Method for phase deflection calibration

Abstract

The invention relates to a phase deflection technique, relates to the technical field of equipment calibration, and particularly relates to a method for phase deflection technique calibration, which comprises a method for calibrating a camera. The LCD pixel point calibration method comprises the following steps: acquiring sampling pixel points of an LCD to be calibrated and three first-class feature point three-dimensional coordinates, further acquiring a three-dimensional surface shape, and reversely calculating actual spatial positions of all pixel points on the currently calibrated LCD according to actual requirements; the reflector calibration method comprises the following steps: acquiring three-dimensional coordinates of a sampled point and three second-class feature points on a reflector, further acquiring a spatial geometrical relationship model, and reversely calculating the spatial position and attitude of the current reflector according to actual requirements. According to the invention, the problem that the reflector and the LCD to be calibrated have surface shapes and need to move is avoided. And the real-time positions of the reflector and the LCD can be obtained only through the positions of the corresponding measurement feature points subsequently, so that the calibration efficiency is greatly improved, and the practicability in a processing workshop is further improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of phase deflectometry and device calibration, and particularly relates to a method for phase deflectometry calibration. BACKGROUND

[0002] Phase deflectometry is a non-contact surface shape detection technology, which has the advantages of fast detection speed, large dynamic range, cost-effectiveness and precision comparable to interferometer. It mainly calculates the sinusoidal fringe image reflected by the mirror to be measured, obtains the phase change and converts it into surface slope, and then integrates it into surface height to realize high-precision surface shape detection. Accurate calculation of surface slope is an important step to obtain high-precision surface topography, and calibration and geometric measurement of the detection system are the key to slope calculation. The detection system is usually composed of a liquid crystal display (LCD for short), a mirror to be measured and a camera. Among them, the LCD not in the field of view of the camera has always been a difficult point in system calibration, and the mirror needs to measure its global coordinates to calculate the position of the sampling points on the reflecting surface. Therefore, the calibration and geometric measurement of the LCD and the mirror are important factors affecting the measurement results of phase deflectometry.

[0003] The calibration of the LCD is essentially the accurate calibration of the pixel point position on the LCD irradiated to the mirror. Due to the limitation of manufacturing cost and daily use demand, the flatness requirement of the pixel array is low, and the flatness further decreases with the increase of the size. In phase deflectometry measurement, the increase of the aperture of the mirror to be measured or the decrease of the curvature will cause the number of LCD pixels used to increase by several times. Large-aperture concave mirrors, plane mirrors and convex mirrors require larger size displays. If the LCD pixel array calibration is not accurate, the calculated incident light vector will be deviated, which will affect the calculation of the reflecting surface slope and significantly reduce the surface shape detection precision. The existing calibration methods, such as indirect calibration using a plane mirror or using a specially designed mirror such as a step mirror, have the problems of high cost or not suitable for use in the workshop. Especially in the mirror processing process, dozens of detections need to be performed frequently, which seriously affects the total calibration time. Therefore, the LCD calibration needs to have high precision and repeated calibration speed. High precision ensures the accuracy of surface shape detection, and repeated calibration speed improves the practicability of phase deflectometry in the processing process. It is of great significance to develop a fast and high-precision LCD calibration method.

[0004] There are few studies on high-precision calibration of reflecting surface position and significant improvement of reflecting surface calibration efficiency in multiple surface shape detection tasks, which is an important step to accurately calculate the reflecting surface slope and improve the calibration efficiency. Therefore, a high-precision and efficient mirror calibration method is needed.

