Control method of adjustable pulse waveform solid laser

Abstract

The invention discloses an adjustable pulse waveform solid laser control method, and particularly relates to the technical field of laser control, and the method comprises the steps: building a solid laser state monitoring model through obtaining the output power information, external environment information, optical element aging information and control response information of a solid laser; the actual operation state of the solid-state laser is evaluated, potential faults and hidden dangers existing in the solid-state laser are effectively identified, and when the potential faults and hidden dangers exist in the solid-state laser, various parameters of pulses are dynamically controlled by adopting a fuzzy PID control algorithm in combination with the temperature rise rate of a heat affected area. The frequency of frequent pulse adjustment caused by the unstable operation state of the laser is effectively reduced, meanwhile, the temperature rising rate of a heat affected area is considered when pulse parameters are adjusted, heat energy accumulation is effectively controlled, excessive expansion of the heat affected area is prevented, machining defects caused by heat damage are reduced, and the defective rate is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of laser control, and more specifically, to a control method for a solid-state laser with adjustable pulse waveform. Background Art

[0002] As an important light source, adjustable pulse waveform solid-state lasers are widely used in industrial processing, medical imaging, scientific research, and national defense. Traditional pulsed solid-state lasers usually output pulses with fixed waveforms, which may be limited in some applications. With the development of technology, the demand for flexible regulation of the pulse waveform output by the laser is becoming more and more urgent, which enables adjustable pulse waveform solid-state lasers to adjust the pulse duration, peak power, pulse interval and other parameters according to actual needs in different application scenarios, thereby achieving precise control.

[0003] In the existing adjustable pulse waveform solid laser, the pulse characteristics of the laser output are usually monitored in real time through a feedback loop, and the information is fed back to the control system to dynamically adjust the working state of the laser, so as to achieve precise control of the pulse waveform. Although this post-feedback control method performs well in the control of specific waveforms and does not require more monitoring of the operating state of the solid laser, it only needs to effectively monitor the pulse characteristics of the laser output and continuously adjust the various parameters of the pulse to achieve precise control of the pulse waveform. However, the instability of the operating state of the solid laser in the actual operation process may cause the pulse adjusted each time to not meet expectations, thereby increasing the number of pulse adjustments and causing irreversible effects. Especially in the processing of some composite materials, the continuous adjustment of the various parameters of the pulse will cause the heat energy of the heat-affected zone of the processed material to accumulate continuously, the heat-affected zone continues to expand, and the defective rate caused by thermal damage is increased. (The heat-affected zone refers to the area where the material undergoes microstructural changes due to the action of laser heat energy during laser processing. Although the main target area of ​​laser processing is the direct removal area of ​​the material, due to the heat conduction effect, the laser heat energy will diffuse to the surrounding area that is not directly irradiated, thereby forming a heat-affected zone). Summary of the invention

[0004] In order to overcome the above-mentioned defects of the prior art, an embodiment of the present invention provides a solid-state laser control method with adjustable pulse waveform to solve the problems raised in the above-mentioned background technology.

[0005] To achieve the above object, the present invention provides the following technical solutions: A method for controlling a solid-state laser with adjustable pulse waveform comprises the following steps: Step S1, obtaining output power information, external environment information, optical element aging information and control response information during the operation of the solid-state laser; Step S2, constructing a solid-state laser state monitoring model, evaluating the actual operating state of the solid-state laser, and outputting a solid-state laser state monitoring index according to the solid-state laser state monitoring model; Step S3, comparing the solid-state laser state monitoring index with a preset hidden danger threshold value to generate a fault hidden danger signal or an operation steady-state signal; Step S4, when a fault potential signal is generated, the corresponding solid laser state monitoring index and the temperature rise rate of the heat-affected zone are obtained, and the fuzzy PID control algorithm is used to dynamically control various parameters of the pulse.

[0006] In a preferred embodiment, the output power information includes an output power fluctuation coefficient, the external environment information includes an environmental abnormal interference coefficient, the optical element aging information includes an optical element aging coefficient, and the control response information includes a control response abnormality coefficient.

[0007] In a preferred implementation, the logic for obtaining the output power fluctuation coefficient is as follows: The output power time series of the solid-state laser is obtained by a high-precision photodetector and marked as ,in represents the output power of the solid-state laser at time t, t={1,2,3,...,N}; The output power time series is reconstructed into a high-dimensional phase space as follows: The pseudo nearest neighbor method is used to determine the embedding dimension m, and the average mutual information method is used to determine the time delay. ; According to the determined embedding dimension m and time delay , reconstruct the output power time series into a high-dimensional phase space and obtain the embedding vector ; For each time t, we can get an m-dimensional embedding vector , construct The phase space of points; In the reconstructed phase space, randomly select an initial point , and calculate its nearest neighbor The initial distance , the expression is as follows ; According to the trajectory evolution formula, let the initial point and nearest neighbor Evolving with time in phase space, the initial point The trajectory evolution formula is: , the nearest neighbor The trajectory evolution formula is: , where k represents the preset number of evolution time steps; Calculate the distance after trajectory evolution ; Calculate output power sensitivity , the expression is as follows ; Repeatedly select the initial point and calculate the output power turbulence coefficient , the expression is as follows , where i represents the sequence number of the selected initial point and M is a positive integer.

