A method for controlling an adjustable pulse waveform solid-state laser

Abstract

The application discloses a kind of adjustable pulse waveform solid laser control method, specifically relates to laser control technical field, by obtaining the output power information of solid laser, external environment information, optical element aging information and control response information, construct solid laser state monitoring model, the actual running state of solid laser is evaluated, potential fault hidden danger existing in solid laser is effectively identified, when potential fault hidden danger existing in solid laser is combined with the temperature rising rate of thermal influence area, uses fuzzy PID control algorithm to carry out dynamic control to each parameter of pulse, effectively reduce the frequency of pulse regulation times caused by unstable laser running state, simultaneously consider the temperature rising rate of thermal influence area when adjusting pulse parameter, effectively control heat energy accumulation, prevent excessive expansion of thermal influence area, reduce the processing defects caused by thermal damage, reduce the rate of defective products.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of laser control, more particularly, the present application relates to a kind of adjustable pulse waveform solid laser control method. BACKGROUND

[0002] As an important light source, adjustable pulse waveform solid laser has wide applications in industrial processing, medical imaging, scientific research and national defense, etc. Traditional pulse solid laser usually outputs fixed waveform pulses, which may be limited in some applications. With the development of technology, there is an increasing demand for flexible control of the pulse waveform of the laser output, so that the adjustable pulse waveform solid laser can 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 existing adjustable pulse waveform solid lasers, 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 operating state of the laser, thereby achieving precise control of the pulse waveform. Although this post-feedback control method performs well in the control of specific waveforms and does not need to monitor the operating state of the solid laser more, it only needs to effectively monitor the pulse characteristics of the laser output and continuously adjust the 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 adjusted pulse not to meet the expectations each time, thereby increasing the number of pulse adjustments and causing irreparable damage, especially in the processing of some composite materials. The continuous adjustment of the parameters of the pulse may cause the thermal energy in the heat-affected zone to accumulate continuously, and the heat-affected zone to expand continuously, thereby increasing the rate of defective products caused by thermal damage. (The heat-affected zone refers to the area of the material that undergoes microstructure changes due to the action of laser thermal 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 thermal energy will spread to the surrounding areas not directly irradiated, thereby forming a heat-affected zone). SUMMARY

[0004] In order to overcome the above-mentioned defects of the prior art, embodiments of the present application provide an adjustable pulse waveform solid laser control method to solve the problems raised in the background art.

[0005] To achieve the above-mentioned purpose, the present application provides the following technical solutions:

[0006] An adjustable pulse waveform solid laser control method, comprising the following steps:

[0007] Step S1, obtaining output power information, external environment information, optical component aging information, and control response information during the operation of the solid-state laser;

[0008] 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;

[0009] Step S3, comparing 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;

[0010] 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.

[0011] 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.

[0012] In a preferred embodiment, the logic for obtaining the output power fluctuation coefficient is as follows:

[0013] The output power time series of the solid-state laser is obtained by a high-precision photodetector, and the output power time series is marked as ,in represents the output power of the solid-state laser at time t, t={1,2,3,...,N};

[0014] The output power time series is reconstructed into the high-dimensional phase space as follows:

[0015] 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. ;

[0016] According to the determined embedding dimension m and time delay , reconstruct the output power time series into the high-dimensional phase space and obtain the embedding vector ;

[0017] For each time t, an m-dimensional embedding vector can be obtained , construct The phase space of points;

[0018] In the reconstructed phase space, randomly select an initial point , and calculate its nearest neighbor The initial distance , the expression is as follows ;

[0019] According to the trajectory evolution formula, let the initial point and the nearest neighbor point evolve in the phase space over time, the trajectory evolution formula of the initial point is , and the trajectory evolution formula of the nearest neighbor point is , wherein k represents a preset evolution time step number;

[0020] Calculate the distance after trajectory evolution;

[0021] Calculate the output power sensitivity value , the expression is as follows ;

[0022] Repeat the selection of the initial point, calculate the output power jolt coefficient , the expression is as follows , wherein i represents the order number of the selected initial point, and M is a positive integer.

