Position measurement and calibration method and device for position-sensitive detectors

Abstract

This disclosure provides a method and apparatus for calibrating the position of a position-sensitive detector. The method includes: fixing the position-sensitive detector on a precision displacement stage; generating a laser beam to illuminate the position-sensitive detector, with the laser beam perpendicular to the photosensitive surface of the detector; moving the position-sensitive detector along a movement path at a preset step size; collecting the analog voltage generated by the laser beam in response to the position-sensitive detector at different positions to obtain a conversion coefficient between the analog voltage and the position of the position-sensitive detector; repeating the above steps with different step sizes to obtain multiple conversion coefficients; calculating correction coefficients based on the multiple conversion coefficients; correcting the conversion coefficients for errors based on the correction coefficients; and using the error-corrected conversion coefficients for position measurement calibration. This method uses a simple and easy-to-operate apparatus, corrects the calibration coefficients for the position information of the position-sensitive detector, and improves the accuracy of position detection.

Description

Technical Field

[0001] This disclosure relates to the field of micro-displacement measurement technology, and in particular to a position measurement and calibration method and apparatus for a position-sensitive detector. Background Technology

[0002] A position-sensitive detector (PSD) is an optoelectronic device based on the lateral photoelectric effect of semiconductors. It has advantages such as fast response speed, simple signal processing circuit, low requirements for light source and optical system, wide spectral response, and the ability to simultaneously measure spot position and light intensity. It has wide applications in distance measurement, contour detection, surface analysis, level acquisition, feature extraction, beam positioning, acceleration measurement, vibration testing, etc.

[0003] When incident light illuminates the photosensitive layer of the PSD, a charge proportional to the incident light intensity is generated at the incident position. This charge moves directionally, forming a current, which is output through the electrodes at both ends of the photosensitive layer. The magnitude of the current output by the electrodes is related to the distance from the incident light spot to each electrode. The PSD determines the position of the incident light spot based on the magnitude of the current output by the two electrodes. The current output by the PSD electrodes is usually quite weak and needs to be amplified by an amplifier to output an analog voltage signal. This voltage signal is then acquired using a data acquisition card to calculate the light spot position. In practical applications, the light spot position calculated from the analog voltage signal contains errors. To improve the detection accuracy of the PSD, precise calibration is required. Therefore, achieving high-precision calibration of the analog voltage and position information and optimizing and correcting calibration errors are crucial prerequisites for ensuring the detection accuracy of the PSD.

[0004] Existing solutions propose a PSD chip parameter calibration device and a PSD nonlinear distortion calibration method. Based on the true PSD coordinates and PSD coordinate readings, a coordinate error model of the PSD chip at each vertex of the grid is established. Distortion compensation is performed on the error model using interpolation methods. This method mainly focuses on the coefficient calibration of the PSD body coordinate system and the calibration of PSD nonlinear distortion, but it ignores the accuracy of the PSD's output position information. Other existing error calibration methods mainly address the relationship between the PSD's positioning error and the angle error of the PSD's photosensitive surface, resulting in low accuracy and no optimization of the fitting coefficients. None of the above solutions consider the calibration error and optimization issues during the PSD position information acquisition process. Summary of the Invention

[0005] In view of the above problems, the present invention provides a position measurement and calibration method and apparatus for a position-sensitive detector to solve the calibration error and optimization problems in the process of acquiring PSD position information.

[0006] One aspect of this disclosure provides a method for calibrating the position of a position-sensitive detector, comprising: fixing the position-sensitive detector on a precision displacement stage; generating a laser beam to illuminate the position-sensitive detector, the laser beam being perpendicular to the photosensitive surface of the position-sensitive detector; moving the position-sensitive detector along a movement path by a preset movement step size; collecting analog voltages generated by the position-sensitive detector in response to the laser beam at different positions; obtaining a conversion coefficient between the analog voltage and the position of the position-sensitive detector; repeating the above steps using different movement step sizes to obtain multiple conversion coefficients; calculating correction coefficients based on the multiple conversion coefficients; correcting errors in the conversion coefficients based on the correction coefficients; and using the error-corrected conversion coefficients for position measurement calibration.

