An XR virtual imaging position calibration module, assembly method and calibration method

Abstract

An XR virtual imaging position calibration module includes a relay mirror, a housing, a test camera calibration chart, and a backlight arranged sequentially. The housing is vertically continuous, and the relay mirror is horizontally mounted on the housing with its upper horizontal surface parallel to the upper horizontal surface of the housing. The relay mirror is used to simulate charts at different distances. The test camera calibration chart is set on the lower horizontal surface of the housing, and the backlight is horizontally positioned on the side of the test camera calibration chart away from the housing. The horizontal plane of the relay mirror is parallel to the test camera calibration chart, and their centers are coaxial. By employing a relay mirror and a high-precision machining and calibration method, the module can simulate the imaging effect of a virtual chart several meters away, similar to XR. This allows for the calibration of the camera's center offset, rotation, and verticality at a virtual chart several meters away, even in a confined installation space, while maintaining the test camera's telephoto distance, thus improving the accuracy of the calibration position.

Description

Technical Field

[0001] This invention relates to the field of optical technology, specifically to an XR virtual imaging position calibration module, assembly method, and calibration method. Background Technology

[0002] XR, or Extended Reality, is a collective term for immersive technologies such as Virtual Reality (VR), Augmented Reality (AR), and Mixed Reality (MR). Advances in Extended Reality technology have transformed the way we work, live, and play. From gaming to virtual production and product design, XR enables unprecedented creation, collaboration, and exploration in computer-generated environments, shifting human interaction from 2D to more efficient 3D interaction. Currently, with the rise of the "metaverse," the XR headset market, as a crucial pathway and primary entry point for its development, experienced explosive growth in 2021. In the VR industry chain, the display screen is the core bottleneck, accounting for approximately 34% of the cost, while AR accounts for even more at 43%. This demonstrates that the display screen is the most critical requirement in XR. With the development of the metaverse, the demand for display screens will explode in XR applications, following mobile phones. Therefore, the demand for near-eye display quality testing of XR screens is also increasing.

[0003] Compared to mobile phone screen testing, the biggest difference in XR screen near-eye display testing is that XR uses near-eye virtual imaging, with a very short exit pupil distance, typically around 10-30mm. Therefore, the near-eye display test distance must simulate the exit pupil distance of the human eye. The camera's position, including center offset, rotation, and perpendicularity, has a crucial impact on the test results. Especially in such a confined space, calibrating the perpendicularity, center offset, and rotation of the test camera is extremely complex. Currently, in the early stages of XR production lines, it is not possible to provide a physical calibration machine for the test camera; therefore, mechanical calibration methods must be used for camera calibration.

[0004] For the above solutions, mechanical calibration methods have relatively low accuracy and cannot calibrate the center and perpendicularity of the camera's optical axis, resulting in inaccurate test data. If actual position chart calibration is used, the test camera's focal length for XR virtual imaging is far, and the chart distance is far, making the entire design very large and the installation space insufficient. Summary of the Invention

[0005] This invention provides an XR virtual imaging position calibration module, assembly method, and calibration method for calibrating the center offset, rotation, and verticality of a camera in a confined installation space, while keeping the telephoto distance of the test camera constant.

[0006] According to the first aspect, one embodiment provides an XR virtual imaging position calibration module.

[0007] An XR virtual imaging position calibration module includes a relay mirror, a housing, a test camera calibration chart, and a backlight arranged sequentially. The housing is vertically continuous, and the repeater is horizontally mounted on the housing, with the horizontal upper surface of the repeater parallel to the horizontal upper surface of the housing. The repeater is used to simulate maps at different distances. The test camera calibration chart is set on the horizontal lower surface of the housing, and the backlight is set horizontally on the side of the test camera calibration chart away from the housing; the horizontal plane of the relay mirror is parallel to the test camera calibration chart and its center is set along the coaxial line.

[0008] In another embodiment, it also includes an AA camera calibration chart and a surface light source. The AA camera calibration chart is arranged around the relay mirror, and the surface light source is arranged on the upper surface of the housing and is used to provide light to the AA camera calibration chart. The upper surface of the AA camera calibration chart and the horizontal upper surface of the housing are arranged parallel to each other and their centers are arranged along the same axis.

[0009] In another embodiment, the test camera calibration chart and the AA camera calibration chart are prepared by photolithography printing.

[0010] According to the second aspect, one embodiment provides an assembly method for an XR virtual imaging position calibration module.

