A quadrant-based calibration method and experimental device based on PSD angle measurement accuracy

Abstract

The application discloses a quadrant calibration method and experimental device based on PSD angle measurement accuracy in the field of photoelectric measurement technology, comprising: a laser, a theta x photoelectric autocollimator, a theta y photoelectric autocollimator, a two-dimensional turntable, a mirror, a PSD angle measurement system and a vibration isolation table; wherein the PSD angle measurement system is installed on the vibration isolation table through a translation lifting adjustment mechanism, and is used for receiving and measuring the position of an incident laser spot; the laser and the mirror are fixedly installed on the two-dimensional turntable, the two-dimensional turntable can drive the laser and the mirror to rotate, so that the direction of the light beam is changed, and different quadrants of the target surface of the PSD angle measurement system are calibrated. The application can systematically compensate various factors such as device nonlinearity, installation error and environmental disturbance, simplify the calibration process and improve the long-term stability and practicability of the system.

Description

Technical Field

[0001] This invention relates to a quadrant calibration method and experimental apparatus based on PSD angle measurement accuracy, belonging to the field of photoelectric measurement technology. Background Technology

[0002] In the field of photoelectric measurement, angle measurement systems based on position-sensitive detectors (PSDs) are widely used in precision angle detection, motion platform attitude feedback, and optical alignment due to their advantages such as non-contact operation, high resolution, and high frequency response. However, the inherent characteristics of PSD devices, such as nonlinear response, dark current, spot non-uniformity, and circuit noise, directly affect the correspondence between the output signal and the incident light angle, leading to systematic errors in the angle measurement results. To obtain high-precision angle measurements, accurate data calibration of the PSD angle measurement system is essential.

[0003] Traditional calibration methods typically rely on high-precision mechanical turntables or optical references. These methods place extremely high demands on the accuracy of the calibration equipment and the stability of the environment, and the calibration process is cumbersome and inefficient, making it difficult to meet the needs of mass production or rapid on-site calibration. Furthermore, in practical applications, factors such as lens distortion in the optical path, optical axis misalignment due to installation errors, and temperature drift introduce additional systematic errors, complicating the calibration model. In existing technologies, most calibration schemes fail to fully consider the combined effects of these multiple factors, resulting in limited calibration accuracy, especially at the edge of the measurement range or when environmental conditions change, leading to a significant decrease in accuracy.

[0004] Therefore, how to design an efficient, comprehensive, and high-precision PSD angle measurement data calibration method that can systematically compensate for various factors such as device nonlinearity, installation errors, and environmental disturbances, simplify the calibration process, and improve the long-term stability and practicality of the system has become a technical problem to be solved in this field. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a quadrant calibration experimental device based on PSD angle measurement accuracy for detecting dynamic angles, which can shorten the calibration time and improve the accuracy of the results.

[0006] To achieve the above objectives, the present invention is implemented using the following technical solution:

[0007] In a first aspect, the present invention provides a quadrant calibration experimental device based on PSD angular measurement accuracy, comprising: a laser, θ x Photoelectric autocollimator, θ yThe system comprises an optoelectronic autocollimator, a two-dimensional turntable, a reflector, a PSD angle measurement system, and a vibration isolation table. The PSD angle measurement system is mounted on the vibration isolation table via a translation and lifting adjustment mechanism and is used to receive and measure the position of the incident laser spot. The laser and the reflector are fixedly mounted on the two-dimensional turntable, which can drive the laser and the reflector to rotate, thereby changing the beam direction and calibrating different quadrants of the PSD angle measurement system target surface. The θ... x Photoelectric autocollimator and the θ y The photoelectric autocollimator is fixed on the vibration isolation platform, serving as a reference for measuring the deflection angle of the laser beam in the horizontal and vertical directions, respectively; the laser generates a stable, narrow laser beam, the output optical axis of which is perpendicular to θ. y The optical axis of the photoelectric autocollimator is arranged coaxially; the θ x The optical axis of the photoelectric autocollimator is arranged perpendicular to the optical axis of the laser; the reflector and the θ x Photoelectric autocollimator and θ y The optical axis of the photoelectric autocollimator corresponds to the beam emitted by the autocollimator, reflecting it back to itself to read the reference angle value; the θ x Photoelectric autocollimator, θ y The photoelectric autocollimator and PSD angle measurement system are electrically connected to the software processing terminal.