[0008] In a preferred embodiment, the logic for obtaining the environmental anomaly interference coefficient is as follows: The actual temperature value, actual humidity value and actual vibration value of the solid-state laser during operation are obtained through the temperature sensor, humidity sensor and vibration sensor respectively; Get the reference temperature range of the solid-state laser operation and mark the reference temperature range as ; Marking the actual temperature value beyond the reference temperature range as abnormal temperature; Calculate temperature anomaly deviation value , the expression is as follows , where represents the ath abnormal temperature value, A is a positive integer; Get the reference humidity range for the solid-state laser operation and mark the reference humidity range as ; Marking the actual humidity value beyond the reference humidity range as abnormal humidity; Calculate humidity anomaly deviation value , the expression is as follows , where represents the bth abnormal humidity value, where B is a positive integer; Get the reference vibration range of the solid-state laser and mark it as ; Marking the actual vibration value beyond the reference vibration range as abnormal vibration; Calculate the vibration abnormality deviation value , the expression is as follows , where represents the e-th abnormal vibration value, where E is a positive integer; Normalize the temperature anomaly deviation value, humidity anomaly deviation value, and vibration anomaly deviation value to calculate the environmental anomaly interference coefficient , the expression is as follows , where , , , respectively represent the weight factors of temperature anomaly deviation value, humidity anomaly deviation value, and vibration anomaly deviation value, and , , Both are greater than 0.

[0009] In a preferred embodiment, the logic for obtaining the optical element aging coefficient is as follows: An optical interferometer is used to collect the first interference fringe image of the optical element, the first interference fringe image is converted into a grayscale image, and the grayscale image is convolved using a horizontal gradient convolution kernel and a vertical gradient convolution kernel respectively to obtain a horizontal gradient image and a vertical gradient image; the gradient amplitude of the pixel in the gradient image is calculated , the expression is as follows , where Represents the gradient value of the pixel in the horizontal gradient image, The gradient value of the pixel in the vertical gradient image; Compare the gradient amplitude of the pixel with the gradient amplitude threshold, take the pixel whose gradient amplitude is greater than the gradient amplitude threshold as the stripe edge pixel, splice all the stripe edge pixels and remove the pixel whose gradient amplitude is less than or equal to the gradient amplitude threshold to obtain the first stripe image of the surface of the optical element; Changing the parameter setting of the optical interferometer, and collecting the second interference fringe image of the optical element again, so that the phase difference between the collected second interference fringe image and the first interference fringe image is 90 degrees; Acquire a second fringe image on the surface of the optical element according to the second interference fringe image; Calculate the phase value between the first fringe image and the second fringe image at the fth pixel , the expression is as follows , where represents the gray value of the f-th pixel in the first fringe image, represents the gray value of the f-th pixel in the second fringe image; According to the phase value Calculate the height value of the fth pixel , the expression is as follows , where It represents the wavelength of interference light emitted by the optical interferometer; Calculation of aging factors for optical components , the expression is as follows , where Indicates the height value of the f-th pixel, Represents the initial height value of the f-th pixel, where F is a positive integer.

[0010] In a preferred embodiment, the logic for obtaining the control response abnormality coefficient is as follows: Get the timestamp c1 when the solid-state laser receives the instruction to adjust the pulse waveform and the timestamp c2 when the pulse waveform is actually adjusted, and calculate the control response time c3. The expression is as follows ; Calculate the average control response time , the expression is as follows , where It represents the control response time of the solid-state laser for adjusting the pulse waveform for the qth time, where Q is a positive integer; Calculate the standard deviation of the control response time mean , the expression is as follows ; Calculate the control response anomaly coefficient , the expression is as follows .

[0011] In a preferred embodiment, in step S2, a solid-state laser state monitoring model is constructed to evaluate the actual operating state of the solid-state laser, and a solid-state laser state monitoring index is output according to the solid-state laser state monitoring model, as follows: The output power fluctuation coefficient, environmental abnormal interference coefficient, optical component aging coefficient, and control response abnormal coefficient are normalized, and a solid-state laser state monitoring model is constructed based on the normalized output power fluctuation coefficient, environmental abnormal interference coefficient, optical component aging coefficient, and control response abnormal coefficient to generate a solid-state laser state monitoring index. The model is based on the following formula , where , , , They represent the preset weight factors of the output power fluctuation coefficient, the environmental abnormal interference coefficient, the optical element aging coefficient, and the control response abnormality coefficient, respectively, and , , , Both are greater than 0.

[0012] In a preferred embodiment, step S3 compares the solid-state laser state monitoring index with a preset hidden danger threshold to generate a fault hidden danger signal or an operation steady-state signal, as follows: If the solid-state laser state monitoring index is greater than the hidden danger threshold, a fault hidden danger signal is generated; If the solid-state laser state monitoring index is less than or equal to the hidden danger threshold, an operation steady-state signal is generated.

