Radio frequency carbon dioxide laser fast switching control method based on acousto-optic modulation

Abstract

The application discloses a kind of based on the fast switch control method of radio frequency carbon dioxide laser of acoustooptic modulation, it is applied to radio frequency carbon dioxide laser, comprising: initialization system monitoring and parameter configuration;Load driving signal generation effective light;Including using control module to apply driving signal to acoustooptic modulator, excitation ultrasonic wave is formed phase grating in acoustooptic modulator;Make laser resonant cavity output laser beam with Bragg angle incidence phase grating, form deflected effective light;Output laser and feedback optimization;Including: output laser and monitor the output laser characteristic parameter, in monitoring current output laser characteristic parameter is lower than laser characteristic parameter target value, then using control module selects PID control optimization driving signal;Cut off driving signal and absorb invalid light;Including in need to close laser output, using control module to stop acoustooptic modulator to apply driving signal, stop output laser.The application can meet the demand of high-precision, high-speed laser processing.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of laser control, in particular to a radio frequency carbon dioxide laser fast switching control method based on acousto-optic modulation. BACKGROUND

[0002] In the field of industrial laser processing, radio frequency excited carbon dioxide lasers have shown great advantages in metal cutting, non-metal engraving, material surface treatment and many other application scenarios due to their high energy conversion efficiency, good beam quality and stable output characteristics. With the continuous development of manufacturing industry towards high precision and high speed, the performance requirements of laser processing equipment are also increasing, especially in the switching control of laser, which directly affects the precision, efficiency and quality of processing.

[0003] In the existing radio frequency excited carbon dioxide laser, the switching control of laser usually adopts an external PWM digital controller to generate a pulse signal, and the switching control is performed through the modulation port of the radio frequency power supply. Specifically, the digital controller outputs a high / low level signal to control the opening and closing of the radio frequency power supply, thereby realizing the pulse output of the laser. However, the traditional PWM modulation method has obvious limitations. Due to the response delay of the radio frequency power supply and the long relaxation time of the gas discharge, the switching speed of the laser is difficult to further improve, resulting in slow rising and falling edges of the pulse. In laser cutting applications, slow switching speed can cause non-ideal distribution of laser energy during the switching transition, resulting in problems such as "expansion of heat affected zone, residue of molten slag or roughness of cutting surface", which affects the processing precision and surface finish. In addition, the traditional PWM modulation method may cause pulse waveform distortion when working at high frequency due to insufficient dynamic response of the radio frequency power supply and discharge plasma, affecting the processing stability and making it difficult to meet the needs of high-precision and high-speed laser processing. SUMMARY

[0004] In order to meet the needs of high-precision and high-speed laser processing, the present application provides a radio frequency carbon dioxide laser fast switching control method based on acousto-optic modulation.

[0005] In the first aspect, the present application provides a radio frequency carbon dioxide laser fast switching control method based on acousto-optic modulation, applied to a radio frequency carbon dioxide laser, comprising a laser resonant cavity located at the outlet side of a radio frequency power supply, an acousto-optic modulator located at the light outlet side of the laser resonant cavity, an absorption device located at the outlet side of the acousto-optic modulator, a first mirror and a second mirror, and a control module; the radio frequency carbon dioxide laser fast switching control step comprises:

[0006] Initialize system monitoring and parameter configuration; including: using the control module to start the laser self-test, monitoring the laser resonator output parameters, acousto-optic modulator status parameters, absorption device thermal load parameters, and laser characteristic parameters; and setting the initial parameters of the RF power supply output, the initial parameters of the drive signal, the absorption device temperature setpoint, and the target values ​​of the laser characteristic parameters according to processing requirements.

[0007] The process of generating effective light by loading a driving signal includes: applying a driving signal to the piezoelectric transducer of the acousto-optic modulator using a control module to excite ultrasonic waves to form a phase grating in the acousto-optic medium of the acousto-optic modulator; and causing the laser beam output from the laser resonator to be incident on the phase grating at a Bragg angle to form deflected effective light.

[0008] Output laser and feedback optimization; including: outputting effective light after reflection by the first and second reflectors; monitoring the output laser characteristic parameters, and if the current output laser characteristic parameters are lower than the target value, then the control module uses PID control to optimize the drive signal parameters or RF power supply output.

[0009] Cutting off the drive signal and absorbing invalid light includes: when it is necessary to shut down the laser output, using the control module to stop the piezoelectric transducer of the acousto-optic modulator from applying the drive signal, thereby stopping the laser output.

[0010] By adopting the above scheme, rapid switching control of the radio frequency carbon dioxide laser was achieved, the laser switching speed was improved, and the problem of limited switching speed in traditional control methods was solved. By monitoring and optimizing the output laser characteristic parameters, the cutting quality was improved, and the cutting edge problem caused by slow switching speed was avoided.

[0011] Preferably, the step of performing rapid switching control of the radio frequency carbon dioxide laser further includes:

[0012] Perform cyclic control and mode switching; including: according to the needs of continuous processing or the processing needs of switching to pulse output mode, repeatedly perform initialization system monitoring and parameter configuration, load drive signal to generate effective light, output laser and feedback optimization, and cut off drive signal and absorb ineffective light;

[0013] The initialization system monitoring and parameter configuration can obtain initial control parameters from a process recipe library according to current processing requirements, including radio frequency power output initial parameters, drive signal initial parameters, absorption device temperature set values and laser characteristic parameter target values and is configured; the process recipe library stores processing requirements as an index and initial control parameters corresponding to the processing requirements; the processing requirements include processing materials and thickness, processing types and processing quality requirements; the initial control parameters include radio frequency power output initial parameters, drive signal initial parameters, absorption device temperature set values and laser characteristic parameter target values, specifically control parameters obtained by a deep learning algorithm under different processing requirements, which meet the processing requirements and have the best processing performance indicators; the processing performance indicators are obtained by evaluating the monitored output laser characteristic parameters according to a preset performance evaluation rule.

