A three-dimensional profile synchronous scanning measurement method of a lens module

Abstract

The application provides a three-dimensional profile synchronous scanning measurement method of a lens module, and relates to the technical field of lens detection. The method comprises the following steps: constructing a three-dimensional profile measurement system, and measuring a lens module to be measured based on the three-dimensional profile measurement system; calibrating a line confocal sensor to determine the corresponding relationship between the actual position of a lens in the lens module and the corresponding point in the light strip profile image captured by a high-speed camera assembly; adjusting the distance between the optical measurement module and the lens module to be measured to a focusing position through a Z-axis motion assembly; driving the lens module to be measured to move according to a planned path through an XY motion assembly, and simultaneously acquiring the light strip profile image of the entire lens module through the high-speed camera assembly; and performing data processing on the light strip profile image of the entire lens module to generate a three-dimensional profile image of the lens module. The application effectively solves the requirement of fast and accurate measurement of the three-dimensional profile of the lens module.

Description

Technical Field

[0001] This invention relates to the field of lens inspection technology, and specifically to a method for synchronous scanning and measurement of the three-dimensional contour of a lens module. Background Technology

[0002] Cameras, mobile phone cameras, and other devices all employ lens modules composed of multiple lenses, and the three-dimensional geometric parameters and microscopic surface quality of these lens modules play a crucial role in imaging performance. During manufacturing, the three-dimensional geometric parameters of the lens module are increasingly emphasized because they more accurately reflect the quality of the lens assembly. By measuring these three-dimensional geometric parameters, we can comprehensively evaluate the quality of the lens module, thereby confirming the rationality of lens design, processing, and assembly. The measured data parameters can be used to guide processing and optimize assembly processes to manufacture high-quality lens modules, ensuring the lens's functionality is achieved.

[0003] Unlike measuring the three-dimensional morphological geometry of individual lenses, lens modules cannot be inspected using traditional methods after assembly. Three-dimensional contour inspection of a lens module requires considering not only the surface contour quality of individual lenses but also the geometric parameters of the entire lens assembly, including the relative distances between lenses, lens coaxiality, thickness, and other geometric parameters. Furthermore, the production, processing, and assembly of lens assemblies are characterized by: difficulty in direct contact, significant impact from positioning errors, and interference from dust or foreign objects on the measurement results.

[0004] Therefore, the measurement of three-dimensional geometric parameters of lens groups has always faced the practical problem of not being able to balance accuracy and efficiency. There is an urgent need for a high-precision and high-efficiency measurement method and device to solve the problem of measuring the three-dimensional geometric parameters of lens groups.

[0005] Currently, the main methods for measuring the 3D contour of a lens module after assembly and adjustment are optical methods, including photogrammetry, structured light, and optical interferometry. Photogrammetry uses images of the object to reconstruct its spatial position and 3D shape. By photographing the object's surface, 3D topographic information can be reconstructed. However, measuring the 3D topography of a lens module requires obtaining the 3D contour information of each lens element within the module, as well as their relative positions. Photogrammetry can only measure the surface 3D contour information of the outermost lens element, and cannot obtain the specific contour information of each lens element within the module; therefore, it is not suitable for measuring the 3D contour of a lens module. Structured light is a system consisting of a projector and a camera. The projector projects specific light information onto the object's surface and background, and the camera collects the changes in the light signal caused by the object, calculating the object's position and depth, thereby reconstructing the entire 3D space. However, structured light measurement also only measures the 3D contour information of the object's surface, and cannot obtain the specific contour information of all lenses within the lens module; therefore, it is not suitable for measuring the 3D contour of the entire module. Interferometry can measure the three-dimensional contours of an object, including information such as roughness and microstructure, and can obtain good information about the three-dimensional contours of the object's surface. However, for measuring the three-dimensional shape of a lens module, interferometry can only obtain the surface three-dimensional contour information of a single lens element and cannot perform three-dimensional measurements on the lenses inside the lens. Therefore, it is not suitable for measuring the three-dimensional contours of a lens module.

[0006] In summary, a high-precision, high-efficiency method for measuring the 3D contour of lens modules is currently lacking. Existing conventional inspection methods cannot accurately measure the 3D geometry of lens modules, and the applicability of existing measurement systems is also significantly limited, failing to meet the need for complete measurement of the entire lens assembly's 3D contour. Therefore, it is necessary to research and develop a measurement system capable of accurately and rapidly detecting the 3D contour of lens modules. Such a system would help to promptly identify and analyze problems arising during processing and assembly, further improving processing techniques and enhancing the quality of lens module manufacturing. Furthermore, this system could provide valuable insights into the relationship between lens imaging performance and its 3D contour. Simultaneously, employing such a measurement system could improve the production and inspection efficiency of lens modules.