[0023] In a preferred embodiment, the logic for obtaining the environmental abnormal interference coefficient is as follows:

[0024] Obtain the actual temperature value, the actual humidity value and the actual vibration value of the solid-state laser during operation through the temperature sensor, the humidity sensor and the vibration sensor respectively;

[0025] Obtain the reference temperature range of the solid-state laser during operation, and mark the reference temperature range as ;

[0026] Mark the actual temperature value exceeding the reference temperature range as an abnormal temperature;

[0027] Calculate the temperature abnormal deviation value , the expression is as follows , wherein represents the a-th abnormal temperature value, and A is a positive integer;

[0028] Obtain the reference humidity range of the solid-state laser during operation, and mark the reference humidity range as ;

[0029] Mark the actual humidity value exceeding the reference humidity range as an abnormal humidity;

[0030] Calculate the humidity abnormal deviation value , the expression is as follows , wherein represents the b-th abnormal humidity value, and B is a positive integer;

[0031] Get the reference vibration range of the solid-state laser and mark it as ;

[0032] Marking actual vibration values ​​that exceed the reference vibration range as abnormal vibration;

[0033] Calculate the vibration abnormal deviation value , the expression is as follows , where represents the e-th abnormal vibration value, where E is a positive integer;

[0034] 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.

[0035] In a preferred embodiment, the logic for obtaining the optical element aging coefficient is as follows:

[0036] An optical interferometer is used to collect the first interference fringe image of the optical element, and the first interference fringe image is converted into a grayscale image. The grayscale image is convolved with the horizontal gradient convolution kernel and the vertical gradient convolution kernel respectively to obtain the horizontal gradient image and the 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;

[0037] Comparing the gradient amplitude of the pixel with the gradient amplitude threshold, taking pixels with gradient amplitudes greater than the gradient amplitude threshold as fringe edge pixels, concatenating all fringe edge pixels and removing pixels with gradient amplitudes less than or equal to the gradient amplitude threshold to obtain a first fringe image on the surface of the optical element;

[0038] Changing the parameter settings of the optical interferometer and collecting a 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;

[0039] acquiring a second fringe image on the surface of the optical element according to the second interference fringe image;

[0040] 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;

[0041] According to the phase value Calculate the height value of the f-th pixel , the expression is as follows , where Represents the wavelength of interference light emitted by the optical interferometer;

[0042] Calculating the aging coefficient of 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.

[0043] In a preferred embodiment, the logic for obtaining the control response abnormality coefficient is as follows:

[0044] 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 ;

[0045] Calculate the average control response time , the expression is as follows , where It represents the control response time of the solid-state laser for the qth adjustment of the pulse waveform, where Q is a positive integer;

[0046] Calculate the mean and standard deviation of control response time , the expression is as follows ;

[0047] Calculate the control response anomaly coefficient , the expression is as follows .

[0048] 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:

[0049] The output power fluctuation coefficient, environmental abnormal interference coefficient, optical component aging coefficient, and control response abnormal coefficient are normalized. According to the normalized output power fluctuation coefficient, environmental abnormal interference coefficient, optical component aging coefficient, and control response abnormal coefficient, a solid-state laser state monitoring model is constructed to generate a solid-state laser state monitoring index. The model is based on the following formula , where 、 、 、 They represent the preset weighting factors of output power fluctuation coefficient, environmental abnormal interference coefficient, optical component aging coefficient, and control response abnormality coefficient, respectively, and 、 、 、 Both are greater than 0.

[0050] 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:

[0051] If the solid-state laser state monitoring index is greater than the hidden danger threshold, a fault hidden danger signal is generated;

[0052] 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.

