Rapid reflector angle automatic calibration system and method based on PSD sensor

Abstract

The invention discloses a rapid reflector angle automatic calibration system and method based on a PSD sensor, and belongs to the technical field of rapid reflector surface calibration. The method solves the technical problems of low efficiency and low accuracy of rapid mirror surface angle calibration in the prior art. The invention provides a high-efficiency automatic calibration method by utilizing the characteristics of high resolution and quick response of a PSD (Phase Sensitive Detector). The narrow-band optical filter is combined with power ripples to remove noise influence, so that the problem that the position calculation of the PSD sensor is easily interfered by photoelectric noise is effectively inhibited, and the measurement stability is improved. In the calibration process, through real-time data filtering and automatic acquisition, the influence of manual intervention and observation errors caused by the manual intervention is reduced. Compared with a traditional calibration method, the method does not need an autocollimator, and is higher in calibration speed and lower in cost. According to the invention, the limitation of application of the PSD as a linear displacement sensor in high-precision angle measurement is broken through, and an efficient and low-cost solution is provided for quick calibration of the angle of the reflector.

Description

Technical Field

[0001] The invention belongs to the technical field of fast reflector mirror surface calibration, and in particular relates to a fast reflector angle automatic calibration system and method based on a PSD sensor. Background Art

[0002] Fast Steering Mirror (FSM) is an optical device used to accurately and quickly control and adjust the direction of a light beam. It is often used in optical systems that require high precision and fast response, such as laser communications, optical imaging, and adaptive optics. It has the characteristics of high angular resolution, fast response speed, and high bandwidth.

[0003] Since the eddy current position sensor in the fast reflector is an analog device, it is affected by factors such as the nonlinear characteristics of components and structural installation errors. The fast reflector surface has a nonlinear relationship with the AD code value of the eddy current sensor output value when the fast reflector surface is at different angles, which makes the pointing accuracy of the fast reflector surface worse and requires fitting correction to improve the accuracy.

[0004] Usually, the fast reflector mirror angle calibration is carried out by using an autocollimator. Under different code values ​​of eddy current output, the autocollimator is used to read the actual value of the mirror angle corresponding to it. Through the corresponding relationship curve of the two sets of values, a nonlinear formula or interpolation calculation is fitted to improve the angle pointing accuracy of the fast reflector mirror. A complete two-axis fast reflector calibration process requires manual reading and recording of nearly 100 angle position data of the X and Y axes, and then fitting processing with mathematical processing software, which makes the calibration efficiency of the fast reflector very low, and there is also a problem of low calibration accuracy. Summary of the invention

[0005] In order to solve the technical problem of low efficiency and accuracy in the previous rapid reflector mirror angle calibration, the present invention provides a rapid reflector angle automatic calibration system and method based on a PSD sensor.

[0006] The system includes a calibration control board and a computer, wherein the calibration control board includes a center axis alignment laser module, an X-axis laser module, a Y-axis laser module, an X-axis one-dimensional PSD sensor, a Y-axis one-dimensional PSD sensor, an X-axis ready indicator light, and a Y-axis ready indicator light; The center of the X-axis laser module, the center of the Y-axis laser module, the center of the X-axis one-dimensional PSD sensor, and the center of the Y-axis one-dimensional PSD sensor together form a circle with the central axis alignment laser module as the center and a radius of r. The line connecting the center of the X-axis laser module and the center of the X-axis one-dimensional PSD sensor is parallel to the horizontal plane, and the line connecting the center of the Y-axis laser module and the center of the Y-axis one-dimensional PSD sensor is parallel to the vertical plane.

[0007] Furthermore, narrow-band filters are attached to the surfaces of the X-axis one-dimensional PSD sensor and the Y-axis one-dimensional PSD sensor to filter external light noise.