[0007] Therefore, researching a measurement system that can accurately and quickly detect the three-dimensional contour of lens modules is of great significance for improving the manufacturing quality of lens modules, improving processing technology, and increasing production and testing efficiency. Summary of the Invention

[0008] This invention aims to at least partially solve one of the technical problems in the prior art. Therefore, the object of this invention is to provide a method for synchronous scanning and measuring the three-dimensional contour of a lens module, effectively addressing the need for rapid and accurate measurement of the three-dimensional contour of a lens module.

[0009] Technical solution: This invention provides a method for synchronous scanning and measurement of the three-dimensional contour of a lens module, including:

[0010] A three-dimensional contour measurement system is constructed, and the lens module under test is measured based on the three-dimensional contour measurement system. The three-dimensional contour measurement system includes a multi-degree-of-freedom motion axis system and an optical measurement module. The multi-degree-of-freedom motion axis system includes an XY motion component, a Z-axis motion component and a motion turntable. The lens module under test is set on the motion turntable. The optical measurement module includes a line confocal sensor and a high-speed camera component.

[0011] The line confocal sensor is calibrated to determine the correspondence between the actual position of the lens in the lens module and the corresponding point in the light stripe contour image captured by the high-speed camera assembly.

[0012] The distance between the optical measurement module and the lens module under test is adjusted to the focusing position using the Z-axis motion component;

[0013] The XY motion component drives the lens module under test to move according to the planned path, while the high-speed camera component cooperates to acquire the light bar contour image of the entire lens module.

[0014] Data processing is performed on the light bar contour image of the entire lens module to generate a three-dimensional contour image of the lens module.

[0015] Furthermore, the data processing of the light bar contour image of the entire lens module to generate a three-dimensional contour image of the lens module includes extracting the three-dimensional contour edges of the lenses in the lens module using edge detection with the Canny operator.

[0016] Furthermore, the extraction of the three-dimensional contour edges of the lens in the lens module using edge detection with the Canny operator includes:

[0017] A Gaussian filter is used to filter and reduce noise in the acquired light stripe contour image of the entire lens module;

[0018] The gradient magnitude and gradient direction in four directions are calculated using the gradient operator. The difference in the horizontal and vertical directions is calculated using the first-order differential operator as a template, and the gradient intensity and gradient direction are obtained.

[0019] By preserving the maxima of the gradient direction, the wide edges obtained from the gradient magnitude image can be thinned.

[0020] Perform dual threshold detection and edge connectivity.

[0021] Furthermore, the dual threshold detection and edge connection includes the Canny operator using high and low thresholds to distinguish edge pixels. If the gradient of a pixel is greater than the high threshold, it is a strong edge point; if it is less than the low threshold, the gray level is set to 0. If it is between the high and low thresholds, it is considered a weak edge. The strong edge breakpoint search is used to connect the weak edges and extract the complete edge.

[0022] Furthermore, the data processing of the light bar contour image of the entire lens module includes coordinate transformation:

[0023] The pixel coordinates of the light bar outline image of the entire lens module in the pixel coordinate system are converted into the image physical coordinate system established with the center of the imaging plane. After being converted from the image physical coordinate system to the camera coordinate system, it is then converted to the world coordinate system.

[0024] Furthermore, the transformation relationship for converting the pixel coordinates of the light bar contour image of the entire lens module in the pixel coordinate system to the image physical coordinate system established with the center of the imaging plane is as follows:

[0025]

[0026] Where (u, v) are pixel coordinates, and dx and dy represent the physical dimensions of each pixel on the horizontal axis x and vertical axis y of the image physical coordinate system, respectively;

[0027] The transformation relationship from the image physical coordinate system to the camera coordinate system is as follows:

[0028]

[0029] Among them, Z c Let f be the working distance of the focusing position of the line confocal sensor, and f be the focal length of the line confocal sensor. c Y c Z c ) represents the corresponding point in the camera coordinate system;

[0030] The transformation relationship to the world coordinate system is as follows:

[0031]