[0053] 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 the various parameters of the pulse, as follows:

[0054] Step S4-1, using the solid-state laser state monitoring index and the temperature rise rate as input variables, converting the input variables into a membership function, and using the various pulse parameters as output variables;

[0055] The output variables include but are not limited to pulse duration, peak power, and pulse frequency;

[0056] Step S4-2, formulate a set of fuzzy rules;

[0057] Step S4-3, fuzzifying the obtained data, and calculating the fuzzy set of the output variable based on the fuzzy set of the input variable and the rule base;

[0058] In step S4-4, the aggregated fuzzy output set is mapped back to the actual value to obtain the final PID output. The PID output is used as the final value of each pulse parameter to dynamically control each pulse parameter.

[0059] Technical effects and advantages of the present application:

[0060] 1、The present application obtains the output power information of the solid-state laser, the external environment information, the optical element aging information and the control response information, constructs a solid-state laser state monitoring model, evaluates the actual running 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 to effectively identify the potential fault hidden danger of the solid-state laser. When the potential fault hidden danger of the solid-state laser exists, the temperature rising rate of the thermal influence area is combined, and a fuzzy PID control algorithm is used to dynamically control various parameters of the pulse, effectively reducing the frequent pulse adjustment times caused by unstable running state of the laser. This preventive control method avoids the instability of processing caused by frequent adjustment of pulse parameters, and considers the temperature rising rate of the thermal influence area when adjusting the pulse parameters, effectively controls the heat accumulation, prevents the excessive expansion of the thermal influence area, reduces the processing defects caused by thermal damage, and reduces the scrap rate. BRIEF DESCRIPTION OF DRAWINGS

[0061] In order to facilitate those skilled in the art to understand, the present application will be further described below in conjunction with the drawings;

[0062] Figure 1 The structure diagram of the embodiment method of the present application is shown. DETAILED DESCRIPTION

[0063] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings of the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0064] Embodiment: Figure 1 A solid-state laser control method with adjustable pulse waveform is given, which includes the following steps:

[0065] Step S1, obtaining the output power information, external environment information, optical element aging information and control response information of the solid-state laser running process;

[0066] Step S2, constructing a solid-state laser state monitoring model, evaluating the actual running state of the solid-state laser, and outputting a solid-state laser state monitoring index according to the solid-state laser state monitoring model;

[0067] Step S3, comparing the solid-state laser state monitoring index with the preset hidden danger threshold to generate a fault hidden danger signal or a running steady signal;

[0068] Step S4, when a fault potential signal is generated, obtaining the corresponding solid-state laser state monitoring index and the temperature rise rate of the heat-affected zone, and dynamically controlling various pulse parameters using a fuzzy PID control algorithm;

[0069] Due to the instability of the operating state of the solid-state laser during actual operation, the pulse adjusted each time may not meet expectations, thereby increasing the number of pulse adjustments and causing irreversible effects. In particular, in the processing of some composite materials, continuous adjustment of various pulse parameters will cause continuous accumulation of heat energy in the heat-affected zone of the processed material, which will continue to expand and increase the defective rate due to thermal damage. Therefore, in step S1, the output power information, external environment information, optical component aging information, and control response information of the solid-state laser operation process are obtained;

[0070] 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;

[0071] The output power fluctuation coefficient, environmental abnormal interference coefficient, optical element aging coefficient, and control response abnormality coefficient are marked as 、 、 、 ;

[0072] The output power fluctuation coefficient is used to measure the instability of the output power of a solid-state laser. It reflects the fluctuation amplitude and frequency of the output power of the solid-state laser. 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 the 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.

[0073] The logic for obtaining the output power fluctuation coefficient is as follows:

[0074] The output power time series of the solid-state laser is obtained by a high-precision photodetector, and the output power time series is marked as ,in represents the output power of the solid-state laser at time t, t={1,2,3,...,N};

[0075] The output power time series is reconstructed into the high-dimensional phase space as follows:

[0076] 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. ;

[0077] The embedding dimension m determines the dimension of the phase space, that is, the dimension of the vector space after reconstructing the output power time series data. Obtaining m ensures that the phase space can fully capture the dynamic behavior of the output power. The false nearest neighbor method (FNN) calculates the false nearest neighbor ratios at different embedding dimensions and selects the dimension that makes the false nearest neighbor ratio equal to 0 as the final embedding dimension m. It should be noted that using 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.