[0011] An assembly method for an XR virtual imaging position calibration module, comprising the aforementioned XR virtual imaging position calibration module, includes the following steps: Housing preparation: The upper and lower surfaces of the housing are horizontal, and the through opening of the housing is arranged in the vertical direction; Install the test camera calibration chart and backlight: Sequentially control the test camera calibration chart and backlight to be horizontally installed on the lower surface of the housing; Calibrate the test camera calibration chart: Measure the parallelism, position center offset, and rotation of the test camera calibration chart relative to the housing, and adjust the position of the test camera calibration chart based on the measurement data to make it more consistent with the housing; Install the repeater mirror: Control the repeater mirror to be horizontally installed on one side of the upper surface of the housing; Calibrate the repeater: Measure the parallelism and center offset between the repeater and the test camera calibration chart, and adjust the position of the repeater based on the measurement data to make it consistent with the test camera calibration chart; Install the surface light source and AA camera calibration chart: Horizontally install the surface light source on the upper surface of the housing, and horizontally install the AA camera calibration chart above the surface light source; Calibrate the AA camera calibration chart: Measure the parallelism, position center offset, and rotation of the AA camera calibration chart relative to the housing, and adjust the position of the AA camera calibration chart based on the measurement data to make it more consistent with the housing.

[0012] In another embodiment, the housing, the test camera calibration chart, and the AA camera calibration chart all need to be retested before assembly, so that the flatness machining accuracy of each horizontal base surface of the housing is ±0.01-±0.1mm, and the flatness of the test camera calibration chart and the AA camera calibration chart is ±0.01-±0.1mm.

[0013] In another embodiment, both the surface light source and the backlight source can be detachably mounted on the housing, and the AA camera calibration chart and the test camera calibration chart are connected by applying adhesive first and then curing.

[0014] According to a third aspect, one embodiment provides a location calibration method based on XR virtual imaging.

[0015] A location calibration method based on XR virtual imaging includes the following steps: The XR virtual imaging position calibration module is deployed below the position of the camera under test; The camera under test is controlled to capture calibration charts to obtain calibration images, wherein the type of calibration chart corresponds to the type of camera under test; The calibration image is analyzed using a preset algorithm to obtain the first position parameters of the camera under test; The position of the camera under test is adjusted based on the first position parameter to achieve position calibration of the camera under test.

[0016] In another embodiment, after adjusting the position of the camera under test based on the first position parameter to calibrate the position of the camera under test, the following steps are included: The second position parameter of the camera under test at the current position and the third position parameter after the XR virtual imaging position calibration module is flipped by a preset angle are collected. The XR virtual imaging position calibration module is set symmetrically along the central axis. Determine whether the difference between the second position parameter and the third position parameter is less than a preset value; If the difference between the second position parameter and the third position parameter is less than the preset value, the camera under test is deemed to be calibrated as qualified.

[0017] In another embodiment, the XR virtual imaging position calibration module is slidably connected to the test equipment at the theoretical installation position of the test object, and the XR virtual imaging position calibration module can slide to below the AA camera and the test camera. The sliding direction of the XR virtual imaging position calibration module is parallel to the straight line where the AA camera and the test camera are located.

[0018] In another embodiment, the step of parsing the calibration image using a preset algorithm to obtain the first position parameters of the camera under test includes: The position of the XR virtual imaging position calibration module is determined based on the XR virtual imaging position calibration module. Based on the preset algorithm, the XR virtual imaging position calibration module calculates the first position parameter of the camera under test according to its position on the calibration image. The first position parameter represents the offset data of the camera under test relative to the XR virtual imaging position calibration module, wherein the offset data includes center offset, rotation and perpendicularity.

[0019] According to the aforementioned XR virtual imaging position calibration module and method, on the one hand, by incorporating a relay lens into the module, it can simulate maps at different distances, enabling position calibration of cameras with different focal lengths. Moreover, its small size facilitates installation at the actual XR test location without requiring an extended calibration distance, significantly reducing equipment space and calibration difficulty. Simultaneously, by designing different relay lens distances and FOVs based on varying virtual image distances, a calibration tool for various XR product testing equipment can be developed, offering good versatility. On the other hand, the test camera captures images of the virtual map, and the algorithm quickly calculates the test camera's optical axis perpendicularity, center offset, and rotation. Through an electric adjustment device, the perpendicularity, center offset, and rotation calibration of the test camera can be automatically completed. The calibration method is direct, without intermediate components or process conversions, greatly improving efficiency. Furthermore, using this module as a benchmark, the accuracy of the optical axis perpendicularity, center, and rotation of other cameras on the test equipment can be simultaneously calibrated, thereby improving the overall accuracy and consistency of the XR testing equipment. Attached Figure Description

[0020] Figure 1 An exploded view of the overall structure of the XR virtual imaging position calibration module; Figure 2 A schematic diagram showing the installation location of the XR virtual imaging position calibration module on the test equipment; Figure 3 Assembly flowchart for the XR virtual imaging position calibration module; Figure 4 This is a flowchart of the calibration method used by the XR virtual imaging position calibration module for XR virtual imaging position calibration.

