Beam quality testing device and method for mid-infrared special-shaped structured beams based on Python

Abstract

A Python-based device and method for testing the beam quality of a mid-infrared irregularly shaped beam. The device includes: a CCD intelligent moving system comprising a ball screw transmission guide, stepper motor A, and a CCD camera; an automatic beam intensity attenuation system comprising a hollow rotary table, an attenuator, and a stepper motor B; and a reflective dispersion-free focusing system comprising off-axis parabolic mirrors M1 and M2. A control system is connected to stepper motor A, stepper motor B, and the CCD camera. The method involves attenuating the beam through the attenuator and then reflecting it through the mirrors to obtain reflected light. The CCD camera transmits the irregularly shaped beam spot to the control system, which automatically attenuates the beam according to a set threshold, reducing stray light in the irregularly shaped beam spot. Based on image tracking and capture technology, the beam spot in the irregularly shaped beam is captured, and its beam intensity, spot radius, and divergence angle are calculated, ultimately obtaining the beam quality of M1. 2 This device and method can automate the precise testing of beam quality.

Description

Technical Field

[0001] This invention belongs to the fields of intelligent control technology and mid-infrared beam quality testing technology, specifically relating to a beam quality testing device and method for mid-infrared irregular structure beams based on Python. Background Technology

[0002] With the development of technology, lasers have become an integral part of our lives. From laser cutting to laser communication, from medical surgery to laser printing, laser technology has been widely used in various fields. In laser technology, beam quality is a key parameter that directly affects the performance and application effects of the laser.

[0003] Beam quality is one of the important indicators for measuring laser beam performance, usually expressed in M. 2 Represented by factors. M 2 The factor describes the degree of deviation of the actual laser beam from the ideal Gaussian beam. M 2 The closer the value is to the theoretical value (the minimum theoretical value is 1), the higher the beam quality and the closer it is to an ideal Gaussian beam. A high-quality beam means better focusing performance of the laser beam, enabling it to transmit more energy in a smaller area, which is crucial for many precision machining and demanding applications.

[0004] Laser beam quality is one of the key factors determining laser performance, directly affecting the effectiveness and efficiency of laser applications in various fields. Understanding and improving beam quality is of great significance for optimizing laser systems, improving processing accuracy and efficiency, and ensuring operational safety. With continuous technological advancements, research and optimization of laser beam quality will continue to drive the development and application of laser technology, bringing more innovation and progress to various industries.

[0005] While current beam quality testing devices have many advantages, they also have some significant shortcomings. For example, these devices lack sufficient attenuation capability for laser light, making them prone to damage during high-power laser testing; interference fringes caused by reflection merge with the ring light, affecting measurement accuracy; and their level of intelligence is insufficient, making them unable to automate complex testing tasks. Summary of the Invention

[0006] To address the problems existing in the prior art, this invention provides a beam quality testing device and method for mid-infrared irregular structure beams based on Python. The device is highly intelligent and can automatically and accurately test beam quality. The method is simple to implement and can reliably and accurately evaluate beam quality for different types of beams.

[0007] This invention provides a beam quality testing device for mid-infrared irregular structure beams based on Python, including a control system, a CCD intelligent moving system, an automatic beam intensity attenuation system, and a reflective dispersion-free focusing system;

[0008] The CCD intelligent mobile system includes a ball screw transmission guide, a stepper motor A, and a CCD camera; the ball screw transmission guide includes a lead screw and a slider mounted on the lead screw; the output shaft of the stepper motor A is connected to the lead screw in the ball screw transmission guide to provide driving force for the ball screw transmission guide; the CCD camera is mounted on the slider in the ball screw transmission guide to acquire high-definition image data;

[0009] The automatic beam intensity attenuation system includes a hollow rotary table, an attenuator, and a stepper motor B. The hollow rotary table is used to rotate clockwise or counterclockwise. The attenuator is mounted on the hollow rotary table and distributed opposite to the CCD camera to adjust the laser intensity to suit the measurement requirements. The output shaft of the stepper motor B is connected to the input end of the hollow rotary table to provide driving force for the hollow rotary table to rotate the attenuator clockwise or counterclockwise.

[0010] The reflective dispersion-free focusing system is positioned between the attenuator and the CCD camera. The system includes an off-axis parabolic mirror M1 and an off-axis parabolic mirror M2. The off-axis parabolic mirror M1 is angled relative to the attenuator and is used to receive the light emitted from the attenuator and reflect it. The off-axis parabolic mirror M2 is angled relative to the off-axis parabolic mirror M1 and is used to receive the light emitted from the off-axis parabolic mirror M1 and reflect it to the CCD camera.

[0011] Both the off-axis parabolic reflector M1 and M2 are polished and plated with gold or silver, or coated with a highly reflective dielectric film in the 1800–3000 nm wavelength range, with a reflectivity >97%. The reflectors are off-axis parabolic, reflecting at 90 degrees, with a reflection focal length of 200 mm in the incident direction and a parent focal length of 100 mm. The reflected wavefront distortion is <λ / 4, ensuring distortion-free transmission of irregularly shaped beams and preventing the introduction of astigmatism and chromatic aberration.