[0008] Furthermore, the PSD angle measurement system includes a telephoto lens, a first reflector, a second reflector, and a PSD. The telephoto lens has a diameter of 80mm and a focal length of 500mm. The PSD is fixed at the focal point of the telephoto lens and electrically connected to the software processing terminal.

[0009] Furthermore, the PSD is a two-dimensional detector chip with a target surface size of 20*20mm and a response wavelength range of 300-1100nm.

[0010] Furthermore, the light source wavelength of the laser is within the wavelength response range of the PSD position-sensitive detector chip, and the laser divergence angle is less than 1 mrad. The maximum output power of the laser is less than the damage threshold of the PSD.

[0011] Furthermore, the center height of the laser is consistent with the center height of the PSD unit.

[0012] Secondly, this invention proposes a quadrant calibration method based on PSD angle measurement accuracy, implemented using any of the aforementioned quadrant calibration experimental devices based on PSD angle measurement accuracy, comprising:

[0013] Set up the experimental setup and preheat it. Adjust the laser spot to the center of the target surface of the PSD angle measuring system and set the value of the photoelectric autocollimator to zero.

[0014] Control the two-dimensional turntable to rotate at equal intervals, and sequentially perform "bow"-shaped trajectory calibration on the four quadrants of the detector's photosensitive surface in the PSD angle measurement system;

[0015] At each calibration point, after the system stabilizes, the coordinate values ​​and θ measured by the PSD angle measurement system are synchronously recorded via the software processing terminal. x Photoelectric autocollimator and θ y The reference angle value measured by the photoelectric autocollimator;

[0016] The acquired PSD measurement data is corrected using a two-dimensional linear interpolation method. The corrected PSD angle data is then compared with the reference angle data of the autocollimator to calculate the measurement error and evaluate the system accuracy.

[0017] Furthermore, the software processing terminal is based on LabVIEW software programming. It obtains the two-dimensional position coordinates of the light spot according to the PSD's serial communication protocol, calculates the displacement of the light spot in the horizontal and vertical directions, and then converts it into the beam pointing coordinates, expressed as:

[0018]

[0019]

[0020] in, The horizontal deflection angle. The vertical deflection angle. This represents the horizontal displacement difference of the light spot on the PSD. This represents the vertical displacement difference of the light spot on the PSD. This is the focal length of the lens.

[0021] Furthermore, the PSD measurement data is corrected using a two-dimensional linear interpolation method. Specifically, the angular coordinates corresponding to the four grid points measured by the PSD are represented as θ. a (α a , β a ), θ b (α b , β b ), θ c (α c , β c ), θ d (α d , β d ), and the angular coordinates θ corresponding to the points to be measured within the grid. x (α x , β x The interpolation parameters are solved, and then the angular coordinates corresponding to the four grid points measured by the autocollimator are used as the reference coordinates θ. A (αA , β A ), θ B (α B , β B ), θ C (α C , β C ), θ D (α D , β D Perform coordinate transformation to obtain the angular coordinates θ corresponding to the measured point after correction. X (α X , β X ), where the point to be measured θ x The angular coordinates are:

[0022]

[0023] Where, α x β represents the x-coordinate of the point to be measured. x Represents the ordinate of the point to be measured. and Let α be the interpolation parameter to be determined. a Represents grid point θ a x-coordinate, β a Represents grid point θ a The ordinate, α b Represents grid point θ b x-coordinate, β b Represents grid point θ b The ordinate, α c Represents grid point θ c x-coordinate, β c Represents grid point θ c The ordinate, α d Represents grid point θ d x-coordinate, β d Represents grid point θ d The ordinate;

