Method for measuring double surface deflection of transparent element based on two-channel partition projection

Abstract

The application discloses a transparent element double-surface deflection measurement method based on a double-channel partition projection, and belongs to the technical field of deflection measurement. The double-channel measurement system is jointly calibrated, the transparent element in the refraction channel is positioned through light ray tracing, the double-channel measurement system calibration and workpiece positioning parameters are used to trace the nominal model of the measured element to realize screen partitioning, and two sets of partition sequence projection stripes are designed based on the same to avoid aliasing of the reflection signals. During measurement, the non-full duty cycle stripes designed through alternating projection are used to obtain the un-aliased reflection signals on the upper and lower surfaces of the transparent element, the corresponding relationship between the to-be-measured point, the screen and the camera is determined through binoculars, and finally the geometric surface shape is obtained through gradient integration, so that the problem of double-surface signal aliasing in the deflection measurement of the transparent element is solved.

Description

Technical Field

[0001] This invention relates to the field of deflection measurement technology, and in particular to a method for measuring the deflection of a transparent element on both surfaces based on dual-channel partitioned projection. Background Technology

[0002] With the rapid development of major assemblies and advanced instruments, various complex optical components, micro- and nanostructures, and related manufacturing technologies are advancing rapidly, leading to an increasing demand for high-precision measurement and inspection of these optical components and structures. Transparent optical components (such as lenses and optical windows) are among the most widely used, and the demand is particularly urgent. The quality of both their surfaces has a crucial impact on their performance. Accurately measuring the surface shape of these components can effectively improve their optical performance, reduce optical distortion and imaging errors, thereby ensuring high-quality optical imaging and beam transmission.

[0003] Phase measurement deflection is a promising optical inspection technique that enables high-precision and high-efficiency surface measurement and inspection without contact. Compared to traditional methods, deflection offers significant advantages in measurement speed, sensitivity, and adaptability, thus finding widespread application in optical manufacturing, semiconductor industry, aerospace, and precision instruments. It holds significant research value and broad application prospects. However, optical measurements of transparent components based on deflection are often unsuitable due to the aliasing of signals from both surfaces. To utilize the superior performance of deflection, numerous researchers have conducted extensive research. One of the simplest and most effective methods is to apply a blackening or coating to the lower surface, causing diffuse reflection and thus suppressing the reflected signal from the lower surface. A projection mode based on ultraviolet light sources was developed (SPRENGER D, FABERC, SERAPHIM M, et al. UV-def ectometry: no parasitic ref ect ions[C] / / Proc. 112th Annual Meeting of the DGaOA. 2010, 19.), because most mineral glasses are opaque to light below 330nm, so the camera only receives the reflected signal from the upper surface. Although this method is the most direct, smearing may affect the surface quality of optical components and reduce measurement efficiency, while ultraviolet light sources are expensive and complex to operate. Su et al. (SU T, PARK WH, PARKS RE, et al. Scanning long-wave optical test system: a new ground optical surface slope test system[C] / / Optical Manufacturing and Testing IX. Proceedings of SPIE, 2011, 8126:81260E.DOI:10.1117 / 12.892666.) achieved a sparse projection method by displaying only a bright line on the screen, causing the reflected signals from the upper and lower surfaces to be misaligned at the camera's shooting angle, thus preventing superposition. While this sparse projection method avoids aliasing, it requires scanning, resulting in low efficiency, and it cannot completely separate signals for complex components.Li et al. proposed a method to decouple the upper and lower surface reflection stripes by projecting stripe patterns of different frequencies, using Fourier transform to treat the screen position corresponding to the camera as a constant, and using the changing frequencies to form beat frequencies at specific positions (Wang R, Li D, Li L, et al. Surface shape measurement of transparent plane elements with phase measurement def electrometry[J]. Optical Engineering, 2018, 57(10): 104104-104104.). However, this method is mainly applicable to thicker parallel flat crystals. Huang et al. proposed a dual-frequency four-step phase-shifting fringe decoupling method (Huang L, Asund i AK. Phase retrieving from reflective fringe patterns of double-sided transparent objects[J]. Measurement Science and Technology, 2012, 23(8): 085201.), which constructs a full-rank equation by removing the background term and solves the modulation and phase of the upper and lower surfaces point by point. Ye et al. constructed an iterative phase solver by projecting multiple single-frame fringes of different frequencies and using a product-sum-difference approach. They then separated the phase signals of the upper and lower surfaces through alternating iterations (Ye J, Niu Z, Zhang X, et al. Simultaneous measurement of double surfaces of transparent lenses with phase measuring def ectometry[J]. Optics and Lasers in Engineering, 2021, 137:106356.), essentially similar to Huang's method. While this type of method mathematically constructs a full-rank solver, the complex equations only allow for optimization, requiring very high initial values. Furthermore, the periodic variation of the fringes often leads to local optima at the truncation points, which then propagate to the global optimum. In addition, compared to traditional deflection measurement models based on tracing a single reflected ray, this method cannot reconstruct the lower surface of transparent elements. Summary of the Invention