[0012] The control system has a Python platform and a built-in communication module. The control system is connected to stepper motor A, stepper motor B and CCD camera respectively. It is used to drive stepper motor A and stepper motor B to perform actions, control the CCD camera to perform actions, receive high-definition image data from the CCD camera, and perform irregular structure beam optimization and beam quality measurement based on the high-definition image data.

[0013] Furthermore, to improve control precision, the ball screw transmission guide is a high-precision ball screw.

[0014] As a preferred embodiment, the attenuator is of the absorption type, with a response wavelength of 1800–3000 nm. Its absorptivity increases clockwise with the tangential direction of the center angle, satisfying α = kθ, where α is the absorptivity, θ is the azimuth angle in polar coordinates, α is between 0 dB and 30 dB, k is the absorption coefficient of the attenuator material for 1800–3000 nm laser light, and the surface wavefront distortion is < λ / 4.

[0015] As a preferred embodiment, the control system is a laptop or desktop computer.

[0016] In this invention, a CCD camera is mounted on a slider in a ball screw transmission guide. Simultaneously, a stepper motor A drives the lead screw of the ball screw transmission guide, automatically controlling the displacement of the CCD camera. An attenuator is mounted on a hollow rotary table, and a stepper motor B drives the rotation of the hollow rotary table, automatically controlling the rotation of the attenuator. A reflective, dispersion-free focusing system composed of two off-axis parabolic mirrors is placed between the CCD camera and the attenuator. Through two consecutive reflections, astigmatism and chromatic aberration in the attenuated laser beam are effectively removed, ensuring that the beam entering the CCD camera is a pure measurement beam, thus effectively ensuring imaging accuracy. A control system simultaneously connects the CCD camera, stepper camera A, and stepper camera B. Based on the analysis of the images captured by the CCD camera, closed-loop control of stepper camera A and stepper camera B can be performed, thereby achieving automatic adjustment of the CCD camera displacement and the rotation angle of the attenuator.

[0017] This device integrates a CCD intelligent movement system and an automatic beam intensity attenuation system, enabling precise beam positioning and intensity adjustment, thus ensuring the reliability of test results. This innovative combination makes beam quality testing more automated and intelligent, applicable to multiple fields such as laser technology and optical communication.

[0018] Specifically, compared with the prior art, the present invention has the following advantages:

[0019] (1) Unlike other devices, this device is based on the Python platform, offering higher intelligence, flexibility, and controllability. Furthermore, the use of Python enables compatibility with AI algorithms, allowing for easy integration of machine learning and deep learning models, thereby achieving intelligent decision-making and automated control. In addition, Python's rich libraries and frameworks provide powerful support for data processing and algorithm development, further enhancing the system's performance and adaptability. This device can not only quickly respond to the needs of different application scenarios but also continuously learn and optimize, improving operational efficiency and intelligence. This flexible architecture allows users to customize according to specific needs, achieving more efficient resource utilization and innovative applications.

[0020] (2) This device features automatic attenuation, a feature not found in other beam quality testing devices. This function monitors and automatically adjusts the beam intensity in real time based on the light intensity displayed in the CCD, ensuring the output beam is within its optimal operating range. Through precise light intensity detection, the device effectively suppresses beam oversaturation, preventing image distortion and inaccurate data caused by excessive light intensity. The introduction of automatic attenuation not only improves the reliability and accuracy of the test but also provides crucial protection for the CCD camera. When the light intensity exceeds a preset threshold, the system automatically reduces the beam intensity, thus preventing damage to the CCD camera. This intelligent protection mechanism ensures long-term stable operation of the equipment and reduces equipment failures and maintenance costs caused by excessive light.

[0021] (3) The system in this device can automatically select the optimal processing strategy according to different spot shapes and characteristics, thereby optimizing the spot of irregularly shaped beams. This intelligent adjustment capability enables the system to maintain high efficiency even when facing complex optical environments and application requirements. This not only improves processing speed and accuracy, but also helps to maintain stable output quality during long-term operation.

[0022] (4) The attenuator in this device is placed at an angle, which helps to eliminate or reduce the influence of stray light and interference fringes. This design can effectively change the propagation path of the light, so that the incident light and the attenuator form a certain deviation angle, thereby reducing unnecessary light reflection and scattering. In this way, the attenuator can effectively absorb and attenuate unwanted stray light when the beam passes through, improving the overall quality of the beam.