[0024] The angular coordinates corresponding to the measured point after correction are:

[0025]

[0026] Where, α X β is the interpolated x-coordinate. X Let α be the interpolated ordinate. A Represents the reference coordinate value θ A The x-coordinate, N a Represents the reference coordinate value θ A The ordinate, α B Represents θ B x-coordinate, βB Represents the reference coordinate value θ B The ordinate, α C Represents the reference coordinate value θ C x-coordinate, β C Represents the reference coordinate value θ C The ordinate, α D Represents the reference coordinate value θ D x-coordinate, β D Represents the reference coordinate value θ D The ordinate.

[0027] Furthermore, the expression for calculating the measurement error is as follows:

[0028]

[0029] in, Let θ be a point at θ x Measurement error in direction; Let θ be a point at θ y Measurement error in direction, , The point θ solved by the PSD system at θ x θ y The angle value of the direction, , For the point θ measured by the autocollimator at θ x θ y The angle value of the direction.

[0030] Furthermore, the accuracy of the evaluation system includes: through θ x Root mean square error of direction and θ y The root mean square error in the direction and two other indices are used to quantify the corrected systematic error. The expression is as follows:

[0031]

[0032] in, For θ x Root mean square error in direction; For θ y Root mean square error in direction; The number of data points measured.

[0033] Compared with the prior art, the beneficial effects achieved by the present invention are as follows:

[0034] This invention proposes an efficient, comprehensive, and high-precision PSD angle measurement data calibration method and experimental setup. It systematically compensates for various factors such as device nonlinearity, installation errors, and environmental disturbances, simplifying the calibration process and improving the long-term stability and practicality of the system. Through a quadrant-based calibration strategy, this invention accurately characterizes the response characteristics of the PSD in different regions, effectively correcting the inherent nonlinearity error and inter-quadrant inconsistencies of the PSD, significantly improving measurement accuracy. Furthermore, the invention features a simple structure and a highly efficient and reliable method, providing crucial technical support for the widespread application of PSDs in high-precision optoelectronic measurement systems. Attached Figure Description

[0035] The accompanying drawings, which form part of this specification, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0036] Figure 1 This is a three-dimensional view of an experimental device for quadrant calibration based on PSD angle measurement accuracy, provided in Embodiment 1 of the present invention.

[0037] Figure 2 This is an optical path diagram of a calibration system for a quadrant calibration experimental device based on PSD angle measurement accuracy, provided in Embodiment 1 of the present invention.

[0038] Figure 3 This is a three-dimensional view of a PSD angle measurement system for a quadrant calibration experimental device based on PSD angle measurement accuracy, provided in Embodiment 1 of the present invention.

[0039] Figure 4 The "bow"-shaped route for data acquisition in the quadrant calibration experimental device based on PSD angle measurement accuracy provided in Embodiment 1 of the present invention;

[0040] Figure 5 This is a flowchart of a quadrant calibration method based on PSD angle measurement accuracy provided in Embodiment 2 of the present invention.

[0041] In the diagram: 1. Laser; 2. θ x Photoelectric autocollimator; 3, θ y 4. Photoelectric autocollimator; 5. Two-dimensional turntable; 6. Reflector; 7. PSD angle measurement system; 8. Telephoto lens; 9. First reflector; 10. Second reflector; 11. PSD; 2. Vibration isolation table. Detailed Implementation

[0042] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other.

[0043] The following detailed description is exemplary and intended to provide further detailed explanation of the invention. Unless otherwise specified, all technical terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used in this invention is for describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention.

