Laser system parameter measurement system and method, storage medium and electronic device

Abstract

A laser system parameter measurement system and method, storage medium, and electronic device are disclosed. The method includes the following steps: S1, zero-point calibration of the detection system: when the incident light is an ideal flat-top light, the focal point of the beam focused by the lens array is located on the center line of the lens. The centroid coordinates of the focal point output by the detector corresponding to each sub-lens are recorded as (X0, Y0), and used as the reference centroid; S2, the laser system under test emits light, and the centroid coordinates of the focal spot output by the detector corresponding to each sub-lens are recorded as (X0, Y0). i ,Y i S3, which is the actual measured centroid; S4, obtain the wavefront average slope (Gx) within each sub-lens region. i ,Gy i S4: The wavefront reconstruction matrix is ​​determined by the number of sub-lenses and the order of the restored Zernike polynomial, and then the average slope of the wavefront (Gx) is used. i ,Gy i The wavefront can be reconstructed using the Zernike mode method. This invention solves the problem of atmospheric disturbance in the original laser intensity measurement method, and allows for direct measurement at the laser system exit, ensuring the accuracy of beam parameter measurement.

Description

Technical Field

[0001] This invention belongs to the technical field of laser parameter measurement and optical imaging, and particularly relates to laser system parameter measurement systems and methods, storage media and electronic devices. Background Technology

[0002] In recent years, with the rapid development of laser technology, it has been more widely used in industries such as industry, medicine, and national defense. As a result, the requirements for laser beam quality in various industries are also increasing. The prerequisite for improving beam quality is better laser measurement technology. Currently, the main approach is to measure the spatiotemporal distribution of laser intensity in the far field and obtain relevant laser beam parameters accordingly.

[0003] Currently, there are numerous methods and techniques for measuring far-field laser intensity, including photosensitive methods, scanning methods, ablation methods, camera imaging methods, and array detector methods. Among these, the array detector method, as a direct measurement method of the spatiotemporal distribution of laser intensity, is widely used in the field of laser measurement due to its high signal-to-noise ratio and good real-time performance. However, when laser light propagates through the atmosphere, it may be affected by turbulence, molecular absorption, and other factors, making it difficult for the measurement system to accurately obtain the beam parameters at the laser system's exit point. Therefore, finding a method that can significantly reduce or avoid atmospheric influences to improve measurement accuracy and conducting related research is of great significance.

[0004] To address atmospheric disturbances in laser measurement systems, directly measuring beam parameters at the system's exit point can significantly mitigate atmospheric influences. Hartmann-Shack wavefront sensors can measure not only the phase distribution but also the intensity distribution of the light field. The slope structure correlation coefficient and slope normalization coefficient measured by the Hartmann wavefront sensor can be used to measure atmospheric turbulence-related parameters. Furthermore, using an iterative extrapolation method, even when the beam spot after passing through each sub-lens is outside its corresponding sub-lens region, each sub-spot can still find its corresponding sub-lens, thus expanding the dynamic range of the Hartmann-Shack wavefront sensor. However, for the wavefront distribution of large-aperture beams, especially high-power lasers, the Hartmann-Shack wavefront detection method is no longer applicable due to limitations in aperture size and the detection threshold of the detection components. Summary of the Invention

[0005] To address the problem of directly measuring the parameters of large-aperture, high-power laser systems, this invention proposes a laser system parameter measurement system and method, a storage medium, and electronic devices. The specific technical solutions are as follows:

[0006] The laser system parameter measurement system includes a lens array, a detector array, and a processing computer. The output beam of the laser system under test is irradiated onto the detector array after passing through the lens array, forming an actual measurement centroid on each detector unit. The detector array is connected to the processing computer.

[0007] Specifically, the sub-lenses in the lens array are replaceable, and the lens size and duty cycle are variable.

[0008] Specifically, the beam diameter of the laser system under test is set to D, the number of lens units in each row of the lens array is N≥5, the proportion of each sub-lens in its row is D / N, the duty cycle of the lens array is A≥0.6, the sub-lens size is d=(D / N)×A, the number of detector pixels occupied by the focused sub-spot is P≥10, and then the lens focal length f≥22d under the current conditions is calculated according to the formula 2.44(λ / d)×(f / P)≥10; where λ is the beam wavelength.