[0023] This invention also provides a method for testing the beam quality of mid-infrared irregularly shaped beams based on Python, employing a Python-based beam quality testing device for mid-infrared irregularly shaped beams, comprising the following steps:

[0024] Step 1: In the Python platform, pre-input the motion parameters of stepper motor A and stepper motor B;

[0025] Step Two: A laser beam is output from a laser and fed into an attenuator. The attenuator is used to adjust the laser intensity to suit the measurement requirements. The adjusted laser beam is then emitted to an off-axis parabolic mirror M1, then reflected by M1 to an off-axis parabolic mirror M2, and finally reflected by M2 to a CCD camera. During this process, the astigmatism and chromatic aberration in the beam are reduced through reflections by M1 and M2, resulting in a clean test beam. The CCD camera then captures an image of the annular spot of the test beam and transmits it to the control system. The control system analyzes and processes the annular spot image using a Python platform to obtain the physical quantity information of the test beam. The specific process is as follows:

[0026] S21: Perform data preprocessing and filtering on the ring-shaped light spot image, capture the light spot using image tracking and capture technology, and further determine the center (x) of the ring-shaped light spot. c y c Then, using formulas (1) and (2), the image coordinate system is transformed to the center coordinate system of the light spot to obtain the new coordinates (x′, y′);

[0027] x′=xx c (1);

[0028] y′=yy c (2);

[0029] S22: The intensity distribution along the x-axis and y-axis is obtained by integration or projection; for the intensity I(x′, y′) of the light spot at position (x′, y′), the intensity distribution along the x-axis and y-axis is obtained according to formula (3) and formula (4) respectively;

[0030]

[0031]

[0032] S23: First, process the obtained I x (x′) and I y (y′) is smoothed to reduce noise, and then normalized according to formulas (6) and (5) to obtain the laser intensity data I′ on the x-axis. x Laser intensity data I′ along the (x′) and y axes y (y′), where I' x (x′), I′ y (y′) represents the intensity distribution of the light beam along the x-axis and y-axis;

[0033]

[0034]

[0035] In the formula, I x，min I represents the minimum intensity of the light spot along the x-axis. x，max I represents the maximum intensity of the light spot along the x-axis. y，min I represents the minimum intensity of the y-axis light spot. y，max This represents the maximum intensity of the light spot along the y-axis.

[0036] Step 3: Control system 4 compares the real-time physical quantity information with the set threshold. When the real-time physical quantity information does not reach the set threshold, control system 4 controls stepper motor A1.1 to adjust the attenuation of the incident laser beam by rotating the attenuator 2.2. At the same time, it controls stepper motor B2.3 to adjust the lateral displacement of CCD camera 1.3 to obtain a high-quality ring spot image. This adjustment process is repeated until the real-time physical quantity information reaches or exceeds the set threshold. The ring spot image in the current state is recorded, and step 4 is executed.

[0037] Step 4: Based on the annular spot image in the current state, perform beam quality M on the irregularly shaped final beam. 2 The evaluation and calculation process is as follows:

[0038] S41: Construct an intensity profile of the beam by measuring the intensity distribution at different locations;

[0039] S42: The minimum radius ω0 of the light beam at the focal point was measured experimentally.

[0040] S43: At different propagation positions z, the measurement beam is calculated according to formula (7). Intensity radius ω(z);

[0041]

[0042] Where z R Indicates Rayleigh length;

[0043] S44: Calculate the divergence angle θ according to formula (8);

[0044]

[0045] In the formula, λ represents the wavelength of light;

[0046] S45: Calculate the beam quality M according to formula (9) 2 ;

[0047]

[0048] As a preferred embodiment, in step one, the motion parameters of stepper motor A1.1 include rotational speed, rotational direction, and number of rotations; the motion parameters of stepper motor B2.3 include rotational speed, rotational direction, and number of rotations.

[0049] As a preferred embodiment, in step three, the physical quantity information includes beam intensity and beam radius.

[0050] As a preferred embodiment, in step S21 of step two, data preprocessing includes denoising, normalization, and background subtraction.

[0051] As a preferred option, in step S21 of step two, the filtering process employs Gaussian filtering and mean filtering techniques.

[0052] As a preferred option, in step S21 of step two, the image tracking and capture technique includes the centroid method or the Hough transform.

[0053] This invention is simple to implement. It uses a Python platform to intelligently extract CCD data and calculate beam quality, enabling rapid acquisition and processing of beam data for subsequent accurate analysis. Through data preprocessing and filtering, interference is effectively eliminated, improving the clarity of beam imaging.

[0054] This invention utilizes multivariate M measurement 2 This method enables reliable and accurate evaluation of beam quality for different types of beams. For the ring-shaped beams exhibited by Laguerre-Gaussian beams, M in the x and y directions can be measured. 2 For Hermitian-Gaussian beams, a combination of individual and unified measurements can yield multiple M values. 2 This provides a comprehensive assessment of beam quality, offering a novel method for measuring beam quality. Attached Figure Description

[0055] Figure 1 This is a schematic diagram of the beam quality testing device in this invention;

[0056] Figure 2 This is a flowchart of the beam quality testing method in this invention;

[0057] Figure 3 LG is an embodiment of the present invention. 01 A schematic diagram of the incident light spot and wavelength as presented in the CCD;

[0058] Figure 4 LG is an embodiment of the present invention. 01 M of the beam 2 Schematic diagram of measurement results.