[0007] Optionally, the step of moving the position-sensitive detector along the movement path by a preset movement step size, and collecting the analog voltage generated by the position-sensitive detector in response to the laser beam at different positions to obtain the conversion coefficient between the analog voltage and the position of the position-sensitive detector includes: moving the position-sensitive detector sequentially along the movement path according to the preset movement step size; collecting the analog voltage generated by the position-sensitive detector in response to the laser beam at each position; and linearly fitting the relationship function between the analog voltage and the position of the position-sensitive detector based on the least squares method to obtain the conversion coefficient between the analog voltage and the position of the position-sensitive detector.

[0008] Optionally, the step of acquiring the simulated voltage generated by the position-sensitive detector in response to the laser beam at each position includes: acquiring the voltage generated by the position-sensitive detector in response to the laser beam multiple times at each position of the position-sensitive detector; calculating the average value of the voltage to obtain the simulated voltage.

[0009] Optionally, calculating the correction coefficient based on the plurality of conversion coefficients includes: calculating the standardized value of each of the plurality of conversion coefficients, and calculating the weight of each of the plurality of conversion coefficients based on the standardized value; calculating the importance evaluation coefficient of each of the plurality of conversion coefficients based on the weight; and calculating the correction coefficient based on the importance evaluation coefficient.

[0010] Optionally, the formula for calculating the standardized value of each of the plurality of transformation coefficients is:

[0011]

[0012] Where, k i This represents the conversion coefficient corresponding to the i-th movement step, where i = 1, 2, ..., n, n represents the number of possible values ​​for the movement step, and k represents the conversion coefficient. min Indicates k iThe minimum value in, k max Indicates k i The maximum value in K i Represents the conversion factor k i The standardized value;

[0013] The formula for calculating the proportion of each of the multiple conversion coefficients is as follows:

[0014]

[0015] Where, p i Represents the conversion factor k i The proportion it accounts for.

[0016] Optionally, the formula for calculating the importance evaluation coefficient of each of the plurality of conversion coefficients based on the proportion is:

[0017]

[0018]

[0019] Among them, E i The transformation coefficient k corresponds to the i-th movement step. i The proportion of weight, p i Represents the conversion factor k i The proportion, i = 1, 2, ..., n, where n represents the number of possible values ​​for the movement step size, α i Represents the conversion factor k i Importance rating coefficient.

[0020] Optionally, the formula for calculating the correction coefficient based on the importance evaluation coefficient is as follows:

[0021]

[0022] Where, k i Let α represent the conversion coefficient corresponding to the i-th movement step. i Represents the conversion factor k i The importance evaluation coefficient, i = 1, 2, ... n, where n represents the number of values ​​for the moving step size, and β represents the correction coefficient.

[0023] Optionally, the step of correcting the conversion coefficient based on the correction coefficient and using the error-corrected conversion coefficient for position measurement calibration includes: calculating the product of the correction coefficient and the conversion coefficient to obtain the error-corrected conversion coefficient; when the position-sensitive detector performs position measurement, calculating the product of the error-corrected conversion coefficient and the voltage generated by the position-sensitive detector at the current position to obtain the position information of the current position.

[0024] This disclosure also provides a position measurement and calibration device for a position-sensitive detector, applied to the position measurement and calibration method for a position-sensitive detector as described in any one of the first aspects, comprising: a laser for generating a laser beam to illuminate the position-sensitive detector, the laser beam being perpendicular to the photosensitive surface of the position-sensitive detector; a precision displacement stage for fixing the position-sensitive detector and moving the position-sensitive detector along a movement path by a preset movement step size, the movement direction being perpendicular to the direction of the laser beam; an amplifier connected to the position-sensitive detector via a cable for amplifying the voltage generated by the position-sensitive detector in response to the laser beam at different positions; a data acquisition card connected to the amplifier for acquiring the analog voltage output by the amplifier; an integrated circuit module for calculating a conversion coefficient between the analog voltage and the position of the position-sensitive detector; obtaining multiple conversion coefficients corresponding to different movement step sizes; calculating a correction coefficient based on the multiple conversion coefficients; and performing error correction on the conversion coefficient based on the correction coefficient, using the error-corrected conversion coefficient for position measurement calibration.