[0021] Reference numerals: 0. XR virtual imaging position calibration module; 1. Housing; 2. AA camera calibration chart; 3. Test camera calibration chart; 4. Relay mirror; 5. Surface light source; 6. Backlight source; 7. AA camera; 8. Test camera; 9. Guide rail. Detailed Implementation

[0022] The present invention will now be described in further detail with reference to specific embodiments and accompanying drawings. Similar elements in different embodiments are referred to by associated similar element reference numerals. In the following embodiments, many details are described to facilitate a better understanding of this application. However, those skilled in the art will readily recognize that some features may be omitted in different situations, or may be replaced by other elements, materials, or methods. In some cases, certain operations related to this application are not shown or described in the specification. This is to avoid obscuring the core parts of this application with excessive description. For those skilled in the art, detailed description of these related operations is not necessary; they can fully understand the related operations based on the description in the specification and general technical knowledge in the art.

[0023] Furthermore, the features, operations, or characteristics described in the specification can be combined in any suitable manner to form various embodiments. At the same time, the steps or actions in the method description can be rearranged or adjusted in a manner obvious to those skilled in the art. Therefore, the various orders in the specification and drawings are only for the clear description of a particular embodiment and do not imply a necessary order, unless otherwise stated that a particular order must be followed.

[0024] The serial numbers assigned to components in this document, such as "first" and "second," are used only to distinguish the described objects and have no sequential or technical meaning. The terms "connection" and "linkage" used in this application, unless otherwise specified, include both direct and indirect connections (linkages).

[0025] With the rise of the "metaverse," the XR headset market, as an essential step and primary entry point for its development, experienced explosive growth in 2021. In the VR industry chain, the display screen is a core bottleneck, accounting for approximately 34% of the cost. AR accounts for even more, at 43%. This clearly demonstrates that the display screen is the most critical requirement for XR. With the development of the metaverse, the demand for display screens will follow that of mobile phones in XR applications, experiencing explosive growth. Therefore, the demand for near-eye display quality testing for XR screens is also increasing daily.

[0026] With the development of XR technology, the demand for near-eye display quality testing of XR screens is also increasing. The biggest difference between near-eye display testing of XR screens and mobile phone screen testing is that XR uses near-eye virtual imaging, with a very short exit pupil distance, typically around 10-30mm. Therefore, the near-eye display testing distance needs to simulate the exit pupil distance of the human eye. The camera position, including factors such as center offset, rotation, and perpendicularity, has a crucial impact on the test performance of XR screens. Especially in such a confined space, calibrating the perpendicularity, center offset, and rotation position of the test camera 8 is extremely complex.

[0027] Under traditional conditions, camera position calibration can be performed using a gold-plated tester (in the mobile phone industry, a gold-plated tester refers to a machine whose various indicators and parameters are at their optimal levels. For example, the gold-plated tester in a mobile phone is a relatively stable testing machine used to detect system errors. Generally speaking, the gold-plated tester intentionally adjusts various parameters to fixed optimal values; when used on the production line, it can be used to check whether the deviation of the testing equipment has increased). However, in the early stages of the XR production line, a gold-plated tester cannot be provided for the calibration and setup of the test camera 8. Therefore, only mechanical calibration methods can be used to calibrate the test camera 8. If mechanical calibration methods are used, the accuracy is relatively low, and mechanical calibration methods cannot calibrate the center and perpendicularity of the camera's optical axis, resulting in inaccurate test data. If actual position chart calibration is used, because the focal length of the test camera 8 for XR virtual imaging is far, the chart distance is far, making the entire design size very large and the installation space insufficient.

[0028] The AA camera 7 described in this application, officially called an Active Alignment camera, is used in the testing equipment to photograph the position of each incoming material, calculate the center offset and rotation of the material, and then feed this information back to the incoming material position adjustment device to correct the center offset and rotation of the material. Therefore, the accuracy of the position of the AA camera 7 is also important for the test results. The test camera 8 described in this application is a camera used for XR near-eye display testing, including but not limited to industrial cameras, XR imaging colorimeters, imaging luminance meters, and conoscopes.

[0029] This application designs an XR virtual imaging position calibration module and its assembly method, as well as an XR virtual imaging position calibration method based on this XR virtual imaging position calibration module 0. This XR virtual imaging position calibration module 0 can simulate the imaging effect of a virtual map card several meters away, just like XR. After assembly, it is installed on the test equipment and can calibrate the camera center offset, rotation, and perpendicularity of the virtual map card position several meters away in a narrow installation space, while keeping the telephoto distance of the test camera 8 unchanged. At the same time, through the new design method and processing assembly, coupled with high-precision measurement and calibration technology, higher position accuracy than XR metal cameras can be achieved, thus replacing XR metal cameras for camera position calibration of test equipment.