[0059] In the diagram: 1. CCD intelligent moving system, 1.1. Stepper motor A, 1.2. Ball screw transmission guide rail, 1.3. CCD camera; 2. Automatic beam intensity attenuation system, 2.1. Hollow rotary table, 2.2. Attenuator, 2.3. Stepper motor B; 3. Reflective dispersion-free focusing system, 3.1. Off-axis parabolic mirror M1, 3.2. Off-axis parabolic mirror M2; 4. Control system. Detailed Implementation

[0060] like Figure 1 As shown, the present invention provides a beam quality testing device for mid-infrared irregular structure beams based on Python, including a control system 4, a CCD intelligent moving system 1, a beam intensity automatic attenuation system 2, and a reflective dispersion-free focusing system 3.

[0061] The CCD intelligent moving system 1 includes a ball screw transmission guide 1.2, a stepper motor A1.1, and a CCD camera 1.3. The ball screw transmission guide 1.2 includes a lead screw and a slider mounted on the lead screw. The output shaft of the stepper motor A1.1 is connected to the lead screw in the ball screw transmission guide 1.2 to provide driving force for the ball screw transmission guide 1.2. The CCD camera 1.3 is mounted on the slider in the ball screw transmission guide 1.2 to acquire high-definition image data. In this way, by precisely controlling the stepper motor A1.1, the lead screw can drive the slider to move the CCD camera 1.3, thereby realizing the automated control of the movement of the CCD camera 1.3.

[0062] The automatic beam intensity attenuation system 2 includes a hollow rotary stage 2.1, an attenuator 2.2, and a stepper motor B2.3. The hollow rotary stage 2.1 is used for clockwise or counterclockwise rotation. The attenuator 2.2 is mounted on the hollow rotary stage 2.1 and distributed opposite to the CCD camera 1.3 to adjust the laser intensity to suit the measurement requirements. The output shaft of the stepper motor B2.3 is connected to the input end of the hollow rotary stage 2.1 to provide driving force for the hollow rotary stage 2.1 to rotate the attenuator 2.2 clockwise or counterclockwise. The automatic beam intensity attenuation system 2 utilizes the stepper motor B2.3 to drive the hollow rotary stage 2.1 and rotate the attenuator 2.2. This allows for precise control of the stepper motor B2.3, enabling accurate adjustment of the attenuator 2.2's rotation angle. This effectively regulates the intensity of the sensed light, preventing oversaturation and damage to the CCD camera 1.3.

[0063] The reflective dispersion-free focusing system 3 is disposed between the attenuator 2.2 and the CCD camera 1.3. The reflective dispersion-free focusing system 3 includes an off-axis parabolic mirror M13.1 and an off-axis parabolic mirror M23.2. The off-axis parabolic mirror M13.1 is angled to the attenuator 2.2 and is used to receive the light emitted from the attenuator 2.2 and reflect it. The off-axis parabolic mirror M23.2 is angled to the off-axis parabolic mirror M13.1 and is used to receive the light emitted from the off-axis parabolic mirror M13.1 and reflect it to the CCD camera 1.3. The reflective dispersion-free focusing system 3 effectively reduces the astigmatism and chromatic aberration of the light beam through reflection, thereby ensuring that the CCD camera 1.3 can obtain a pure light beam and thus obtain an accurate image.

[0064] As a preferred embodiment, both the off-axis parabolic mirror M13.1 and the off-axis parabolic mirror M23.2 are polished and plated with gold or silver, or coated with a highly reflective dielectric film in the 1800–3000 nm wavelength range, with a reflectivity >97%. The mirrors employ an off-axis parabolic surface, reflect at 90 degrees, have a reflection focal length of 200 mm in the incident direction, a parent focal length of 100 mm, and a wavefront distortion <λ / 4, ensuring distortion-free transmission of irregularly shaped beams and preventing the introduction of astigmatism and chromatic aberration.

[0065] The control system 4 has a Python platform and a built-in communication module. The control system 4 is connected to stepper motor A1.1, stepper motor B2.3 and CCD camera 1.3 respectively. It is used to drive stepper motor A1.1 and stepper motor B2.3 to perform actions, control CCD camera 1.3 to perform actions, receive high-definition image data from CCD camera 1.3, and perform irregular structure beam optimization and beam quality measurement based on high-definition image data.

[0066] As a further optimization, the Python platform is built on the ESP32 development board. The Python platform can capture and seize light spots through image tracking, and can also perform multi-dimensional M-mode analysis on irregularly shaped beams. 2 Evaluation and measurement. Specifically, for Laguerreotype and Hermitian-Gaussian beams, image tracking capture and measurement techniques can adapt to different beam environments and measure M. 2 For the Laguerre Gaussian beam LG m,n The presented ring light was analyzed by selecting different z-positions to obtain multiple sets of beam cross-section diagrams. The beam diameters in the x and y directions were measured, and the M value in the x and y directions was calculated. 2 For Hermitian Gaussian beams HG m，nThe presented irregularly shaped beam was analyzed by selecting different z-positions to obtain multiple beam cross-sectional images. When the beam spot contained two sub-spots, the system tracked and captured the sub-spots, measuring the beam diameter in the x and y directions respectively. Then, the beam diameter of the complete beam spot in the x and y directions was measured, and a total of 6 M-values ​​in the x and y directions were calculated. 2 When the light spot contains 4 sub-spots, the system tracks and captures the sub-spots, measures the beam diameter in the x and y directions respectively, and then measures the beam diameter of the complete light spot in the x and y directions, calculating a total of 10 M in the x and y directions. 2 There are n sub-spots, corresponding to 2(n+1) M... 2 .