[0025] The above-described at least one technical solution adopted in the embodiments of this disclosure can achieve the following beneficial effects:

[0026] According to the embodiments of this disclosure, a position measurement and calibration method and apparatus for a position-sensitive detector (PSD) is provided. Using the movement of a high-precision displacement stage as a reference, different stage lengths are set to fit the collected analog voltage data and light spot position change data to obtain the conversion coefficient k between the analog voltage and the light spot position change. Then, a correction coefficient β is used to correct the error of k, ultimately achieving high-precision calibration of the PSD position detection. This method uses a simple and easy-to-operate apparatus, corrects the calibration coefficients of the PSD position information, and improves the accuracy of PSD position detection. Attached Figure Description

[0027] To gain a more complete understanding of this disclosure and its advantages, reference will now be made to the following description taken in conjunction with the accompanying drawings, wherein:

[0028] Figure 1 This schematic diagram illustrates a position measurement and calibration device for a position-sensitive detector provided in an embodiment of the present disclosure.

[0029] Figure 2 This schematic diagram illustrates the working principle of a position-sensitive detector provided in an embodiment of the present disclosure.

[0030] Figure 3 The flowchart illustrates a position measurement and calibration method for a position-sensitive detector provided in an embodiment of this disclosure. Detailed Implementation

[0031] The embodiments of the present disclosure will now be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the disclosure. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the embodiments of the present disclosure for ease of explanation. However, it will be apparent that one or more embodiments may be practiced without these specific details. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concepts of the present disclosure.

[0032] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. The terms “comprising,” “including,” etc., as used herein indicate the presence of the stated features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0033] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein are to be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.

[0034] The accompanying drawings show some block diagrams and / or flowcharts. It should be understood that some blocks or combinations thereof in the block diagrams and / or flowcharts can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing device, so that when executed by the processor, these instructions can create means for implementing the functions / operations described in these block diagrams and / or flowcharts.

[0035] Figure 1 The schematic diagram illustrates a position measurement and calibration device for a position-sensitive detector provided in an embodiment of the present disclosure.

[0036] like Figure 1 As shown in the figure, the position measurement and calibration device for a position-sensitive detector provided in this embodiment includes a laser 1, a precision displacement stage 3, an amplifier 4, a data acquisition card 5, and an integrated circuit module (not shown in the figure).

[0037] Laser 1 is fixed on the optical experimental platform by a fixing device and is used to generate a laser beam to irradiate the position-sensitive detector. The laser beam is perpendicular to the photosensitive surface of the position-sensitive detector 2.

[0038] The precision displacement stage 3 is fixed on the optical experimental platform to fix the position sensitive detector 2. The position sensitive detector 2 is moved along the moving path according to the preset moving step size, and its moving direction is perpendicular to the direction of the laser beam.

[0039] The two-dimensional position-sensitive detector 2 is fixed to the precision displacement stage 3 by screws and moves with the precision displacement stage 3. The normal of its photosensitive surface is perpendicular to the direction of movement of the precision displacement stage 3.

[0040] Amplifier 4 is connected to position-sensitive detector 2 via a cable to amplify the current generated by the position-sensitive detector 2 in response to the laser beam at different positions and convert the current into an analog voltage.

[0041] Data acquisition card 5 is connected to amplifier 4 and is used to acquire the analog voltage output by amplifier 4.

[0042] The integrated circuit module is used to calculate the conversion coefficient between the analog voltage and the position of the position-sensitive detector 2; to obtain multiple conversion coefficients for different movement step sizes; to calculate correction coefficients based on multiple conversion coefficients; to correct the conversion coefficients for errors based on the correction coefficients; and to use the error-corrected conversion coefficients for position measurement calibration.

[0043] Figure 2 The schematic diagram illustrates the working principle of a position-sensitive detector provided in an embodiment of this disclosure.