[0004] The purpose of this invention is to provide a method for measuring the deflection of a transparent element on two surfaces based on dual-channel partitioned projection. The method uses a refraction channel to position the workpiece and combines system parameters to perform partitioned projection on the screen, thereby avoiding signal aliasing in the reflection channel. A dual-channel fold-reflection-fold tracing model is used to establish the correspondence between the measured points, solve the gradient of the measured points, and integrate to reconstruct the surface shape of the two surfaces. This method can solve the signal aliasing problem in the existing transparent element dual-surface deflection measurement technology mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A method for measuring the dual-surface deflection of transparent elements based on dual-channel partitioned projection is implemented using a dual-surface deflection measurement system, which includes a camera, a screen, and the following steps:

[0007] The transparent element is positioned by a refraction channel, the signal aliasing between the two surfaces is avoided by designing a partitioned stripe pattern, and the two surfaces of the transparent element are reconstructed simultaneously by binoculars with different sensitivities.

[0008] Furthermore, the specific steps include the following:

[0009] S1. Determine the structure of the dual-surface deflection measurement system using a computer-aided system: Simulate the structure of the dual-surface deflection measurement system based on the actual hardware parameters, determine the geometric parameters of each hardware component using a computer-aided system, so that the camera in the refraction channel can observe the screen, and place the device under test in the measurement field of view so that the camera can also observe the screen.

[0010] S2. Constructing a dual-surface deflection measurement system: Based on the simulated dual-surface deflection measurement system structure, construct a dual-channel phase measurement deflection system and verify the correctness of the dual-surface deflection measurement system structure using a reference mirror;

[0011] S3. Calibrate the parameters of the constructed dual-surface deflection measurement system: Determine the intrinsic parameters of the two cameras through Zhang Zhengyou calibration, display the marker points on the screen, calibrate the geometric pose of the camera and screen in the refraction channel based on the PnP algorithm, and calibrate the geometric pose of the camera and screen in the reflection channel with the help of the plane mirror with marker points.

[0012] S4. Joint optimization of parameters of dual-surface deflection measurement system: Establish a joint optimizer based on the bundle adjustment method to simultaneously optimize the camera intrinsic parameters and system geometric parameters of the two channels, shortening the error propagation chain;

[0013] S5. Positioning of transparent elements in the refraction channel: Establish a ray tracing positioning optimizer for the refraction channel and achieve positioning by analyzing the wave aberrations introduced by the transparent elements;

[0014] S6. Partitioned projection stripe design: Based on the above-calibrated parameters and workpiece pose, perform ray tracing, partition the screen, and set the screen area corresponding to the unwanted surface reflection signal as a black area.

[0015] S7. Acquisition of dual-channel signals: According to the light source layout designed in S6, project the four-step phase-shifting stripe pattern with non-full duty cycle in sequence to acquire the signals of the upper and lower surfaces without aliasing.

[0016] S8. Signal demodulation and matching: Demodulate the signal acquired by the reflection channel, match the source of the signal according to the ray tracing, and stitch them together into a complete, non-aliased dual-surface signal. The refraction channel is non-aliased, and the dual-surface signal is decoded.

[0017] S9. Gradient acquisition: The measured point is determined by using a dual-channel tracking model with inversion and decoupling. The correspondence between the two cameras and the screen is determined based on the parameters of the dual-surface deflection measurement system, and the normal of the measured point is determined.

[0018] S10, Surface Reconstruction: Obtain the surface shape of the two surfaces of the transparent element under test through gradient integration.

[0019] Furthermore, the computer-aided system includes a hardware model library containing geometric parameters of various types of hardware. By inputting different hardware types, sizes, and related parameters, specific hardware can be added to the hardware model library, and corresponding geometric parameters can be assigned.