[0008] The method is performed using the PSD sensor-based rapid reflector angle automatic calibration system as described above, and the method is specifically as follows: S1. Calibration preparation: the fast reflector is parallel to the calibration control board and aligned with the central axis. The emission angles of the X-axis laser module and the Y-axis laser module are adjusted so that the parallel light emitted by them is reflected by the fast reflector. The light spot illuminates the center position of the X-axis one-dimensional PSD sensor and the Y-axis one-dimensional PSD sensor respectively. The calibration preparation is completed. S2, start calibration, the computer sends calibration instructions to the fast reflector and calibration control board, and sends regular calibration instructions to the X axis of the fast reflector , , … , , … The AD code value instruction of the eddy current is then sent to the Y axis of the fast reflector at a fixed time , , … , , … AD code value instruction of eddy current; S3, after receiving the computer control instruction, the fast reflector moves to the specified AD code value position in sequence, and the calibration control board returns the calculated fast reflector angle data to the computer in sequence, and the computer stores the AD code value and the returned corresponding fast reflector angle data information in sequence; S4. Use mathematical tool software to fit or interpolate the data stored in the computer, select a nonlinear mathematical model to fit a formula or generate a difference table, and enter the fitting formula or difference table into the fast reflector controller when calculating the actual mirror angle for correction.

[0009] Furthermore, the parallel and aligned central axis is specifically as follows: the fast reflection mirror is placed on a fixed platform, the calibration control board is placed on an adjustable two-dimensional platform, after the computer sends a preparation command, the electric mirror surface on the fast reflection mirror is locked and kept stationary at the zero position of the X and Y axes, and at the same time, the central axis alignment laser module placed vertically at the center of the calibration control board is lit, and the placement angles of the two-dimensional platform and the calibration control board are adjusted so that the parallel light emitted by the central axis alignment laser module placed vertically at the center of the calibration control board is vertically irradiated to the center of the mirror surface of the fast reflection mirror, and then returns to the center position of the calibration control board. At this time, the mirror surface of the fast reflection mirror is parallel to the calibration control board and the centers are aligned, and the distance L between the two is measured and recorded.

[0010] Further, the adjustment of the emission angle of the X-axis laser module and the Y-axis laser module is specifically as follows: the quick reflector mirror surface is kept at the X and Y-axis zero positions, the parallel light emitted by the X-axis laser module and the Y-axis laser module is reflected by the quick reflector mirror surface, and the mounting angle screws of the X-axis laser module and the Y-axis laser module are adjusted respectively so that the return light spot falls on the center position of the PSD sensor of the corresponding axis. When the light spot position is correct, the X-axis ready indicator light and the Y-axis ready indicator light up automatically, indicating that the calibration preparation work of the quick reflector and the calibration control board is completed and calibration can be performed.

[0011] Furthermore, after receiving the computer control command, the fast reflector moves to the specified AD code value position in sequence. The difference between the maximum and minimum eddy current code values ​​of the total X-axis travel of the fast reflector is , The code value of the center position is , each step code value is , N is the number of steps, that is, , , … , , … The position code value is equivalent to , , … , , … , the same calculation method is used for the Y-axis of the fast reflector.

[0012] Further, the fast reflector angle data is calculated as follows: When the fast reflector mirror moves to the specified AD code value position, the angle value of the fast reflector mirror corresponding to the X-axis zero position is , the calibration control board calculates the mirror angle change relationship as follows: ; in, When the fast reflector moves to the specified AD code value, the distance between the X-axis one-dimensional PSD sensor spot and the X-axis one-dimensional PSD sensor zero position is ,in and is the photocurrent code value of the electrodes at both ends of the one-dimensional PSD sensor on the X axis, The same solution method is used to calculate the angle value of the fast reflector mirror surface rotation corresponding to the Y-axis zero position, which is half the effective photosensitive surface length of the one-dimensional PSD sensor on the X-axis.

[0013] The beneficial effects of the present invention are: The system of the present invention can simultaneously realize continuous calibration of the X-axis and Y-axis of the fast reflector, saving the time for calibrating the mirror angle of the fast reflector, and adopts the structure that the X-axis laser module center, the Y-axis laser module center and the X-axis one-dimensional PSD sensor center and the Y-axis one-dimensional PSD sensor center together form a circle with the central axis alignment laser module as the center and a radius of r, which can minimize the calibration error between the X-axis and the Y-axis, which is very important for accurately calibrating the fast reflector.