[0044] like Figure 2 As shown, when the laser beam emitted by laser 1 is perpendicularly incident on the photosensitive surface of position-sensitive detector 2, the light spot on the photosensitive surface of position-sensitive detector 2 generates a weak current at its four ends. The current generated by electrodes X1 and X2 can represent the position of the light spot in the X direction, and the current generated by electrodes Y1 and Y2 can represent the position of the light spot in the Y direction. Here, L represents the length of the photosensitive surface of position-sensitive detector 2.

[0045]

[0046]

[0047] In this embodiment, the current generated by the position-sensitive detector 2 is a weak current, which needs to be amplified by the amplifier 4. Then, the analog voltage related to the position of the position-sensitive detector 2 is obtained by calculation using equations (1) and (2). The analog voltage output is then acquired by the data acquisition card 5. Finally, the conversion relationship between the spot position and the analog voltage is obtained by the position measurement and calibration method of the position-sensitive detector provided in this embodiment.

[0048] In this embodiment, the position-sensitive detector 2 has a resolution of 0.1 μm and the precision displacement stage 3 has a resolution of 0.3 nm. Therefore, the position detection of the PSD is calibrated based on the movement of the precision displacement stage 3.

[0049] Figure 3The flowchart illustrates a position measurement and calibration method for a position-sensitive detector provided in an embodiment of this disclosure.

[0050] like Figure 3 As shown, an embodiment of this disclosure provides a position-sensitive detector including operations S310 to S350.

[0051] S310, the position-sensitive detector 2 is fixed on the precision displacement stage 3, and a laser beam is generated to irradiate the position-sensitive detector 2. The normal of the photosensitive surface of the position-sensitive detector 2 is perpendicular to the moving direction of the precision displacement stage 3, and the laser beam is perpendicular to the photosensitive surface of the position-sensitive detector 2.

[0052] S320, the position-sensitive detector 2 is moved along the moving path by a preset moving step size, and the analog voltage generated by the laser beam in response to the position-sensitive detector 2 at different positions is collected to obtain the conversion coefficient between the analog voltage and the position of the position-sensitive detector 2.

[0053] Specifically, S320 includes S321 to S323.

[0054] S321, according to the preset moving step size, the position sensitive detector 2 is moved sequentially along the moving path.

[0055] S322, acquires the analog voltage generated by the position-sensitive detector 2 in response to the laser beam at each position.

[0056] In this embodiment, the voltage generated by the position-sensitive detector 2 in response to the laser beam is collected multiple times at the position of each position-sensitive detector 2; the average value of the voltage is calculated to obtain the simulated voltage.

[0057] S323, based on the least squares method, linearly fit the relationship function between the analog voltage and the position of the position-sensitive detector 2 to obtain the conversion coefficient between the analog voltage and the position of the position-sensitive detector 2.

[0058] For example, control the precision stage 3 to move to 0μm and record the voltage value output by the PSD at this time; control the precision stage 3 to perform stepping motion with a step size of 10μm, and record the output voltage value of the PSD for each movement; measure multiple times and average the multiple measurements; plot a curve with the movement of the precision stage 3 as the Y-axis and the PSD output voltage as the X-axis, and obtain the conversion relationship between voltage and position by linear fitting using the least squares method: L=kU, where L is the movement of the precision stage 3, U is the PSD output voltage, and k is the conversion coefficient.

[0059] S330, using different moving step sizes, repeat the above steps to obtain multiple conversion coefficients.

[0060] S340 calculates correction coefficients based on multiple conversion coefficients.

[0061] Specifically, S340 includes S341 to S343.

[0062] S341, calculate the standardized values ​​of each of the multiple transformation coefficients, and calculate the weight of each of the multiple transformation coefficients based on the standardized values.

[0063] The formula for calculating the standardized values ​​of multiple transformation factors is as follows:

[0064]

[0065] Where, k i K represents the conversion coefficient corresponding to the i-th movement step, where i = 1, 2, ..., n, and n represents the number of possible movement step values. min Indicates k i The minimum value in, k max Indicates k i The maximum value in K i Represents the conversion factor k i The standardized value;

[0066] The formula for calculating the proportion of each of the multiple conversion factors is as follows:

[0067]

[0068] Where, p i Represents the conversion factor k i The proportion it accounts for.

[0069] S342, calculate the importance evaluation coefficient of each of the multiple conversion coefficients based on the proportion.