[0030] According to the first aspect, one embodiment provides an XR virtual imaging position calibration module.

[0031] Please refer to Figure 1An XR virtual imaging position calibration module includes a relay mirror 4, a housing 1, a test camera calibration chart 3, and a backlight 6 arranged sequentially from top to bottom. The housing 1 is vertically continuous, with its upper and lower surfaces horizontally aligned. The test camera calibration chart 3 has horizontally aligned upper and lower surfaces, connected horizontally to the lower surface of the housing 1. The test camera calibration chart 3 closes the opening on the lower surface of the housing 1. The backlight 6 is horizontally positioned on the side of the test camera calibration chart 3 facing away from the housing 1. The relay mirror 4 includes a lens and a base. The base is mounted on and fixed to the housing 1. The base can be mounted on the upper surface of the housing 1 or inside the housing 1. The base is continuous and used to mount the lens, which is mounted above the base. Both the upper and lower surfaces of the lens and the base are arc-shaped, parallel, and horizontally aligned. The entire calibration module is used to calibrate a test camera 8 on an XR testing device.

[0032] In another embodiment, to improve the accuracy of the XR testing equipment in locating the incoming material, the XR virtual imaging position calibration module 0 can also incorporate an AA camera calibration chart 2 and a surface light source 5 for calibrating the AA camera 7. The AA camera 7 is used in the testing equipment to photograph the positions of each incoming material, calculate the center offset and rotation of the material, and then feed this information back to the incoming material position adjustment device to correct the center offset and rotation. The AA camera calibration chart 2 is arranged around the repeater mirror 4, and has a circular hole for fitting and fixing it around the repeater mirror 4. The surface light source 5 is mounted on the upper surface of the housing 1 and provides light to the AA camera calibration chart 2. The surface light source 5 uses two strip light sources, which are parallel to each other and symmetrically arranged about the repeater mirror 4. Applying the same XR virtual imaging position calibration module 0 to calibrate the AA camera 7 and the test camera 8 sequentially improves the consistency between the AA camera 7 and the test camera 8, making the position of the incoming material more accurate after adjustment by the AA camera 7, thus making the test results more accurate.

[0033] The AA camera calibration chart 2 is installed above the XR virtual imaging position calibration module 0, which can pre-calibrate the AA camera 7. The AA camera calibration chart 2 has a circular hole, and the test camera calibration chart 3 below the housing 1 can be photographed through the relay mirror 4 and the through housing 1, thereby realizing the sequential calibration of the AA camera 7 and the test camera 8.

[0034] In the above technical solution, the horizontal plane of the relay mirror 4, the overall plane of the AA camera calibration chart 2, and the overall plane of the test camera 8 chart are all arranged parallel to each other, and their centers are arranged along the coaxial line. The XR virtual imaging position calibration module 0 serves as the calibration module for both the AA camera 7 and the test camera 8. Both the AA camera 7 and the test camera 8 need to correct their positions through the XR virtual imaging position calibration module 0. Therefore, the XR virtual imaging position calibration module 0 requires very high precision. The relay mirror 4, the AA camera calibration chart 2, and the test camera 8 chart are the main components of the XR virtual imaging position calibration module 0, and a high degree of consistency is required to ensure the overall precision of the XR virtual imaging position calibration module 0.

[0035] When focusing and testing a camera module, the ideal solution is to perform the test within the nominal focal length of the camera module, which often reaches several meters. However, testing at this distance requires a very large test area, which is obviously impractical. Therefore, in this embodiment, a repeater lens 4 is used. When the object distance is less than the focal length, the object under test, through the repeater lens 4, can become a virtual image that appears farther and larger, thereby reducing the perceived size of the space and the volume of the object under test. Therefore, depending on the different needs of XR, including AR, VR, MR, and other sample testing machines, different models of repeater lenses 4 are used to simulate different distances and FOVs (field of view) based on different virtual image distance requirements. This makes it a suitable calibration tool for testing equipment of different XR products, with good versatility.

[0036] In this embodiment, the relay mirror 4 can simulate maps at different distances, enabling position calibration of cameras with different focal lengths. This breaks the limitations of the equipment installation range, allowing for the calibration of the camera's center offset, rotation, and verticality at a distant virtual map position within a confined installation space, while maintaining the same telephoto distance for the test camera 8. The backlight 6 provides illumination to the test camera calibration map 3 for calibrating the position of the test camera 8, improving the accuracy of the test camera 8's position calibration. Simultaneously, the surface light source 5 provides light to the AA camera calibration map 2 for calibrating the position of the test camera 8, improving the accuracy of the AA camera 7's position calibration, and ensuring a high correlation between the AA camera 7 and the test camera 8.