[0005] The calibration accuracy and repeatability of the LCD and mirror are crucial for phase deflection. High calibration accuracy ensures the accuracy of the surface shape results, while repeatability ensures the practicality of phase deflection in actual processing. There is an urgent need to develop a fast and high-precision calibration method for the detection system. Summary of the Invention

[0006] Therefore, the present invention aims to overcome the deficiencies in the prior art described above, thereby providing a high-precision system calibration method for phase deflection. The method for phase deflection calibration includes a method for calibrating a camera, and further includes: An LCD pixel calibration method: obtain the sampled pixel points of the pattern displayed on the LCD to be calibrated and the three-dimensional coordinates of three first-type feature points pre-fixed to the LCD to be calibrated for reference, further combine the fitting algorithm to obtain the three-dimensional surface shape of the entire LCD pixel array, and reverse calculate the actual spatial position of all pixels on the currently calibrated LCD according to actual needs. A mirror calibration method: obtain the three-dimensional coordinates of the sampled points on the reflecting surface of the mirror and three second-type feature points pre-fixed to the mirror for reference, further combine the fitting algorithm to obtain the spatial geometric relationship model between the sampled points on the reflecting surface of the mirror and the three second-type feature points, and reverse calculate the current spatial position and attitude of the mirror according to actual needs.

[0007] Preferably, an LCD pixel calibration method specifically includes the following steps: Initial calibration: Establish LCD measurement reference benchmark: S101. An LCD to be calibrated is held in place using an LCD calibration tool coupled with feature points; S102. Connect the LCD to be calibrated to the image generation device to generate a calibration pattern; S103. Use a measuring tool to obtain the sampling pixel points of the calibration pattern and the three-dimensional coordinate data of three first-type feature points on an LCD calibration tool coupled with feature points for fixing and holding the LCD; S104. Using the fitting algorithm and the three-dimensional coordinate data obtained in step S103, reconstruct the three-dimensional surface shape of the entire LCD pixel array to describe the three-dimensional positional relationship between all pixels and three first-class feature points on the LCD. When it is necessary to obtain the actual positions of all pixels on the LCD again based on actual needs: S105. Use a measurement tool to obtain the current three-dimensional coordinate data of three first-type feature points; S106. Combine the data obtained in S105 with the three-dimensional surface shape obtained in S104, and reverse calculate the actual spatial position of all pixels on the currently calibrated LCD.

[0008] Preferably, an LCD calibration fixture coupled with feature points includes: a vertical plate, three clamping plates, reinforcing ribs, a fixture base plate, and three gaskets; A groove is provided on one side of the vertical plate fixed to the base plate of the fixture, and multiple bosses are provided in the groove; The reinforcing rib is fixedly connected to the other side of the vertical plate and the base plate of the clamp, forming a triangular stable structure; The three clamping plates are respectively bolted to the vertical plate to clamp the LCD to be calibrated that fits the boss; and the three clamping plates are respectively provided with holes corresponding to the three first-type feature points; At the three locations where the clamping plate forces are applied, shims are placed between the LCD to be calibrated and the boss.

[0009] Preferably, the three clamping plates are a first clamping plate, a second clamping plate, and a third clamping plate; Both the first clamping plate and the second clamping plate are inclined plates; The two ends of the first clamping plate are respectively bolted to the top edge of the vertical plate and the first vertical edge; The two ends of the second clamping plate are respectively bolted to the top edge and the second vertical edge of the vertical plate; The first clamping plate and the second clamping plate are of the same length and are adapted to the structural dimensions of the vertical plate; The third clamping plate is a horizontal plate and is fixedly connected to the bottom edge of the vertical plate.

[0010] Preferably, a mirror calibration method includes the following steps: Initial calibration: Establish a reference standard for mirror measurement, specifically including: S201. A feature with three feature points coupled together is mounted on the side of a reflector; S202. Use a three-dimensional spatial measurement device to obtain the three-dimensional coordinate data of the sampling points on the reflecting surface of the mirror and three second-type feature points on the feature object; S203. Using the fitting algorithm and the three-dimensional coordinate data obtained in step S202, establish a spatial geometric relationship model between the sampling points of the reflecting surface and the three second-type feature points; When it is necessary to obtain the precise pose of the mirror in the global coordinate system again: S204. Use a spatial three-dimensional measurement device to measure the three-dimensional coordinate data of the three current second-type feature points, and combine the spatial rigid body registration algorithm and spatial geometric relationship model to calculate the overall pose transformation matrix of the current reflector; S205. Apply the overall pose transformation matrix of the current reflector to the three-dimensional coordinate data of the sampling points of the reflective surface obtained in step S202 to obtain the spatial position and orientation of the reflective surface of the current reflector.