[0014] The method of the present invention sends a timing signal to the X-axis of the fast reflector during calibration. , , … , , … AD code value instruction of eddy current, is the code value of the center position, and each step code value is , N is the number of steps, that is, , , … , , … The position code value is equivalent to , , … , , … This calibration method is different from the conventional calibration method of gradually increasing the code value. The calibration method of the present invention first determines the center position code value, and then expands it until and then again return with adjacent This step is approximately equivalent to confirming the center position again and then calibrating outward; the above calibration method can better improve the calibration accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a schematic diagram of a calibration control panel in an embodiment of the present invention; Figure 2 Schematic diagram of a fast reflector angle automatic calibration system based on a PSD sensor in an embodiment of the present invention; Figure 3 Schematic diagram of the calibration of the fast reflection mirror in an embodiment of the present invention. DETAILED DESCRIPTION

[0016] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the protection scope of the present invention.

[0017] This embodiment provides a fast reflector angle automatic calibration system based on a PSD sensor, such as Figure 1-2 As shown, the system includes a calibration control board 1 and a computer 9. The calibration control board 1 includes a center axis alignment laser module 2, an X-axis laser module 3, a Y-axis laser module 4, an X-axis one-dimensional PSD sensor 5, a Y-axis one-dimensional PSD sensor 6, an X-axis ready indicator light 7 and a Y-axis ready indicator light 8.

[0018] The center of the X-axis laser module 3, the center of the Y-axis laser module 4, the center of the X-axis one-dimensional PSD sensor 5, and the center of the Y-axis one-dimensional PSD sensor 6 together form a circle with the central axis alignment laser module 2 as the center and a radius r, in this embodiment, r = 100mm; the line connecting the center of the X-axis laser module 3 and the center of the X-axis one-dimensional PSD sensor 5 is parallel to the horizontal plane, and the line connecting the center of the Y-axis laser module 4 and the center of the Y-axis one-dimensional PSD sensor 6 is parallel to the vertical plane.

[0019] In order to reduce the impact of ambient light source noise on PSD signal resolution, narrow-band filters are attached to the surfaces of the X-axis one-dimensional PSD sensor 5 and the Y-axis one-dimensional PSD sensor 6 to filter external light noise. The purpose is to filter out the noise interference caused by stray light and only accept the light spot signal emitted by the laser module wavelength. In one implementation, the spectrum range passed by the narrow-band filter is 808nm ±10nm. At the same time, in order to reduce the impact of electronic noise, the laser module, PSD and amplifier processing circuits all use LDO power chips to reduce the impact of power ripple on the PSD signal. In one implementation, the power ripple is controlled within ±5mv.

[0020] The calibration control board 1 communicates data commands via the RS422 interface.

[0021] This embodiment also provides a method for automatic calibration of a fast reflector angle based on a PSD sensor. The method is performed using the automatic calibration system for a fast reflector angle based on a PSD sensor as described above. The method is specifically as follows: S1, calibration preparation, the fast reflector mirror surface is parallel to the calibration control board 1 and aligned with the central axis, the emission angles of the X-axis laser module 3 and the Y-axis laser module 4 are adjusted so that the parallel light emitted by them is reflected by the fast reflector mirror surface, and the light spot irradiates the center position of the X-axis one-dimensional PSD sensor 5 and the Y-axis one-dimensional PSD sensor 6 respectively, and the calibration preparation work is completed; S2, start calibration, the computer 9 sends calibration instructions to the fast reflector and calibration control board 1, and sends a timing command to the X axis of the fast reflector , , … , , … The AD code value instruction of the eddy current is then sent to the Y axis of the fast reflector at a fixed time , , … , , … AD code value instruction of eddy current; S3, after receiving the control instruction of the computer 9, the fast reflector moves to the specified AD code value position in sequence, and the calibration control board 1 returns the calculated fast reflector angle data to the computer 9 in sequence, and the computer 9 stores the AD code value and the returned corresponding fast reflector angle data information in sequence; S4. Use mathematical tool software to fit or interpolate the data stored in the computer 9, select a nonlinear mathematical model to fit a formula or generate a difference table, and enter the fitting formula or difference table into the fast reflector controller when calculating the actual mirror angle for correction.