[0037] According to a second aspect, one embodiment provides an assembly method for an XR virtual imaging position calibration module, including the aforementioned XR virtual imaging position calibration module 0, with reference to... Figure 3 The steps are as follows: S1: Housing 1 prepared; During assembly preparation, each horizontal base surface of housing 1 is flat and parallel to each other, and the flatness machining accuracy of each horizontal base surface of housing 1 is required to be ±0.01-±0.1mm; the upper and lower surfaces of housing 1 are horizontal, and the through opening of housing 1 is set in the vertical direction. Before assembly, the shell 1 needs to be re-inspected: the flatness of the shell 1 is re-measured and adjusted by combining the CMM coordinate measuring machine and OMM (optical coordinate measuring machine) until the flatness of the shell 1 meets the predetermined standard. The high machining accuracy requirement for housing 1 is mainly because the upper surface of housing 1 needs to support or compare the installation of the base below the relay mirror 4, and the lower surface of housing 1 needs to be connected to the test camera calibration chart 3 to ensure the parallelism of the upper and lower surfaces of housing 1 with other components, thereby improving the overall assembly accuracy of the module.

[0038] S2: Install test camera calibration chart 3 and backlight 6: Sequentially control the test camera calibration chart 3 and backlight 6 to be horizontally installed on the lower surface of housing 1; The test camera calibration chart 3 is preferably prepared by photolithography printing. Other existing equipment and methods that can achieve the manufacturing accuracy of the test camera calibration chart 3 are not listed here. The printing accuracy is ±0.01-±0.1mm, thereby ensuring that the test camera calibration chart 3 has a flat surface and a flatness requirement of ±0.01-±0.1mm. Before assembly, the test camera calibration chart 3 needs to be retested. The flatness of the test camera calibration chart 3 is retested and adjusted using a CMM coordinate measuring machine until the flatness of the test camera calibration chart 3 meets the predetermined standard. Then, the qualified test camera calibration chart 3 is horizontally installed on the lower surface of the housing 1. Finally, the backlight 6 is installed below the test camera calibration chart 3.

[0039] S3: Calibrate test camera calibration chart 3: Measure the parallelism, position center offset and rotation of test camera calibration chart 3 relative to housing 1, and adjust the position of test camera calibration chart 3 based on the measurement data to make it consistent with housing 1; Before calibration, the backlight 6 needs to be turned on, and the parallelism of the test camera calibration chart 3 needs to be measured by the ACM autocollimator. The position center offset and rotation data of the test camera calibration chart 3 need to be measured by the OMM. Based on the test data, the position of the test camera calibration chart 3 is adjusted using a fine-tuning device until the parallelism between the test camera calibration chart 3 and the housing 1 reaches 0.01-0.1°, the center offset reaches ±0.01-±0.1mm, and the relative rotation angle is <0.05°; when installing the test camera calibration chart 3, the installation accuracy between the test camera calibration chart 3 and the housing 1 is ensured, thereby ensuring the assembly accuracy of the entire XR virtual imaging position calibration module; S4: Install repeater mirror 4: Control the repeater mirror 4 to be horizontally installed on one side of the upper surface of housing 1; Due to the size limitations of the testing equipment, a small relay mirror 4 is used in this application based on the installation space of the module. The parallelism between the lower surface of the prepared lens and the upper surface of the base of the relay mirror 4 is required to be ±0.01-±0.1mm. Before assembly, a CMM measuring instrument is used to re-measure and adjust until the relay mirror 4 meets the predetermined requirements. Before assembly, the focal length of repeater lens 4 is re-inspected and adjusted using a focal length meter to ensure its accuracy is between 0.2% and 0.05%. At the same time, the distortion rate of repeater lens 4 is re-measured and adjusted to ensure that the distortion rate of repeater lens 4 is less than 0.2%. This ensures that repeater lens 4 will not introduce its own distortion into the test system after installation, thus affecting the overall test accuracy of the test system.

[0040] S5: Calibrate repeater 4: Measure the parallelism and center offset of repeater 4 and test camera calibration chart 3, and adjust the position of repeater 4 based on the measurement data to make it consistent with test camera calibration chart 3; When the repeater 4 is installed on the housing 1, the parallelism between the repeater 4 and the test camera calibration chart 3 is tested using an ACM autocollimator, and the parallelism between the two is adjusted to 0.01-0.1°. Then, an OMM camera is used to measure the offset between the center of the repeater 4 and the center of the test camera calibration chart 3. Based on the measured center offset data, it is determined whether there is a center offset between the repeater 4 and the test camera calibration chart 3. If there is an offset, the repeater 4 is finely adjusted using a fine-tuning device until the center offset between the center of the repeater 4 and the center of the test camera chart 3 is within the range of ±0.02-±0.1mm.