[0011] Preferably, the feature and the mirror mounting area have an arc structure so that the feature and the side mounting area of ​​the mirror fit together completely; Three second-type feature points are set on the edge of the feature object, namely the second first feature point, the second second feature point, and the second third feature point; Among them, the second feature point is adjacent to the side of the mirror; the second feature point and the second and third feature points are orthogonal at the second feature point.

[0012] Preferably, the diameter of the spherical model fitted by the sampling points of the reflector surface based on the fitting algorithm is consistent with the diameter of the optimal fitted spherical model of the reflector surface.

[0013] The technical solution of this invention has the following advantages: This invention proposes a fast and high-precision LCD pixel calibration method. The LCD to be calibrated is held in place using an LCD calibration tool coupled with feature points. By fitting the positions of sampled pixels and the positions of first-type feature points, the positions of all pixels on the LCD relative to the first-type feature points are obtained. In subsequent inspections, only the global coordinates of three first-type feature points need to be quickly calibrated to obtain the global coordinates of the target pixel, achieving fast and high-precision pixel positioning. This avoids the inaccurate calibration problems caused by poor flatness of the LCD pixel array and poor repeatability of manual pixel position measurements. It eliminates the need to move plane mirrors, use special stepped reflectors, or use light-diffusing sheets, significantly reducing operational complexity and cost. Furthermore, measuring the feature point positions provides the real-time positions of all pixels, greatly improving the efficiency of subsequent LCD calibration and further enhancing its practicality in manufacturing workshops.

[0014] This invention proposes a method for rapidly and accurately calibrating the position of a reflector. A feature object with three characteristic points is stably coupled to the side of the reflector under test. A three-dimensional spatial measurement device is used to calibrate the positional relationship between the sampling points on the reflective surface and the three characteristic points. Subsequently, only the positions of the three characteristic points need to be measured to quickly obtain the precise position of the reflective surface. Combined with the precise calibration of LCD pixels, this greatly improves the accuracy of the reflective surface slope calculation and the calibration efficiency. It is particularly applicable in scenarios involving multiple movements of the reflector, such as phase deflection verification experiments or reflector fabrication, and has strong practicality. Attached Figure Description

[0015] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0016] Figure 1A schematic diagram of an LCD calibration fixture structure coupled with feature points; Figure 2 for Figure 1 The front view of the structure shown; Figure 3 This is a schematic diagram of the calibration pattern; Figure 4 This is a schematic diagram of a feature object with coupled characteristic points mounted on a reflector.

[0017] Explanation of reference numerals in the attached figures: 1-Vertical plate; 2-LCD; 301-First clamping plate; 302-Second clamping plate; 303-Third clamping plate; 401-First feature point; 402-First and second feature points; 403-First and third feature points; 5-Reinforcing rib; 6-Clamp base plate; 7-Shim; 8-Boss; 9-Feature object; 10-Reflector; 1101-Second feature point; 1102-Second feature point; 1103-Second feature point. Detailed Implementation

[0018] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. 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.

[0019] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0020] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0021] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0022] Example 1 In current technologies, LCD display calibration requires both high precision and high repeatability. High precision ensures accurate surface shape detection, while high repeatability improves the practicality of phase refraction techniques during manufacturing. Therefore, developing a fast and high-precision LCD display calibration method is of great significance.