[0009] Specifically, the duty cycle of the lens array is 0.8.

[0010] The method for measuring the parameters of the laser system described above includes the following steps:

[0011] S1. Zero-point calibration of the detection system ensures that the center of each detector and the optical axis of each sub-lens in the lens array are on the same straight line. That is, when the incident light is an ideal flat-top light, the focal point of the beam focused by the lens array is located on the center line of the lens. Record the focal centroid coordinates of the corresponding detector output of each sub-lens at this time as (X0, Y0) and use it as the reference centroid.

[0012] S2. The laser system under test emits light, and the laser beam is focused onto the detection surface of each detector unit by the lens array. The centroid coordinates of the focal spot output by the corresponding detector of each sub-lens are recorded as (X... i ,Y i ), which is the actual measured centroid;

[0013] S3. The centroid offset is calculated based on the actual measured position of the centroid and the reference centroid position as (ΔX). i ΔY i By combining the focal length f of the sub-lenses in the lens array, the average wavefront slope (Gx) within each sub-lens region is obtained. i ,Gy i );

[0014] S4: The wavefront reconstruction matrix is ​​determined by the number of sub-lenses and the order of the restored Zernike polynomial, and then the average wavefront slope (Gx) within each sub-lens region is calculated. i ,Gy i The wavefront can be reconstructed using the Zernike model method.

[0015] In step S3, the wavefront mean slope (Gx) is calculated. i ,Gy i The specific steps are as follows:

[0016] S31, combined with the lens focal length f according to The average slope of the wavefront within each sub-lens region was calculated.

[0017] S32. The wavefront slope of the sub-aperture in the x and y directions is expressed by the partial derivatives of the Zernike polynomials of each order with respect to x and y.

[0018] Step S4 is as follows:

[0019] S41. Define Si as the normalized area corresponding to the i-th sub-lens, and further denot the wavefront reconstruction relation as follows:

[0020]

[0021]

[0022] S42. The wavefront reconstruction matrix Z is determined by the number of sub-lenses m and the order N of the restored Zernike polynomial. Z is a reconstruction matrix that is only related to the number of sub-lens units and the number of Zernike polynomial terms used in the restored wavefront, and the matrix size is 2m×N.

[0023] S43. The wavefront reconstruction algorithm based on the Zernike mode method is simplified to G = Z·A. The generalized inverse matrix Z is obtained using the singular value decomposition method. + By using the least squares method, and by using A=Z + ·G calculates the coefficient matrix A, and substitutes the coefficient matrix A back into formula (1) to restore the wavefront to be measured;

[0024]

[0025] In the formula: l is the number of patterns; a k Z represents the coefficient of the k-th Zernike polynomial; k Let k be the k-th Zernike polynomial.

[0026] A storage medium storing a computer program, wherein the computer program is configured to execute the above-described method at runtime.

[0027] An electronic device includes a memory and a processor, wherein the memory stores a computer program and the processor is configured to run the computer program to perform the method described above.

[0028] The advantages of this invention are:

[0029] (1) The atmospheric disturbance problem encountered in the original laser intensity measurement method has been solved. This system can directly measure at the laser system exit, ensuring the measurement accuracy of beam parameters.

[0030] (2) This invention solves the problem of measuring beam parameters of large-aperture, high-power laser systems, and is of great significance for measuring beam quality of large-aperture, high-power laser systems.

[0031] (3) The present invention can flexibly change the lens size, lens array duty cycle and other components to realize the detection of laser beams with different apertures. Attached Figure Description

[0032] Figure 1 This is a flowchart of the measurement method of the present invention.

[0033] Figure 2 This is a schematic diagram of the measurement method of the present invention.