[0022] The fast reflector mirror moves to the specified DN code value position according to the instruction sequence, and the fast reflector returns to the specified DN code value position after all Y-axis positions are completed. The zero position DN is maintained. In one implementation, the time for the fast reflector to move to the specified AD code value position is in the millisecond level, and the computer 9 sends it at intervals of 1 second to ensure that after each AD code value is sent, the mirror moves to the right position, and the calibration control board 1 calculates the mirror angle and returns it to the computer 9 for recording.

[0023] The parallel and aligned central axis is specifically as follows: the fast reflector is placed on a fixed platform, the calibration control board 1 is placed on an adjustable two-dimensional platform, after the computer 9 sends a preparation command, the electric mirror surface on the fast reflector is locked and kept stationary at the zero position of the X and Y axes, and at the same time, the central axis alignment laser module 2 placed vertically at the center of the calibration control board 1 is lit, and the placement angles of the two-dimensional platform and the calibration control board 1 are adjusted so that the parallel light emitted by the central axis alignment laser module 2 placed vertically at the center of the calibration control board 1 is vertically irradiated to the center of the mirror surface of the fast reflector, and then returns to the center position of the calibration control board 1. At this time, the mirror surface of the fast reflector is parallel to the calibration control board 1 and the centers are aligned, and the distance L between the two is measured and recorded.

[0024] The adjustment of the emission angle of the X-axis laser module 3 and the Y-axis laser module 4 is specifically as follows: the quick reflector mirror surface is kept at the X and Y-axis zero positions, and the parallel light emitted by the X-axis laser module 3 and the Y-axis laser module 4 is reflected by the quick reflector mirror surface. By adjusting the mounting angle screws of the X-axis laser module 3 and the Y-axis laser module 4 respectively, the return light spot is made to fall on the center position of the corresponding axis PSD sensor. When the light spot position is correct, the X-axis ready indicator light 7 and the Y-axis ready indicator light 8 are automatically lit, indicating that the calibration preparation work of the quick reflector and the calibration control board 1 is completed and calibration can be performed.

[0025] After receiving the control instruction from computer 9, the fast reflector moves to the specified AD code value position in sequence. The difference between the maximum and minimum eddy current code values ​​of the total X-axis travel of the fast reflector is , that is It is the difference between the maximum and minimum AD code values ​​of the left and right limits of the X-axis. The code value of the center position is , each step code value is , N is the number of steps, that is, , , … , , … The position code value is equivalent to , , … , , … , the fast reflector Y axis uses the same calculation method; the larger the N value, the more accurate the calibration, and the longer the calibration time. In an implementation, the X axis There are 1204 code values, N is 100, and the step code value of the X axis is Take 12 code values.

[0026] The specific solution for calculating the fast reflector angle data is: like Figure 3 As shown, when the computer 9 sends the AD code value instruction sequence to the fast reflector X axis at a fixed time, the fast reflector X axis moves to the specified AD code value position in sequence, and at the same time, the light beam emitted by the X axis laser module is reflected by the fast reflector, and the position of the light spot on the PSD photosensitive surface of the X axis also changes in sequence. The calibration control board 1 calculates the distance d between the light spot and the PSD zero center, and then according to the distance L between the fast reflector and the center of the calibration control board 1, the rotation angle of the fast reflector mirror surface can be calculated, and the data sequence of the X axis angle of the fast reflector is returned to the computer 9 in sequence. , , … , , … ,in It is when the light spot is projected to the center position of the X-axis one-dimensional PSD sensor 5, that is, the X-axis center zero-degree position of the fast reflection mirror.