[0023] Therefore, as Figures 1-2 This embodiment discloses an LCD calibration fixture coupled with feature points, including: a vertical plate 1, three clamping plates, a reinforcing rib 5, a fixture base plate 6, and three gaskets 7; The vertical plate 1, which is fixed to the base plate 6 of the fixture, has a groove on one side. The groove has multiple protrusions 8, which makes the fit between the vertical plate 1 and the LCD 2 to be calibrated better than the direct full fit, and avoids damage to the LCD 2 to be calibrated due to uneven force during the clamping process.

[0024] The reinforcing rib 5 is fixedly connected to the other side of the vertical plate 1 and the clamp base plate 6 to form a triangular stable structure; Three clamping plates are bolted to the vertical plate 1 to clamp the LCD2 to be calibrated, which is attached to the boss 8; and for the convenience of calibration and coordinate transformation, holes corresponding to the three first-type feature points are opened on the three clamping plates; in this embodiment, they are specifically standard conical holes. At the three points where the clamping force applies, a shim 7 is placed between the LCD2 to be calibrated and the boss 8. In this embodiment, the shim 7 is made of soft silicone to prevent damage to the LCD2 to be calibrated during clamping. The three clamping plates are the first clamping plate 301, the second clamping plate 302, and the third clamping plate 303; Both the first clamping plate 301 and the second clamping plate 302 are inclined plates; The two ends of the first clamping plate 301 are respectively bolted to the top edge of the vertical plate 1 and the first vertical edge. The two ends of the second clamping plate 302 are respectively bolted to the top edge and the second vertical edge of the vertical plate 1; The first clamping plate 301 and the second clamping plate 302 have the same length and are compatible with the structural dimensions of the vertical plate 1; The third clamping plate 303 is a horizontal plate and is fixedly connected to the bottom edge of the vertical plate 1.

[0025] like Figure 1As shown, the three first-class feature points, namely the first feature point 401, the first second feature point 402, and the first third feature point 403, are all located on the axis of symmetry of the corresponding clamping plate and correspond to the LCD2 to be calibrated.

[0026] It should be noted that this embodiment is adapted to consumer-grade LCD displays; in practical applications, a flat panel display is used by default. Furthermore, due to cost-effectiveness and manufacturing limitations, the pixel array flatness of flat panel displays is worse than other types, and a single plane cannot represent the spatial distribution of the entire pixel array. This is especially true for large-size displays, where the problem of poor pixel array flatness is even more pronounced. For phase-deflection techniques, accurately calibrating the display pixel positions can significantly improve the accuracy of the final three-dimensional surface shape.

[0027] Example 2 Based on Example 1, this example further discloses an LCD pixel calibration method, which specifically includes the following steps: Initial calibration: Establish LCD measurement reference benchmark: S101. Use an LCD calibration tool with coupled feature points to hold the LCD2 to be calibrated; specifically, in this embodiment, an LCD-type display with a resolution of 3840×2160 is selected as the experimental object. S102. Connect the LCD2 to be calibrated to the image generating device to generate a calibration pattern; specifically: use the image generating device to encode the calibration pattern and display it on the LCD2 to be calibrated; such as Figure 3 As shown, the calibration pattern is an image composed of a white dot matrix; in this image, each white dot is 5×5 pixels in size, and the dots are evenly arranged at intervals of 200 pixels in both the horizontal and vertical directions, thus forming 19 rows and 11 columns, totaling 209 sampling pixels across the entire screen. These sampling pixels uniformly cover the entire display area of ​​the LCD2 to be calibrated, effectively characterizing the large-scale morphological changes of the LCD's display.

[0028] It should be noted that in this embodiment... Figure 3 This is merely the optimal implementation pattern, intended to facilitate the introduction of the core idea of ​​this embodiment. In practical applications, the calibration pattern can be implemented in various forms and is not limited to the illustration given in this embodiment. Figure 3 .

[0029] S103. Use a measuring tool to obtain the sampling pixel points of the calibration pattern and the three-dimensional coordinate data of three first-type feature points on an LCD calibration tool coupled with feature points for fixing and clamping the LCD; Specifically: It should be noted that the total number of pixels corresponding to the resolution of this embodiment exceeds 8.3 million. If the three-dimensional coordinates are measured point by point, it is not feasible in terms of time and resources.