[0034] In the picture:

[0035] 1. Laser system under test; 2. Lens array; 3. Detector array; 4. Reference centroid; 5. Actual measured centroid; 6. Processing computer. Detailed Implementation

[0036] like Figure 1 As shown, the laser system parameter measurement system includes a lens array 2, a detector array 3, and a processing computer 6. The output beam of the laser system under test 1 illuminates the detector array 3 after passing through the lens array 2, forming an actual measurement centroid 5 on each detector unit. The detector array 3 is connected to the processing computer 6. The sub-lenses in the lens array 2 are arranged at a set distance, which is not close together. Specifically, the sub-lenses in the lens array 2 are replaceable, and the lens size and duty cycle are variable. For a laser system under test 1 with a beam diameter of D, to ensure measurement accuracy, the number of lens units N in each row of the lens array 2 is ≥ 5, the proportion of each sub-lens in its row is D / N, and the duty cycle of the lens array 2 is A ≥ 0.6. Therefore, the sub-lens size d = (D / N) × A. To ensure the accuracy of centroid detection, the number of detector pixels P occupied by the focused sub-spot is required to be ≥ 10. Then, according to Equation 2.44 (λ / d) × (f / P) ≥ 10, the lens focal length f ≥ 22d under the current conditions is calculated. In the formula, λ = 1.064 μm, which is the wavelength of the light beam. In this scheme, the duty cycle of the lens array 2 is 0.8.

[0037] The wavefront is reconstructed using the Zernike mode method, and the wavefront phase distribution can be represented by Zernike polynomials:

[0038]

[0039] In the formula: l is the number of patterns; a k Z represents the coefficient of the k-th Zernike polynomial; k Let k be the k-th Zernike polynomial.

[0040] The orthogonal set of Zernike polynomials can be constructed through a summation process. This is achieved by creating a single Zernike polynomial and then dividing it by its norm. The terms of the Zernike polynomials can be calculated using formula (2):

[0041]

[0042] in,

[0043]

[0044] Therefore, as long as the wavefront slope within each sub-lens region is obtained based on the centroid offset of each sub-lens, the corresponding wavefront reconstruction matrix is ​​calculated, and the coefficients of each Zernike polynomial are calculated according to the Zernike mode method, the wavefront shape of the beam to be measured can be reconstructed by substituting them into formula (1).

[0045] The method for measuring the parameters of the laser system described above includes the following steps:

[0046] S1. Zero-point calibration of the detection system ensures that the center of each detector is on the same straight line as the optical axis of each sub-lens in lens array 2. That is, when the incident light is an ideal flat-top light, the focal point of the beam focused by lens array 2 is located on the center line of the lens. Record the centroid coordinates of the focal point output by the corresponding detector of each sub-lens at this time as (X0, Y0), and use it as the reference centroid 4. Figure 2 As shown;

[0047] S2. The laser system under test 1 emits light, and the laser beam is focused onto the detection surface of each detector unit by the lens array 2. The centroid coordinates of the focal spot output by the corresponding detector of each sub-lens are recorded as (X... i ,Y i ), where the actual measured centroid is 5, such as Figure 2 As shown, the duty cycle of the lens array 2 used in this invention is 0.8;

[0048] S3. The centroid offset is calculated based on the actual measured position of centroid 5 and the reference centroid 4 position as (ΔX). i ΔY i By combining the focal length f of the sub-lenses in lens array 2, the average wavefront slope (Gx) within each sub-lens region is obtained. i ,Gy i The specific steps are as follows:

[0049] S31, combined with the lens focal length f according to The average slope of the wavefront within each sub-lens region was calculated.

[0050] S32. The wavefront slope of the sub-aperture in the x and y directions is expressed by the partial derivatives of the Zernike polynomials of each order with respect to x and y.

[0051] S4: The wavefront reconstruction matrix is ​​determined by the number of sub-lenses and the order of the restored Zernike polynomial, and then the average wavefront slope (Gx) within each sub-lens region is calculated. i ,Gy i The wavefront can be reconstructed using the Zernike pattern method, specifically:

[0052] S41. Define Si as the normalized area corresponding to the i-th sub-lens, and further denot the wavefront reconstruction relation as follows:

[0053]

[0054]

[0055] S42. The wavefront reconstruction matrix Z is determined by the number of sub-lenses m and the order N of the restored Zernike polynomial. Z is a reconstruction matrix that is only related to the number of sub-lens units and the number of Zernike polynomial terms used in the restored wavefront, and the matrix size is 2m×N.