[0014] By adopting the above scheme, the control steps are cyclically executed according to continuous processing requirements or switching pulse output mode processing requirements, and the best initial control parameters are obtained according to different processing requirements through the process recipe library and the deep learning algorithm, so that the requirements of different processing scenes are met, and the processing performance and efficiency are further improved.

[0015] Preferably, when the monitored current output laser characteristic parameter is lower than the laser characteristic parameter target value, the control module selects PID control to optimize the drive signal parameter or the radio frequency power output, including:

[0016] A hierarchical control architecture is adopted, including: an outer ring PID control as a main control loop, including: a final output power control loop; an inner ring PID control as a secondary control loop, including: a radio frequency power control loop and a derived efficiency control loop of an acousto-optic modulator; when the monitored current output laser characteristic parameter is lower than the laser characteristic parameter target output power, the output power control loop is combined to calculate an output power error value and convert the output power error value into a power demand; a power distribution algorithm is used to distribute the power demand to the radio frequency power supply and the acousto-optic modulator to obtain optimal radio frequency power supply set values and acousto-optic modulator derived efficiency set values; wherein, the power distribution algorithm formula includes:

[0017] In the formula, is the power demand, represents the radio frequency power supply set value; is the comprehensive efficiency of gas discharge and optical cavity; is the derived efficiency set value of the acousto-optic modulator; Specifically, different efficiency set values are matched according to the scene, when the power demand is less than 1 / 2 of the target output power, it is determined that the current is a low power demand scene, and the first efficiency is matched; when the power demand is not less than 1 / 2 of the target output power, it is determined that the current is a high power demand scene, and the second efficiency is matched. is a preset minimum power limit value, is a preset maximum power limit value; is a preset minimum diffraction efficiency limit; by querying a pre-stored total efficiency curve constructed according to a radio frequency power supply efficiency curve and an acousto-optic modulator efficiency curve, a radio frequency power supply setting value and an acousto-optic modulator derived efficiency setting value combination with maximum total efficiency are found as optimal radio frequency power supply setting value and acousto-optic modulator derived efficiency setting value;

[0018] In combination with a radio frequency power supply power control loop, the duty cycle of the PWM control signal is adjusted according to the obtained radio frequency power supply setting value to further adjust the radio frequency power supply output; in combination with an acousto-optic modulator derived efficiency control loop, the driving signal parameters of the acousto-optic modulator are adjusted according to the obtained acousto-optic modulator derived efficiency setting value.

[0019] By adopting the above scheme, when it is monitored that the output power is lower than the target output power, the radio frequency power supply output and the driving signal parameters of the acousto-optic modulator are adjusted by using the hierarchical control architecture and the power distribution algorithm, so that the power can be reasonably distributed under different power demand scenarios, the laser output power can be accurately controlled, and the stability of the laser output can be guaranteed.

[0020] Preferably, in the applied radio frequency carbon dioxide laser, the acousto-optic modulator adopts a multi-channel acousto-optic modulator design formed by dividing a single transducer into multiple independently controllable electrode segments, and the control module is used to control the driving state of each electrode to realize multiple working modes of the acousto-optic modulator; the radio frequency carbon dioxide laser fast switching control step further includes:

[0021] According to the processing requirement, the working mode of the acousto-optic modulator is further set; including: in the initialization system monitoring and parameter configuration process, on the basis of obtaining the pulse sequence parameters in the radio frequency power supply output initial parameters or the driving signal parameters, according to the parameter threshold range in which the radio frequency power supply output initial parameters or the pulse sequence parameters are located, the recommended working mode of the acousto-optic modulator is selected correspondingly, and then the working mode of the acousto-optic modulator is set; including: when the pulse width in the pulse sequence parameters is less than the preset pulse width threshold, the recommended relay driving mode of each electrode is recommended, and when the output power in the radio frequency power supply output initial parameters is greater than the preset power threshold, the recommended synchronous driving mode of each electrode is recommended.

[0022] By adopting the above scheme, multiple working modes of the acousto-optic modulator are realized, the appropriate working mode can be selected according to the parameter threshold range in which the radio frequency power supply output initial parameters or the pulse sequence parameters are located, the flexibility and adaptability of laser control are improved, and different processing requirements can be better met.

[0023] Preferably, the applied acousto-optic modulator in the radio frequency carbon dioxide laser is also connected to a multi-zone refrigeration device, and the absorption device in the radio frequency carbon dioxide laser is also connected to an auxiliary cooling device; the radio frequency carbon dioxide laser fast switching control step further comprises:

[0024] According to the multi-zone temperature of the acousto-optic modulator in the acousto-optic modulator state parameter obtained by real-time monitoring, if the zone temperature is greater than the preset temperature threshold, the PID control is selected by the control module to optimize the acousto-optic modulator temperature output, and the inner loop PID control as the secondary control loop further comprises: the temperature control loop of the acousto-optic modulator; the regional temperature difference is calculated combined with the temperature control loop, and the output cooling demand value is sent to the corresponding regional refrigeration device to drive the regional refrigeration device to reduce the temperature of the acousto-optic modulator to below the preset temperature threshold.

[0025] According to the temperature in the heat load parameter of the absorption device obtained by real-time monitoring, when the temperature exceeds the temperature set value, the auxiliary cooling device is driven or the delay loading drive signal is driven by the control module.