[0032] In this context, the world coordinate system is used to represent the absolute coordinates of spatial objects, using (X... w Y w Z w This indicates that the world coordinate system can be obtained by rotation and translation to obtain the camera coordinate system (X). c Y c Z cThis involves moving the world coordinate system origin to the camera coordinate system origin. The rotation has three degrees of freedom: rotation around the x-axis, y-axis, and z-axis. The rotation matrices R in each of the three directions can be obtained based on the rotation angle. x R y R z The rotation matrix is ​​R = R x ×R y ×R z R is the rotation matrix, and t is the translation matrix;

[0033] The transformation relationship between pixel coordinates and world coordinates is as follows:

[0034]

[0035] Furthermore, after generating the three-dimensional contour image of the lens module, the method further includes obtaining the geometric parameters of the lens module based on the three-dimensional contour image. The geometric parameters include thickness, centerness, and distance between lenses.

[0036] Furthermore, adjusting the distance between the optical measurement module and the lens module under test to the focusing position via the Z-axis motion component includes: the optical measurement module is mounted on the Z-axis motion component, the Z-axis motion component drives the optical measurement module to perform vertical scanning motion, and acquires the cross-sectional profile image of the lens module under test in real time. Based on the Sobel operator, the gradient in the vertical direction of the acquired cross-sectional profile image of the lens module under test is calculated to obtain the average gradient value of the cross-sectional profile image of the lens module under test. The average gradient value represents the sharpness. The sharpness at different positions is judged, and the position of the sharpest cross-sectional profile image is defined as the focusing position.

[0037] Beneficial effects: The three-dimensional contour synchronous scanning measurement method of the present invention effectively solves the need for rapid and accurate measurement of the three-dimensional contour of the lens module, and can realize the complete measurement of the three-dimensional contour of the entire lens module. It has a high degree of automation, high measurement accuracy and high measurement efficiency. Attached Figure Description

[0038] Figure 1 A flowchart illustrating a three-dimensional contour synchronous scanning measurement method for a lens module provided by the present invention;

[0039] Figure 2 A schematic diagram of the structure of the three-dimensional contour measurement system provided by the present invention;

[0040] Figure 3 A schematic diagram of the structure for simultaneous measurement by two line confocal sensors provided by the present invention;

[0041] Figure 4A top view of the lens module path scanning by a centerline confocal sensor using a synchronous scanning method for the three-dimensional contour of a lens module provided by this invention;

[0042] Figure 5 This invention provides a method for synchronous scanning and measuring the three-dimensional contour of a lens module, including a cutaway image of the lens module.

[0043] Figure 6 A detailed flowchart of a three-dimensional contour synchronous scanning measurement method for a lens module provided by the present invention.

[0044] In the diagram: 1. Marble gantry; 2. Linear confocal sensor; 3. Z-axis motion assembly; 4. Objective lens assembly; 5. Lens module; 6. Motion turntable; 7. XY motion assembly; 8. Base bracket; 9. Marble base. Detailed Implementation

[0045] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0046] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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, 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.

[0047] It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. Furthermore, in the description of this application, terms such as "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0048] like Figure 1 As shown, the first embodiment of the present invention provides a method for synchronous scanning and measuring the three-dimensional contour of a lens module, comprising:

[0049] S1. Construct a three-dimensional contour measurement system, and measure the lens module under test based on the three-dimensional contour measurement system. The three-dimensional contour measurement system includes a multi-degree-of-freedom motion axis system and an optical measurement module. The multi-degree-of-freedom motion axis system includes an XY motion component, a Z-axis motion component and a motion turntable. The lens module under test is set on the motion turntable. The optical measurement module includes a line confocal sensor and a high-speed camera component.

[0050] S2. Calibrate the line confocal sensor to determine the correspondence between the actual position of the lens in the lens module and the corresponding point in the light stripe contour image captured by the high-speed camera assembly.

[0051] S3. Adjust the distance between the optical measurement module and the lens module under test to the focusing position using the Z-axis motion component;

[0052] S4 and XY motion components drive the lens module under test to move according to the planned path, while the high-speed camera component cooperates to acquire the light bar contour image of the entire lens module.

[0053] S5. Process the light bar contour image of the entire lens module to generate a three-dimensional contour image of the lens module.