[0044] Example 1:

[0045] Please see Figure 1 This embodiment provides an experimental apparatus for quadrant calibration based on PSD angular measurement accuracy, including: laser 1, θ x Photoelectric autocollimator 2, θ y The system comprises a photoelectric autocollimator 3, a two-dimensional turntable 4, a reflector 5, a PSD angle measuring system 6, and a vibration isolation table 7. Specifically, the PSD angle measuring system 6 is mounted on the vibration isolation table 7 via a translation and lifting adjustment mechanism; the laser 1 and the reflector 5 are mounted on the two-dimensional turntable 4; and θ... x Photoelectric autocollimator 2 and θ y The photoelectric autocollimator 3 is fixed on the vibration isolation table 7.

[0046] It should be noted that laser 1 is used to generate a stable, narrow laser beam; laser 1 is fixed on the two-dimensional turntable 4; θ x The photoelectric autocollimator 2 is mounted on the vibration isolation table 7, perpendicular to the laser 1; the θ y The photoelectric autocollimator 3 is mounted on the vibration isolation table 7 and is aligned with the laser 1; the reflector 5 is mounted on the two-dimensional turntable 4 and aligned with θ. x Photoelectric autocollimator 2 and θ y The photoelectric autocollimator 3 corresponds to and is at the same horizontal height; the two-dimensional turntable 4 is installed on the vibration isolation table 7; the vibration isolation table 7 is used to avoid interference from external vibrations, which would cause inaccurate measurement results.

[0047] The PSD angle measurement system 6 includes a telephoto lens 601, a first reflector 602, a second reflector 603, and a PSD 604. The telephoto lens 601 has a diameter of 80mm and a focal length of 500mm. The PSD 604 is fixed at the focal point of the telephoto lens 601 and electrically connected to the software processing terminal. It is used to accurately measure the position of the spot of a thin laser beam incident on the PSD 604 after passing through the telephoto lens 601, the first reflector 602, and the second reflector 603. The PSD 604 is a two-dimensional detector chip with a target surface size of 20*20mm and a response wavelength range of 300-1100nm. It is recommended to use a maximum range of ±8mm, a resolution of 1µm, a linear accuracy of ±10µm, an ideal linear measurement range of ±3mm, and a linear accuracy of 0.002mm within the ideal linear range.

[0048] The wavelength of the laser 1 source is within the wavelength response range of the PSD position-sensitive detector chip, and the laser divergence angle is less than 1 mrad. The maximum output power of the laser 1 is less than the damage threshold of the PSD604. The center height of the laser 1 is consistent with the center height of the PSD angle measurement system 6.

[0049] In this scheme, the beam emitted by laser 1 passes through telephoto lens 601, first reflector 602, and second reflector 603 to reach PSD 604. The software processing terminal collects data on the position of the light spot in the PSD position-sensitive detector and compares it with θ. x Photoelectric autocollimator 2 and θ y The accuracy of the measurement results is obtained by comparing the data collected by the photoelectric autocollimator 3.

[0050] Example 2:

[0051] Please refer to the following: Figure 2-5 This embodiment presents a quadrant calibration method based on PSD angle measurement accuracy, including the following steps:

[0052] Step 1: First, for laser 1, θ x Photoelectric autocollimator 2, θ y The photoelectric autocollimator 3, the two-dimensional turntable 4, the reflector 5 and the PSD angle measuring system 6 are installed on the vibration isolation table 7 to complete the construction of the experimental device;

[0053] Step 2: Turn on the power to laser 1, adjust the height so that the light spot passes through the telephoto lens 601, the first reflector 602, and the second reflector 603, and is centered at the PSD 604 in the PSD angle measuring system 6. Position laser 1 and θ... x Photoelectric autocollimator 2 and θ y After the photoelectric autocollimator 3 is preheated, the light spot is moved to the center of the PSD604 target surface, i.e., the quadrant origin, and the autocollimator value is set to zero.

[0054] Step 3: Control the 2D turntable 4, rotating it at equal intervals each time, sequentially calibrating the points in the first, second, third, and fourth quadrants of the PSD604 chip's photosensitive surface in a "bow" shape from the origin. The rotation method of the 2D turntable 4 during calibration is as follows: Figure 3 As shown. At each point, after the system stabilizes, record the position θ of the PSD604 and the autocollimator spot. x With θ y The measurement results were obtained.