[0026] By adopting the above scheme, the multi-zone temperature of the acousto-optic modulator and the heat load parameter of the absorption device are monitored in real time, the acousto-optic modulator is cooled by PID control and temperature control loop, and the auxiliary cooling device is automatically started or the delay loading drive signal is driven when the temperature of the absorption device exceeds the limit, so that the acousto-optic modulator and the absorption device work at an appropriate temperature, and the stable operation of the laser is ensured.

[0027] Preferably, the radio frequency carbon dioxide laser fast switching control step further comprises:

[0028] According to the processing requirement, a timing parameter is set, including: a radio frequency power output advance timing parameter and a drive signal timing compensation parameter.

[0029] The time difference between the radio frequency power output time and the acousto-optic modulator loading drive signal time is greater than the radio frequency power output advance timing parameter by adjusting the control module;

[0030] If the time difference between the laser generation time in the laser resonant cavity output parameter and the entering diffraction state time in the acousto-optic modulator state parameter is not less than the preset timing deviation, the drive signal loading time is adjusted according to the drive signal timing compensation parameter, so that the time difference between the laser generation time in the laser resonant cavity output parameter and the entering diffraction state time in the acousto-optic modulator state parameter is less than the preset timing deviation.

[0031] By adopting the above scheme, the reasonable time difference between the radio frequency power output and the loading time of the acousto-optic modulator driving signal, and the accurate matching between the laser generation time and the entering diffraction state time are ensured, so that the time precision and stability of the laser output are optimized, and the efficiency and quality of the laser processing are improved.

[0032] Preferably, the step of performing the fast switching control of the radio frequency carbon dioxide laser further comprises:

[0033] In addition to the switching to the pulse output mode processing requirement condition, based on the use of the control module to select the PID control to optimize the driving signal parameters or the radio frequency power output process, the transient response curve of the laser output power is obtained and the performance evaluation result is performed, including: overshoot, rise time, steady time and steady state error; based on the preset adjustment rule, the PID control parameters are adjusted according to the gap between the current performance and the target performance; the preset adjustment rule includes: the overshoot is greater than the preset overshoot, the proportional gain is reduced or the differential gain is increased; the rise time is greater than the preset rise time, the proportional gain is increased; the steady time is greater than the preset steady time, the proportional gain is reduced, and the differential gain is increased; the steady state error exists, and the integral gain is increased.

[0034] By adopting the above scheme, according to the performance evaluation result of the transient response curve of the laser output power, the PID control parameters are adjusted according to the preset rule, so that the overshoot, rise time, steady time and steady state error of the laser output power and other performance indicators are closer to the target performance, and the stability and accuracy of the laser output power are improved.

[0035] Preferably, the step of performing the fast switching control of the radio frequency carbon dioxide laser further comprises: in the process of applying the driving signal to the piezoelectric transducer of the acousto-optic modulator by the control module, the driving signal is filtered in advance.

[0036] By adopting the above scheme, the driving signal is filtered in advance when the driving signal is applied to the piezoelectric transducer of the acousto-optic modulator, which can avoid the interference of impurity signals to the driving signal, ensure the purity and stability of the driving signal, and make the acousto-optic modulator work more stably and accurately.

[0037] In a third aspect, a computer readable storage medium is provided, which includes a stored computer program, wherein the computer readable storage medium controls the device where the computer readable storage medium is located to perform the method as described above when the computer program is running.

[0038] In a fourth aspect, a computer device is provided, which includes a memory, a processor and a program stored on the memory and executable by the processor, and the program is executed by the processor to implement the steps of the method as described above.

[0039] By setting an acousto-optic modulator outside the light output port of the laser resonant cavity to control and turn off the laser output, the speed of the laser output and turn-off is improved, the laser switching speed is improved, the problem of cutting quality decline is solved; The laser power and pulse parameters are accurately controlled, the parameters can be set according to the processing requirements and adjusted in real time, the problem of limited repetition frequency of the traditional PWM modulation mode is solved, and the requirements of different processing technologies are met. BRIEF DESCRIPTION OF DRAWINGS

[0040] Figure 1 A flowchart of the method for rapidly switching and controlling the RF CO2 laser based on acousto-optic modulation is described in the specific embodiment.

[0041] Figure 2 A structure diagram of the RF CO2 laser applied in the method for rapidly switching and controlling the RF CO2 laser based on acousto-optic modulation is described in the specific embodiment. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical scheme and advantages of the present application clearer, the present application will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and not to limit the present application.

[0043] As shown in Figure 1 The embodiment of the present application discloses a method for rapidly switching and controlling an RF CO2 laser based on acousto-optic modulation, which is applied to an RF CO2 laser, including: a radio frequency power supply, a laser resonant cavity, an acousto-optic modulator, an absorption device, a first mirror and a second mirror, and a control module, as shown in Figure 2 .

[0044] The laser resonant cavity is located at the outlet side of the radio frequency power supply, and is used to accelerate photon accumulation and output a laser beam by injecting energy through the radio frequency power supply; the acousto-optic modulator is arranged outside the light output port of the laser resonant cavity, and includes a piezoelectric transducer, an acousto-optic medium, and an ultrasonic wave absorption layer; the piezoelectric transducer generates a phase grating with periodic refractive index variation in the acousto-optic medium through a high-frequency driving signal, and the ultrasonic wave absorption layer is arranged on the side of the acousto-optic medium away from the laser resonant cavity; the laser beam output by the laser resonant cavity is divided into effective light and ineffective light through the acousto-optic modulator; the first mirror and the second mirror are arranged along the effective light transmission path in sequence, the first mirror deflects the effective light and directs it to the second mirror, and the second mirror reflects the effective light to the output mirror of the laser; the ineffective light is directly transmitted to the absorption device; the absorption device includes a sealed cavity and a graphite layer filled in the cavity, and the cavity is connected to an auxiliary cooling device through a pipeline to realize heat exchange.