[0020] Furthermore, the geometric pose of the reflection channel camera and the screen is determined using a plane mirror with marked points, specifically including:

[0021] Determine a marker point for a plane mirror, and set a rotatable support on the plane mirror so that the plane mirror can rotate freely within a certain range;

[0022] Place a marked plane mirror in a real-world scenario, and set up sensors on the plane mirror to record its position and orientation information;

[0023] A marked plane mirror is placed in front of the object being measured, and the light reflection information between the plane mirror and the object being measured is obtained through a sensor;

[0024] The light reflection information between the plane mirror and the object under test is processed to obtain the intrinsic and extrinsic parameters of the reflection channel camera;

[0025] Using intrinsic and extrinsic parameters and the position information of marker points, the geometric relationship between the reflection channel camera and the screen is calculated. The geometric relationship includes the transformation relationship between the camera coordinate system and the plane mirror coordinate system.

[0026] Furthermore, S4 specifically includes

[0027] Obtain the intrinsic parameter information of the two cameras;

[0028] Determine the corresponding optimization objective based on the positional relationship between the two cameras;

[0029] Establish a joint optimization model, including camera intrinsic parameters and system geometric parameters;

[0030] The joint optimization model was optimized using bundle adjustment.

[0031] Based on the optimized parameter settings, update the intrinsic parameters of each camera and the system geometric parameters.

[0032] Furthermore, in S6, a refraction channel is used to locate the transparent element based on the beam adjustment method, guiding the design of the light source layout.

[0033] Furthermore, in S8, the source of the signal for the partitioned projection is determined by the ray tracing model, which guides the matching of signals on the upper and lower surfaces.

[0034] Furthermore, the ray tracing and positioning optimizer for establishing the refraction channel specifically includes:

[0035] A transmitter used to transmit and receive visible light signals of specific wavelengths;

[0036] A lens array used to detect the reflection or refraction of visible light signals;

[0037] The reflector is located behind the lens array;

[0038] A reflector located in front of the lens array focuses the visible light signal from the transmitter onto the receiver after passing through the lens array and the reflector.

[0039] Furthermore, the demodulation of the signal acquired by the reflection channel specifically includes:

[0040] Receive signals acquired by the reflection channel;

[0041] Detect whether there is distortion in the signal;

[0042] If distortion exists, perform distortion correction.

[0043] If there is no distortion, the signal is demodulated.

[0044] Output the demodulated signal.

[0045] An electronic device includes a memory storing executable program code and a processor coupled to the memory; wherein the processor invokes the executable program code stored in the memory to execute the dual-surface shape measurement method.

[0046] Compared with the prior art, the beneficial effects of the present invention are:

[0047] This invention uses a refraction channel to assist in the positioning of optical elements and partitions the screen light source based on calibration and positioning parameters for ray tracing. Areas corresponding to unwanted surface reflection signals are designated as dark areas to avoid signal aliasing in the reflection channel. For missing signals, the signal and dark areas of the light source layout are reversed to obtain complete signals. Refraction correction is applied to traditional reflection ray tracing, and a refraction-reflection-refraction ray tracing model is used to establish the correspondence of the lower surface. Gradient integration is used to reconstruct the surface shape of both surfaces. Compared to the traditional method of smearing the lower surface, this invention avoids damage to the measured element. Compared to traditional line scanning, this invention is more efficient. Compared to the decoupling method of traditional multi-frequency signal numerical solution, this invention has fewer error sources and higher robustness. The proposed dual-channel method can effectively solve the gradient-height ambiguity inherent in deflection measurement. Without adding hardware costs, it can effectively reconstruct the surface shape of both surfaces of transparent elements, expanding the applicability of deflection measurement and enabling further widespread use. This fundamentally solves the signal problem of the reflection channel. Attached Figure Description

[0048] Figure 1 This is a schematic diagram of the measurement system structure of the present invention;

[0049] Figure 2 This is a schematic diagram of the dual-surface deflection measurement process of the present invention;

[0050] Figure 3 This is the structure of the simulation system in Embodiment 1 of the present invention;

[0051] Figure 4 This is a schematic diagram of the dual-channel camera intrinsic parameter calibration in Embodiment 1 of the present invention;

[0052] Figure 5 This is a schematic diagram of the system geometric pose calibration mirror in Embodiment 1 of the present invention;

[0053] Figure 6 This is a schematic diagram of the light source partitioning principle in Embodiment 1 of the present invention;