[0030] Therefore, in this embodiment, a sparse sampling method is adopted to select representative pixels within the entire LCD display area for three-dimensional coordinate measurement. In this embodiment, the measuring tool for three-dimensional coordinates is an industrial-grade image measurement system equipped with a high-magnification microscope lens and an electric precision displacement platform; and the focal plane calibration is completed after the high-magnification microscope lens is preheated and stabilized to ensure the stability and repeatability of the measurement process.

[0031] High-magnification microscope lens: magnification not less than 20×; The electric precision displacement platform has submicron repeatability, better than ±0.5μm; During measurement: Using software compatible with the industrial-grade image measurement system, the motorized precision displacement platform is controlled to precisely align the optical crosshairs of the industrial-grade image measurement system with the center pixel of the white dot matrix. The industrial-grade image measurement system is then adjusted to its optimal focal position. Due to the extremely small depth of field of the high-magnification microscope lens, it is assumed that the focal point is at the center of the center pixel, thus obtaining the three-dimensional coordinate data of the center pixel. Similarly, this method is used to measure the positions of all 209 sampled pixels and collect the positions of three Type I feature points for subsequent geometric correction and fitting accuracy verification. Additionally, the crosshairs of the industrial-grade image measurement system are aligned with the three Type I feature points on the LCD calibration tool, and the center point position and edge of each Type I feature point are accurately measured.

[0032] S104. Using the fitting algorithm and the 3D coordinate data obtained in step S103, reconstruct the 3D surface shape of the entire LCD pixel array, which describes the 3D positional relationship between all pixels and three first-type feature points on the LCD. It should be noted that in practical applications, the fitting algorithm includes, but is not limited to, bicubic interpolation, B-spline surface fitting, or low-order polynomial surface fitting, such as quadratic polynomial fitting and cubic polynomial fitting. Furthermore, to improve the local adaptability of the fitting algorithm during reconstruction, a weighted least squares strategy is introduced during surface modeling to account for potential nonlinear distortions in edge regions, thereby improving the overall fitting accuracy.

[0033] This embodiment also includes cross-validation to evaluate the spatial accuracy of the constructed 3D surface shape, specifically: A portion of the measured sampled pixels are used for the test set, and the remaining sampled pixels are used for training the 3D surface model. The residuals between the fitted predictions obtained based on the test set and the actual measured values ​​based on the sampled pixels are compared. The root mean square error is used as the main fitting error metric. In practical applications, quantitative metrics such as maximum error and average error can also be statistically analyzed according to the actual situation.

[0034] When it is necessary to obtain the actual positions of all pixels on the LCD again based on actual needs: S105. Use a measurement tool to obtain the current three-dimensional coordinate data of three first-type feature points; S106. Combine the data obtained in S105 with the three-dimensional surface shape obtained in S104, and reverse calculate the actual spatial position of all pixels on the currently calibrated LCD2.

[0035] It should be noted that this embodiment successfully established the three-dimensional positional relationship between all pixels on the LCD2 to be calibrated and the first type of feature points on the LCD calibration tool. This allows for the reverse calculation of the actual spatial positions of all pixels on the currently calibrated LCD2 by measuring only the positions of three first type feature points in subsequent practical applications, thus quickly obtaining high-precision global coordinates of the target pixels. The method of this embodiment has the advantages of simple operation, high accuracy, and applicability to rapid calibration of large-area pixel arrays. It provides stable and reliable basic data support for optical measurement techniques such as phase deflection, which have strict requirements on the projection surface morphology, and has broad engineering application prospects.