[0054] This invention proposes a high-precision, high-efficiency, and fully automated method for measuring the three-dimensional geometric parameters of lens modules based on the principle of linear confocal geometry. This method utilizes the measurement principle of linear confocal geometry. In this method, after the light source passes through a beam splitter and a dispersive objective lens, different wavelengths of light have different refractive indices in the same medium. Therefore, light of different wavelengths will focus at different positions on the optical axis, forming a series of focused light spots and producing an axial dispersion effect. When the surface being measured is located within the axial dispersion region, it reflects the incident light, which is received by a detector. These reflected lights contain the three-dimensional contour information of the sample being measured. Using this automated measurement method, high-precision and high-efficiency measurement of the three-dimensional geometric parameters of lens modules can be achieved. Compared with traditional methods, this method has the following advantages: it can completely measure the three-dimensional contour of the entire lens module, has a high degree of automation, high measurement accuracy, and high measurement efficiency. It can help improve problems in the lens module manufacturing process, improve processing technology and product quality, and enhance production and inspection efficiency. A three-dimensional contour measurement system for lens modules is built by coupling a high-precision linear confocal sensor with a multi-degree-of-freedom motion axis system, realizing a fully automated process of light stripe acquisition, processing, three-dimensional contour reconstruction, and geometric evaluation during the three-dimensional contour measurement of lens modules.

[0055] like Figure 5 As shown, the cutaway image of the lens module, wherein step S3, adjusting the distance between the optical measurement module and the lens module under test to the focus position by means of the Z-axis motion component includes: the optical measurement module is mounted on the Z-axis motion component, the Z-axis motion component drives the optical measurement module to perform vertical scanning motion, and the cutaway image of the lens module under test is acquired in real time. The gradient in the vertical direction of the acquired cutaway image of the lens module under test is calculated based on the Sobel operator to obtain the average gradient value of the cutaway image of the lens module under test. The average gradient value represents the sharpness. The sharpness at different positions is judged and the position of the sharpest cutaway image is defined as the focus position.

[0056] To achieve full automation of the lens module 3D contour measurement system, it is necessary to select suitable high-precision sensors and multi-degree-of-freedom motion axis systems. The selection of a high-precision linear confocal sensor must meet the following requirements: 1. High light transmittance: The sensor should have high light transmittance, allowing the measurement light to penetrate the multiple lenses in the lens module to achieve 3D contour measurement of the multi-layer lenses. The sensor's light source should minimize light loss to provide clear measurement data. 2. Large depth of field: To obtain complete 3D point cloud data of the lens module contour, the sensor needs to have a large depth of field to accommodate the complexity of different layers of the lens module.

[0057] During the measurement process, a multi-degree-of-freedom motion axis system works in conjunction with a high-precision sensor. The multi-degree-of-freedom platform includes displacement stages in the X and Y axes and a rotary stage around the Z axis. The selection of the motion axis system should consider the following factors: 1. High precision: The motion axis system needs to have high-precision positioning capabilities to ensure the accuracy of the measurement position. Through precise control, measurements of different positions of the lens module can be achieved, and accurate 3D contour point cloud data can be obtained. 2. Multiple degrees of freedom: The multi-degree-of-freedom motion axis system should have sufficient degrees of freedom to meet the requirements of omnidirectional measurement of the 3D contour of the lens module.

[0058] Before measurement, the line confocal sensor needs to be calibrated to determine the correspondence between the actual positions of the lenses in the lens module and the corresponding points in the light stripe contour image captured by the high-speed camera assembly, i.e., to determine the camera parameters. The coordinates obtained from the measurement are pixel coordinates (u, v). When evaluating the three-dimensional contour shape of the lens module, the pixel coordinates (u, v) need to be converted into actual spatial coordinates. The conversion process is as follows: pixel coordinate system → image physical coordinate system → camera coordinate system → world coordinate system.

[0059] (1) The pixel coordinate system is a discrete representation of the image coordinate system. In a real CCD camera, each pixel corresponds to a rectangular photosensitive point. dx and dy represent the physical dimensions of each pixel on the horizontal axis x and vertical axis y of the physical image coordinate system, respectively. The transformation relationship between the coordinate system established with the upper left corner of the CCD sensor as the origin and the coordinate system established with the center of the imaging plane is as follows:

[0060]

[0061] (2) The transition from the camera coordinate system to the image physical coordinate system involves perspective projection. The transformation from 3D to 2D is as follows:

[0062]

[0063] Among them, Z c denoted as the sensor's working distance, and f as the sensor's focal length.