[0045] The control module includes a driving circuit, a processor, and various sensor groups (power sensor, temperature sensor, light intensity sensor, etc.), which can adjust the output parameters of the radio frequency power supply and the driving signal parameters of the acousto-optic modulator in real time, and simultaneously monitor the output parameters and state parameters of each structural part, and is mainly used for executing the fast switching control of the radio frequency carbon dioxide laser. The steps include:

[0046] S1, initializing system monitoring and parameter configuration.

[0047] Specifically, the control module is used to start the self-checking of the laser, and to turn on the monitoring of the output parameters of the laser resonant cavity, the state parameters of the acousto-optic modulator, the thermal load parameters of the absorption device, and the laser characteristic parameters. According to the processing requirements, such as continuous output, pulse output, or intensity modulation mode, the initial parameters of the radio frequency power supply output, the initial parameters of the driving signal, the temperature set value of the absorption device, and the target value of the laser characteristic parameters are preset, and the parameter configuration is completed. For example, the initial parameters of the driving signal include the radio frequency, the amplitude, and the pulse sequence mode.

[0048] In order to assist the user in setting parameters to meet the user's processing requirements, the parameter configuration can obtain initial control parameters from the process recipe library according to the current processing requirements and configure them. The process recipe library stores processing requirements as an index and initial control parameters corresponding to specific processing requirements. The processing requirements include processing materials (such as stainless steel, aluminum alloy, and acrylic), thickness (such as 1.0 mm, 1.5 mm, and 2.0 mm), processing type (cutting and punching), and processing quality requirements (speed and quality). The initial control parameters include basic parameters (such as the initial parameters of the radio frequency power supply output, such as average power), driving signal initial parameters (such as radio frequency, typical range: 40-100 MHz, amplitude: 0-100% power, and pulse sequence parameters, such as 10-100 pulses per second in burst mode), absorption device temperature set value (temperature set threshold), PID control parameters, and laser characteristic parameter target value (such as expected output power value).

[0049] These initial control parameters are obtained through a deep learning algorithm, which can meet the processing requirements and achieve the best processing performance indicators under different processing requirements. The processing performance indicators are obtained by evaluating the monitoring output laser characteristic parameters according to the preset performance evaluation rules (evaluation indicators include expected cutting speed, cross-section roughness, and slag condition). If a completely matched item cannot be found in the existing process recipe library, the initial control parameters corresponding to the processing requirements with a similarity higher than a preset similarity are queried and interpolated to obtain the initial control parameters corresponding to the current processing requirements.

[0050] S2, load the driving signal to generate effective light.

[0051] Specifically, the driving circuit of the control module is used to apply a driving signal to the piezoelectric transducer of the acousto-optic modulator, and the piezoelectric transducer converts electrical energy into high-frequency ultrasonic waves under the excitation of the driving power supply. The excitation ultrasonic wave forms a phase grating in the acousto-optic medium of the acousto-optic modulator, which can be glass or crystal. The laser beam output by the laser resonant cavity is incident on the phase grating at the Bragg angle. The laser beam interacts with the acoustic field, and the light beam that satisfies the momentum matching condition is diffracted and deflected to form first-order diffracted light, i.e., effective light, and zero-order transmitted light, i.e., ineffective light. About 90% of the light satisfies the momentum matching condition and is diffracted and deflected to become effective light.

[0052] In addition, during the process of applying the driving signal to the piezoelectric transducer of the acousto-optic modulator by the control module, a filter circuit can be added to the driving circuit to filter the generated driving signal in advance.

[0053] S3, output laser and feedback optimization.

[0054] Specifically, in the step of outputting laser and feedback optimization, the laser after the effective light is reflected by the first mirror and the second mirror. The first mirror and the second mirror are generally made of high-reflectivity materials to reflect the effective light to the output mirror of the laser, and the workpiece is processed by laser.

[0055] The output laser characteristic parameters such as power and stability are monitored. When the current output laser characteristic parameters are lower than the target value of the laser characteristic parameters, the control module is used to select PID control to optimize the driving signal parameters or the output of the radio frequency power supply. The associated control parameters of the final output laser characteristic parameters are considered, and the control output includes: radio frequency power supply output and driving signal parameters, process state: laser resonant cavity output parameters (output power), acousto-optic modulator state parameters (temperature value, reflected light intensity), heat load parameters of the absorption device (temperature value), performance output: final laser characteristic parameters (output instantaneous power, output average power, pulse width, repetition frequency, etc.), and then the processor of the control module is used for PID control optimization. The control input is adjusted through the final laser characteristic parameters, so as to obtain the performance output that meets the final processing requirements.

[0056] In addition, the processing image is obtained by cooperating with the vision device, and the processor in the control module is used to analyze the received processing image. When it is monitored that the reflected light intensity on the workpiece corresponding to the current output laser is greater than the preset light intensity, the amplitude of the loaded driving signal is reduced to reduce the output power.

[0057] S4, cut off the driving signal and absorb the ineffective light.

[0058] Specifically, when the laser output needs to be turned off, the control module is used to stop applying the driving signal to the piezoelectric transducer of the acousto-optic modulator. At this time, the ultrasonic wave in the acousto-optic medium decays rapidly, the refractive index grating disappears, and the laser beam output by the resonant cavity is transmitted in a straight line and directly enters the absorption device. The absorption device is composed of an absorption device cavity and graphite. The graphite absorbs the energy of the invalid light and conducts it to the cooling system to realize no laser output.