[0070] The formula for calculating the importance evaluation coefficient of each of the multiple conversion coefficients based on the proportion is as follows:

[0071]

[0072]

[0073] Among them, E i The transformation coefficient k corresponds to the i-th movement step. i The proportion of weight, p i Represents the conversion factor k i The proportion, i = 1, 2, ..., n, where n represents the number of possible values ​​for the movement step, α i Represents the conversion factor k i Importance rating coefficient.

[0074] S343, calculate the correction coefficient based on the importance evaluation coefficient.

[0075] The formula for calculating the correction coefficient based on the importance evaluation coefficient is as follows:

[0076]

[0077] Where, k i Let α represent the conversion coefficient corresponding to the i-th movement step. i Represents the conversion factor k i The importance evaluation coefficient, i = 1, 2, ..., n, where n represents the number of possible values ​​for the movement step size, and β represents the correction coefficient.

[0078] S350 corrects the conversion coefficients based on the correction factor, and uses the error-corrected conversion coefficients for position measurement calibration.

[0079] S350 includes S351 to S352.

[0080] S351, calculate the product of the correction factor and the conversion factor to obtain the conversion factor after error correction.

[0081] The expression for the error conversion coefficient is k′=βk, where k′ represents the corrected conversion coefficient, k represents the original conversion coefficient, and β represents the correction coefficient.

[0082] S352, when the position-sensitive detector 2 performs position measurement, the product of the error-corrected conversion coefficient and the voltage generated by the position-sensitive detector 2 at the current position is calculated to obtain the position information of the current position.

[0083] When using the position-sensitive detector 2 for position measurement, the formula for calculating the position measured by the position-sensitive detector 2 is: L=k′·U, where U represents the voltage detected by the position-sensitive detector 2, and k′ represents the corrected conversion coefficient.

[0084] According to an embodiment of this disclosure, a position measurement and calibration method for a position-sensitive detector 2 is provided. This method uses the movement of a high-precision displacement stage as a reference, and by setting different stage lengths, it fits the collected analog voltage data and the light spot position change data to obtain the conversion coefficient k between the analog voltage and the light spot position change. Then, it corrects the error of k by the correction coefficient β, and finally achieves high-precision calibration of PSD position detection.

[0085] Those skilled in the art will understand that the features described in the various embodiments and / or claims of this disclosure can be combined or combined in various ways, even if such combinations or combinations are not explicitly described in this disclosure. In particular, the features described in the various embodiments and / or claims of this disclosure can be combined or combined in various ways without departing from the spirit and teachings of this disclosure. All such combinations and / or combinations fall within the scope of this disclosure.

[0086] Although this disclosure has been shown and described with reference to specific exemplary embodiments thereof, those skilled in the art will understand that various changes in form and detail may be made to this disclosure without departing from the spirit and scope of the disclosure as defined by the appended claims and their equivalents. Therefore, the scope of this disclosure should not be limited to the above embodiments, but should be defined not only by the appended claims, but also by their equivalents.

Claims

1. A method for position measurement and calibration of a position-sensitive detector, characterized in that, include: A position-sensitive detector is fixed on a precision displacement stage, and a laser beam is generated to irradiate the position-sensitive detector, with the laser beam perpendicular to the photosensitive surface of the position-sensitive detector. The position-sensitive detector is moved along the movement path by a preset movement step size, and the analog voltage generated by the laser beam in response to the position-sensitive detector at different positions is collected to obtain the conversion coefficient between the analog voltage and the position of the position-sensitive detector. By repeating the above steps with different moving step sizes, multiple conversion coefficients can be obtained; The correction coefficient is calculated based on the multiple conversion coefficients, including: Calculate the standardized value of each of the plurality of conversion coefficients, and calculate the weight of each of the plurality of conversion coefficients based on the standardized value; Calculate the importance evaluation coefficient of each of the multiple conversion coefficients based on the aforementioned proportions; The correction coefficient is calculated based on the importance evaluation coefficient; The conversion coefficient is corrected for error based on the correction coefficient, and the error-corrected conversion coefficient is used for position measurement calibration.