[0055] Step 4: Correct the obtained PSD data and autocollimator data using two-dimensional linear interpolation. Compare the processed PSD data with the autocollimator data to obtain the accuracy of the measurement results.

[0056] The software processing unit, based on LabVIEW programming, can obtain the two-dimensional position coordinates (x, y) of the light spot according to the PSD's serial communication protocol, and calculate the displacement of the light spot in the horizontal and vertical directions. , Then convert it into the beam's pointing coordinates θ. x θ y To achieve precise measurement of changes in the direction of the reflected beam, the data processing algorithm is as follows:

[0057] In paraxial optical paths of geometric optics, the following conditions are met:

[0058]

[0059] Where θ is the beam angle. For image height, Let be the focal length of the lens. Since the angle change is very small, the above formula can be approximated as follows:

[0060]

[0061] in, The horizontal deflection angle. This represents the horizontal displacement difference of the light spot on the PSD.

[0062] Similarly, the angle at which the light spot deflects in the vertical direction is:

[0063]

[0064] in, The vertical deflection angle. This represents the vertical displacement difference of the light spot on the PSD.

[0065] The collected PSD data needs to be corrected using two-dimensional linear interpolation.

[0066] In the measurement coordinate system, let the coordinates of the four grid points be represented as and let the angular coordinates of the four grid points be represented as θ. a (α a , β a ), θ b (α b , β b ), θ c (α c , β c ), θ d (α d , β d For any point θ to be measured within the grid, x (α x ,β xThe relative positional relationship between the grid points and the grid points can be determined by the two-dimensional linear interpolation parameters k and Description. Establish the following two-dimensional linear interpolation equation: where θ a θ b θ c θ d Four grid points and the point to be measured θ x (α x , β x () represents the data measured by PSD.

[0067]

[0068] Where, α x β represents the x-coordinate of the point to be measured. x Represents the ordinate of the point to be measured. and Let α be the interpolation parameter to be determined. a Represents grid point θ a x-coordinate, β a Represents grid point θ a The ordinate, α b Represents grid point θ b x-coordinate, β b Represents grid point θ b The ordinate, α c Represents grid point θ c x-coordinate, β c Represents grid point θ c The ordinate, α d Represents grid point θ d x-coordinate, β d Represents grid point θ d The ordinate;

[0069] Obtain interpolation parameters and Then, the angular coordinates θ corresponding to the reference point are measured using an autocollimator. A (α A ,β A ), θ B (α B , β B ), θ C (α C , β C ), θ D (α D , β D Perform coordinate transformation to obtain the interpolated result θ. X (α X , β X );

[0070]

[0071] Where, α X β is the interpolated x-coordinate. X Let α be the interpolated ordinate. A Represents the reference coordinate value θ A The x-coordinate, N a Represents the reference coordinate value θ A The ordinate, α B Represents θ B x-coordinate, β B Represents the reference coordinate value θ B The ordinate, α C Represents the reference coordinate value θ C x-coordinate, β C Represents the reference coordinate value θ C The ordinate, α D Represents the reference coordinate value θ D x-coordinate, β D Represents the reference coordinate value θ D The ordinate.

[0072] The measurement error of each point in the X and Y directions is calculated based on the collected data:

[0073]

[0074] in, Let θ be a point at θ x Measurement error in direction; Let θ be a point at θ y Measurement error in direction, , The point θ solved by the PSD system at θ x θ y The angle value of the direction, , For the point θ measured by the autocollimator at θ x θ y The angle value of the direction.

[0075] Overall accuracy is assessed by calculating the root mean square error (RMSE) of each axis:

[0076]

[0077] in, For θ x Root mean square error in direction; For θ y Root mean square error in direction; The number of data points measured.