[0059] At the same time, during the entire rapid switching process of the radio frequency carbon dioxide laser, the processor of the control module is also used to analyze the process data such as the laser resonant cavity output parameters, the acousto-optic modulator state parameters, and the heat load parameters of the absorption device monitored in real time. Once there is an abnormal output parameter (all set corresponding preset parameter threshold), it can automatically enter the safety mode and cut off all signals or delay load signals, drive auxiliary cooling devices to run and other control measures; for example, according to the temperature of the heat load parameters of the absorption device obtained by real-time monitoring, when the temperature exceeds the temperature setting value, the control module is used to drive the auxiliary cooling device or delay load driving signal.

[0060] S5, loop control and mode switching.

[0061] Specifically, considering that in the actual processing process, it is necessary to flexibly adjust the output mode of the laser according to different processing needs to realize the switching of continuous processing or pulse output mode. Accordingly, according to the continuous processing requirement or the switching to the pulse output mode processing requirement condition, the contents of steps S1-S4 are repeated to initialize the system monitoring and parameter configuration (such as: pulse output mode switching, preset driving signal parameter setting to pulse sequence mode, 10-100 pulses per second in burst mode or different material workpiece processing, obtaining and configuring corresponding control parameters), loading driving signal to generate effective light, outputting laser and feeding back optimization, and cutting off driving signal and absorbing invalid light.

[0062] By using the above method, the light-on and light-off processes are integrated into a unified dynamic control process, real-time feedback loop, dynamic optimization of driving signal parameters, pulse sequence generation, and safety threshold protection mechanism are introduced, which improves the switching speed of the laser, solves the problem of reduced cutting quality and limited repetition frequency.

[0063] In one specific embodiment, in order to more accurately control the parameters of the radio frequency power supply and the acousto-optic modulator, realize accurate adjustment of the laser output power, and improve energy utilization efficiency and reduce energy consumption, the method further comprises: using a hierarchical control architecture and a power distribution algorithm to realize accurate adjustment of the laser output power.

[0064] The current output laser characteristic parameter is lower than the laser characteristic parameter target value, and the control module is used to select the PID control optimized driving signal parameter or the radio frequency power supply output, which specifically includes:

[0065] The layered control architecture is adopted, the PID control optimization is divided into a multi-layer control structure, the high-frequency fast-changing disturbance is suppressed by the inner ring, and the final output is accurately stable by the outer ring. Specifically, the outer ring PID control as the main control ring includes: the final output power control ring; the inner ring PID control as the secondary control ring includes: the radio frequency power supply power control ring and the derivative efficiency control ring of the acousto-optic modulator.

[0066] When the output power in the monitored current output laser characteristic parameter is lower than the target output power of the laser characteristic parameter (target pulse energy), the energy output by the laser is released in the form of discrete pulses, and the instantaneous power value cannot be directly obtained. The output power in the output laser characteristic parameter refers to the total average power value, i.e. the single pulse energy multiplied by the repetition frequency; in combination with the output power control ring, the output power error value is converted into a power demand; the power demand is distributed to the radio frequency power supply and the acousto-optic modulator by using a power distribution algorithm to obtain the optimal radio frequency power supply set value and the derivative efficiency set value of the acousto-optic modulator; wherein the power distribution algorithm formula includes:

[0067] In the formula, is the power demand, represents the radio frequency power supply set value; is the comprehensive efficiency of gas discharge and optical cavity; is the derivative efficiency set value of the acousto-optic modulator; According to the scene, different efficiency settings are matched. Considering that the radio frequency power supply usually has higher efficiency at certain power points, the optimal working points of the radio frequency power supply and the acousto-optic modulator are selected according to the power demand; according to the scene, different efficiency settings are matched. When the power demand is less than 1 / 2 of the target output power, it is determined that the current is a low-power demand scene, and the radio frequency power supply is set at a high-efficiency point, corresponding to the first efficiency (70%); when the power demand is not less than 1 / 2 of the target output power, it is determined that the current is a high-power demand scene, and the radio frequency power supply is set at a maximum efficiency, corresponding to the second efficiency (100%); is a preset minimum power limit value, is a preset maximum power limit value; is a preset minimum diffraction efficiency limit;

[0068] The total efficiency curve is obtained by querying the pre-stored total efficiency curve constructed according to the radio frequency power supply efficiency curve and the acousto-optic modulator efficiency curve; wherein the radio frequency power supply efficiency curve is calculated and obtained according to the set radio frequency power supply output power and the actual monitored radio frequency power used for exciting the gas; the acousto-optic modulator efficiency curve is calculated and obtained according to the first-order light power and the incident power; the total efficiency curve is obtained by obtaining the final output power / acousto-optic modulator efficiency of the radio frequency power used for exciting the gas; the combination of the radio frequency power supply set value and the derived efficiency set value of the acousto-optic modulator with the maximum total efficiency is found as the optimal radio frequency power supply set value and the derived efficiency set value of the acousto-optic modulator.

[0069] In combination with the radio frequency power supply power control loop, the duty cycle of the PWM control signal is adjusted according to the obtained radio frequency power supply set value, and then the radio frequency power supply output is adjusted; in combination with the derived efficiency control loop of the acousto-optic modulator, the driving signal parameters of the acousto-optic modulator are adjusted according to the obtained derived efficiency set value of the acousto-optic modulator.