[0036] Example 3 This embodiment discloses a feature 9 coupled with feature points, the overall structure of which is a rigid module that can be stably installed, and the entire module is installed on the side of the reflector 10; specifically: The mounting point of feature 9 and reflector 10 is curved to ensure that feature 9 and the side mounting point of reflector 10 fit together completely. Three second-type feature points are provided on the edge of feature 9, namely second first feature point 1101, second second feature point 1102 and second third feature point 1103. The three points, second first feature point 1101, second second feature point 1102 and second third feature point 1103, are not collinear, so as to form a unique and determined rigid reference datum. Among them, the second feature point 1101 is adjacent to the side of the reflector 10; the second feature point 1101 and the second and third feature points 1103 are orthogonal at the second feature point 1102.

[0037] Example 4 Based on Example 3, this example discloses a mirror calibration method with the same principle as Example 2, including the following steps: Initial calibration: Establish a measurement reference standard for mirror 10, specifically including: S201. A feature 9 coupled with three feature points is mounted on the side of the reflector 10; S202. Use a spatial three-dimensional measurement device to acquire the three-dimensional coordinate data of the sampling points on the reflecting surface of the reflector 10 and the three second-type feature points on the feature 9; specifically, the operator needs to collect several spatially uniformly distributed sampling points on the reflecting surface of the reflector 10 according to the preset plan, and simultaneously measure the three-dimensional coordinate data of the three second-type feature points in the same coordinate system. In addition, according to the aperture and surface accuracy requirements of the reflector 10, the initial number of reflecting surface sampling points can be adjusted appropriately according to the actual situation. Generally, in practical applications, it is recommended that the reflecting surface sampling points have good coverage and uniformity on the reflecting surface to ensure the accuracy of surface fitting.

[0038] S203. Establish a spatial geometric relationship model between the sampling points of the reflective surface and the three-dimensional coordinate data obtained in step S202 using the fitting algorithm and the three-dimensional coordinate data; wherein, the fitting algorithm used in the embodiment includes, but is not limited to, the three-dimensional least squares fitting method, which is used to fit the sampling points of the reflective surface into a spherical model; The fitting accuracy is verified by comparing the consistency between the fitted spherical model radius and the actual spherical design radius of the reflective surface. It should be noted that in practical applications, it is sufficient to ensure that the diameter of the spherical model fitted by the sampling points of the reflective surface of the mirror 10 based on the fitting algorithm is consistent with the diameter of the optimal fitted spherical model of the reflective surface to meet the accuracy requirements of existing precision optical systems for the attitude and shape recognition of the reflective surface of the mirror 10.

[0039] When it is necessary to obtain the precise pose of mirror 10 in the global coordinate system again: S204 uses a spatial three-dimensional measurement device to measure the three-dimensional coordinate data of the three current second-type feature points, and calculates the overall pose transformation matrix of the current reflector 10 by combining the spatial rigid body registration algorithm and the spatial geometric relationship model. S205. Apply the overall pose transformation matrix of the current reflector 10 to the three-dimensional coordinate data of the sampling points of the reflector surface obtained in step S202 to obtain the spatial position and attitude of the reflector surface of the current reflector 10, thereby achieving the effect of obtaining high-precision spatial information of the reflector surface without having to measure point by point again.

[0040] It should be noted that the following content is also disclosed in this embodiment: the selection of spatial three-dimensional measurement equipment and the setting of the second type of feature points: The selection of spatial three-dimensional measurement equipment depends on the aperture of the mirror 10 to be measured and the diameter of the best-fit sphere. During phase deflection, the camera and monitor are generally placed at the center of curvature of the best-fit sphere of the mirror 10 to be measured. Generally, the terms such as the radius of curvature of the mirror 10, which are related to parabolic surfaces or quadric surfaces, refer to the parameters of the best-fit sphere of the mirror 10. The prefix "best-fit sphere" is omitted hereafter, and it is directly described as being near the center of curvature, radius, etc.

[0041] a) When the radius of the reflector 10 to be measured is less than or close to the range of the Faro articulated arm < 2 m, the Faro articulated arm shall be selected. b) When the radius of the mirror 10 to be measured is approximately equal to or greater than the range of the Faro articulated arm, a Faro laser tracker must be used. When the radius of the mirror 10 to be measured is approximately equal to the range of the Faro articulated arm, the Faro articulated arm is difficult to use.