[0013] In a preferred embodiment, in step S4, when a fault potential signal is generated, the corresponding solid-state laser state monitoring index and the temperature rise rate of the heat-affected zone are obtained, and the fuzzy PID control algorithm is used to dynamically control various parameters of the pulse, as follows: Step S4-1, using the solid laser state monitoring index and the temperature rise rate as input variables, converting the input variables into a membership function, and using various parameters of the pulse as output variables; The output variables include but are not limited to pulse duration, peak power, and pulse frequency; Step S4-2, formulating a set of fuzzy rules; Step S4-3, fuzzifying the obtained data, and calculating the fuzzy set of the output variable according to the fuzzy set of the input variable and the rule base; Step S4-4, mapping the aggregated fuzzy output set back to the actual value to obtain the final PID output, using the PID output as the final value of each pulse parameter, and dynamically controlling each pulse parameter.

[0014] Technical effects and advantages of the present invention: 1. The present invention acquires the output power information, external environment information, optical element aging information and control response information of the solid-state laser, constructs a solid-state laser state monitoring model, evaluates the actual operating state of the solid-state laser, and outputs a solid-state laser state monitoring index. The solid-state laser state monitoring index is compared with the hidden danger threshold, and the potential hidden dangers of the solid-state laser are effectively identified. When the solid-state laser has potential hidden dangers of failure, the temperature rise rate of the heat-affected zone is combined with the temperature rise rate of the heat-affected zone, and the fuzzy PID control algorithm is used to dynamically control various parameters of the pulse, effectively reducing the number of frequent pulse adjustments caused by the unstable operating state of the laser. This pre-preventive control method avoids processing instability caused by frequent adjustment of pulse parameters. At the same time, the temperature rise rate of the heat-affected zone is considered when adjusting the pulse parameters, effectively controlling the accumulation of heat energy, preventing excessive expansion of the heat-affected zone, reducing processing defects caused by thermal damage, and reducing the defective rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to facilitate understanding by those skilled in the art, the present invention is further described below in conjunction with the accompanying drawings; Figure 1 Schematic diagram of the structure of the method of the embodiment of the present invention. DETAILED DESCRIPTION

[0016] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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 scope of protection of the present invention.