[0054] Figure 7 This is a schematic diagram of the screen projection pattern design in Embodiment 1 of the present invention;

[0055] Figure 8 This is a phase diagram of the upper surface of the reflection channel separation without aliasing in Embodiment 1 of the present invention;

[0056] Figure 9 This is a phase diagram of the lower surface of the reflection channel separation without aliasing in Embodiment 1 of the present invention;

[0057] Figure 10 This is a schematic diagram of the simulated measurement results of the dual surfaces of the transparent flat plate in Embodiment 1 of the present invention;

[0058] Figure 11 This is a schematic diagram of the electronic device of the present invention. Detailed Implementation

[0059] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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 are within the scope of protection of the present invention.

[0060] Example 1: A method for measuring the dual-surface deflection of transparent elements based on dual-channel partitioned projection, implemented using a dual-surface deflection measurement system, such as... Figure 1 As shown, the dual-surface deflection measurement system includes camera 1, camera 2, and screen 3. Figure 2 The bi-surface deflection measurement process is demonstrated below:

[0061] The process involves locating the transparent element using a refractive channel, avoiding signal aliasing between the two surfaces by designing a partitioned stripe pattern, and simultaneously reconstructing both surfaces of the transparent element using binoculars with different sensitivities. The specific steps include:

[0062] S1. Determine the structure of the dual-surface deflection measurement system using a computer-aided system: Simulate the structure of the dual-surface deflection measurement system based on the actual hardware parameters, determine the geometric parameters of each hardware component using a computer-aided system, so that the camera 2 in the refraction channel can observe the screen 3, and place the device under test in the measurement field of view so that the camera 1 can also observe the screen 3.

[0063] Computer-aided systems include hardware model libraries containing geometric parameters of various types of hardware. By inputting different hardware types, sizes, and related parameters, specific hardware can be added to the hardware model library, and corresponding geometric parameters can be assigned.

[0064] The specific implementation of this step is as follows:

[0065] Input the hardware parameters of the dual-surface deflection measurement system into the simulation software, such as the camera's target surface size, pixel size, focal length, screen size, pixel size, etc., and design a correct system structure to ensure that both channels can acquire effective signals in the field of view. Figure 3As shown. Specifically, a dual-channel measurement system is constructed using two cameras with a pixel size of 5µm and a resolution of 1024×1280, paired with lenses with a focal length of 20mm, and a 1536×2048 screen with a pixel size of 78.4µm. Through simulation, a suitable system structure is determined. Using the coordinate system of the calibration mirror as the global coordinate system, the poses of the catadioptric and reflective channel cameras and the screen are shown in Table 1 below:

[0066] Table 1 System Geometric Pose Relationships

[0067]

[0068] S2. Construct the dual-surface deflection measurement system structure: Construct the actual measurement system based on the simulated system parameters, and verify whether a valid new signal can be obtained through a reference mirror, thereby verifying the correctness of the dual-surface deflection measurement system structure.

[0069] S3. Calibrate the parameters of the constructed dual-surface deflection measurement system: Determine the intrinsic parameters of the two cameras using Zhang Zhengyou's calibration, and calibrate the intrinsic parameters of the dual-channel cameras separately using a checkerboard pattern, such as... Figure 4 As shown, using a plane mirror with marked points, the pose relationship between the two cameras and screen 3 is obtained through the PnP algorithm, as follows: Figure 5 As shown, the details are as follows;

[0070] The geometric poses of camera 1 and screen 3 in the reflection channel are determined using a plane mirror with marked points, specifically including:

[0071] Determine a marker point for a plane mirror, and set a rotatable support on the plane mirror so that the plane mirror can rotate freely within a certain range;

[0072] Place a marked plane mirror in a real-world scenario, and set up sensors on the plane mirror to record its position and orientation information;

[0073] A marked plane mirror is placed in front of the object being measured, and the light reflection information between the plane mirror and the object being measured is obtained through a sensor;

[0074] The light reflection information between the plane mirror and the object under test is processed to obtain the intrinsic and extrinsic parameters of camera 1 in the reflection channel;

[0075] Using intrinsic and extrinsic parameters and the position information of marker points, the geometric relationship between camera 1 and screen 3 in the reflection channel is calculated. The geometric relationship includes the transformation relationship between the camera coordinate system and the plane mirror coordinate system.