[0064] (3) The world coordinate system is used to represent the absolute coordinates of spatial objects, using (X... w Y w Z w This indicates that the world coordinate system can be obtained by rotation and translation to obtain the camera coordinate system (X). c Y c Z c This involves moving the world coordinate system origin to the camera coordinate system origin. The rotation has three degrees of freedom: rotation around the x-axis, y-axis, and z-axis. The rotation matrices R in each of the three directions can be obtained based on the rotation angle. x R y R z The rotation matrix is ​​R = R x ×R y ×R z R is the rotation matrix, and t is the translation matrix.

[0065] The homogeneous coordinate representation of the transformation process is as follows:

[0066]

[0067] The above transformation relationships are integrated as follows:

[0068]

[0069] Through the coordinate system transformation described above, it is possible to achieve the transformation between the pixel coordinate system (u, v) and the world coordinate system (X). w Y w Z w The conversion between these parameters facilitates the reconstruction of the three-dimensional contour of the lens module after imaging, thereby evaluating the geometric parameters of the lens module. The camera's intrinsic and extrinsic parameters are obtained through the Zhang Zhengyou calibration method.

[0070] To achieve the goal of measuring the three-dimensional contour of the lens module, the technical solution of this invention is implemented from two aspects: hardware device and algorithm control.

[0071] Firstly, such as Figure 2 As shown, the present invention provides a three-dimensional contour measurement system for a lens module, comprising: a base bracket 8, a marble base 9 disposed on the base bracket, an XY motion component 7 disposed on the marble base, a motion turntable 6 disposed on the XY motion component, a lens module 5 to be tested disposed on the motion turntable, a marble gantry 1 disposed on the marble base, a Z-axis motion component 3 disposed on the marble gantry, and a linear confocal sensor 2 disposed on the Z-axis motion component 3, wherein the lens module 5 to be tested is placed on the motion turntable 6;

[0072] Based on the lens module three-dimensional contour measurement device provided by this invention, the lens module 5 to be tested is arranged on the marble base 9, and the optical measurement module is arranged on the Z-axis motion component 3 of the multi-degree-of-freedom motion axis system, so that the optical measurement module and the lens module 5 to be tested can achieve relative position scanning measurement. The optical measurement module first adjusts the distance between itself and the lens module 5 to be tested through the Z-axis motion component 3 to present a clear light stripe contour, and then obtains the three-dimensional contour shape of the entire lens module by rotating the motion turntable 6 or moving the XY motion component 7. Using this measurement method and device, the scanning measurement of the three-dimensional contour of the lens module can be realized.

[0073] Secondly, embodiments of the present invention provide a measurement process and a final image processing algorithm strategy based on the provided three-dimensional contour measurement device for the lens module, wherein the specific steps of the measurement process include:

[0074] Step 1: Linear Spectrum Autofocus. The optical measurement module, mounted on a Z-axis motion component, moves vertically from top to bottom, gradually approaching the lens module under test for scanning. A high-speed camera component acquires the light stripe profile of the lens group under test at different Z-axis height positions in real time. Then, based on the Tenengrad gradient method, the Sobel operator is used to calculate the horizontal and vertical gradients of the lens module's light stripe profile image acquired by the high-speed camera component in real time, obtaining the average gradient value of the lens module's surface image. Using the average gradient value to represent sharpness, the sharpness at different height positions is determined, and the Z-axis acquisition position of the sharpest lens module profile image is obtained, achieving automatic focusing to acquire a clear image of the lens module's profile under test.

[0075] Step 2: Automated Measurement Path Planning. Based on the multi-degree-of-freedom motion axis system, the lens module under test and the optical measurement module are used to plan the relative measurement position scanning motion path. The specific algorithm flow is as follows:

[0076] (1) After the optical measurement module completes automatic focusing to obtain a clear image of the surface of the lens module under test, the optical measurement module is mounted by the Z-axis motion component and moves to the focusing position Z1;

[0077] (2) The XY motion component moves to carry the lens module under test until the sensor light bar scans through the center position of the top of the lens group, which is the starting point of the scanning measurement path;

[0078] (3) Plan and generate the scanning path for the lens module to be tested. Figure 4As shown, the motion turntable rotates in a certain direction and speed. The solid line represents the initial position of the line confocal sensor light stripe scanning measurement. During the rotation of the motion turntable, the light stripe moves and scans relative to the lens module along the direction of the dashed line, so that the line confocal sensor light stripe can scan the entire lens module, achieving low-time-consuming and high-speed scanning.