[0017] Example: Figure 1 The present invention provides a solid-state laser control method with adjustable pulse waveform, comprising the following steps: Step S1, obtaining output power information, external environment information, optical element aging information and control response information during the operation of the solid-state laser; Step S2, constructing a solid-state laser state monitoring model, evaluating the actual operating state of the solid-state laser, and outputting a solid-state laser state monitoring index according to the solid-state laser state monitoring model; Step S3, comparing the solid-state laser state monitoring index with a preset hidden danger threshold value to generate a fault hidden danger signal or an operation steady-state signal; Step S4, when a fault potential signal is generated, the corresponding solid laser state monitoring index and the temperature rise rate of the heat-affected zone are obtained, and the fuzzy PID control algorithm is used to dynamically control various parameters of the pulse; Due to the instability of the operating state of the solid-state laser during its actual operation, the pulse adjusted each time may not meet expectations, thereby increasing the number of pulse adjustments and causing irreversible effects. Especially in the processing of some composite materials, continuous adjustment of various pulse parameters will lead to continuous accumulation of heat energy in the heat-affected zone of the processed material, which will continue to expand and increase the defective rate caused by thermal damage. Therefore, in step S1, the output power information, external environment information, optical element aging information and control response information of the solid-state laser operation process are obtained; The output power information includes the output power fluctuation coefficient, the external environment information includes the environmental abnormal interference coefficient, the optical element aging information includes the optical element aging coefficient, and the control response information includes the control response abnormality coefficient; The output power fluctuation coefficient, environmental abnormal interference coefficient, optical component aging coefficient, and control response abnormality coefficient are marked as , , , ; The output power fluctuation coefficient is used to measure the instability of the output power of solid-state lasers, reflecting the fluctuation amplitude and frequency of the output power of solid-state lasers. The stability of the output power directly affects the accuracy and consistency of the pulse waveform. If the output power fluctuation coefficient is high, it means that the output power of the laser fluctuates greatly, which may lead to uneven distribution of pulse energy, thereby increasing the number of adjustments to various pulse parameters and affecting the processing quality. By monitoring and obtaining output power information and calculating the output power fluctuation coefficient, the working state of the laser can be adjusted in time to ensure the stability of the output power. The logic for obtaining the output power fluctuation coefficient is as follows: The output power time series of the solid-state laser is obtained by a high-precision photodetector and marked as ,in represents the output power of the solid-state laser at time t, t={1,2,3,...,N}; The output power time series is reconstructed into a high-dimensional phase space as follows: The pseudo nearest neighbor method is used to determine the embedding dimension m, and the average mutual information method is used to determine the time delay. ; The embedding dimension m determines the dimension of the phase space, that is, the dimension of the vector space after the output power time series data is reconstructed. The purpose of obtaining m is to ensure that the phase space can fully capture the dynamic behavior of the output power. False nearest neighbor method (FNN): by calculating the false nearest neighbor ratio under different embedding dimensions, the dimension that makes the false nearest neighbor ratio equal to 0 is selected as the final embedding dimension m. It should be noted that the use of the false nearest neighbor method (FNN) to determine the embedding dimension m is an existing mature technology and will not be described in detail here. Time Delay Determines the time interval between the elements of each vector in the reconstructed phase space, and obtains This is to ensure that the points in the reconstructed phase space are independent and do not introduce too much correlation or repeated information; Average Mutual Information Method (AMI): Calculate the average mutual information under different time delays and select the first local minimum as the final time delay. It should be noted that the average mutual information method (AMI) is used to determine the time delay The existing mature technology will not be described in detail here; According to the determined embedding dimension m and time delay , reconstruct the output power time series into a high-dimensional phase space and obtain the embedding vector ; For each time t, we can get an m-dimensional embedding vector , thus constructing The phase space of points; In the reconstructed phase space, randomly select an initial point , and calculate its nearest neighbor The initial distance , the expression is as follows ; According to the trajectory evolution formula, let the initial point and nearest neighbor Evolving with time in phase space, the initial point The trajectory evolution formula is: , the nearest neighbor The trajectory evolution formula is: , where k represents the preset number of evolution time steps; Calculate the distance after trajectory evolution ; Calculate output power sensitivity , the expression is as follows ; The output power sensitivity value is used to measure the sensitivity of the output power of a solid-state laser to fluctuations and to evaluate the volatility and instability of the output power; Repeatedly select the initial point and calculate the output power turbulence coefficient , the expression is as follows , where i represents the sequence number of the selected initial point, and M is a positive integer; The environmental anomaly interference coefficient is used to measure the degree of interference of external environmental factors on the operating state of the solid-state laser. This coefficient takes into account the potential impact of fluctuations in temperature, humidity, and vibration on the stability of fixed lasers. Changes in environmental factors may cause fluctuations in laser performance, for example, causing a decrease in beam quality or thermal management problems. By monitoring and obtaining external environmental information and calculating the environmental anomaly interference coefficient, the negative impact of the environment on the laser processing process can be prevented or alleviated, and the stability of the pulse waveform can be ensured. The logic for obtaining the environmental anomaly interference coefficient is as follows: The actual temperature value, actual humidity value and actual vibration value of the solid-state laser during operation are obtained through the temperature sensor, humidity sensor and vibration sensor respectively; Get the reference temperature range of the solid-state laser operation and mark the reference temperature range as ; Marking the actual temperature value beyond the reference temperature range as abnormal temperature; Calculate temperature anomaly deviation value , the expression is as follows , where represents the ath abnormal temperature value, A is a positive integer; Get the reference humidity range for the solid-state laser operation and mark the reference humidity range as ; Marking the actual humidity value beyond the reference humidity range as abnormal humidity; Calculate humidity anomaly deviation value , the expression is as follows , where represents the bth abnormal humidity value, where B is a positive integer; Get the reference vibration range of the solid-state laser and mark it as ; Marking the actual vibration value beyond the reference vibration range as abnormal vibration; Calculate the vibration abnormality deviation value , the expression is as follows , where represents the e-th abnormal vibration value, where E is a positive integer; It should be noted that the reference temperature range, reference humidity range, and reference vibration range are obtained according to the design specifications and operating requirements of the solid-state laser, or by referring to the technical manual or industry standards of the solid-state laser, and are not described in detail here; Normalize the temperature anomaly deviation value, humidity anomaly deviation value, and vibration anomaly deviation value to calculate the environmental anomaly interference coefficient , the expression is as follows , where , , , respectively represent the weight factors of temperature anomaly deviation value, humidity anomaly deviation value, and vibration anomaly deviation value, and , , All are greater than 0; It should be noted that , , It is set according to the actual situation. For example, the expert weighting method is adopted, that is, experts in related fields are invited to determine the weights of various indicators through professional opinion surveys and comprehensive evaluations to ensure that the weight coefficients can accurately reflect the importance of various indicators in evaluating the interference of external environmental factors on solid-state lasers. In addition, the use of various methods such as hierarchical analysis method and fuzzy comprehensive evaluation method to determine the weight coefficients can also be considered to ensure the objectivity and scientificity of the weight coefficients. I will not elaborate on this; The optical component aging coefficient is used to measure the aging degree of the optical components inside the solid-state laser. As the use time of optical components (such as lenses and reflectors) increases, their performance will gradually decline, resulting in a decrease in beam quality or energy loss. Aging optical components will affect the quality and consistency of laser output, which will lead to distortion of the pulse waveform. By monitoring and obtaining optical component aging information and calculating the optical component aging coefficient, potential optical problems can be identified in advance; The logic for obtaining the optical component aging coefficient is as follows: An optical interferometer is used to collect the first interference fringe image of the optical element, the first interference fringe image is converted into a grayscale image, and the grayscale image is convolved using a horizontal gradient convolution kernel and a vertical gradient convolution kernel respectively to obtain a horizontal gradient image and a vertical gradient image; the gradient amplitude of the pixel in the gradient image is calculated , the expression is as follows , where Represents the gradient value of the pixel in the horizontal gradient image, The gradient value of the pixel in the vertical gradient image; Compare the gradient amplitude of the pixel with the gradient amplitude threshold, take the pixel whose gradient amplitude is greater than the gradient amplitude threshold as the stripe edge pixel, splice all the stripe edge pixels and remove the pixel whose gradient amplitude is less than or equal to the gradient amplitude threshold to obtain the first stripe image of the surface of the optical element; Changing the parameter setting of the optical interferometer, and