[0027] The solution principle of the calibration control board 1 is: for The angle of rotation of the fast reflector under the command, that is, the angle value of the fast reflector mirror surface corresponding to the zero position of the X-axis , the relationship between the calibration control board 1 and the mirror angle change is: ; This is the principle of using the double angle rotation of the reflector. Angle, the reflected light will rotate Angle, and then use the relationship between the arc length and the radius. When the distance L is much longer than d, d is approximately equal to the arc length. Multiply it by 57.3 to convert the radian value into an angle value to get the rotation angle of the light: ; The length of the spot position d can be calculated by calibrating the photocurrent value generated by the spot collected by the control board 1 on the PSD sensor. The formula is as follows: ; in and is the photocurrent code value of the electrodes at both ends of the X-axis one-dimensional PSD sensor 5, S is half the effective length of the effective photosensitive surface of the PSD device, and the spot position d is the calculated offset position relative to the PSD center zero position. Similarly, it can be solved … , , … and , , … , , … The mirror angle value.

[0028] The data stored in the computer 9 is fitted or interpolated using mathematical tool software, specifically including: The data of the X-axis and Y-axis recorded by the computer 9 are the code value of the given AD and the returned angle value, respectively, which are expressed in a matrix as follows:

[0029] The data stored in the computer 9 is opened by mathematical tool software such as MATLAB and Origin, and a nonlinear mathematical model is selected to fit a formula or calculate a difference. When the actual mirror angle is calculated in the fast reflector controller, the fitting formula or difference table is input for correction.

[0030] In one implementation, the distance L between the calibration control board 1 and the fast reflector is set to 500 mm. The X and Y axis angular travel ranges of the fast reflector are ±1°, and the maximum length of the distance d from the center to one end of the one-dimensional PSD sensor 5, 6 is calculated to be no less than 8.73 mm. A one-dimensional PSD sensor with a total photosensitive surface length of 20 mm is selected.

Claims

1. The fast reflector angle automatic calibration system based on PSD sensor is characterized by: The system comprises a calibration control panel (1) and a computer (9), wherein the calibration control panel (1) comprises a center axis alignment laser module (2), an X-axis laser module (3), a Y-axis laser module (4), an X-axis one-dimensional PSD sensor (5), a Y-axis one-dimensional PSD sensor (6), an X-axis ready indicator light (7) and a Y-axis ready indicator light (8); The center of the X-axis laser module (3), the center of the Y-axis laser module (4), the center of the X-axis one-dimensional PSD sensor (5), and the center of the Y-axis one-dimensional PSD sensor (6) together form a circle with a radius r and the center of the central axis alignment laser module (2). The line connecting the center of the X-axis laser module (3) and the center of the X-axis one-dimensional PSD sensor (5) is parallel to the horizontal plane, and the line connecting the center of the Y-axis laser module (4) and the center of the Y-axis one-dimensional PSD sensor (6) is parallel to the vertical plane.

2. The PSD sensor-based rapid reflector angle automatic calibration system according to claim 1, characterized in that: The surfaces of the X-axis one-dimensional PSD sensor (5) and the Y-axis one-dimensional PSD sensor (6) are attached with narrow-band filters to filter external light noise.