[0079] Step 3: If the lens module has a large number of lenses or a single line confocal sensor cannot scan the contour of each lens in the entire lens module at the focal position Z1 in one scan, then two line confocal sensors are needed to scan the lens module from both sides. Figure 3 As shown.

[0080] Step 4: Process the light stripe data collected by the line confocal sensor to reconstruct the three-dimensional contour image of the lens module.

[0081] Step 5: After the measurement is completed, the light stripe data collected by the line confocal sensor is processed to obtain the complete three-dimensional contour of the lens module. Then, the geometric quantities of the three-dimensional contour of the lens module are evaluated, such as eccentricity, thickness, centering, and distance between lenses, to facilitate the assembly and adjustment of the lens module.

[0082] On the other hand, the 3D contour information data of the lens module after measurement needs to be preprocessed before the 3D contour can be evaluated. After the high-precision sensor coupled with a multi-degree-of-freedom motion axis system completes the measurement of the 3D contour of the lens module, the collected data is the point cloud data of the 3D contour image of the lens module. The measured 3D point cloud data of the lens contour in the lens module may have problems such as abrupt changes or discontinuous small areas with weak signals, which brings certain difficulties to the reconstruction of the 3D contour of the lens module. The quality of the edge extraction algorithm of the lens module contour is crucial for further data evaluation, and the signal needs to be enhanced and amplified before evaluating the quality of the lens module. Therefore, the light stripe data extracted by the sensor needs to be preprocessed to obtain a clear 3D contour light stripe image, which is convenient for subsequent 3D reconstruction.

[0083] When a boundary line appears between two regions with relatively different grayscale values, we can consider this boundary line as an image edge. The Canny algorithm uses Gaussian filtering for preprocessing in its filtering section. Among second-order differential operators, the Canny operator exhibits good performance in various edge detection methods and has formed a complete standard for optimal detection algorithms. The steps for extracting the 3D contour edges of lenses in a lens module using the Canny operator are as follows:

[0084] (1) Use a Gaussian filter to filter and reduce noise in the collected 3D point cloud data.

[0085] (2) Calculate the gradient magnitude and direction in four directions (0°, 45°, 90°, 135°) using the gradient operator, and calculate the difference G in the horizontal and vertical directions using the first-order differential operator as a template. x and G y Then, the gradient intensity G and direction θ are obtained using the following formula:

[0086]

[0087]

[0088] (3) By preserving the maximum points in the gradient direction, the wide edges obtained from the gradient magnitude image are thinned.

[0089] (4) Perform double threshold detection and edge connection. The usual edge extraction algorithm only uses one threshold for noise filtering. The Canny operator uses high and low thresholds to distinguish edge pixels. If the gradient of a pixel is greater than the high threshold, it is a strong edge point. If it is less than the low threshold, the gray level is set to 0. The pixels between the high and low thresholds are considered weak edges. The strong edge breakpoints are used to search and connect the weak edges and extract the complete edge.

[0090] During the measurement process, if one sensor is unable to complete the measurement of the entire lens module outline, i.e., the sensor's depth of field is insufficient, a dual-camera method (such as...) is required. Figure 3 As shown, measurements are performed by installing a high-precision linear confocal sensor on each side of the lens module, with simultaneous measurements on both sides. After measurement, the point cloud coordinates measured by the two sensors are integrated and reconstructed into a unified coordinate system for coordinate reconstruction. This involves stitching together the data measured simultaneously by the two sensors. After data stitching and reconstruction, complete 3D contour point cloud data of the lens module can be obtained. By analyzing the data, geometric parameters of the lens module, such as thickness, centering, and distance between lenses, can be obtained, allowing for the evaluation of the lens module's quality.

[0091] The lens module 3D contour measurement device proposed in this invention has a high degree of automation integration in both hardware and software. It uses a GPU graphics card to process and reconstruct the 3D contour of the lens module in real time. It requires minimal human intervention, has high measurement efficiency, and allows for a complete and comprehensive evaluation of the measurement results.

[0092] like Figure 6 As shown, the specific measurement process of this invention is as follows:

[0093] (1) Measurement begins by loading the lens module 5 to be tested onto the motion turntable 6 using an automated loading device.