collecting the second interference fringe image of the optical element again, so that the phase difference between the collected second interference fringe image and the first interference fringe image is 90 degrees; Acquire a second fringe image on the surface of the optical element according to the second interference fringe image; It should be noted that the method of obtaining the second fringe image on the surface of the optical element according to the second interference fringe image is the same as the method of obtaining the second fringe image on the surface of the optical element according to the first interference fringe image, and will not be described in detail herein; Calculate the phase value between the first fringe image and the second fringe image at the fth pixel , the expression is as follows , where represents the gray value of the f-th pixel in the first fringe image, represents the gray value of the f-th pixel in the second fringe image; According to the phase value Calculate the height value of the fth pixel , the expression is as follows , where It represents the wavelength of interference light emitted by the optical interferometer; Calculation of aging factors for optical components , the expression is as follows , where Indicates the height value of the f-th pixel, Represents the initial height value of the f-th pixel, where F is a positive integer; The control response abnormality coefficient is an indicator used to measure whether there is an abnormality in the response speed of the solid-state laser when adjusting the pulse waveform and the degree of the abnormality. If the response speed of the solid-state laser is slow when adjusting the pulse waveform, the greater the abnormality of the response speed, the pulse waveform output by the solid-state laser may not be adjusted to the expected state in time, resulting in processing errors. By monitoring and obtaining control response information and calculating the control response abnormality coefficient, the performance of the solid-state laser can be optimized to ensure that it can quickly and accurately adjust the pulse waveform and maintain high-quality processing results. The logic for obtaining the control response abnormality coefficient is as follows: Get the timestamp c1 when the solid-state laser receives the instruction to adjust the pulse waveform and the timestamp c2 when the pulse waveform is actually adjusted, and calculate the control response time c3. The expression is as follows ; Calculate the average control response time , the expression is as follows , where It represents the control response time of the solid-state laser for adjusting the pulse waveform for the qth time, where Q is a positive integer; Calculate the standard deviation of the control response time mean , the expression is as follows ; Calculate the control response anomaly coefficient , the expression is as follows ; In step S2, a solid-state laser state monitoring model is constructed to evaluate the actual operating state of the solid-state laser, and a solid-state laser state monitoring index is output according to the solid-state laser state monitoring model, as follows: The output power fluctuation coefficient, environmental abnormal interference coefficient, optical component aging coefficient, and control response abnormal coefficient are normalized, and a solid-state laser state monitoring model is constructed based on the normalized output power fluctuation coefficient, environmental abnormal interference coefficient, optical component aging coefficient, and control response abnormal coefficient to generate a solid-state laser state monitoring index. The model is based on the following formula , where , , , They represent the preset weight factors of the output power fluctuation coefficient, the environmental abnormal interference coefficient, the optical element aging coefficient, and the control response abnormality coefficient, respectively, and , , , All are greater than 0; It should be noted that , , , Set it according to the actual situation. For example, adopt the expert empowerment method, that is, invite experts in related fields to determine the weights of various indicators through professional opinion surveys and comprehensive evaluations. In addition, you can also consider using a variety of methods such as hierarchical analysis method and fuzzy comprehensive evaluation method to determine the weight coefficient to ensure the objectivity and scientificity of the weight coefficient. I will not go into details here; It can be seen from the above calculation expression that the larger the output power fluctuation coefficient, the larger the environmental abnormal interference coefficient, the larger the optical component aging coefficient, and the larger the control response abnormal coefficient, the larger the solid-state laser state monitoring index is, indicating that the probability of the solid-state laser having hidden faults in actual operation is higher; conversely, the smaller the output power fluctuation coefficient, the smaller the environmental abnormal interference coefficient, the smaller the optical component aging coefficient, and the smaller the control response abnormal coefficient, the smaller the solid-state laser state monitoring index is, indicating that the probability of the solid-state laser having hidden faults in actual operation is lower; Step S3, comparing the solid-state laser state monitoring index with a preset hidden danger threshold, generating a fault hidden danger signal or an operation steady-state signal, as follows: If the solid-state laser state monitoring index is greater than the hidden danger threshold, it indicates that the solid-state laser has hidden dangers of failure in actual operation, and a hidden danger signal of failure is generated; If the solid-state laser state monitoring index is less than or equal to the hidden danger threshold, it indicates that no obvious hidden danger of failure is found in the actual operation of the solid-state laser, and an operation steady-state signal is generated; Since the potential faults of solid-state lasers in the actual operation process may lead to the instability of their operating state, and may cause the pulses adjusted each time to not meet expectations, the potential faults of solid-state lasers in the actual operation process are predicted in advance, and the number of pulse adjustments is reduced as much as possible to avoid irreversible effects. In the processing of some composite materials, continuous adjustment of various pulse parameters will lead to continuous accumulation of heat energy in the heat-affected zone of the processed material, and the heat-affected zone will continue to expand, increasing the defective rate caused by thermal damage. Therefore, in step S4, when a potential fault signal is generated, the corresponding solid-state laser state monitoring index and the temperature rise rate of the heat-affected zone are obtained, and the fuzzy PID control algorithm is used to dynamically control various pulse parameters; The calculation expression of temperature rise rate is as follows: , where Indicates the preset unit time Temperature variation of the internal heat affected zone; It should be noted that the preset unit time , can be set according to actual conditions; The heat affected zone refers to the area where the material undergoes microstructural changes due to the laser heat energy during laser processing. Although the main target area of ​​laser processing is the direct material removal area, due to the heat conduction effect, the laser heat energy will diffuse to the surrounding areas that are not directly irradiated, thus forming a heat affected zone; The temperature rise rate is used to measure the accumulation rate of heat energy in the heat-affected zone during laser processing. When the temperature rise rate is too high, the accumulation rate of heat energy in the heat-affected zone will also increase, and the heat-affected zone will gradually expand, thus affecting the processing quality. Therefore, it is necessary to adjust the pulse parameters of the solid-state laser in a timely manner; The fuzzy PID control algorithm is used to dynamically control the various parameters of the pulse, as follows: Step S4-1, taking the solid-state laser state monitoring index and the temperature rise rate as input variables, converting the input variables into membership functions to describe the degree to which they belong to different fuzzy sets. This process uses membership functions to quantify the fuzziness of the input. For example, the solid-state laser state monitoring index and the temperature rise rate can be divided into three fuzzy sets of "low", "medium" and "high", and a membership function is defined for each set. For example, a triangular membership function is selected. The shape of the triangular membership function is similar to a triangle, specifically referring to a function with three linear segments. As the input variable increases in the range from the left support to the peak point, the membership gradually increases, and then gradually decreases in the range from the peak point to the right support. At this time, the membership assignment table of each variable can be obtained, which is a table of membership functions of input variables and output variables; the various parameters of the pulse are used as output variables; The output variables include but are not limited to pulse duration, peak power, and pulse frequency; Step S4-2, formulate a set of fuzzy rules that describe the relationship between input variables and output variables. For example, "if the solid-state laser state monitoring index is high and the temperature rise rate is high, then the pulse duration is low, the peak power is low, and the pulse frequency is high"; When the solid-state laser status monitoring index is high and the temperature rise rate is high, it indicates that the deeper the fault potential of the solid-state laser, the more unstable the operation. The heat energy accumulation rate in the heat-affected zone rises too fast. Reducing the pulse duration can reduce the total heat absorbed by the material, reduce the heat-affected zone, and reduce the risk of processing defects. When the solid-state laser is unstable, maintaining a high peak power may cause overheating and uneven processing. Reducing the peak power helps to reduce heat accumulation and maintain processing accuracy and consistency. Low pulse frequency can reduce the energy input per unit time and prevent the instability of the solid-state laser from further deteriorating the processing quality. Especially in the case of a high temperature rise rate, reducing the pulse frequency can effectively control temperature accumulation. Step S4-3, fuzzy processing is performed on the obtained data. According to the fuzzy set of input variables and the rule base, the fuzzy set of output variables is calculated. The specific solid-state laser state monitoring index and temperature rise rate input values ​​are mapped to the three fuzzy sets of "low", "medium" and "high" to obtain the fuzzy output pulse duration, peak power and pulse frequency. For each rule, for example, "if the solid-state laser state monitoring index is high and the temperature rise rate is high, the pulse duration is low, the peak power is low, and the pulse frequency is high or low", check whether the output fuzzy pulse duration, peak power and pulse frequency meet the conditions of the rule. For the rules that meet the conditions, the membership of the conclusion part is aggregated. The maximum or weighted average method can be used to obtain the aggregated fuzzy output set.