[0070] In addition, in addition to the power-related PID control, temperature-related PID control is also included, so as to cool the abnormal temperature part in time and prevent it from affecting the performance due to excessive temperature. The design basis is that the acousto-optic modulator in the applied radio frequency carbon dioxide laser is also connected with a multi-zone cooling device, such as a cooling device connected and arranged corresponding to the divided zones along the extension direction of the acousto-optic medium of the acousto-optic modulator; the absorption device in the radio frequency carbon dioxide laser is also connected with an auxiliary cooling device; specifically, the multi-zone temperature of the acousto-optic modulator in the acousto-optic modulator state parameters obtained by real-time monitoring is used to monitor whether the zone temperature is greater than the preset temperature threshold, and then the PID control is selected and used to optimize the acousto-optic modulator temperature output by the control module, and the inner loop PID control of the secondary control loop also includes: the temperature control loop of the acousto-optic modulator; the regional temperature difference is calculated and obtained in combination with the temperature control loop, and the output cooling demand value is sent to the corresponding regional cooling device to drive the regional cooling device to reduce the temperature of the acousto-optic modulator to below the preset temperature threshold.

[0071] In addition, in order to maintain optimal performance throughout the processing cycle, the rule-based PID control parameter self-tuning or fuzzy adaptive PID control parameter adjustment can be selected. In this embodiment, the rule-based PID control parameter self-tuning mode is selected. In addition to the switching pulse sequence mode processing requirement condition, in the process of selecting the PID control optimized driving signal parameter or the RF power output by the control module, the transient response curve of the laser output power is obtained and the performance evaluation result is performed, including: overshoot, rise time, settling time and steady-state error. Based on the preset adjustment rule, the PID control parameters are adjusted according to the gap between the current performance and the target performance; the preset adjustment rule includes: the overshoot is greater than the preset overshoot, the proportional gain is reduced or the differential gain is increased; the rise time is greater than the preset rise time, the proportional gain is increased; the steady-state time is greater than the preset steady-state time, the proportional gain is reduced, and the differential gain is increased; the steady-state error exists, and the integral gain is increased.

[0072] In a specific embodiment, the multi-channel acousto-optic modulator design and the multi-working mode setting enable the acousto-optic modulator to flexibly adjust the working mode according to different processing requirements, improve the modulation efficiency and output quality of the laser, and further meet diversified processing requirements. The method further comprises:

[0073] To realize the multi-working mode setting of the multi-channel acousto-optic modulator, it is necessary to have a multi-channel acousto-optic modulator design basis, that is, the acousto-optic modulator in the applied RF CO2 laser adopts a multi-channel acousto-optic modulator design formed by dividing a single transducer into multiple independently controllable electrode segments. For example, multiple parallel piezoelectric transducer electrodes are designed, which are arranged along the sound wave propagation direction (Z axis) and are electrically isolated from each other. The electrode arrangement mode adopts uniform segmentation, all electrode segments have the same size and equal spacing; each electrode segment is connected to an independent RF drive channel controlled by a control module.

[0074] The control module controls the driving state of each electrode to realize the multi-working mode of the acousto-optic modulator; the step of performing RF CO2 laser fast switching control further comprises:

[0075] According to the processing requirement, the working mode of the acousto-optic modulator is set; including: in the initialization system monitoring and parameter configuration process, based on the pulse sequence parameters in the obtained RF power output initial parameters or driving signal parameters, according to the parameter threshold range where the RF power output initial parameters or pulse sequence parameters are located, the recommended working mode of the acousto-optic modulator is selected, and then the working mode of the acousto-optic modulator is set; including: when the pulse width in the pulse sequence parameters is less than the preset pulse width threshold, the recommended relay driving mode of each electrode is selected; when the output power in the RF power output initial parameters is greater than the preset power threshold, the recommended synchronous driving mode of each electrode is selected.

[0076] wherein, the recommended each electrode relay driving mode corresponding to the situation that the pulse width in the pulse sequence parameters is less than the preset pulse width threshold, is mainly to overcome the minimum pulse width limit of the acoustic wave transit time processing, such as 200ns pulse width requires the modulation bandwidth of the acousto-optic modulator to be extremely large, and the relay driving of each electrode shortens the acoustic wave transit time, so as to obtain sufficient bandwidth, and then complete the effective modulation of narrow pulse width; the relay driving is driven with a specific time delay, , v is the speed of sound wave propagation, and d is the center distance between the electrode segments.

[0077] wherein, the recommended each electrode synchronous driving mode corresponding to the situation that the output power in the initial parameters of the radio frequency power output is greater than the preset power threshold, that is, all electrodes are driven synchronously with the same phase and amplitude, the diffraction efficiency is maximized, and it is suitable for occasions that require the highest power output.

[0078] In one specific embodiment, there is a multi-variable coupling optimization problem in the radio frequency CO2 laser based on acousto-optic modulation, and the final laser pulse instruction used in the workpiece is improved by collaborative optimization. The method further comprises:

[0079] Considering that the output of the radio frequency power source and the laser resonant cavity determine the basic laser output, the loaded driving signal determines how much of the basic laser output from the resonant cavity can be diffracted into the processing light path through the acousto-optic modulation, and the collaborative control is used to synchronize the timing. According to the processing requirements, the timing parameters are set, including: radio frequency power output advance timing parameter, driving signal timing compensation parameter.

[0080] wherein, considering that the radio frequency power output needs a certain time to start working and stabilize the laser resonant cavity, it must be stabilized before triggering the driving signal, so as to ensure that a peak stable pulse is output; correspondingly, after the output of the last pulse ends, a certain period of time is also needed to delay, so as to turn off the radio frequency power output. Correspondingly, the time difference between the time of adjusting the radio frequency power output by the control module and the time of loading the driving signal by the acousto-optic modulator is greater than the radio frequency power output advance timing parameter.