[0067] More preferably, the ESP32 development board is equipped with a USB interface, a power driver, a relay, and a power supply.

[0068] To improve control precision, the ball screw transmission guide 1.2 is a high-precision ball screw.

[0069] As a preferred embodiment, the attenuator 2.2 is of the absorption type, with a response wavelength of 1800-3000nm. Its absorptivity increases clockwise with the center angle tangential direction, satisfying a = kθ, where α is the absorptivity, θ is the azimuth angle in polar coordinates, α takes a value between 0dB and 30dB, k is the absorption coefficient of the attenuator material for 1800-3000nm laser, and the surface wavefront distortion is < λ / 4.

[0070] As a preferred embodiment, the control system 4 is a laptop or desktop computer, which serves as the core control and processing component. It can optimize irregularly shaped beams and perform tasks such as measuring beam quality.

[0071] In this invention, a CCD camera is mounted on a slider in a ball screw transmission guide. Simultaneously, a stepper motor A drives the lead screw of the ball screw transmission guide, automatically controlling the displacement of the CCD camera. An attenuator is mounted on a hollow rotary table, and a stepper motor B drives the rotation of the hollow rotary table, automatically controlling the rotation of the attenuator. A reflective, dispersion-free focusing system composed of two off-axis parabolic mirrors is placed between the CCD camera and the attenuator. Through two consecutive reflections, astigmatism and chromatic aberration in the attenuated laser beam are effectively removed, ensuring that the beam entering the CCD camera is a pure measurement beam, thus effectively ensuring imaging accuracy. A control system simultaneously connects the CCD camera, stepper camera A, and stepper camera B. Based on the analysis of the images captured by the CCD camera, closed-loop control of stepper camera A and stepper camera B can be performed, thereby achieving automatic adjustment of the CCD camera displacement and the rotation angle of the attenuator.

[0072] This device integrates a CCD intelligent movement system and an automatic beam intensity attenuation system, enabling precise beam positioning and intensity adjustment, thus ensuring the reliability of test results. This innovative combination makes beam quality testing more automated and intelligent, applicable to multiple fields such as laser technology and optical communication.

[0073] like Figure 2 As shown, this invention also provides a method for testing the beam quality of mid-infrared irregularly shaped beams based on Python, employing a Python-based device for testing the beam quality of mid-infrared irregularly shaped beams, including the following steps:

[0074] Step 1: In the Python platform, pre-input the motion parameters of stepper motor A1.1 and stepper motor B2.3; preferably, the motion parameters of stepper motor A1.1 include rotation speed, rotation direction, and number of rotations; the motion parameters of stepper motor B2.3 include rotation speed, rotation direction, and number of rotations.

[0075] Step 2: A laser beam is output from a laser and fed into attenuator 2.2. Attenuator 2.2 is used to adjust the intensity of the laser to suit the measurement requirements. The adjusted laser beam is then emitted to off-axis parabolic mirror M13.1, and then reflected by off-axis parabolic mirror M13.1 to off-axis parabolic mirror M23.2, and then reflected by off-axis parabolic mirror M23.2 to CCD camera 1.3. During this process, the astigmatism and chromatic aberration in the beam are reduced through the reflection process of off-axis parabolic mirrors M13.1 and M23.2, resulting in a pure test beam. The CCD camera 1.3 is used to acquire the annular spot image of the test beam and transmit it to the control system 4.

[0076] Control system 4 analyzes and processes the annular light spot image based on the Python platform to obtain the physical quantity information of the test beam. The specific process is as follows:

[0077] S21: Perform data preprocessing and filtering on the ring-shaped light spot image, capture the light spot using image tracking and capture technology, and further determine the center (x) of the ring-shaped light spot. c y c Then, using formulas (1) and (2), the image coordinate system is transformed to the center coordinate system of the light spot to obtain new coordinates (x′, y′). Preferably, data preprocessing includes denoising, normalization, and background subtraction. Preferably, filtering uses Gaussian filtering and mean filtering. Preferably, image tracking and capture techniques include centroid method (calculating the centroid of light intensity) or Hough transform (detecting circular features).