[0018] Step S4-4, mapping the aggregated fuzzy output set back to the actual value, and obtaining the final PID output, as follows: The aggregated fuzzy output set is mapped back to the actual value using common defuzzification methods including centroid method, weighted average method, etc.; In this embodiment, the centroid method is used to map the fuzzy output set back to the actual value, and the specific formula is as follows: Actual value = ; In an alternative example: Assume the fuzzy output of pulse duration is: The pulse duration is low (the membership degree is 0.2, corresponding to an output value of 10 ms); Pulse duration (membership degree is 0.5, corresponding output value is 15 ms); The pulse duration is high (the membership degree is 0.3, corresponding to an output value of 20 ms); The centroid method is used to obtain the actual value of the pulse duration, which is expressed as follows: Pulse duration ; The actual values ​​of the defuzzified parameters are output using the PID algorithm, as follows: Proportional control: Proportional control is based on the actual value of the pulse duration. , Peak power actual value , Actual value of pulse frequency The expected pulse duration , expected peak power , expected pulse frequency To adjust the control output. For example, the output P of the proportional term can be expressed as , where is the scale parameter, Indicates the actual value of the pulse duration, represents the expected pulse duration; Integral control: Integral control is based on the actual value of the pulse duration. , Peak power actual value , Actual value of pulse frequency The expected pulse duration , expected peak power , expected pulse frequency To adjust the control output and reduce the steady-state error, for example, the output of the integral term can be expressed as , where is the integration parameter; Derivative control: Derivative control is based on the actual value of the pulse duration. , Peak power actual value , Actual value of pulse frequency The expected pulse duration , expected peak power , expected pulse frequency To adjust the control output to reduce the overshoot of the control algorithm and improve stability. For example, the output of the derivative term can be expressed as , where is the differential parameter; PID output = P + I + D. Take the PID output as the final value of each pulse parameter to dynamically control each pulse parameter. It should be noted that the above-mentioned proportional parameters, integral parameters and differential parameters can be obtained by a variety of methods, such as empirical method, Ziegler-Nichols tuning method, experimental debugging method and system modeling, etc. According to different application scenarios and system requirements, a suitable method is selected to determine the proportional parameters, integral parameters and differential parameters of the PID controller to ensure that the pulse parameters of the laser are accurately controlled, thereby improving the processing quality and efficiency. The above methods are all existing mature calculation methods and will not be elaborated here; The present invention acquires output power information, external environment information, optical element aging information and control response information of the solid-state laser, constructs a solid-state laser state monitoring model, evaluates the actual operating state of the solid-state laser, outputs a solid-state laser state monitoring index, compares the solid-state laser state monitoring index with a hidden danger threshold, effectively identifies potential hidden dangers of failure of the solid-state laser, and adopts a fuzzy PID control algorithm to dynamically control various parameters of the pulse when there are potential hidden dangers of failure of the solid-state laser in combination with the temperature rise rate of the heat-affected zone, effectively reduces the number of frequent pulse adjustments caused by the unstable operating state of the laser, and this pre-preventive control method avoids processing instability caused by frequent adjustment of pulse parameters. At the same time, the temperature rise rate of the heat-affected zone is considered when adjusting the pulse parameters, effectively controls the accumulation of heat energy, prevents excessive expansion of the heat-affected zone, reduces processing defects caused by thermal damage, and reduces the defective rate.