3. A method for automatic calibration of the angle of a fast reflector based on a PSD sensor, characterized in that: The method is performed using the PSD sensor-based rapid reflector angle automatic calibration system as claimed in claim 2, and the method is specifically as follows: S1, calibration preparation, the fast reflector mirror surface is parallel to the calibration control board (1) and aligned with the central axis, the emission angles of the X-axis laser module (3) and the Y-axis laser module (4) are adjusted so that the parallel light emitted by them is reflected by the fast reflector mirror surface, and the light spot illuminates the center position of the X-axis one-dimensional PSD sensor (5) and the Y-axis one-dimensional PSD sensor (6), respectively, and the calibration preparation work is completed; S2, start calibration, the computer (9) sends calibration instructions to the fast reflector and the calibration control board (1), and sends a timing signal to the X axis of the fast reflector , , … , , … The AD code value instruction of the eddy current is then sent to the Y axis of the fast reflector at a fixed time , , … , , … AD code value instruction of eddy current; S3, after receiving the control instruction from the computer (9), the fast reflector moves to the designated AD code value position in sequence, and at the same time, the calibration control board (1) returns the calculated fast reflector angle data to the computer (9) in sequence, and the computer (9) stores the AD code value and the returned corresponding fast reflector angle data information in sequence; S4. Using mathematical tool software to fit or interpolate the data stored in the computer (9), select a nonlinear mathematical model to fit a formula or generate a difference table, and input the fitting formula or difference table into the fast reflector controller to perform correction when calculating the actual mirror angle.

4. The method for automatic calibration of the angle of a fast reflector based on a PSD sensor according to claim 3, characterized in that: The parallel and aligned central axis specifically comprises: placing the fast reflector on a fixed platform, placing the calibration control board (1) on an adjustable two-dimensional platform, and after the computer (9) sends a preparation command, locking the electric mirror surface on the fast reflector to keep the X and Y axes at zero position and not moving, and lighting up the central axis alignment laser module (2) placed vertically at the center of the calibration control board (1), adjusting the placement angle of the two-dimensional platform and the calibration control board (1), so that the parallel light emitted by the central axis alignment laser module (2) placed vertically at the center of the calibration control board (1) is vertically irradiated to the center of the fast reflector mirror surface, and then returns to the center position of the calibration control board (1), at which time the fast reflector mirror surface is parallel to the calibration control board (1) and the centers are aligned, and the distance L between the two is measured and recorded.

5. The method for automatic calibration of the angle of a fast reflector based on a PSD sensor according to claim 4, characterized in that: The adjustment of the emission angle of the X-axis laser module (3) and the Y-axis laser module (4) is specifically as follows: the fast reflector mirror surface is kept at the zero position of the X-axis and the Y-axis, and the parallel light emitted by the X-axis laser module (3) and the Y-axis laser module (4) is reflected by the fast reflector mirror surface. By adjusting the mounting angle screws of the X-axis laser module (3) and the Y-axis laser module (4) respectively, the return light spot falls on the center position of the corresponding axis PSD sensor. When the light spot position is correct, the X-axis ready indicator light (7) and the Y-axis ready indicator light (8) automatically light up, indicating that the calibration preparation work of the fast reflector and the calibration control board (1) is completed and calibration can be performed.

6. The method for automatic calibration of the angle of a fast reflector based on a PSD sensor according to claim 5, characterized in that: After receiving the control command from the computer (9), the fast reflector moves to the specified AD code value position in sequence. The difference between the maximum and minimum eddy current code values ​​of the total X-axis travel of the fast reflector is , The code value of the center position is , each step code value is , N is the number of steps, that is, , , … , , … The position code value is equivalent to , , … , , … , the same calculation method is used for the Y-axis of the fast reflector.

7. The method for automatic calibration of the angle of a fast reflector based on a PSD sensor according to claim 6, characterized in that: The specific solution for calculating the fast reflector angle data is: When the fast reflector mirror moves to the specified AD code value position, the angle value of the fast reflector mirror corresponding to the X-axis zero position is , the calibration control board (1) calculates the mirror angle change relationship as follows: ； in, When the fast reflector mirror moves to the specified AD code value position, the distance between the X-axis one-dimensional PSD sensor (5) light spot and the X-axis one-dimensional PSD sensor (5) zero position, ,in and is the photocurrent code value of the electrodes at both ends of the one-dimensional PSD sensor (5) on the X axis, The same solution method is used to calculate the angle value of the quick reflector mirror surface rotation corresponding to the Y-axis zero position, which is half the effective photosensitive surface length of the X-axis one-dimensional PSD sensor (5).

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