[0076] S4. Joint Optimization of Dual-Surface Deflection Measurement System Parameters: To prevent calibration errors from propagating between the aforementioned rigid steps, a joint optimizer based on bundle adjustment is established to simultaneously tune the camera intrinsic parameters and system geometric parameters of both channels, shortening the error propagation chain. Specifically, this includes...

[0077] Obtain the intrinsic parameter information of the two cameras;

[0078] Determine the corresponding optimization objective based on the positional relationship between the two cameras;

[0079] Establish a joint optimization model, including camera intrinsic parameters and system geometric parameters;

[0080] The joint optimization model was optimized using bundle adjustment.

[0081] Based on the optimized parameter settings, update the intrinsic parameters of each camera and the system geometric parameters.

[0082] Using the S3 calibration parameters as initial values, an optimizer as shown in Equation (1) is established to jointly optimize the system parameters, shorten the transmission and accumulation of errors between rigid steps, and improve the calibration accuracy of the system parameters.

[0083]

[0084] Where s represents the set of measurement system parameters, including the intrinsic parameters of the camera and the screen and the corresponding geometric pose, and L(.) and U(.) represent the reprojection errors of the lower camera and the upper camera, respectively.

[0085] The above method allows for simultaneous optimization of two cameras without altering the intrinsic parameters of a single camera or the system's geometric parameters, thereby improving the overall system performance. Furthermore, this method exhibits good robustness and scalability, making it applicable to various types of optical imaging systems.

[0086] S5. Positioning of transparent elements in the refraction channel: Due to signal aliasing in the reflection channel, a ray tracing positioning optimizer for the refraction channel is established, and positioning is achieved by analyzing the wave aberrations introduced by the transparent elements.

[0087] The ray tracing localization optimizer for establishing the refraction channel specifically includes:

[0088] A transmitter used to transmit and receive visible light signals of specific wavelengths;

[0089] A lens array used to detect the reflection or refraction of visible light signals;

[0090] The reflector is located behind the lens array;

[0091] A reflector located in front of the lens array focuses the visible light signal from the transmitter onto the receiver after passing through the lens array and the reflector.

[0092] A positioning solver is constructed using a refraction channel, as shown in Equation (2). Tracing is performed based on the nominal surface shape of the measured element, and the pose parameters of the measured element are used as optimization variables to minimize the reprojection error.

[0093]

[0094] Where R and T are the rotation matrix and translation vector, respectively, and R(.) represents the reprojection error of the refraction channel.

[0095] This design reduces light occlusion and multipath interference to some extent, thereby improving the accuracy of ray tracing positioning. Furthermore, the effect of ray tracing positioning can be further optimized by adjusting the parameters of the lens array and / or reflectors.

[0096] S6. Zoned Projection Stripe Design: Based on the parameters and workpiece pose specified above, perform ray tracing, such as... Figure 6 As shown, the projection signal of screen 3 is partitioned, and the screen area corresponding to the unwanted surface reflection signal is set as a black area. The transparent element is positioned by using the refraction channel based on the beam adjustment method to guide the design of the light source layout, so as to avoid generating double reflection signals.

[0097] S7. Acquisition of Dual-Channel Signals: Projecting a four-step phase-shifted fringe pattern with a non-full duty cycle according to the light source layout designed in S6, and acquiring the signals from the upper and lower surfaces without aliasing, as follows: Figure 7 As shown;

[0098] S8. Signal Demodulation and Matching: The signal (fringe pattern) acquired from the reflection channel is demodulated to obtain the phase map of the partition. Based on ray tracing, the source of the matched signal is used to guide the matching of the signals on the upper and lower surfaces, stitching them together into a complete, non-aliased dual-surface signal (e.g., ...). Figure 8-9 As shown), the refractive channel is free of aliasing, and the dual-surface signal is decoded. Similarly, the phase signal of the refractive channel is decoupled using a four-step phase-shift algorithm.

[0099] The signal acquired by the reflection channel is demodulated, specifically including...

[0100] Receive signals acquired by the reflection channel;

[0101] Detect whether there is distortion in the signal;

[0102] If distortion exists, perform distortion correction.

[0103] If there is no distortion, the signal is demodulated.

[0104] Output the demodulated signal.