[0078] 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 As it is an existing mature technology, I will not elaborate on it here.

[0079] According to the determined embedding dimension m and time delay , reconstruct the output power time series into the high-dimensional phase space and obtain the embedding vector ;

[0080] For each time t, an m-dimensional embedding vector can be obtained , thus constructing The phase space of points;

[0081] In the reconstructed phase space, randomly select an initial point , and calculate its nearest neighbor The initial distance , the expression is as follows ;

[0082] 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 , nearest neighbor The trajectory evolution formula is , where k represents the preset number of evolution time steps;

[0083] Calculate the distance after trajectory evolution ;

[0084] Calculate output power sensitivity value , the expression is as follows ;

[0085] 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.

[0086] 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;

[0087] 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 a fixed laser. 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.

[0088] The logic for obtaining the environmental anomaly interference coefficient is as follows:

[0089] 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;

[0090] Get the reference temperature range of the solid-state laser operation and mark the reference temperature range as ;

[0091] Marking actual temperature values ​​that exceed the reference temperature range as abnormal temperatures;

[0092] Calculate temperature anomaly deviation value , the expression is as follows , where represents the ath abnormal temperature value, A is a positive integer;

[0093] Get the reference humidity range for solid-state laser operation and mark the reference humidity range as ;

[0094] Marking the actual humidity value beyond the reference humidity range as abnormal humidity;

[0095] Calculate humidity anomaly deviation value , the expression is as follows , where represents the bth abnormal humidity value, where B is a positive integer;

[0096] Get the reference vibration range of the solid-state laser and mark it as ;

[0097] Marking actual vibration values ​​that exceed the reference vibration range as abnormal vibration;

[0098] Calculate the vibration abnormal deviation value , the expression is as follows , where represents the e-th abnormal vibration value, where E is a positive integer;

[0099] It should be noted that the reference temperature range, reference humidity range, and reference vibration range are based on the design specifications and operating requirements of the solid-state laser, or are obtained by referring to the technical manual or industry standards of the solid-state laser, and are not described in detail here.

[0100] 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 greater than 0;

[0101] It should be noted that 、 、 The weights of various indicators can be determined based on actual conditions. For example, the expert weighting method can be used, which involves inviting experts in related fields to conduct professional opinion surveys and comprehensive evaluations to determine the weights of various indicators. This ensures that the weight coefficients accurately reflect the importance of each indicator in evaluating the interference of external environmental factors on solid-state lasers. In addition, various methods such as the hierarchical analysis method and the fuzzy comprehensive evaluation method can also be considered to determine the weight coefficients to ensure their objectivity and scientific nature. This will not be elaborated here.

[0102] The optical component aging coefficient is used to measure the degree of aging 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 reduced beam quality or energy loss. Aging optical components will affect the quality and consistency of the laser output, which in turn will cause 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.

[0103] The logic for obtaining the optical component aging coefficient is as follows:

[0104] An optical interferometer is used to collect the first interference fringe image of the optical element, and the first interference fringe image is converted into a grayscale image. The grayscale image is convolved with the horizontal gradient convolution kernel and the vertical gradient convolution kernel respectively to obtain the horizontal gradient image and the 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;

[0105] Comparing the gradient amplitude of the pixel with the gradient amplitude threshold, taking pixels with gradient amplitudes greater than the gradient amplitude threshold as fringe edge pixels, concatenating all fringe edge pixels and removing pixels with gradient amplitudes less than or equal to the gradient amplitude threshold to obtain a first fringe image on the surface of the optical element;

[0106] Changing the parameter settings of the optical interferometer and collecting a 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;

[0107] acquiring a second fringe image on the surface of the optical element according to the second interference fringe image;

[0108] 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 here.