[0078] In accuracy assessment, based on and Two indicators are used to quantify the corrected systematic error. and They respectively characterize θ x Direction and θ y The root mean square error (RMSE) between the predicted and actual values ​​in each direction directly reflects the overall deviation level of the system in all directions. The lower this value, the closer the measured result is to the true value, and the higher the accuracy of the measurement result.

[0079] The experimental apparatus based on PSD angle measurement accuracy provided by this invention is simple, low-cost, easy to operate, and highly accurate, enabling effective angle measurement. This invention also provides a quadrant calibration method based on PSD angle measurement accuracy, which can shorten calibration time and improve the accuracy of results.

[0080] As is known from common technical knowledge, this invention can be implemented through other embodiments that do not depart from its spirit or essential characteristics. Therefore, the disclosed embodiments described above are merely illustrative and not exhaustive. All modifications within the scope of this invention or its equivalents are included in this invention.

[0081] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A quadrant calibration experimental device based on PSD angle measurement accuracy, characterized in that it comprises: Laser (1), θ x Photoelectric autocollimator (2), θ y The system comprises an opto-collimator (3), a two-dimensional turntable (4), a reflector (5), a PSD angle measurement system (6), and a vibration isolation table (7); wherein the PSD angle measurement system (6) is mounted on the vibration isolation table (7) via a translation and lifting adjustment mechanism, and is used to receive and measure the position of the incident laser spot; the laser (1) and the reflector (5) are fixedly mounted on the two-dimensional turntable (4), and the two-dimensional turntable (4) can drive the laser (1) and the reflector (5) to rotate, so as to change the beam direction and calibrate different quadrants of the target surface of the PSD angle measurement system (6); the θ x Photoelectric autocollimator (2) and the θ y The photoelectric autocollimator (3) is fixed on the vibration isolation table (7) and serves as a reference for measuring the deflection angle of the beam in the horizontal and vertical directions, respectively; the laser (1) generates a stable thin beam of laser light, the output optical axis of which is perpendicular to the θ. y The optical axis of the photoelectric autocollimator (3) is arranged coaxially; the θ x The optical axis of the photoelectric autocollimator (2) is arranged perpendicular to the optical axis of the laser (1); the reflector (5) is perpendicular to the optical axis of the θ. x Photoelectric autocollimator (2) and θ y The optical axis of the photoelectric autocollimator (3) corresponds to the optical axis of the autocollimator, reflecting the light beam emitted by the autocollimator back to itself to read the reference angle value; the θ x Photoelectric autocollimator (2), θ y The photoelectric autocollimator (3) and the PSD angle measurement system (6) are electrically connected to the software processing terminal.

2. The quadrant calibration experimental device based on PSD angle measurement accuracy according to claim 1, characterized in that, The PSD angle measurement system (6) includes a telephoto lens (601), a first reflector (602), a second reflector (603), and a PSD (604). The telephoto lens (601) has a diameter of 80mm and a focal length of 500mm. The PSD (604) is fixed at the focal point of the telephoto lens (601) and electrically connected to the software processing terminal.

3. The quadrant calibration experimental device based on PSD angle measurement accuracy according to claim 2, characterized in that, The PSD (604) is a two-dimensional detector chip with a target size of 20*20mm and a response wavelength range of 300-1100nm.

4. The quadrant calibration experimental device based on PSD angle measurement accuracy according to claim 2, characterized in that, The light source wavelength of the laser (1) is within the wavelength response range of the PSD position-sensitive detector chip, and the laser divergence angle is less than 1 mrad. The maximum output power of the laser (1) is less than the damage threshold of the PSD (604).

5. The quadrant calibration experimental apparatus based on PSD angle measurement accuracy according to claim 1, characterized in that, The center height of the laser (1) is consistent with the center height of the PSD angle measurement system (6).

