补偿 =G i / C(i,j), C(i,j) = G(i,j) / Gmax, where G 补偿 G represents the compensated grayscale value. i Let C(i,j) represent the grayscale value in the test image, C(i,j) represent the correction coefficient of pixel (i,j) in the calibration image, Gmax be the peak grayscale value, and G(i,j) be the grayscale response value of any pixel (i,j), thereby achieving grayscale value correction. Several compensated and corrected grayscale values are obtained. The display performance of the diffracted waveguide is evaluated based on the uniformity of the grayscale distribution data. The brightness uniformity of the diffracted waveguide can be obtained based on at least two of the maximum, minimum, and average values of the compensated grayscale values.
[0049] In step S12, the position information includes the azimuth and elevation angles relative to the optical axis of the image acquisition device.
[0050] The spherical light source module 20 constructed in this application can realistically reflect the brightness uniformity of the diffracted waveguide under different light angles. Based on the difference between the brightness uniformity reference and the actual image grayscale, compensation and correction are performed to match the human eye's actual experience of the diffracted waveguide's imaging brightness from different viewing angles. This satisfies the imaging requirements of the diffracted waveguide in real-world scenarios, ensuring that the compensated brightness distribution is highly consistent with human perception. This method overcomes the limitations of traditional methods that rely solely on planar illumination calibration. By constructing a full-view calibration model through multi-angle spherical sampling, it significantly improves the visual test consistency of AR displays under dynamic viewing angle switching.
[0051] During the calibration and testing phase, the image acquisition device 10 is fixed in a preset position and always maintains a constant attitude to ensure that the geometric relationship of the image acquisition device 10 is stable and reliable during the testing of the diffractive waveguide. On the one hand, this avoids the introduction of additional errors due to pose drift. On the other hand, and more importantly, it ensures that the true optical characteristics of the diffractive waveguide are accurately captured to restore the real optical scene and provide a stable and reproducible data basis for subsequent full-view brightness uniformity analysis.
[0052] The diffractive waveguide testing system and method provided by this invention uses a spherical light source module to simulate incident light conditions at multiple angles. Calibration is completed by fixing the camera and light source, which can be lit separately at multiple angles. This effectively compensates for the optical defects of the camera itself, accurately characterizes the brightness performance of the diffractive waveguide at different incident angles, and accurately obtains the compensation relationship between the brightness uniformity reference surface and the grayscale information of the actual image of the diffractive waveguide. This is closer to the real visual experience of the human eye for near-eye display devices, so as to achieve accurate characterization of the brightness distribution and brightness uniformity of the diffractive waveguide. This calibration process provides a reliable testing method for the design optimization and quality inspection of diffractive waveguides.
[0053] Of course, based on the foregoing embodiments, a testing method for a diffractive optical waveguide is also provided, based on the aforementioned testing system for a diffractive optical waveguide, including a calibration stage and a testing stage: During the calibration phase, the following steps are performed: The position and orientation of the image acquisition device are fixed, and the image acquisition device maintains a constant posture during the calibration process; The spherical light source module is controlled to illuminate the light-emitting units located in different spatial positions or all of them. In each illumination state, the image acquisition device is triggered to capture the calibration image and simultaneously record the spatial orientation information of the currently illuminated light-emitting unit. Spatial orientation information includes the azimuth angle, elevation angle and distance parameters of a certain light-emitting unit relative to the image acquisition device, which are used to construct a three-dimensional spatial light field mapping relationship; Depending on the different incident angle requirements, select to fully or partially illuminate the light-emitting unit 21 to cover the target test viewing angle range; capture multiple sets of calibration images.
[0054] Based on the grayscale response value of a specific pixel location in each calibration image and the spatial orientation information of the corresponding light-emitting unit, a correction mapping relationship between pixel grayscale values and standard grayscale values is constructed within the entire field of view. It should be noted that when illuminating light-emitting units at different locations, the angular intervals between image acquisitions should be equal or approximately equal to achieve full field-of-view coverage. Equal-interval sampling ensures spatial sampling uniformity and avoids deviations in the correction model within specific viewing angle ranges due to uneven angular distribution.
[0055] During the testing phase, the following steps are performed: Place the diffractive waveguide under test at the test position, so that the optical center of the diffractive waveguide coincides with the position of the spherical light source module; The image acquisition device is triggered to capture a complete test image of the diffractive waveguide in a single operation. Based on the position index of each pixel in the complete test image, the corresponding correction coefficient in the correction mapping relationship is retrieved to perform grayscale correction and generate compensated grayscale distribution data. The display performance of the diffractive waveguide is evaluated based on the uniformity of the compensated grayscale distribution data.
[0056] In detail, grayscale correction generates compensated grayscale distribution data, including the following: The compensated grayscale distribution data, G, is obtained according to the following formula. 补偿 =G i / C(i,j), where the uniformity of the compensated grayscale distribution data represents the brightness uniformity of the diffracted waveguide; where G 补偿 G represents the compensated grayscale value. i Let C(i,j) represent the grayscale value in the test image, and let C(i,j) represent the correction coefficient for pixel (i,j) in the calibration image.
[0057] Evaluating the display performance of the diffractive waveguide includes evaluating the brightness uniformity of the diffractive waveguide, including: based on the compensated grayscale distribution data G. 补偿 The maximum, minimum, and average values are used to calculate the brightness uniformity index, thereby characterizing the actual display performance of the diffractive waveguide under different light angles.
[0058] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.