[0019] The above formulas are all dimensionless and numerical calculations. The formula is a formula for the most recent real situation obtained by collecting a large amount of data and performing software simulation. The preset parameters in the formula are set by technicians in this field according to actual conditions.

[0020] It should be understood that in the various embodiments of the present application, the size of the serial numbers of the above-mentioned processes does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0021] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A method for controlling a solid-state laser with adjustable pulse waveform, characterized in that: The steps include: Step S1, obtaining output power information, external environment information, optical element aging information and control response information during the operation of the solid-state laser; Step S2, constructing a solid-state laser state monitoring model, evaluating the actual operating state of the solid-state laser, and outputting a solid-state laser state monitoring index according to the solid-state laser state monitoring model; Step S3, comparing the solid-state laser state monitoring index with a preset hidden danger threshold value to generate a fault hidden danger signal or an operation steady-state signal; Step S4, when a fault potential signal is generated, the corresponding solid laser state monitoring index and the temperature rise rate of the heat-affected zone are obtained, and the fuzzy PID control algorithm is used to dynamically control various parameters of the pulse.

2. The method for controlling a solid-state laser with adjustable pulse waveform according to claim 1, characterized in that: The output power information includes the output power fluctuation coefficient, the external environment information includes the environmental abnormal interference coefficient, the optical element aging information includes the optical element aging coefficient, and the control response information includes the control response abnormality coefficient.

3. The method for controlling a solid-state laser with adjustable pulse waveform according to claim 2, characterized in that: The logic for obtaining the output power fluctuation coefficient is as follows: The output power time series of the solid-state laser is obtained by a high-precision photodetector and marked as ,in represents the output power of the solid-state laser at time t, t={1,2,3,...,N}; The output power time series is reconstructed into a high-dimensional phase space as follows: The pseudo nearest neighbor method is used to determine the embedding dimension m, and the average mutual information method is used to determine the time delay. ; According to the determined embedding dimension m and time delay , reconstruct the output power time series into a high-dimensional phase space and obtain the embedding vector ; For each time t, we can get an m-dimensional embedding vector , construct The phase space of points; In the reconstructed phase space, randomly select an initial point , and calculate its nearest neighbor The initial distance , the expression is as follows ; According to the trajectory evolution formula, let the initial point and nearest neighbor Evolving over time in phase space, the initial point The trajectory evolution formula is: , the nearest neighbor The trajectory evolution formula is: , where k represents the preset number of evolution time steps; Calculate the distance after trajectory evolution ; Calculate output power sensitivity , the expression is as follows ; Repeatedly select the initial point and calculate the output power turbulence coefficient , the expression is as follows , where i represents the sequence number of the selected initial point and M is a positive integer.

4. The method for controlling a solid-state laser with adjustable pulse waveform according to claim 2, characterized in that: The logic for obtaining the environmental anomaly interference coefficient is as follows: The actual temperature value, actual humidity value and actual vibration value of the solid-state laser during operation are obtained through the temperature sensor, humidity sensor and vibration sensor respectively; Get the reference temperature range of the solid-state laser operation and mark the reference temperature range as ; Marking the actual temperature value beyond the reference temperature range as abnormal temperature; Calculate temperature anomaly deviation value , the expression is as follows , where represents the ath abnormal temperature value, A is a positive integer; Get the reference humidity range for the solid-state laser operation and mark the reference humidity range as ; Marking the actual humidity value beyond the reference humidity range as abnormal humidity; Calculate humidity anomaly deviation value , the expression is as follows , where represents the bth abnormal humidity value, where B is a positive integer; Get the reference vibration range of the solid-state laser and mark it as ; Marking the actual vibration value beyond the reference vibration range as abnormal vibration; Calculate the vibration abnormality deviation value , the expression is as follows , where represents the e-th abnormal vibration value, where E is a positive integer; Normalize the temperature anomaly deviation value, humidity anomaly deviation value, and vibration anomaly deviation value to calculate the environmental anomaly interference coefficient , the expression is as follows , where , , , respectively represent the weight factors of temperature anomaly deviation value, humidity anomaly deviation value, and vibration anomaly deviation value, and , , Both are greater than 0.