[0042] c) When the aperture of the reflector 10 to be tested is very close to the diameter of the laser tracking ball base (30 mm), it is difficult to place the tracking ball on the surface of the reflector 10 to be tested for reflective surface calibration, and the Faro articulated arm must be selected.

[0043] d) When the aperture of the reflector 10 to be tested is much larger than the diameter of the laser tracking ball base 30 mm, the Faro laser tracker shall be selected.

[0044] The setting of the second type of feature points depends on the spatial three-dimensional measurement equipment.

[0045] a) When using a Faro laser tracker for ranging, the second type of feature point is a ferromagnetic circular hole that is precisely coupled to the base of the laser tracking ball; b) When using Faro articulated arm distance measurement, the second type of feature point is a standard cone that is precisely coupled to the articulated arm probe.

[0046] The method proposed in this embodiment introduces a stable and repeatably identifiable feature 9 on the side of the reflector 10, enabling rapid and automated reproduction of the spatial position of the reflecting surface with only one high-precision initial calibration. This calibration method significantly improves the calibration efficiency and repeatability of the reflector 10, and is particularly suitable for the installation, calibration, and long-term tracking applications of high-precision reflectors 10.

[0047] Example 5 Methods for phase-deflection calibration, including methods for camera calibration, also include: Example 2: An LCD pixel calibration method: obtain the sampled pixel points of the pattern displayed on the LCD2 to be calibrated and the three-dimensional coordinates of three first-type feature points pre-fixed on the LCD2 to be calibrated for reference; further combine the fitting algorithm to obtain the three-dimensional surface shape of the entire LCD pixel array; and reverse calculate the actual spatial position of all pixels on the currently calibrated LCD2 according to actual needs. Example 4: A method for calibrating a reflector: The three-dimensional coordinates of the sampled points on the reflector surface of the reflector 10 and three second-type feature points pre-fixed on the reflector 10 for reference are obtained. The spatial geometric relationship model between the sampled points on the reflector surface of the reflector 10 and the three second-type feature points is further obtained by combining the fitting algorithm. The spatial position and attitude of the reflector 10 are then calculated in reverse according to the actual needs.

[0048] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for phase deflection calibration, including a method for calibrating a camera, characterized in that, Also includes: An LCD pixel calibration method: obtain the sampled pixel points of the pattern displayed on the LCD (2) to be calibrated and the three-dimensional coordinates of three first-class feature points pre-fixed on the LCD (2) to be calibrated for reference, further combine the fitting algorithm to obtain the three-dimensional surface shape of the entire LCD pixel array, and reverse calculate the actual spatial position of all pixels on the currently calibrated LCD (2) according to actual needs. A method for calibrating a reflector (10): obtain the three-dimensional coordinates of the sampled points on the reflective surface of the reflector (10) and three second-type feature points pre-fixed on the reflector (10) for reference, further combine the fitting algorithm to obtain the spatial geometric relationship model between the sampled points on the reflective surface of the reflector (10) and the three second-type feature points, and reverse the calculation of the spatial position and attitude of the reflector (10) according to actual needs.

2. The method for phase deflection calibration according to claim 1, characterized in that, An LCD pixel calibration method specifically includes the following steps: Initial calibration: Establish LCD measurement reference benchmark: S101. Use an LCD calibration tool with coupled feature points to clamp the LCD to be calibrated (2); S102. Connect the LCD (2) to be calibrated to the image generation device to generate a calibration pattern; S103. Use a measuring tool to obtain the sampling pixel points of the calibration pattern and the three-dimensional coordinate data of three first-type feature points on an LCD calibration tool coupled with feature points for fixing and holding the LCD; S104. Using the fitting algorithm and the three-dimensional coordinate data obtained in step S103, reconstruct the three-dimensional surface shape of the entire LCD pixel array to describe the three-dimensional positional relationship between all pixels and three first-class feature points on the LCD. When it is necessary to obtain the actual positions of all pixels on the LCD again based on actual needs: S105. Use a measurement tool to obtain the current three-dimensional coordinate data of three first-type feature points; S106. Combine the data obtained in S105 with the three-dimensional surface obtained in S104, and reverse calculate the actual spatial position of all pixels on the currently calibrated LCD (2).