[0109] 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;

[0110] According to the phase value Calculate the height value of the f-th pixel , the expression is as follows , where Represents the wavelength of interference light emitted by the optical interferometer;

[0111] Calculating the aging coefficient of 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;

[0112] The control response anomaly 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 anomaly coefficient, the performance of the solid-state laser can be optimized to ensure that it can adjust the pulse waveform quickly and accurately to maintain high-quality processing results.

[0113] The logic for obtaining the control response anomaly coefficient is as follows:

[0114] 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 ;

[0115] Calculate the average control response time , the expression is as follows , where It represents the control response time of the solid-state laser for the qth adjustment of the pulse waveform, where Q is a positive integer;

[0116] Calculate the mean and standard deviation of control response time , the expression is as follows ;

[0117] Calculate the control response anomaly coefficient , the expression is as follows ;

[0118] 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:

[0119] The output power fluctuation coefficient, environmental abnormal interference coefficient, optical component aging coefficient, and control response abnormal coefficient are normalized. According to the normalized output power fluctuation coefficient, environmental abnormal interference coefficient, optical component aging coefficient, and control response abnormal coefficient, a solid-state laser state monitoring model is constructed to generate a solid-state laser state monitoring index. The model is based on the following formula , where 、 、 、 They represent the preset weighting factors of output power fluctuation coefficient, environmental abnormal interference coefficient, optical component aging coefficient, and control response abnormality coefficient, respectively, and 、 、 、 All greater than 0;

[0120] It should be noted that 、 、 、 The weights of various indicators can be determined based on the actual situation. For example, the expert weighting method can be used, which involves inviting experts in related fields to conduct professional opinion surveys and comprehensive evaluations to determine the weights of various indicators. In addition, various methods such as the hierarchical analysis method and the fuzzy comprehensive evaluation method can also be considered to determine the weight coefficients to ensure their objectivity and scientificity. This will not be elaborated here.

[0121] 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, 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, indicating that the probability of the solid-state laser having hidden faults in actual operation is lower;

[0122] Step S3, comparing the solid-state laser state monitoring index with a preset hidden danger threshold, and generating a fault hidden danger signal or an operation steady-state signal, as follows:

[0123] 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 is generated;

[0124] 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;

[0125] Since the solid-state laser may have hidden faults during its actual operation, which may lead to instability in its operating state and may cause the pulse adjusted each time to not meet expectations, the hidden faults of the solid-state laser during its actual operation 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 cause continuous accumulation of heat energy in the heat-affected zone of the processed material, which will continue to expand and increase the defective rate due to thermal damage. Therefore, in step S4, when a hidden 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 the various pulse parameters.

[0126] The calculation expression of temperature rise rate is as follows , where Indicates the preset unit time Temperature variation of the internal heat-affected zone;

[0127] It should be noted that the preset unit time , can be set according to actual conditions;

[0128] The heat-affected zone (HAZ) is 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 spread to the surrounding areas that are not directly irradiated, thus forming a heat-affected zone.

[0129] The temperature rise rate is used to measure the rate of heat energy accumulation in the heat-affected zone during laser processing. When the temperature rise rate is too high, the heat energy accumulation rate 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;

[0130] The fuzzy PID control algorithm is used to dynamically control the various parameters of the pulse, as follows:

[0131] Step S4-1, takes the solid laser state monitoring index and temperature rise rate as input variables, and converts 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 laser state monitoring index and 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, a membership assignment table for each variable can be obtained. The membership assignment table is a table of membership functions of input variables and output variables; the various parameters of the pulse are used as output variables;

[0132] The output variables include but are not limited to pulse duration, peak power, and pulse frequency;

[0133] 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 condition 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.”