5. The method for controlling a solid-state laser with adjustable pulse waveform according to claim 2, characterized in that: The logic for obtaining the optical component aging coefficient is as follows: An optical interferometer is used to collect the first interference fringe image of the optical element, the first interference fringe image is converted into a grayscale image, and the grayscale image is convolved using a horizontal gradient convolution kernel and a vertical gradient convolution kernel respectively to obtain a horizontal gradient image and a vertical gradient image; the gradient amplitude of the pixel in the gradient image is calculated , the expression is as follows , where Represents the gradient value of the pixel in the horizontal gradient image, The gradient value of the pixel in the vertical gradient image; Compare the gradient amplitude of the pixel with the gradient amplitude threshold, take the pixel whose gradient amplitude is greater than the gradient amplitude threshold as the stripe edge pixel, splice all the stripe edge pixels and remove the pixel whose gradient amplitude is less than or equal to the gradient amplitude threshold to obtain the first stripe image of the surface of the optical element; Changing the parameter setting of the optical interferometer, collecting the second interference fringe image of the optical element again, so that the phase difference between the collected second interference fringe image and the first interference fringe image is 90 degrees; Acquire a second fringe image on the surface of the optical element according to the second interference fringe image; Calculate the phase value between the first fringe image and the second fringe image at the fth pixel , the expression is as follows , where represents the gray value of the f-th pixel in the first fringe image, represents the gray value of the f-th pixel in the second fringe image; According to the phase value Calculate the height value of the fth pixel , the expression is as follows , where It represents the wavelength of interference light emitted by the optical interferometer; Calculation of aging factors for optical components , the expression is as follows , where Indicates the height value of the f-th pixel, Represents the initial height value of the f-th pixel, where F is a positive integer.

6. The method for controlling a solid-state laser with adjustable pulse waveform according to claim 2, characterized in that: The logic for obtaining the control response abnormality coefficient is as follows: Get the timestamp c1 when the solid-state laser receives the instruction to adjust the pulse waveform and the timestamp c2 when the pulse waveform is actually adjusted, and calculate the control response time c3. The expression is as follows ; Calculate the average control response time , the expression is as follows , where It represents the control response time of the solid-state laser for adjusting the pulse waveform for the qth time, where Q is a positive integer; Calculate the standard deviation of the control response time mean , the expression is as follows ; Calculate the control response anomaly coefficient , the expression is as follows .

7. The method for controlling a solid-state laser with adjustable pulse waveform according to claim 2, characterized in that: In step S2, a solid-state laser state monitoring model is constructed to evaluate the actual operating state of the solid-state laser, and a solid-state laser state monitoring index is output according to the solid-state laser state monitoring model, as follows: The output power fluctuation coefficient, environmental abnormal interference coefficient, optical component aging coefficient, and control response abnormal coefficient are normalized, and a solid-state laser state monitoring model is constructed based on the normalized output power fluctuation coefficient, environmental abnormal interference coefficient, optical component aging coefficient, and control response abnormal coefficient to generate a solid-state laser state monitoring index. The model is based on the following formula , where , , , They represent the preset weight factors of the output power fluctuation coefficient, the environmental abnormal interference coefficient, the optical element aging coefficient, and the control response abnormality coefficient, respectively, and , , , Both are greater than 0.

8. The method for controlling a solid-state laser with adjustable pulse waveform according to claim 7, characterized in that: Step S3, comparing the solid-state laser state monitoring index with a preset hidden danger threshold, generating a fault hidden danger signal or an operation steady-state signal, as follows: If the solid-state laser state monitoring index is greater than the hidden danger threshold, a fault hidden danger signal is generated; If the solid-state laser state monitoring index is less than or equal to the hidden danger threshold, an operation steady-state signal is generated.

9. The method for controlling a solid-state laser with adjustable pulse waveform according to claim 8, characterized in that: In step S4, when a fault potential signal is generated, the corresponding solid laser state monitoring index and the temperature rise rate of the heat-affected zone are obtained, and the fuzzy PID control algorithm is used to dynamically control various parameters of the pulse, as follows: Step S4-1, using the solid laser state monitoring index and the temperature rise rate as input variables, converting the input variables into a membership function, and using various parameters of the pulse as output variables; The output variables include but are not limited to pulse duration, peak power, and pulse frequency; Step S4-2, formulating a set of fuzzy rules; Step S4-3, fuzzifying the obtained data, and calculating the fuzzy set of the output variable according to the fuzzy set of the input variable and the rule base; Step S4-4, mapping the aggregated fuzzy output set back to the actual value to obtain the final PID output, using the PID output as the final value of each pulse parameter, and dynamically controlling each pulse parameter.

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