[0078] x′=xxc (1);

[0079] y′=yy c (2);

[0080] S22: The intensity distribution along the x-axis and y-axis is obtained by integration or projection; for the intensity I(x′, y′) of the light spot at position (x′, y′), the intensity distribution along the x-axis and y-axis is obtained according to formula (3) and formula (4) respectively;

[0081]

[0082]

[0083] S23: First, process the obtained I x (x′) and I y (y′) is smoothed to reduce noise; common methods include moving average and low-pass filtering. Then, it is normalized according to formulas (4) and (5) respectively for subsequent processing and analysis to obtain the laser intensity data I′ on the x-axis. x Laser intensity data I′ along the (x′) and y axes y (y′), where I' x (x′), I′ y (y′) represents the intensity distribution of the light beam along the x-axis and y-axis, which can be represented by a one-dimensional array;

[0084]

[0085]

[0086] In the formula, I x，min I represents the minimum intensity of the light spot along the x-axis. x，max I represents the maximum intensity of the light spot along the x-axis. y，min I represents the minimum intensity of the y-axis light spot. y，max This represents the maximum intensity of the light spot along the y-axis.

[0087] Step 3: Control system 4 compares the real-time physical quantity information with the set threshold. When the real-time physical quantity information does not reach the set threshold, control system 4 controls stepper motor A1.1 to adjust the attenuation of the incident laser beam by rotating the attenuator 2.2. At the same time, it controls stepper motor B2.3 to adjust the lateral displacement of CCD camera 1.3 to obtain a high-quality ring spot image. This adjustment process is repeated until the real-time physical quantity information reaches or exceeds the set threshold. The ring spot image in the current state is recorded, and step 4 is executed.

[0088] Preferably, the physical quantity information includes beam intensity and beam radius. More preferably, beam intensity is used as the primary comparison reference parameter, wherein the set threshold is also a set beam intensity threshold.

[0089] Step 4: Based on the annular spot image in the current state, perform beam quality M on the irregularly shaped final beam. 2 The evaluation and calculation process is as follows:

[0090] S41: The transverse intensity distribution of the laser beam is approximately Gaussian in shape, and the intensity profile of the beam can be constructed by measuring the intensity distribution at different locations;

[0091] S42: The minimum radius ω0 of the light beam at the focal point (or near the focal point) is measured experimentally. ω0 is usually the minimum diameter or the narrowest part of the light spot. If it cannot be obtained directly by experimental measurement, it can be estimated based on the beam size and propagation properties at other locations.

[0092] S43: At different propagation positions z (a certain distance from the focal point), the measurement beam is calculated according to formula (7). Intensity radius ω(z); this data reflects the expansion of the beam spot as the propagation distance increases.

[0093]

[0094] Where z R Indicates Rayleigh length;

[0095] S44: Calculate the divergence angle θ according to formula (8);

[0096]

[0097] In the formula, λ represents the wavelength of light;

[0098] S45:M 2 This indicates the degree of deviation of the beam from an ideal Gaussian beam. In an ideal case, the M of the fundamental mode Gaussian beam... 2 The value equals 1, while for other types of beams, the beam quality is greater than 1, such as the ring-shaped Laguerre Gaussian beam LG. p，1 M 2 The theoretical value is 2p + l + 1. Hermitian Gaussian beam HG m，n M 2 The theoretical value is m+n+1. In practice, due to astigmatism and wavefront phase distortion, its M... 2 It will be greater than the theoretical value. Specifically, the beam quality M is calculated according to formula (9). 2 ;

[0099]

[0100] M of the laser beam 2 The closer the beam is to the theoretical value, the smaller the divergence angle, the better the beam quality, and the stronger the focusing performance. As an optimal choice, the calculated beam quality M can be used as a reference. 2 Draw the beam image.

[0101] The present invention will be further described below with reference to specific embodiments:

[0102] Example 1:

[0103] 1. Experimental environment:

[0104] The experiment was conducted in a laboratory with a temperature controlled at 20±1℃ and a relative humidity of 40%-50% to ensure the stability of the optical components.

[0105] 2. Equipment Composition:

[0106] (1) Laser: LG with an output wavelength of 1960nm beam.

[0107] (2) CCD intelligent moving system: A high-precision stepper motor A drives the ball screw to transmit the guide rail to realize the movement of the CCD camera, and its movement accuracy can reach 0.1mm.

[0108] (3) Automatic beam intensity attenuation system: Adjustable optical attenuator, which automatically adjusts the beam intensity, using attenuator OD0-1 with a radius of 25mm.

[0109] (4) Reflective non-dispersion focusing system: a high-reflectivity gold-plated parabolic mirror is used, with a reflective focal length of 200mm.

[0110] (5) Control system: Real-time monitoring of beam parameters and output of beam quality indicators.

[0111] 3. Experimental steps:

[0112] (1) Mount the laser on the experimental platform, ensuring its optical axis is aligned with the test area. Install the slider of the CCD camera ball screw transmission rail, ensuring it can capture the light spot in the beam path, and connect the control system for data acquisition. Set the automatic beam intensity attenuation system and the reflective dispersion-free focusing system between the laser and the CCD camera.