[0081] wherein, considering the source of the timing deviation, the radio frequency power output needs a delay of 10-20ns to drive the resonant cavity to generate laser; the driving signal loading needs a delay of 5-8ns to enter the diffraction state. Correspondingly, the time difference between the laser generation time in the laser resonant cavity output parameter and the diffraction state time in the acousto-optic modulator state parameter is monitored. If it is not less than the preset timing deviation (for example, 3ns), the driving signal loading time is adjusted according to the driving signal timing compensation parameter, so that the time difference between the laser generation time in the laser resonant cavity output parameter and the diffraction state time in the acousto-optic modulator state parameter is less than the preset timing deviation.

[0082] The embodiment of the present application further discloses a computer readable storage medium.

[0083] Specifically, the computer readable storage medium stores a computer program capable of being loaded and executed by the processor to implement the above-mentioned method for controlling a fast switch of a radio frequency carbon dioxide laser based on acousto-optic modulation, and the computer readable storage medium includes, for example, a U disk, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk, and various media capable of storing program codes.

[0084] The embodiment of the present application further discloses a computer device.

[0085] Specifically, the computer device includes a memory and a processor, and the memory stores a computer program capable of being loaded and executed by the processor to implement the above-mentioned method for controlling a fast switch of a radio frequency carbon dioxide laser based on acousto-optic modulation.

[0086] The above are preferred embodiments of the present application, and are not intended to limit the protection scope of the present application, and any feature disclosed in the specification (including the abstract and the drawings) can be replaced by other equivalent or similar features unless specifically described, that is, each feature is only an example of a series of equivalent or similar features.

Claims

1. A method for controlling a fast switch of a radio frequency carbon dioxide laser based on acousto-optic modulation, applied to a radio frequency carbon dioxide laser, comprising: The laser resonant cavity is located at the outlet side of the radio frequency power supply, the acousto-optic modulator is located at the light outlet side of the laser resonant cavity, the absorption device is located at the outlet side of the acousto-optic modulator, and the first mirror and the second mirror are located at the outlet side of the absorption device; the control module is characterized in that the radio frequency carbon dioxide laser fast switching control step comprises: Initializing system monitoring and parameter configuration; including: starting the laser self-checking by using the control module, monitoring the laser resonant cavity output parameter, the acousto-optic modulator state parameter, the heat load parameter of the absorption device and the laser characteristic parameter; according to the processing requirement, setting the radio frequency power supply output initial parameter, the driving signal initial parameter, the absorption device temperature setting value and the laser characteristic parameter target value; Loading the driving signal to generate effective light; including: applying the driving signal to the piezoelectric transducer of the acousto-optic modulator by using the control module, exciting the ultrasonic wave to form a phase grating in the acousto-optic medium of the acousto-optic modulator; the laser beam output by the laser resonant cavity is incident on the phase grating at the Bragg angle to form deflected effective light; Outputting the laser and feeding back optimization; including: outputting the laser after the effective light is reflected by the first mirror and the second mirror; monitoring the output laser characteristic parameter, and if the current output laser characteristic parameter is lower than the laser characteristic parameter target value, selecting the PID control to optimize the driving signal parameter or the radio frequency power supply output by using the control module; Cutting off the driving signal and absorbing the invalid light; including: when it is required to close the laser output, stopping the piezoelectric transducer of the acousto-optic modulator from applying the driving signal by using the control module to stop outputting the laser; The current output laser characteristic parameter is lower than the laser characteristic parameter target value, and the control module is used to select the PID control to optimize the driving signal parameter or the radio frequency power supply output, which comprises: A hierarchical control architecture is adopted, including: an outer ring PID control as a main control loop, including: a final output power control loop; an inner ring PID control as a secondary control loop, including: a radio frequency power supply power control loop and an acousto-optic modulator diffraction efficiency control loop; when the output power in the current output laser characteristic parameter is lower than the laser characteristic parameter target output power, the output power control loop is combined to calculate the output power error value and convert the output into a power requirement; the power requirement is distributed to the radio frequency power supply and the acousto-optic modulator by using a power distribution algorithm to obtain the optimal radio frequency power supply setting value and the acousto-optic modulator diffraction efficiency setting value; wherein, the power distribution algorithm formula comprises: wherein, is the power demand, represents the RF power setting value; is the comprehensive efficiency of the gas discharge and optical cavity; is the diffraction efficiency setting value of the acousto-optic modulator; According to the scene, different efficiency settings are matched. When the power demand is less than 1 / 2 of the target output power, it is determined that the current is a low-power demand scene, and the first efficiency is matched. When the power demand is not less than 1 / 2 of the target output power, it is determined that the current is a high-power demand scene, and the second efficiency is matched. is the preset minimum power limit value, is the preset maximum power limit value; is the preset minimum diffraction efficiency limit; by querying the total efficiency curve constructed according to the RF power efficiency curve and the acousto-optic modulator efficiency curve, the combination of the RF power setting value and the diffraction efficiency setting value of the acousto-optic modulator with the maximum total efficiency is found as the optimal RF power setting value and the diffraction efficiency setting value of the acousto-optic modulator. The duty cycle of the PWM control signal is adjusted according to the obtained radio frequency power supply setting value to further adjust the radio frequency power supply output in combination with the radio frequency power supply power control loop; the driving signal parameter of the acousto-optic modulator is adjusted according to the obtained acousto-optic modulator diffraction efficiency setting value in combination with the acousto-optic modulator diffraction efficiency control loop.