Claims
1. A testing system for a diffractive optical waveguide, characterized in that, include: The image acquisition device is fixedly set in a preset position and maintains a constant posture. It is used to receive and record the outgoing light signal of the spherical light source module or the diffractive waveguide under test. A spherical light source module includes at least one light-emitting unit arranged on a spherical surface. Each light-emitting unit corresponds to a different light incident direction. By selectively illuminating light-emitting units at different or all positions, light is simulated to be incident on the image acquisition device at different angles. A control processing module is electrically connected to both the image acquisition device and the spherical light source module. In calibration mode, the control processing module is configured to: activate light-emitting units located at different spatial positions in the spherical light source module; trigger the image acquisition device to capture a calibration image and simultaneously record the spatial orientation information of the currently activated light-emitting unit in each activation state; and construct a correction mapping relationship between pixel grayscale values and standard grayscale values within the entire field of view based on the grayscale response value of a specific pixel position in each calibration image and the spatial orientation information of the corresponding light-emitting unit. In test mode, the control processing module is configured to: trigger the image acquisition device to capture a complete test image of the diffractive waveguide under test in a single operation. The grayscale is corrected by retrieving the corresponding correction coefficients in the correction mapping relationship based on the position index of each pixel in the complete test image, and the compensated grayscale distribution data is generated; the display performance of the diffractive waveguide is evaluated based on the consistency of the compensated grayscale distribution data.
2. The testing system for a diffractive optical waveguide according to claim 1, characterized in that, The spatial distribution of each light-emitting unit in the spherical light source module is configured such that, on a sphere formed with the optical center of the image acquisition device as the center and the exit pupil distance of the diffractive waveguide as the radius, the arrangement of each light-emitting unit covers the complete field of view of the diffractive waveguide.
3. A testing system for a diffractive optical waveguide according to claims 1-2, characterized in that, The specific configuration for the control processing module to construct the correction mapping relationship includes: For each of the calibration images, determine the pixel coordinates of the light-emitting unit imaged on the photosensitive surface of the image acquisition device; Extract the grayscale response values at each pixel coordinate position and filter out the peak grayscale value among all grayscale response values; Calculate the ratio C(i,j) of the grayscale response value to the peak grayscale value at each pixel coordinate position, use the ratio C(i,j) as the correction coefficient for that pixel coordinate position, and establish a mapping table between pixel coordinates and correction coefficients.
4. The testing system for a diffractive optical waveguide according to claim 3, characterized in that, In test mode, the specific configuration for grayscale correction by the control processing module includes: For each pixel location in the complete test image, obtain its original measured grayscale value; The corresponding correction coefficient is obtained by querying the mapping table based on the coordinate index of the pixel position. The original measured grayscale value is processed by the correction coefficient to obtain the compensated grayscale value at the pixel position.
5. The testing system for a diffractive optical waveguide according to claim 1, characterized in that, The evaluation of the display performance of the diffractive waveguide includes: calculating a brightness uniformity index based on the maximum, minimum and average values in the compensated grayscale distribution data. The brightness uniformity index is used to characterize the display brightness uniformity of the diffractive waveguide at different incident angles.
6. A testing system for a diffractive optical waveguide according to claims 4-5, characterized in that, The optical axis of the image acquisition device coincides with the optical central axis of the diffractive waveguide, and the photosensitive surface of the image acquisition device is parallel to the light-emitting surface of the diffractive waveguide.
7. A testing method for a diffractive optical waveguide, based on the testing system for a diffractive optical waveguide according to any one of claims 1 to 6, characterized in that, Includes calibration and testing phases: During the calibration phase, the following steps are performed: The position and orientation of the image acquisition device are fixed, and the image acquisition device maintains a constant posture during the calibration process; The spherical light source module is controlled to illuminate the light-emitting units located at different or all spatial positions. In each illumination state, the image acquisition device is triggered to capture the calibration image and simultaneously record the spatial orientation information of the currently illuminated light-emitting unit. Based on the grayscale response value of a specific pixel location in each calibration image and the spatial orientation information of the corresponding light-emitting unit, a correction mapping relationship between pixel grayscale values and standard grayscale values is constructed within the entire field of view. During the testing phase, the following steps are performed: Place the diffractive waveguide under test at the test position, so that the optical center of the diffractive waveguide coincides with the position of the spherical light source module; The image acquisition device is triggered to capture a complete test image of the diffractive waveguide in a single operation. Based on the position index of each pixel in the complete test image, the corresponding correction coefficient in the correction mapping relationship is retrieved to perform grayscale correction and generate compensated grayscale distribution data. The display performance of the diffractive waveguide is evaluated based on the uniformity of the compensated grayscale distribution data.
8. The testing method for a diffractive optical waveguide according to claim 7, characterized in that, The grayscale correction generates compensated grayscale distribution data, which includes the following details: The compensated grayscale distribution data, G, is obtained according to the following formula. 补偿 =G i / C(i,j), where the uniformity of the compensated grayscale distribution data represents the brightness uniformity of the diffracted waveguide; and G 补偿 G represents the compensated grayscale value. i Let C(i,j) represent the grayscale value in the test image, and let C(i,j) represent the correction coefficient for pixel (i,j) in the calibration image.
9. The testing method for a diffractive optical waveguide according to claim 7, characterized in that, The lighting sequence of the light-emitting units in the spherical light source module is either to light up all light-emitting units or to light up any light-emitting unit in a specific time sequence.
10. The testing method for a diffractive optical waveguide according to claim 8, characterized in that, The brightness uniformity of the diffracted waveguide is evaluated based on the compensated grayscale distribution data G. 补偿 The brightness uniformity index is calculated using the maximum, minimum, and average values in the range.