[0041] S6: Install surface light source 5 and AA camera calibration chart 2: Move surface light source 5 and install it horizontally on the upper surface of housing 1, and move AA camera calibration chart 2 and install it horizontally above surface light source 5. The AA camera calibration chart 2 is preferably prepared by photolithography printing. Other existing equipment and methods that can achieve the manufacturing accuracy of the test camera calibration chart 3 are not listed here. The printing accuracy is ±0.01-±0.1mm to ensure that the plane of the AA camera calibration chart 2 is flat and the flatness requirement is ±0.01-±0.1mm. Before assembling the AA camera calibration chart 2, the flatness of the AA camera calibration chart 2 is re-measured and adjusted using a CMM coordinate measuring machine until the flatness of the AA camera calibration chart 2 reaches the predetermined standard. Then, the qualified AA camera calibration chart 2 is set on and installed on the relay mirror 4, and the surface light source 5 is horizontally installed on the upper surface of the housing 1. When the AA camera calibration chart 2 is installed on the housing 1, the parallelism of the AA camera calibration chart 2 is calibrated using an ACM autocollimator, and the parallelism between the two is adjusted to 0.01-0.1°. The position center offset and rotation of the AA camera calibration chart 2 are measured using an OMM. If there is offset or rotation, the center offset of the AA camera calibration chart 2 is calibrated to ±0.01-±0.1mm and the relative rotation angle is adjusted to <0.05° using a fine-tuning device.

[0042] S7: Calibrate the XR virtual imaging position calibration module 0; In the assembly of the XR virtual imaging position calibration module, the parallelism calibration between the relay mirror 4, the AA camera calibration chart 2, and the test camera calibration chart 3 is to ensure the perpendicularity of the AA camera 7 and the test camera 8. In order to improve the overall accuracy of the module, the parallelism of the test camera calibration chart 3, the relay mirror 4, and the AA camera calibration chart 2 of the module is calibrated from bottom to top using an ACM autocollimator, with a calibration accuracy of 0.01-0.1°. The OMM camera is a high-precision visual calibration platform with its verticality, center, and rotation already calibrated. To improve the overall accuracy of the module, using the OMM camera as a reference, the center offset and rotation of the module's test camera calibration chart 3, repeater mirror 4, and AA camera calibration chart 2 are calibrated from bottom to top to ensure that the center offset accuracy of the OMM camera meets ±0.02-±0.1mm, and the rotation accuracy meets ±0.01-±0.1°.

[0043] The above-mentioned AA camera calibration chart 2 and test camera calibration chart 3 are installed with the repeater lens 4 by applying glue first and then curing it, so that the calibration position will not change significantly. The backlight 6 and the surface light source 5 are detachably fixed to the housing 1, for example by using screws or clips.

[0044] According to a third aspect, one embodiment provides a method for calibrating the position of an XR virtual imaging device.

[0045] A calibration method for an XR virtual imaging position calibration module, please refer to... Figure 4 It includes the following steps: S100: Deploy the XR virtual imaging position calibration module 0 below the position of the camera under test, i.e., the theoretical installation position of the test object of the XR test equipment; In this embodiment of the application, the camera under test includes AA camera 7 and test camera 8, or other cameras used for testing XR equipment can be set on the XR test equipment. Please refer to Figure 2Both the AA camera 7 and the test camera 8 are mounted on the test equipment. The XR virtual imaging position calibration module is slidably connected to the test equipment at the theoretical installation position of the test object, and the XR virtual imaging position calibration module can slide below the AA camera 7 and the test camera 8. Specifically, a guide rail 9 is mounted on the test equipment, and the guide rail 9 is installed below the AA camera 7 and the test camera 8; the AA camera 7 and the test camera 8 are on the same straight line, and the length direction of the guide rail 9 is parallel to the straight line where the two cameras are located; the XR virtual imaging position calibration module is slidably connected to the test equipment at the theoretical installation position of the test object via the guide rail 9. S200: Controls the camera under test to capture calibration charts and obtain calibration images, wherein the type of calibration chart corresponds to the type of camera under test; S300: The calibration image is analyzed using a preset algorithm to obtain the first position parameters of the camera under test; Using the XR virtual imaging position calibration module 0 as a reference, determine the position of the XR virtual imaging position calibration module 0; that is, move the XR virtual imaging position calibration module below the position of the AA camera 7 or the test camera 8, and use the position parameters of the XR virtual imaging position calibration module as the reference zero point.

[0046] The AA camera 7 or the test camera 8 takes a picture of the calibration chart of the corresponding camera. Based on the preset algorithm, the position of the XR virtual imaging position calibration module 0 on the calibration image is calculated to obtain the first position parameter of the AA camera 7 or the test camera 8. The first position represents the offset data of the camera under test relative to the XR virtual imaging position calibration module. The offset data includes center offset, rotation and perpendicularity.