2. The method according to claim 1, characterized in that, The process of moving the position-sensitive detector along the movement path by a preset step size, collecting the analog voltage generated by the position-sensitive detector in response to the laser beam at different positions, and obtaining the conversion coefficient between the analog voltage and the position of the position-sensitive detector includes: The position-sensitive detector is moved sequentially along the movement path according to the preset movement step size; The analog voltage generated by the position-sensitive detector in response to the laser beam at each position is collected; Based on the least squares method, a linear fitting of the relationship function between the analog voltage and the position of the position-sensitive detector is performed to obtain the conversion coefficient between the analog voltage and the position of the position-sensitive detector.

3. The method according to claim 2, characterized in that, The acquisition of the analog voltage generated by the position-sensitive detector in response to the laser beam at each position includes: At the location of each of the position-sensitive detectors, the voltage generated by the position-sensitive detector in response to the laser beam is collected multiple times; The average value of the voltage is calculated to obtain the simulated voltage.

4. The method according to claim 1, characterized in that, The formula for calculating the standardized value of each of the plurality of transformation coefficients is as follows: ； Where, k i This represents the conversion coefficient corresponding to the i-th movement step, where i = 1, 2, ..., n, and n represents the number of possible values ​​for the movement step. min Indicates k i The minimum value in, k max Indicates k i The maximum value in K i Represents the conversion factor k i The standardized value; The formula for calculating the proportion of each of the multiple conversion coefficients is as follows: ； Where, p i Represents the conversion factor k i The proportion it accounts for.

5. The method according to claim 1, characterized in that, The formula for calculating the importance evaluation coefficient of each of the multiple conversion coefficients based on the proportion is as follows: ； ； Among them, E i The transformation coefficient k corresponds to the i-th movement step. i The proportion of weight, p i Represents the conversion factor k i The proportion, i=1,2,…n, where n represents the number of possible values ​​for the movement step size, α i Represents the conversion factor k i Importance rating coefficient.

6. The method according to claim 1, characterized in that, The formula for calculating the correction coefficient based on the importance evaluation coefficient is as follows: ； Where, k i Let α represent the conversion coefficient corresponding to the i-th movement step. i Represents the conversion factor k i The importance evaluation coefficient, i=1,2,…n, where n represents the number of possible values ​​for the moving step size, and β represents the correction coefficient.

7. The method according to claim 1, characterized in that, The step of correcting the conversion coefficient based on the correction coefficient and then using the error-corrected conversion coefficient for position measurement calibration includes: Calculate the product of the correction factor and the conversion factor to obtain the error-corrected conversion factor; When the position-sensitive detector performs position measurement, it calculates the product of the error-corrected conversion coefficient and the voltage generated by the position-sensitive detector at the current position to obtain the position information of the current position.

8. A position measurement and calibration device for a position-sensitive detector, applied to the position measurement and calibration method for a position-sensitive detector as described in any one of claims 1 to 7, characterized in that, include: A laser is used to generate a laser beam to illuminate a position-sensitive detector, wherein the laser beam is perpendicular to the photosensitive surface of the position-sensitive detector. A precision displacement stage is used to fix the position-sensitive detector and move the position-sensitive detector along the movement path by a preset movement step size. Its movement direction is perpendicular to the direction of the laser beam. An amplifier, connected to the position-sensitive detector via a cable, is used to amplify the voltage generated by the position-sensitive detector in response to the laser beam at different positions; A data acquisition card, connected to the amplifier, is used to acquire the analog voltage output by the amplifier; An integrated circuit module is used to calculate the conversion coefficient between the analog voltage and the position of the position-sensitive detector; For different movement step sizes, multiple conversion coefficients are obtained; The correction coefficient is calculated based on the multiple conversion coefficients, including: Calculate the standardized value of each of the plurality of conversion coefficients, and calculate the weight of each of the plurality of conversion coefficients based on the standardized value; Calculate the importance evaluation coefficient of each of the multiple conversion coefficients based on the aforementioned proportions; The correction coefficient is calculated based on the importance evaluation coefficient; and The conversion coefficient is corrected for error based on the correction coefficient, and the error-corrected conversion coefficient is used for position measurement calibration.

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