[0105] S9. Gradient Acquisition: The position of the test point on the upper surface is determined by the binocular normal consistency constraint, and the test point is determined by the anti-reflection dual-channel tracing model. On the one hand, the binocular method avoids the gradient height ambiguity inherent in deflection, and on the other hand, the two channels with different sensitivities help improve the accuracy of the solution. Combined with the above decoupled signals, the correspondence between the two cameras and screen 3 is determined based on the parameters of the dual-surface deflection measurement system. Based on Snier's law, the normal information of the test point can be determined by the geometric parameters and the decoupled signals.

[0106] S10, Surface Reconstruction: By performing gradient integration between the position and normal of the point to be measured, the surface shape of the two surfaces of the component under test can be obtained, as shown in Equation (3).

[0107] z = intg(x,y,G) x G y (3)

[0108] Where (x, y) represents the lateral position of the measured point, (Gx, Gy) represents the gradient of the measured point along the x- and y- directions, and intg(.) is the integration operator. The final reconstructed surface of the bisurface is as follows: Figure 10 As shown.

[0109] Example 2: By slightly modifying the method steps of Example 1, various variant measurement structures can be constructed, such as multi-view or multi-screen structures. In S5, the number of refracting cameras can be increased to improve the workpiece positioning accuracy. Furthermore, in S5, the positioning solver can use not only reprojection error but also wave aberration functions, further improving convergence sensitivity. This is essentially no different from the proposed method; other specific procedures are consistent with Example 1 and will not be repeated here.

[0110] Example 3: An electronic device, such as Figure 11 As shown, the device includes a memory and a connected processor. The memory contains executable program code, which the processor calls to execute a series of method steps. These processors include various conventional processors; correspondingly, the storage module can also take various forms, such as a memory card, hard drive, or cloud server. When this device is used as a commercial measurement tool, it will also include a data acquisition module, a display module, and a power supply module. The data acquisition module transmits measurement data to the memory via communication methods such as network cables, and the memory then transmits this data and pre-stored program code to the processor. The measurement results processed by the processor are sent back to the storage module and displayed through the display module. Simultaneously, the power supply module is responsible for supplying power to all modules of the device.

[0111] The description of this invention is based on a series of flowcharts and structural diagrams that detail the internal logic of methods, apparatus (systems), and computer program products. It is important to understand that every element, block, and even combination thereof in the diagrams can be implemented using carefully designed computer program code. This code enables general-purpose, special-purpose, or embedded computer processors to build intelligent machines that perform specific tasks. Furthermore, this program code is carefully encapsulated within a computer-readable medium, whether local hard drive, cloud storage, or other storage media, to guide a computer or other programmable device to operate in a predetermined manner, thereby achieving the functions depicted in the flowcharts or structural diagrams.

[0112] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The functions specified in one or more boxes. These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable apparatus for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0113] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for measuring the dual-surface deflection of transparent elements based on dual-channel partitioned projection, implemented using a dual-surface deflection measurement system comprising a first camera (1), a second camera (2), and a screen (3), characterized in that, Includes the following steps: The process involves locating the transparent element using a refractive channel, avoiding signal aliasing between the two surfaces by designing a partitioned stripe pattern, and simultaneously reconstructing both surfaces of the transparent element using binoculars with different sensitivities. The specific steps include: S1. Determine the structure of the dual-surface deflection measurement system through a computer-aided system: Simulate the structure of the dual-surface deflection measurement system according to the actual hardware parameters, determine the geometric parameters of each hardware through a computer-aided system, so that the second camera (2) of the refraction channel can observe the screen (3), and place the test piece in the measurement field of view so that the first camera (1) can also observe the screen (3). S2. Constructing a dual-surface deflection measurement system: Based on the simulated dual-surface deflection measurement system structure, construct a dual-channel phase measurement deflection system and verify the correctness of the dual-surface deflection measurement system structure using a reference mirror; S3. The parameters of the constructed dual-surface deflection measurement system are calibrated: the intrinsic parameters of the two cameras are determined by Zhang Zhengyou calibration, the marker points are displayed on the screen (3), the geometric poses of the second camera (2) and the screen (3) of the refraction channel are calibrated based on the PnP algorithm, and the geometric poses of the first camera (1) and the screen (3) of the reflection channel are calibrated by the plane mirror with marker points. S4. Joint optimization of parameters of dual-surface deflection measurement system: Establish a joint optimizer based on the bundle adjustment method to simultaneously optimize the camera intrinsic parameters and system geometric parameters of the two channels, shortening the error propagation chain; S5. Positioning of transparent elements in the refraction channel: Establish a ray tracing positioning optimizer for the refraction channel and achieve positioning by analyzing the wave aberrations introduced by the transparent elements; S6, Partitioned projection stripe design: Based on the calibrated parameters and workpiece pose, perform ray tracing, partition the screen (3), and set the screen area corresponding to the unwanted surface reflection signal as a black area; The refraction channel is used to locate transparent elements based on the beam adjustment method, which guides the design of the light source layout; S7. Acquisition of dual-channel signals: According to the light source layout designed in S6, project the four-step phase-shifting stripe pattern with non-full duty cycle in sequence to acquire the signals of the upper and lower surfaces without aliasing. S8. Signal demodulation and matching: Demodulate the signal acquired by the reflection channel, match the source of the signal according to the ray tracing, and stitch them together into a complete, non-aliased dual-surface signal. The refraction channel is non-aliased, and the dual-surface signal is decoded. S9. Gradient acquisition: The measured point is determined by using a dual-channel tracking model with inversion and decoupling. Based on the parameters of the dual-surface deflection measurement system, the correspondence between the two cameras and the screen (3) is determined, and the normal of the measured point is determined. S10, Surface Reconstruction: Obtain the surface shape of the two surfaces of the transparent element under test through gradient integration.