[0047] A test pattern is a standard test pattern made on cardboard, which includes various pattern information. It is used to test the overall focus and resolution of the camera lens under test, adjust the lens, and check the geometric distortion and resolution of the lens center back focus and various areas. There are many types of test patterns, and different test patterns are selected according to different testing purposes.

[0048] The preset algorithm in this embodiment, i.e., the test chart detection method, involves: acquiring a captured image of a test chart used for the resolution of the camera under test, or acquiring a captured image of a test chart used for phase-detection autofocus of the camera under test; determining multiple consecutive sets of image blocks and their size information within the target area from the captured image; comparing the size information with a preset size threshold range to determine whether the offset information of the camera under test relative to the test chart is within the required range; or, determining the tilt angle of each image block within the target area relative to the horizontal direction from the captured image; averaging the tilt angles corresponding to each image block within the target area to obtain the tilt information of the camera under test relative to the test chart; comparing the tilt information with a preset angle threshold range to determine whether the offset of the camera under test relative to the test chart is within the required range. Since various detection methods for test charts are existing technologies, they will not be elaborated upon here.

[0049] S400: Adjust the position of the camera under test based on the first position parameter to achieve position calibration of the camera under test; Based on the offset data and the orientation of the XR virtual imaging position calibration module 0, the camera under test is adjusted to be consistent with the XR virtual imaging position calibration module 0. If the center offset, rotation, and perpendicularity of the AA camera 7 or test camera 8 deviate from those of the XR virtual imaging position calibration module 0, the AA camera 7 or test camera 8 is adjusted using a fine-tuning device to bring the deviation of these deviations from the XR virtual imaging position calibration module 0 to near zero. For example, if the center offset data of the AA camera 7 is +0.03, then adjusting the AA camera 7 in the opposite direction of the offset by 0.03 will suffice.

[0050] S500: Turn the XR virtual imaging position calibration module to 0 position and repeat the calibration of the camera under test; Reference Figure 1 The XR virtual imaging position calibration module 0 is symmetrically arranged along the central axis. S410: Collect the second position parameters of the camera under test at the current position. The second position parameters are the center offset, rotation and perpendicularity data of AA camera 7 and test camera 8 relative to XR virtual imaging position calibration module 0 after adjustment.

[0051] S420: Acquire the third position parameter after the XR virtual imaging position calibration module 0 flips at a preset angle; The third position parameter is the center offset, rotation, and verticality data of the AA camera 7 and the test camera 8 relative to the XR virtual imaging position calibration module 0 after the center offset, rotation, and verticality are adjusted by 180°, installed, photographed, calculated, and adjusted.

[0052] S430: Determine whether the difference between the second position parameter and the third position parameter is less than the preset value; if the difference between the second position parameter and the third position parameter is less than the preset value, the camera under test is deemed to be calibrated as qualified; if the difference between the second position parameter and the third position parameter is not less than the preset value, the camera under test is recalibrated until the difference between the second position parameter and the third position parameter is not less than the preset value.

[0053] Because the AA camera calibration chart 2 and the test camera calibration chart 3 are relatively small, and the XR virtual imaging position calibration module 0 is a symmetrical body for more accurate calibration of the perpendicularity of the two cameras, it is installed after being rotated 180° by a preset angle. Then, the camera center offset, rotation, and perpendicularity are recalculated by taking another picture. If the difference in the center offset, rotation, and perpendicularity data calibrated by the XR virtual imaging position calibration module 0 between its original position and after being rotated 180° is less than the preset value (preferably set to 1%), then the perpendicularity calibration of the AA camera 7 and the test camera 8 is qualified; otherwise, it is unqualified.

[0054] The above examples illustrate the present invention only to aid in understanding it and are not intended to limit the scope of the invention. Those skilled in the art can make various simple deductions, modifications, or substitutions based on the principles of this invention.

Claims

1. An XR virtual imaging position calibration module, comprising: The system includes a relay mirror (4), a housing (1), a test camera calibration chart (3), a backlight (6), an AA camera calibration chart (2), and a surface light source (5), arranged sequentially. The housing (1) is vertically through, and the relay mirror (4) is horizontally mounted on the housing (1). The horizontal upper surface of the relay mirror (4) is parallel to the horizontal upper surface of the housing (1). The relay mirror (4) is used to simulate maps at different distances. The test camera calibration chart (3) is set on the horizontal lower surface of the housing (1), and the backlight (6) is horizontally set on the side of the test camera calibration chart (3) away from the housing (1); the horizontal plane of the relay mirror (4) is parallel to the test camera calibration chart (3) and its center is set along the same axis. The AA camera calibration chart (2) is arranged around the relay mirror (4), and the surface light source (5) is arranged on the upper surface of the housing (1) and is used to provide a light source for the AA camera calibration chart (2); the upper surface of the AA camera calibration chart (2) is parallel to the horizontal upper surface of the housing (1) and the center is arranged along the same axis. The housing (1) is kept relatively fixed with the relay mirror (4), the AA camera calibration chart (2), and the test camera calibration chart (3).