2. The method of claim 1, wherein the method further comprises: The radio frequency carbon dioxide laser fast switching control step further comprises: Carrying out cycle control and mode switching; including: repeating the initialization system monitoring and parameter configuration, loading the driving signal to generate effective light, outputting the laser and feeding back optimization and cutting off the driving signal and absorbing the invalid light under the conditions of continuous processing requirement or switching to the pulse output mode processing requirement; The initialization system monitoring and parameter configuration can obtain initial control parameters from a process recipe library according to current processing requirements and configure the initial control parameters; the process recipe library stores processing requirements as indexes and initial control parameters corresponding to the processing requirements; the processing requirements include processing materials and thickness, processing type, and processing quality requirements; the initial control parameters include radio frequency power output initial parameters, driving signal initial parameters, absorption device temperature set values, and laser characteristic parameter target values, specifically, control parameters that meet processing requirements and have optimal processing performance indicators under different processing requirements are obtained through a deep learning algorithm; the processing performance indicators are evaluated according to the laser characteristic parameters monitored and output according to a preset performance evaluation rule.

3. The method of claim 2, wherein the acousto-optic modulator of the RF CO2 laser is designed as a multi-channel acousto-optic modulator by dividing a single transducer into multiple independently controllable electrode segments, and wherein the control module is configured to control the acousto-optic modulator in multiple operating modes by individually controlling the drive state of each electrode segment. The step of performing the fast switching control of the radio frequency carbon dioxide laser further includes: According to the processing requirements, the working mode of the acousto-optic modulator is set; including: in the initialization system monitoring and parameter configuration process, on the basis of obtaining the pulse sequence parameters in the radio frequency power output initial parameters or the driving signal parameters, according to the parameter threshold range in which the radio frequency power output initial parameters or the pulse sequence parameters are located, the recommended working mode of the acousto-optic modulator is selected, and then the working mode of the acousto-optic modulator is set; including: when the pulse width in the pulse sequence parameters is less than the preset pulse width threshold, the recommended relay driving mode of each electrode is correspondingly recommended, and when the output power in the radio frequency power output initial parameters is greater than the preset power threshold, the recommended synchronous driving mode of each electrode is correspondingly recommended.

4. The method of claim 1, wherein the acousto-optic modulator of the RF CO2 laser is further connected with a multi-zone refrigeration device, and the absorption device of the RF CO2 laser is further connected with an auxiliary cooling device. The step of performing the fast switching control of the radio frequency carbon dioxide laser further includes: According to the multi-zone temperature of the acousto-optic modulator in the acousto-optic modulator state parameters obtained through real-time monitoring, if it is monitored that the zone temperature is greater than the preset temperature threshold, the PID control of the control module is correspondingly used to optimize the acousto-optic modulator temperature output, and the inner loop PID control as the secondary control loop further includes: the temperature control loop of the acousto-optic modulator; the regional temperature difference is calculated in combination with the temperature control loop, and the output cooling demand value is sent to the corresponding regional refrigeration device to drive the regional refrigeration device to reduce the temperature of the acousto-optic modulator to below the preset temperature threshold; According to the temperature in the heat load parameters of the absorption device obtained through real-time monitoring, when it is monitored that the temperature exceeds the temperature set value, the control module is used to drive the auxiliary cooling device or delay the loading of the driving signal.

5. The method of claim 1, wherein the method further comprises: The step of performing the fast switching control of the radio frequency carbon dioxide laser further includes: According to the processing requirements, the timing parameters are set, including: radio frequency power output advance timing parameters and driving signal timing compensation parameters; The time difference between the radio frequency power output time and the acousto-optic modulator driving signal loading time is greater than the radio frequency power output advance timing parameters by using the control module; If the time difference between the laser generation time in the laser resonant cavity output parameters and the entering diffraction state time in the acousto-optic modulator state parameters is not less than the preset timing deviation, the driving signal loading time is adjusted according to the driving signal timing compensation parameters, so that the time difference between the laser generation time in the laser resonant cavity output parameters and the entering diffraction state time in the acousto-optic modulator state parameters is less than the preset timing deviation.

6. The method of claim 1, wherein the method further comprises: The step of performing fast switching control of the radio frequency carbon dioxide laser further comprises: In addition to the switching to the pulse output mode processing requirements, based on the use of control module selected PID control optimization driving signal parameters or radio frequency power output process, to obtain the transient response curve of the laser output power and performance evaluation results, including: overshoot, rise time, steady state time and steady state error; based on the preset adjustment rule, according to the gap between the current performance and the target performance, adjust the PID control parameters; the preset adjustment rule includes: overshoot greater than the preset overshoot, reduce the proportional gain or increase the differential gain; the rise time is greater than the preset rise time, the proportional gain is increased; the steady state time is greater than the preset steady state time, the proportional gain is reduced, and the differential gain is increased; there is a steady state error, and the integral gain is increased.

7. The method of claim 1, wherein the method further comprises: The step of performing fast switching control of the radio frequency carbon dioxide laser further comprises: in the process of applying the driving signal to the piezoelectric transducer of the acousto-optic modulator by the control module, the driving signal is filtered in advance.

8. A computer-readable storage medium, characterized in that, The computer readable storage medium comprises a stored computer program, wherein the computer program controls the device where the computer readable storage medium is located to perform the method of any one of claims 1 to 7 when the computer program is running.

9. A computer device, comprising: The computer device comprises a memory, a processor and a program stored on the memory and executable by the processor, and the program is executed by the processor to realize the steps of the method of any one of claims 1 to 7.

Images