[0056] S43. The wavefront reconstruction algorithm based on the Zernike mode method is simplified to G = Z·A. The generalized inverse matrix Z is obtained using the singular value decomposition method. + By using the least squares method, and by using A=Z + ·G calculates the coefficient matrix A, and substitutes the coefficient matrix A back into formula (1) to restore the wavefront to be measured;

[0057]

[0058] In the formula: l is the number of patterns; a k Z represents the coefficient of the k-th Zernike polynomial; k Let k be the k-th Zernike polynomial.

[0059] This invention also provides a storage medium storing a computer program, wherein the computer program is configured to execute the steps in any of the above method embodiments when running.

[0060] Specifically, in this embodiment, the storage medium can be configured to store a computer program for performing the following steps:

[0061] S1. Zero-point calibration of the detection system to ensure that the center of each detector and the optical axis of each sub-lens in the lens array 2 are on the same straight line. That is, when the incident light is an ideal flat-top light, the focal point of the beam focused by the lens array 2 is located on the center line of the lens. Record the focal centroid coordinates of the corresponding detector output of each sub-lens at this time as (X0, Y0) and use it as the reference centroid 4.

[0062] S2. The laser system under test 1 emits light, and the laser beam is focused onto the detection surface of each detector unit by the lens array 2. The centroid coordinates of the focal spot output by the corresponding detector of each sub-lens are recorded as (X... i ,Y i ), which is the actual measured centroid 5;

[0063] S3. The centroid offset is calculated based on the actual measured position of centroid 5 and the reference centroid 4 position as (ΔX). i ΔY i By combining the focal length f of the sub-lenses in lens array 2, the average wavefront slope (Gx) within each sub-lens region is obtained. i ,Gy i );

[0064] S4: The wavefront reconstruction matrix is ​​determined by the number of sub-lenses and the order of the restored Zernike polynomial, and then the average wavefront slope (Gx) within each sub-lens region is calculated. i ,Gy i The wavefront can be reconstructed using the Zernike model method.

[0065] Specifically, in this embodiment, the storage medium may include, but is not limited to, USB flash drives, read-only memory (ROM), random access memory (RAM), portable hard drives, magnetic disks, or optical disks, and other media capable of storing computer programs.

[0066] This invention also provides an electronic device, including a memory and a processor, wherein the memory stores a computer program, and the processor is configured to run the computer program to perform the steps in any of the above method embodiments.

[0067] Specifically, the aforementioned electronic device may further include a transmission device and an input / output device, wherein the transmission device is connected to the aforementioned processor, and the input / output device is connected to the aforementioned processor.

[0068] Specifically, in this embodiment, the processor can be configured to perform the following steps via a computer program:

[0069] S1. Zero-point calibration of the detection system to ensure that the center of each detector and the optical axis of each sub-lens in the lens array 2 are on the same straight line. That is, when the incident light is an ideal flat-top light, the focal point of the beam focused by the lens array 2 is located on the center line of the lens. Record the focal centroid coordinates of the corresponding detector output of each sub-lens at this time as (X0, Y0) and use it as the reference centroid 4.

[0070] S2. The laser system under test 1 emits light, and the laser beam is focused onto the detection surface of each detector unit by the lens array 2. The centroid coordinates of the focal spot output by the corresponding detector of each sub-lens are recorded as (X... i ,Y i ), which is the actual measured centroid 5;

[0071] S3. The centroid offset is calculated based on the actual measured position of centroid 5 and the reference centroid 4 position as (ΔX). i ΔY i By combining the focal length f of the sub-lenses in lens array 2, the average wavefront slope (Gx) within each sub-lens region is obtained. i ,Gy i );

[0072] S4: The wavefront reconstruction matrix is ​​determined by the number of sub-lenses and the order of the restored Zernike polynomial, and then the average wavefront slope (Gx) within each sub-lens region is calculated. i ,Gy i The wavefront can be reconstructed using the Zernike model method.