6. A quadrant calibration method based on PSD angle measurement accuracy, characterized in that, The experimental apparatus for quadrant calibration based on PSD angle measurement accuracy, as described in any one of claims 1 to 5, includes: Set up the experimental setup and preheat it. Adjust the laser spot to the center of the target surface of the PSD angle measuring system (6) and set the value of the photoelectric autocollimator to zero. Control the two-dimensional turntable (4) to rotate at the same interval, and sequentially perform "bow" shaped trajectory calibration on the four quadrants of the detector photosensitive surface in the PSD angle measurement system (6); At each calibration point, after the system stabilizes, the coordinate values ​​and θ measured by the PSD angle measurement system (6) are synchronously recorded through the software processing terminal. x Photoelectric autocollimator (2) and θ y The reference angle value measured by the photoelectric autocollimator (3); The acquired PSD measurement data is corrected using a two-dimensional linear interpolation method. The corrected PSD angle data is then compared with the reference angle data of the autocollimator to calculate the measurement error and evaluate the system accuracy.

7. The quadrant calibration method based on PSD angle measurement accuracy according to claim 6, characterized in that, The software processing terminal is programmed using LabVIEW software. It obtains the two-dimensional position coordinates of the light spot according to the PSD's serial communication protocol, calculates the displacement of the light spot in the horizontal and vertical directions, and then converts it into the beam's pointing coordinates, expressed as: in, The horizontal deflection angle. The vertical deflection angle. This represents the horizontal displacement difference of the light spot on the PSD. This represents the vertical displacement difference of the light spot on the PSD. This is the focal length of the lens.

8. The quadrant calibration method based on PSD angle measurement accuracy according to claim 6, characterized in that, The PSD measurement data is corrected using a two-dimensional linear interpolation method. Specifically, the angular coordinates corresponding to the four grid points measured by the PSD are represented as θ. a (α a , β a ), θ b (α b , β b ), θ c (α c , β c ), θ d (α d , β d ), and the angular coordinates θ corresponding to the points to be measured within the grid. x (α x , β x The interpolation parameters are solved, and then the angular coordinates corresponding to the four grid points measured by the autocollimator are used as the reference coordinates θ. A (α A , β A ), θ B (α B , β B ), θ C (α C , β C ), θ D (α D , β D Perform coordinate transformation to obtain the angular coordinates θ corresponding to the measured point after correction. X (α X , β X ), where the point to be measured θ x The angular coordinates are: Where, α x β represents the x-coordinate of the point to be measured. x Represents the ordinate of the point to be measured. and Let α be the interpolation parameter to be determined. a Represents grid point θ a x-coordinate, β a Represents grid point θ a The ordinate, α b Represents grid point θ b x-coordinate, β b Represents grid point θ b The ordinate, α c Represents grid point θ c x-coordinate, β c Represents grid point θ c The ordinate, α d Represents grid point θ d x-coordinate, β d Represents grid point θ d The ordinate; The angular coordinates corresponding to the measured point after correction are: Where, α X β is the interpolated x-coordinate. X Let α be the interpolated ordinate. A Represents the reference coordinate value θ A The x-coordinate, N a Represents the reference coordinate value θ A The ordinate, α B Represents θ B x-coordinate, β B Represents the reference coordinate value θ B The ordinate, α C Represents the reference coordinate value θ C x-coordinate, β C Represents the reference coordinate value θ C The ordinate, α D Represents the reference coordinate value θ D x-coordinate, β D Represents the reference coordinate value θ D The ordinate.

9. The quadrant calibration method based on PSD angle measurement accuracy according to claim 6, characterized in that, The expression for calculating the measurement error is as follows: in, Let θ be a point at θ x Measurement error in direction; Let θ be a point at θ y Measurement error in direction, , The point θ solved by the PSD system at θ x θ y The angle value of the direction, , For the point θ measured by the autocollimator at θ x θ y The angle value of the direction.

10. The quadrant calibration method based on PSD angle measurement accuracy according to claim 6, characterized in that, The accuracy of the evaluation system includes: via θ x Root mean square error of direction and θ y The root mean square error in the direction and two other indices are used to quantify the corrected systematic error. The expression is as follows: in, For θ x Root mean square error in direction; For θ y Root mean square error in direction; The number of data points measured.

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