[0134] When the solid-state laser status monitoring index is high and the temperature rise rate is high, it indicates that the deeper the fault risk of the solid-state laser, the more unstable the operation. The heat energy accumulation rate in the heat-affected zone increases too quickly. 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 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 high temperature rise rate, reducing the pulse frequency can effectively control temperature accumulation.

[0135] 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 laser state monitoring index and temperature rise rate input values ​​are mapped to the three fuzzy sets of "low", "medium" and "high", and the pulse duration, peak power and pulse frequency of the fuzzy output are obtained. For each rule, for example, "If the solid 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.

[0136] Step S4-4 maps the aggregated fuzzy output set back to the actual value to obtain the final PID output, which is as follows:

[0137] The aggregated fuzzy output set is mapped back to the actual value using common defuzzification methods including centroid method, weighted average method, etc.

[0138] In this embodiment, the centroid method is used to map the fuzzy output set back to the actual value. The specific formula is as follows: Actual value = ;

[0139] In an alternative example: Assume the fuzzy output of pulse duration is:

[0140] The pulse duration is low (the membership degree is 0.2, corresponding to an output value of 10 ms);

[0141] Pulse duration (membership degree is 0.5, corresponding output value is 15 ms);

[0142] The pulse duration is high (the membership degree is 0.3, corresponding to an output value of 20 ms);

[0143] The actual value of the pulse duration is obtained by the centroid method, and the expression is as follows: Pulse duration ;

[0144] The actual value of each parameter after deblurring is output by the PID algorithm, as follows:

[0145] Proportional control: the proportional control adjusts the control output according to the actual value of the pulse duration , the actual value of the peak power , the actual value of the pulse frequency and the expected pulse duration , the expected peak power , and the expected pulse frequency . For example, the output P of the proportional term can be represented as , wherein is the proportional parameter, represents the actual value of the pulse duration, represents the expected pulse duration;

[0146] Integral control: the integral control adjusts the control output according to the actual value of the pulse duration , the actual value of the peak power , the actual value of the pulse frequency and the expected pulse duration , the expected peak power , and the expected pulse frequency to reduce the steady-state error. For example, the output of the integral term can be represented as , wherein is the integral parameter;

[0147] Derivative control: the derivative control adjusts the control output according to the actual value of the pulse duration , the actual value of the peak power , the actual value of the pulse frequency and the expected pulse duration , the expected peak power , and the expected pulse frequency to reduce the overshoot of the control algorithm and improve stability. For example, the output of the derivative term can be represented as , wherein is the derivative parameter;

[0148] PID output = P + I + D, the PID output is taken as the final value of each parameter of the pulse, and each parameter of the pulse is dynamically controlled;

[0149] It should be noted that the above-mentioned proportional parameter, integral parameter and differential parameter can be obtained by various methods, such as empirical method, Ziegler-Nichols tuning method, experimental debugging method and system modeling, and for different application scenarios and system requirements, the proportional parameter, integral parameter and differential parameter of the PID controller are selected by a suitable method to ensure that the pulse parameters of the laser are accurately controlled, thereby improving the processing quality and efficiency, and the above methods are all mature calculation methods, and details are not repeated here.

[0150] The application obtains 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 running state of the solid-state laser, and outputs a solid-state laser state monitoring index, compares the solid-state laser state monitoring index with a hidden danger threshold, effectively identifies potential fault hidden dangers of the solid-state laser, adopts a fuzzy PID control algorithm to dynamically control various parameters of the pulse when the potential fault hidden dangers of the solid-state laser exist, effectively reduces the frequency of pulse adjustment caused by unstable running state of the laser, the preventive control method avoids instability of processing caused by frequent adjustment of pulse parameters, and the temperature rising rate of the heat affected zone is considered when the pulse parameters are adjusted, heat energy accumulation is effectively controlled, excessive expansion of the heat affected zone is prevented, processing defects caused by thermal damage are reduced, and the rate of defective products is reduced.

[0151] The above formulas are dimensionless values, and the formulas are obtained by collecting a large amount of data to simulate a formula of the nearest real situation, and the preset parameters in the formula are set by a person skilled in the art according to the actual situation.