[0113] (2) Set the laser power to 10mW and wait for the beam to stabilize. After the beam is attenuated by the attenuator, it is reflected by the mirror to reduce the astigmatism and chromatic aberration of the beam, resulting in reflected light in the 1800-3000nm wavelength range. Move the CCD camera position using the Python platform. The CCD camera transmits the irregularly shaped beam spot to the control system (laptop or desktop computer). The control system automatically attenuates the beam according to the set threshold, reducing stray light in the irregularly shaped beam spot and controlling the beam at 0.6mW.

[0114] (3) The Python platform, based on image tracking and capture technology, captures the light spot in the irregularly shaped beam, calculates its beam intensity, spot radius, and divergence angle, and performs multiple measurements. 2 The results show M x 2 =2.6, M y 2 =2.4 indicates that the beam quality is good, close to the theoretical value of 2, such as Figure 3 and Figure 4 As shown.

[0115] This invention is simple to implement. It uses a Python platform to intelligently extract CCD data and calculate beam quality, enabling rapid acquisition and processing of beam data for subsequent accurate analysis. Through data preprocessing and filtering, interference is effectively eliminated, improving the clarity of beam imaging.

[0116] This invention utilizes multivariate M measurement 2 This method enables reliable and accurate evaluation of beam quality for different types of beams. For the ring-shaped beams exhibited by Laguerre-Gaussian beams, M in the x and y directions can be measured. 2 For Hermitian-Gaussian beams, a combination of individual and unified measurements can yield multiple M values. 2 This provides a comprehensive assessment of beam quality, offering a novel method for measuring beam quality.

Claims

1. A method for testing the beam quality of a mid-infrared irregular structure beam based on Python, wherein a beam quality testing device for a mid-infrared irregular structure beam based on Python is used, the beam quality testing device for a mid-infrared irregular structure beam based on Python includes a control system (4), a CCD intelligent moving system (1), an automatic beam intensity attenuation system (2), and a reflective non-dispersion focusing system (3). The CCD intelligent mobile system (1) includes a ball screw transmission guide rail (1.2), a stepper motor A (1.1), and a CCD camera (1.3); the ball screw transmission guide rail (1.2) includes a lead screw and a slider mounted on the lead screw; the output shaft of the stepper motor A (1.1) is connected to the lead screw in the ball screw transmission guide rail (1.2) to provide driving force for the ball screw transmission guide rail (1.2); the CCD camera (1.3) is mounted on the slider in the ball screw transmission guide rail (1.2) to acquire high-definition image data; The automatic beam intensity attenuation system (2) includes a hollow rotary stage (2.1), an attenuator (2.2), and a stepper motor B (2.3). The hollow rotary stage (2.1) is used to perform clockwise or counterclockwise rotation. The attenuator (2.2) is mounted on the hollow rotary stage (2.1) and distributed opposite to the CCD camera (1.3) to adjust the intensity of the laser to suit the measurement requirements. The output shaft of the stepper motor B (2.3) is connected to the input end of the hollow rotary stage (2.1) to provide driving force to the hollow rotary stage (2.1) to drive the attenuator (2.2) to perform clockwise or counterclockwise rotation. The reflective dispersion-free focusing system (3) is disposed between the attenuator (2.2) and the CCD camera (1.3). The reflective dispersion-free focusing system (3) includes an off-axis parabolic mirror M1 (3.1) and an off-axis parabolic mirror M2 (3.2). The off-axis parabolic mirror M1 (3.1) is angled to the attenuator (2.2) and is used to receive the light emitted from the attenuator (2.2) and reflect it out. The off-axis parabolic mirror M2 (3.2) is angled to the off-axis parabolic mirror M1 (3.1) and is used to receive the light emitted from the off-axis parabolic mirror M1 (3.1) and reflect it to the CCD camera (1.3). Both the off-axis parabolic reflector M1 (3.1) and the off-axis parabolic reflector M2 (3.2) are polished and plated with gold or silver, or coated with a highly reflective dielectric film in the 1800-3000nm wavelength band, with a reflectivity >97%. The reflector adopts an off-axis parabolic surface, reflects at 90 degrees, has a reflection focal length of 200mm in the incident direction, a parent focal length of 100mm, and a reflection wavefront distortion <λ / 4, ensuring distortion-free transmission of irregular beams and preventing the introduction of accessory astigmatism and chromatic aberration. The control system (4) has a Python platform and a built-in communication module. The control system (4) is connected to stepper motor A (1.1), stepper motor B (2.3) and CCD camera (1.3) respectively. It is used to drive stepper motor A (1.1) and stepper motor B (2.3) to perform actions, to control CCD camera (1.3) to perform actions, to receive high-definition image data from CCD camera (1.3), and to optimize irregular structure beams and measure beam quality based on high-definition image data. Its features are, Includes the following steps: Step 1: In the Python platform, pre-input the motion parameters of stepper motor A (1.1) and stepper motor B (2.3); Step 2: A laser beam is output from a laser and fed into an attenuator (2.2). The attenuator (2.2) is used to adjust the intensity of the laser to suit the measurement requirements. The adjusted laser beam is then emitted to an off-axis parabolic mirror M1 (3.1), and then reflected by the off-axis parabolic mirror M1 (3.1) to an off-axis parabolic mirror M2 (3.2), and then reflected by the off-axis parabolic mirror M2 (3.2) to a CCD camera (1.3). In this process, the astigmatism and chromatic aberration in the beam are reduced through the reflection process of the off-axis parabolic mirrors M1 (3.1) and M2 (3.2), resulting in a pure test beam. The CCD camera (1.3) is used to acquire the annular spot image of the test beam and transmit it to the control system (4). The control system (4) analyzes and processes the annular spot image based on the Python platform to obtain the physical quantity information of the test beam. The specific process is as follows: S21: Perform data preprocessing and filtering on the ring-shaped light spot image, capture the light spot using image tracking and capture technology, and further determine the center (x) of the ring-shaped light spot. c ,y c Then, using formulas (1) and (2), the image coordinate system is transformed to the center coordinate system of the light spot to obtain the new coordinates (x', y'). x'=x-x c (1); y'=yy c (2); S22: The intensity distribution along the x-axis and y-axis is obtained by integration or projection; for the intensity I(x',y') of the light spot at position (x',y'), the intensity distribution along the x-axis and y-axis is obtained according to formula (3) and formula (4) respectively; S23: First, process the obtained I x (x') and I y (y') is smoothed to reduce noise, and then normalized according to formulas (4) and (5) to obtain the laser intensity data I on the x-axis. ’ x Laser intensity data I' along the (x') and y axes y (y'), where I ’ x (x'), I' y (y') represents the intensity distribution of the light beam along the x-axis and y-axis; In the formula, I x,min I represents the minimum intensity of the light spot along the x-axis. x,max I represents the maximum intensity of the light spot along the x-axis. y,min I represents the minimum intensity of the y-axis light spot. y,max This represents the maximum intensity of the light spot along the y-axis. Step 3: The control system (4) compares the real-time physical quantity information with the set threshold. When the real-time physical quantity information does not reach the set threshold, the control system (4) controls the stepper motor A (1.1) to adjust the attenuation of the incident laser beam by rotating the attenuator (2.2). At the same time, the control system controls the stepper motor B (2.3) to adjust the displacement of the CCD camera (1.3) in the lateral direction to obtain a high-quality ring spot image. This adjustment process is repeated until the real-time physical quantity information reaches or exceeds the set threshold. The ring spot image in the current state is recorded, and step 4 is executed. Step 4: Based on the annular spot image in the current state, perform beam quality M on the irregularly shaped final beam. 2 The evaluation and calculation process is as follows: S41: Construct an intensity profile of the beam by measuring the intensity distribution at different locations; S42: The minimum radius ω0 of the light beam at the focal point was measured experimentally. S43: At different propagation positions z, the measurement beam is calculated according to formula (7). Intensity radius ω(z); Where z R Indicates Rayleigh length; S44: Calculate the divergence angle θ according to formula (8); In the formula, λ represents the wavelength of light; S45: Calculate the beam quality M according to formula (9) 2 ; 2. The method for testing the beam quality of a mid-infrared irregularly shaped beam based on Python, as described in claim 1, is characterized in that... In step one, the motion parameters of stepper motor A (1.1) include rotation speed, rotation direction and number of rotations; the motion parameters of stepper motor B (2.3) include rotation speed, rotation direction and number of rotations.