3. The method for phase deflection calibration according to claim 2, characterized in that, An LCD calibration fixture coupled with feature points includes: a vertical plate (1), three clamping plates, a reinforcing rib (5), a fixture base plate (6), and three gaskets (7); A groove is provided on one side of the vertical plate (1) fixed on the base plate (6) of the fixture, and multiple bosses (8) are provided in the groove; The reinforcing rib (5) is fixedly connected to the other side of the vertical plate (1) and the clamp base plate (6) to form a triangular stable structure; The three clamping plates are bolted to the vertical plate (1) to clamp the LCD (2) to be calibrated that fits the boss (8); and the three clamping plates are respectively provided with holes corresponding to the three first-class feature points; At the three clamping plate force application positions, a shim (7) is placed between the LCD (2) to be calibrated and the boss (8).

4. The method for phase deflection calibration according to claim 3, characterized in that, The three clamping plates are the first clamping plate (301), the second clamping plate (302), and the third clamping plate (303). Among them, the first clamping plate (301) and the second clamping plate (302) are both inclined plates; The two ends of the first clamping plate (301) are respectively bolted to the top edge of the vertical plate (1) and the first vertical edge; The two ends of the second clamping plate (302) are respectively bolted to the top edge and the second vertical edge of the vertical plate (1); The first clamping plate (301) and the second clamping plate (302) have the same length and are compatible with the structural dimensions of the vertical plate (1); The third clamping plate (303) is a horizontal plate and is fixedly connected to the bottom edge of the vertical plate (1).

5. The method for phase deflection calibration according to claim 1, characterized in that, A method for calibrating a reflector (10) includes the following steps: Initial calibration: Establish a measurement reference standard for the reflector (10), specifically including: S201. A feature (9) coupled with three feature points is installed on the side of the reflector (10); S202. Use a spatial three-dimensional measurement device to obtain the three-dimensional coordinate data of the sampling points on the reflecting surface of the reflector (10) and the three second-type feature points on the feature object (9); S203. Using the fitting algorithm and the three-dimensional coordinate data obtained in step S202, establish a spatial geometric relationship model between the sampling points of the reflecting surface and the three second-type feature points; When it is necessary to obtain the precise pose of the reflector (10) in the global coordinate system again: S204. Use a spatial three-dimensional measurement device to measure the three-dimensional coordinate data of the three current second-type feature points, and combine the spatial rigid body registration algorithm and spatial geometric relationship model to calculate the overall pose transformation matrix of the current reflector (10); S205. Apply the overall pose transformation matrix of the current reflector (10) to the three-dimensional coordinate data of the sampling points of the reflective surface obtained in step S202 to obtain the spatial position and orientation of the reflective surface of the current reflector (10).

6. The method for phase deflection calibration according to claim 5, characterized in that, The mounting points of the feature (9) and the reflector (10) are curved to ensure that the side mounting points of the feature (9) and the reflector (10) fit together completely. Three second-class feature points are provided on the edge of the feature (9), namely the second first feature point (1101), the second second feature point (1102), and the second third feature point (1103). Among them, the second feature point (1101) is adjacent to the side of the reflector (10); the second feature point (1101) and the second and third feature points (1103) are orthogonal at the second feature point (1102).

7. The method for phase deflection calibration according to claim 5, characterized in that, The diameter of the spherical model of the reflective surface sampling point of the reflector (10) is consistent with the diameter of the best-fit spherical model of the reflective surface.

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