[0152] It should be understood that the size of the sequence number of each process described above in various embodiments of the present application does not mean the order of execution, and the execution order of each process should be determined according to its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0153] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto, any person skilled in the art can easily think of changes or replacements within the technical range disclosed in the present application, which should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to 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 component 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 to generate a fault hidden danger signal or an operation steady-state signal; Step S4, when a fault potential signal is generated, obtaining the corresponding solid-state laser state monitoring index and the temperature rise rate of the heat-affected zone, and dynamically controlling various pulse parameters using a fuzzy PID control algorithm; 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 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 the output power time series is 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 the 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 the high-dimensional phase space and obtain the embedding vector ; For each time t, an m-dimensional embedding vector can be obtained , 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 , 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 value , the expression is as follows ; Repeatedly select the initial point and calculate the output power fluctuation coefficient , the expression is as follows , where i represents the sequence number of the selected initial point and M is a positive integer.

2. The method for controlling a solid-state laser with adjustable pulse waveform according to claim 1, wherein: 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 actual temperature values ​​that exceed the reference temperature range as abnormal temperatures; 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 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 actual vibration values ​​that exceed the reference vibration range as abnormal vibration; Calculate the vibration abnormal 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.

3. The method for controlling a solid-state laser with adjustable pulse waveform according to claim 1, wherein: 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, and the first interference fringe image is converted into a grayscale image. The grayscale image is convolved with the horizontal gradient convolution kernel and the vertical gradient convolution kernel respectively to obtain the horizontal gradient image and the 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; Comparing the gradient amplitude of the pixel with the gradient amplitude threshold, taking pixels with gradient amplitudes greater than the gradient amplitude threshold as fringe edge pixels, concatenating all fringe edge pixels and removing pixels with gradient amplitudes less than or equal to the gradient amplitude threshold to obtain a first fringe image on the surface of the optical element; Changing the parameter settings of the optical interferometer and collecting a 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; acquiring 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 f-th pixel , the expression is as follows , where Represents the wavelength of interference light emitted by the optical interferometer; Calculating the aging coefficient of 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.

4. The method for controlling a solid-state laser with adjustable pulse waveform according to claim 1, wherein: The logic for obtaining the control response anomaly 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 mean and standard deviation of control response time , the expression is as follows ; Calculate the control response anomaly coefficient , the expression is as follows .

5. The method for controlling a solid-state laser with adjustable pulse waveform according to claim 1, wherein: 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. According to the normalized output power fluctuation coefficient, environmental abnormal interference coefficient, optical component aging coefficient, and control response abnormal coefficient, a solid-state laser state monitoring model is constructed to generate a solid-state laser state monitoring index. The model is based on the following formula , where is the output power fluctuation coefficient, is the environmental abnormal interference coefficient, is the optical element aging coefficient, To control the response anomaly coefficient, 、 、 、 They represent the preset weighting factors of output power fluctuation coefficient, environmental abnormal interference coefficient, optical component aging coefficient, and control response abnormality coefficient, respectively, and 、 、 、 Both are greater than 0.

6. The method for controlling a solid-state laser with adjustable pulse waveform according to claim 5, wherein: Step S3, comparing the solid-state laser state monitoring index with a preset hidden danger threshold, and 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.

7. The method for controlling a solid-state laser with adjustable pulse waveform according to claim 6, wherein: 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 the various parameters of the pulse, as follows: Step S4-1, using the solid-state laser state monitoring index and the temperature rise rate as input variables, converting the input variables into a membership function, and using the various pulse parameters 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; Step S4-3, fuzzifying the obtained data, and calculating the fuzzy set of the output variable based on the fuzzy set of the input variable and the rule base; In step S4-4, the aggregated fuzzy output set is mapped back to the actual value to obtain the final PID output. The PID output is used as the final value of each pulse parameter to dynamically control each pulse parameter.

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