[0094] (2) The line confocal sensor 2, equipped with the objective lens assembly 4, scans and measures the three-dimensional contour of the lens module 5 under test. The Z-axis motion assembly 3 performs vertical scanning motion, acquiring real-time images of the cross-sectional contour of the lens module 5. Based on the Sobel operator, the gradient in the vertical direction of the acquired image of the lens module 5 under test is calculated to obtain the average gradient value of the cross-sectional contour image. The average gradient value represents the sharpness. The sharpness at different locations is determined, and the position of the sharpest cross-sectional contour image of the lens module 5 under test is obtained, completing the automatic focusing measurement.

[0095] (3) Automated measurement path planning is performed based on the motion module carrying the lens module under test 5 and the line confocal sensor measurement module 2. First, it is determined whether the line confocal sensor 2 can measure the entire lens module and see the cross-sectional contours of all lenses in the entire lens module. If so, a measurement coordinate system is established for the three-dimensional shape measurement device of the lens module, with the center position of the lens module as the origin coordinate (0, 0). After the line confocal sensor measurement module completes automatic focusing and obtains a clear image of the cross-sectional contours of the lens module under test, the optical measurement module is mounted on the high-precision Z-axis and moves to the focusing position Z1. Then, the XY motion component moves the lens module under test to the (0, 0) coordinate position, so that the scanning light strip of the line confocal sensor 2 covers the coordinate (0, 0), which is the starting point of the scanning measurement path. Finally, the scanning path of the lens module under test 5 is planned and generated. The motion turntable 6 rotates in a certain direction, driving the lens module under test 5 to rotate. Figure 4 As shown. Based on the scanning of the entire lens module under test, low-time, high-speed scanning is achieved in terms of scanning efficiency. If a single line confocal sensor measurement module cannot see all lenses of the entire lens module at once, two line confocal sensors 2 are used to simultaneously measure from both sides of the lens module under test 5. Figure 3 As shown, the images measured by the two line confocal sensors 2 are finally stitched together to obtain a complete three-dimensional contour map of the lens module 5.

[0096] (4) Under the automated measurement path planning, the light stripe data of the cross-section of the lens module 5 under test extracted by the line confocal sensor 2 is extracted, and the extracted pixel values ​​(u, v) are converted into the spatial Cartesian coordinate system (x, y, z) to realize the extraction of light stripe data and the reconstruction of the three-dimensional contour of the lens module.

[0097] (5) After the three-dimensional contour reconstruction of the lens module to be tested is completed, the three-dimensional contour reconstruction results of the lens module need to be evaluated to obtain information such as the eccentricity of each lens and the relative distance between lenses, so as to assist the lens module in online assembly and adjustment.

[0098] (6) Finally, the lens module 5 to be tested is unloaded by an automated feeding device, and the measurement ends.

[0099] In summary, this embodiment constructs a three-dimensional contour measurement method for lens modules based on the principle of linear confocal measurement, integrates a multi-degree-of-freedom motion axis system, and builds a three-dimensional contour measurement system for lens modules. The system processes data using a GPU image processing card to reconstruct the three-dimensional contour of the lens module, reducing the time required for reconstruction and result evaluation. It automates the entire process of light stripe data extraction, processing, reconstruction, and geometric evaluation during the three-dimensional contour measurement of the lens module, effectively solving the problem of complete scanning measurement of the three-dimensional shape of the lens module and addressing the difficulty of simultaneously achieving both measurement accuracy and efficiency in existing technologies. It can achieve complete measurement of the three-dimensional contour of the entire lens module, with a high degree of automation, high measurement accuracy, and high measurement efficiency.

[0100] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media containing computer-usable program code. These computer program instructions can also be stored in a computer-readable storage medium capable of directing a computer or other programmable data processing apparatus 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 implemented in a process. Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0101] In the embodiments provided in this application, it should be understood that the disclosed apparatus and methods can be implemented in other ways. The apparatus embodiments described above are merely illustrative. For example, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. Furthermore, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Additionally, the displayed or discussed mutual couplings, direct couplings, or communication connections may be through some communication interfaces; indirect couplings or communication connections between devices or units may be electrical, mechanical, or other forms.