2. The XR virtual imaging position calibration module as described in claim 1, characterized in that, The test camera calibration chart (3) and the AA camera calibration chart (2) are prepared by photolithography printing.

3. A method for assembling an XR virtual imaging position calibration module, comprising the XR virtual imaging position calibration module (0) as described in any one of claims 1 or 2, characterized in that, Includes the following steps: Housing (1) preparation: The upper and lower surfaces of the housing (1) are horizontal, and the through opening of the housing (1) is set in the vertical direction; Install the test camera calibration chart (3) and backlight (6): Sequentially control the test camera calibration chart (3) and backlight (6) to be horizontally installed on the lower surface of the housing (1); Calibrate the test camera calibration chart (3): Measure the parallelism, position center offset and rotation of the test camera calibration chart (3) relative to the housing (1), and adjust the position of the test camera calibration chart (3) based on the measurement data so that it is consistent with the housing (1); Install relay mirror (4): Control the relay mirror (4) to be horizontally installed on one side of the upper surface of the housing (1); Calibrate the relay mirror (4): Measure the parallelism and center offset of the relay mirror (4) and the test camera calibration chart (3), and adjust the position of the relay mirror (4) based on the measurement data so that it is consistent with the test camera calibration chart (3); Install the surface light source (5) and the AA camera calibration chart (2): Horizontally install the surface light source (5) on the upper surface of the housing (1) and horizontally install the AA camera calibration chart (2) above the surface light source (5); Calibrate the AA camera calibration chart (2): Measure the parallelism, position center offset and rotation of the AA camera calibration chart (2) relative to the housing (1), and adjust the position of the AA camera calibration chart (2) based on the measurement data so that it is consistent with the housing (1).

4. The assembly method of the XR virtual imaging position calibration module of claim 3, wherein, Before assembly, the housing (1), the test camera calibration chart (3), and the AA camera calibration chart (2) must all be re-tested so that the flatness machining accuracy of each horizontal base surface of the housing (1) is ±0.01-±0.1mm, and the flatness of the test camera calibration chart (3) and the AA camera calibration chart (2) is ±0.01-±0.1mm.

5. The assembly method of the XR virtual imaging position calibration module of claim 3, wherein, Both the surface light source (5) and the backlight source (6) can be detachably installed on the housing (1). The AA camera calibration chart (2) and the test camera calibration chart (3) are connected by applying glue first and then curing.

6. A position calibration method based on XR virtual imaging, characterized in that, Includes the following steps: The XR virtual imaging position calibration module (0) as described in any one of claims 1 or 2 is deployed below the position of the camera under test; The camera under test is controlled to capture a calibration chart to obtain a calibration image, wherein the type of the calibration chart corresponds to the type of the camera under test; The calibration image is analyzed using a preset algorithm to obtain the first position parameters of the camera under test; The position of the camera under test is adjusted based on the first position parameter to achieve position calibration of the camera under test; The second position parameter of the camera under test at the current position and the third position parameter after the XR virtual imaging position calibration module (0) is flipped by a preset angle are collected, wherein the XR virtual imaging position calibration module (0) is symmetrically arranged along the central axis. Determine whether the difference between the second position parameter and the third position parameter is less than a preset value; If the difference between the second position parameter and the third position parameter is less than the preset value, then the camera under test is deemed to be calibrated successfully.

7. The XR virtual imaging-based position calibration method of claim 6, wherein, The XR virtual imaging position calibration module (0) is slidably connected to the test equipment at the theoretical installation position of the test object, and the XR virtual imaging position calibration module (0) can slide to below the AA camera (7) and the test camera (8). The sliding direction of the XR virtual imaging position calibration module (0) is parallel to the straight line where the AA camera (7) and the test camera (8) are located.

8. The XR virtual imaging based position calibration method of any one of claims 6-7, wherein, The step of parsing the calibration image using a preset algorithm to obtain the first position parameters of the camera under test includes: Using the XR virtual imaging position calibration module (0) as a reference, determine the position of the XR virtual imaging position calibration module (0); Based on the preset algorithm, the XR virtual imaging position calibration module (0) is used to calculate the first position parameter of the camera under test according to its position on the calibration image. The first position parameter represents the offset data of the camera under test relative to the XR virtual imaging position calibration module (0). The offset data includes center offset, rotation and perpendicularity.

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