3. The method for testing the beam quality of a mid-infrared irregularly shaped beam based on Python, as described in claim 2, is characterized in that... In step three, the physical quantity information includes beam intensity and beam radius.

4. The method for testing the beam quality of a mid-infrared irregularly shaped beam based on Python, as described in claim 3, is characterized in that... In step S21 of step two, data preprocessing includes noise reduction, normalization, and background subtraction.

5. The beam quality testing device for mid-infrared irregularly shaped beams based on Python according to claim 4, characterized in that, In step S21 of step two, the filtering process employs Gaussian filtering and mean filtering techniques.

6. The method for testing the beam quality of a mid-infrared irregularly shaped beam based on Python according to claim 5, characterized in that, In step S21 of step two, the image tracking and capture techniques include the centroid method or the Hough transform.

7. The beam quality testing device for mid-infrared irregularly shaped beams based on Python according to claim 1, characterized in that, The ball screw transmission guide (1.2) is a high-precision ball screw.

8. The method for testing the beam quality of a mid-infrared irregularly shaped beam based on Python, as described in claim 1, is characterized in that... The attenuator (2.2) is an absorption type with a response wavelength of 1800-3000nm. Its absorptivity increases clockwise with the center angle tangential direction, satisfying α = kθ, where α is the absorptivity, θ is the azimuth angle in polar coordinates, α is between 0dB and 30dB, k is the absorption coefficient of the attenuator material for 1800-3000nm laser, and the surface wavefront distortion is < λ / 4.

9. The method for testing the beam quality of a mid-infrared irregularly shaped beam based on Python, as described in claim 1, is characterized in that... The control system (4) is a laptop or desktop computer.

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