2. The method for measuring the dual-surface deflection of transparent elements based on dual-channel partitioned projection as described in claim 1, characterized in that, The computer-aided system includes a hardware model library containing geometric parameters of various types of hardware. By inputting different hardware types, sizes, and related parameters, specific hardware can be added to the hardware model library and assigned corresponding geometric parameters.

3. The method for measuring the dual-surface deflection of transparent elements based on dual-channel partitioned projection as described in claim 1, characterized in that, The geometric pose of the first camera (1) and the screen (3) in the reflection channel is determined by using a plane mirror with marked points. Specifically, this includes: Determine a marker point for a plane mirror, and set a rotatable support on the plane mirror so that the plane mirror can rotate freely within a certain range; Place a marked plane mirror in a real-world scenario, and set up sensors on the plane mirror to record its position and orientation information; A marked plane mirror is placed in front of the object being measured, and the light reflection information between the plane mirror and the object being measured is obtained through a sensor; The light reflection information between the plane mirror and the object under test is processed to obtain the intrinsic and extrinsic parameters of the camera (1) in the reflection channel; Using intrinsic and extrinsic parameters and the position information of marker points, the geometric relationship between the first camera (1) and the screen (3) of the reflection channel is calculated, where the geometric relationship includes the transformation relationship between the camera coordinate system and the plane mirror coordinate system.

4. The method for measuring the dual-surface deflection of transparent elements based on dual-channel partitioned projection as described in claim 1, characterized in that, S4 specifically includes Obtain the intrinsic parameter information of the two cameras; Determine the corresponding optimization objective based on the positional relationship between the two cameras; Establish a joint optimization model, including camera intrinsic parameters and system geometric parameters; The joint optimization model was optimized using bundle adjustment. Based on the optimized parameter settings, update the intrinsic parameters of each camera and the system geometric parameters.

5. The method for measuring the dual-surface deflection of transparent elements based on dual-channel partitioned projection as described in claim 1, characterized in that, In S8, the source of the signal for the partition projection is determined by the ray tracing model, which guides the matching of signals on the upper and lower surfaces.

6. The method for measuring the dual-surface deflection of transparent elements based on dual-channel partitioned projection as described in claim 1, characterized in that, The ray tracing and positioning optimizer for establishing the refraction channel specifically includes: A transmitter used to transmit and receive visible light signals of specific wavelengths; A lens array used to detect the reflection or refraction of visible light signals; The reflector is located behind the lens array; A reflector located in front of the lens array focuses the visible light signal from the transmitter onto the receiver after passing through the lens array and the reflector.

7. The method for measuring the dual-surface deflection of transparent elements based on dual-channel partitioned projection as described in claim 1, characterized in that, The demodulation of the signal acquired by the reflection channel specifically includes: Receive signals acquired by the reflection channel; Detect whether there is distortion in the signal; If distortion exists, perform distortion correction. If there is no distortion, the signal is demodulated. Output the demodulated signal.

8. An electronic device, characterized in that, It includes a memory storing executable program code and a processor coupled to the memory; wherein the processor calls the executable program code stored in the memory to execute the dual-surface shape measurement method as described in any one of claims 1-7.

Images