Claims

1. A method for synchronous scanning and measuring the three-dimensional contour of a lens module, characterized in that, include: A three-dimensional contour measurement system is constructed, and the lens module under test is measured based on the three-dimensional contour measurement system. The three-dimensional contour measurement system includes a multi-degree-of-freedom motion axis system and an optical measurement module. The multi-degree-of-freedom motion axis system includes an XY motion component, a Z-axis motion component and a motion turntable. The lens module under test is set on the motion turntable. The optical measurement module includes a line confocal sensor and a high-speed camera component. The line confocal sensor is calibrated to determine the correspondence between the actual position of the lens in the lens module and the corresponding point in the light stripe contour image captured by the high-speed camera assembly. The distance between the optical measurement module and the lens module under test is adjusted to the focusing position using the Z-axis motion component; The XY motion component drives the lens module under test to move according to the planned path, while the high-speed camera component cooperates to acquire the light bar contour image of the entire lens module. Data processing is performed on the light stripe contour image of the entire lens module to generate a three-dimensional contour image of the lens module, including using edge detection with the Canny operator to extract the three-dimensional contour edges of the lenses in the lens module; The edge detection extraction of the three-dimensional contour edges of the lens in the lens module using the Canny operator includes: A Gaussian filter is used to filter and reduce noise in the acquired light stripe contour image of the entire lens module; The gradient magnitude and gradient direction in four directions are calculated using the gradient operator. The difference in the horizontal and vertical directions is calculated using the first-order differential operator as a template, and the gradient intensity and gradient direction are obtained. By preserving the maxima of the gradient direction, the wide edges obtained from the gradient magnitude image can be thinned. Perform dual threshold detection and edge connectivity; The dual-threshold detection and edge connection include the Canny operator, which uses high and low thresholds to distinguish edge pixels. If the gradient of a pixel is greater than the high threshold, it is a strong edge; if it is less than the low threshold, the grayscale is set to 0. If the gradient is between the high and low thresholds, it is considered a weak edge. The strong edge breakpoint is used to search and connect the weak edges and extract the complete edge.

2. The method for synchronous scanning and measuring the three-dimensional contour of a lens module according to claim 1, characterized in that, The data processing of the light bar contour image of the entire lens module includes coordinate transformation: The pixel coordinates of the light bar outline image of the entire lens module in the pixel coordinate system are converted into the image physical coordinate system established with the center of the imaging plane. After being converted from the image physical coordinate system to the camera coordinate system, it is then converted to the world coordinate system.

3. The method for synchronous scanning and measuring the three-dimensional contour of a lens module according to claim 2, characterized in that, The transformation relationship between the pixel coordinates of the light bar contour image of the entire lens module in the pixel coordinate system and the image physical coordinate system established with the center of the imaging plane is as follows: ， Where (u, v) are pixel coordinates, and dx and dy represent the physical dimensions of each pixel on the horizontal axis x and vertical axis y of the image physical coordinate system, respectively; The transformation relationship from the image physical coordinate system to the camera coordinate system is as follows: ， Where Zc is the working distance of the focusing position of the line confocal sensor, and f is the focal length of the line confocal sensor. These are the corresponding points in the camera coordinate system; The transformation relationship to the world coordinate system is as follows: ， The world coordinate system is used to represent the absolute coordinates of spatial objects. This indicates that the camera coordinate system is obtained by rotating and translating the world coordinate system. This involves moving the world coordinate system origin to the camera coordinate system origin. The rotation has three degrees of freedom: rotation around the x-axis, y-axis, and z-axis. The rotation matrices for each of the three directions are obtained based on the rotation angle. The rotation matrix is... R is the rotation matrix, and t is the translation matrix; The transformation relationship between pixel coordinates and world coordinates is as follows: 。 4. A method for synchronous scanning and measuring the three-dimensional contour of a lens module according to any one of claims 1-3, characterized in that, After generating the three-dimensional contour image of the lens module, the method further includes obtaining the geometric parameters of the lens module based on the three-dimensional contour image. The geometric parameters include thickness, centering, and distance between lenses.

5. The method for synchronous scanning and measuring the three-dimensional contour of a lens module according to claim 4, characterized in that, The step of adjusting the distance between the optical measurement module and the lens module under test to the focusing position via the Z-axis motion component includes: the optical measurement module is mounted on the Z-axis motion component, the Z-axis motion component drives the optical measurement module to perform vertical scanning motion, and acquires the cross-sectional profile image of the lens module under test in real time. Based on the Sobel operator, the gradient in the vertical direction of the acquired cross-sectional profile image of the lens module under test is calculated to obtain the average gradient value of the cross-sectional profile image of the lens module under test. The average gradient value represents the sharpness. The sharpness at different positions is judged and the position of the sharpest cross-sectional profile image is defined as the focusing position.

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