[0073] The above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A laser system parameter measurement system, characterized in that, The system includes a lens array (2), a detector array (3), and a processing computer (6). The beam emitted by the laser system under test (1) passes through the lens array (2) and then shines onto the detector array (3), forming an actual measurement centroid (5) on each detector unit. The detector array (3) is connected to the processing computer (6). The sub-lenses in the lens array (2) are replaceable, and the lens size and duty cycle are variable; The beam diameter of the laser system under test (1) is set to D, the number of lens units in each row of the lens array (2) is N≥5, the proportion of each sub-lens in its row is D / N, the duty cycle of the lens array (2) is A≥0.6, the sub-lens size is d=(D / N)×A, the number of detector pixels occupied by the focused sub-spot is P≥10, and the lens focal length f≥22d under the current conditions is calculated according to the formula 2.44(λ / d)×(f / P)≥10; where λ is the beam wavelength.

2. The laser system parameter measurement system according to claim 1, characterized in that, The duty cycle of the lens array (2) is 0.

8.

3. A method for measuring laser system parameters using the laser system parameter measurement system according to any one of claims 1-2, characterized in that, Includes the following steps: S1. Zero-point calibration of the detection system ensures that the center of each detector and the optical axis of each sub-lens in the lens array (2) are on the same straight line. That is, when the incident light is an ideal flat-top light, the focal point of the beam focused by the lens array (2) is located on the center line of the lens. Record the centroid coordinates of the focal point output by the detector corresponding to each sub-lens as (X0, Y0) and use it as the reference centroid (4). The method to obtain the lens focal length is to set the beam diameter of the laser system (1) to be tested as D, the number of lens units in each row of the lens array (2) as N≥5, the proportion of each sub-lens in the row as D / N, the duty cycle of the lens array (2) as A≥0.6, the sub-lens size as d=(D / N)×A, the number of detector pixels occupied by the focused sub-spot as P≥10, and then calculate the lens focal length f≥22d under the current conditions according to the formula 2.44(λ / d)×(f / P)≥10; where λ is the beam wavelength. S2. The laser system under test (1) emits light, and the laser beam is focused onto the detection surface of each detector unit by the lens array (2). The centroid coordinates of the focal spot output by the corresponding detector of each sub-lens are recorded as (X). i ,Y i ), which is the actual measured centroid (5); S3. The centroid offset is calculated as (ΔX) based on the actual measured position of centroid (5) and the reference centroid (4). i ΔY i ), combined with the focal length f of the sub-lenses in the lens array (2), the wavefront average slope (Gx) in each sub-lens region is obtained. i ,Gy i ); S4: The wavefront reconstruction matrix is ​​determined by the number of sub-lenses and the order of the restored Zernike polynomial, and then the average wavefront slope (Gx) within each sub-lens region is calculated. i ,Gy i The wavefront can be reconstructed using the Zernike pattern method.

4. The method according to claim 3, characterized in that, In step S3, the wavefront mean slope (Gx) is calculated. i ,Gy i The specific steps are as follows: S31, combined with the lens focal length f according to The average slope of the wavefront in each sub-lens region was calculated. ); S32. The wavefront slope of the sub-aperture in the x and y directions is expressed by the partial derivatives of the Zernike polynomials of each order with respect to x and y. , .

5. The method according to claim 4, characterized in that, Step S4 is as follows: S41. Define Si as the normalized area corresponding to the i-th sub-lens, and further denot the wavefront reconstruction relation as follows: ； ； S42. The wavefront reconstruction matrix is ​​determined by the number of sub-lenses m and the order N of the restored Zernike polynomial. , It is a reconstruction matrix that is only related to the number of sub-lens units and the number of Zernike polynomial terms used in the restored wavefront, and the matrix size is 2m×N; S43, The wavefront reconstruction algorithm based on the Zernike pattern method is simplified to... The singular value decomposition method is used to find generalized inverse matrix By using the least squares method, Calculate the coefficient matrix A, and substitute the coefficient matrix A back into formula (1) to restore the wavefront to be measured; (1) In the formula: l is the number of patterns; The coefficients of the k-th Zernike polynomial; Let k be the k-th Zernike polynomial.

6. A storage medium, characterized in that, The storage medium stores a computer program, wherein the computer program is configured to execute the method described in any one of claims 3 to 5 when it is run.

7. An electronic device comprising a memory and a processor, characterized in that, The memory stores a computer program, and the processor is configured to run the computer program to perform the method according to any one of claims 3-5.

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