Laser feedback adjusting method and system based on pulse waveform monitoring

Abstract

The invention provides a laser feedback adjusting method and system based on pulse waveform monitoring, and the system comprises a beam splitter and a detector which are disposed in a laser, the beam splitter splits the laser outputted by the laser into a main output light beam and a monitoring light beam, and the detector carries out the photoelectric conversion of the monitoring light beam to obtain a monitoring electric signal; the positive end of the comparator is connected with a monitoring electric signal, and the negative end of the comparator is connected with a periodically circulating reference voltage threshold signal so as to output a digital waveform signal containing pulse width modulation information; the FPGA processing unit calculates a waveform reconstruction parameter in real time according to the digital waveform signal based on a TDC digital time conversion technology, and generates a reconstructed waveform; the digital signal processor performs deviation analysis on the reconstructed waveform and the target waveform to obtain a deviation analysis result; and the FPGA processing unit generates a feedback control quantity according to the deviation analysis result so as to adjust the laser based on the feedback control quantity in the next feedback period to realize accurate tracking of the output waveform of the laser on the target waveform.

Description

Technical Field

[0001] The present invention relates to the technical field of laser control, and in particular to a laser feedback adjustment method and system based on pulse waveform monitoring. Background Art

[0002] Feedback regulation of pulsed lasers is a technology used to improve the energy stability of pulsed lasers. This technology primarily collects the laser's pulse waveform and converts it into an electrical signal through photoelectric conversion. The system then determines whether the waveform parameters of the electrical signal meet preset requirements. If the waveform parameters do not meet these requirements, feedback regulation is achieved by changing the output light energy of the pulsed laser.

[0003] In the existing technology, the acquisition of laser pulse waveforms is generally achieved using devices built outside the laser, which have a complex structure and poor stability. In addition, the waveform parameter monitoring process requires the use of a high-speed space detector, combined with a high-speed DAC and a high-bandwidth oscilloscope to acquire the pulse width waveform, which is costly to implement. Summary of the Invention

[0004] In view of the above problems, the present invention is proposed to provide a laser feedback adjustment method and system based on pulse waveform monitoring that solves the above technical problems or at least partially solves the above technical problems.

[0005] One aspect of the present invention provides a laser feedback adjustment system based on pulse waveform monitoring, the system comprising:

[0006] The beam splitter and detector are built into the laser. The beam splitter splits the laser output into a main output beam and a monitoring beam. The detector collects the monitoring beam and performs photoelectric conversion to obtain a monitoring electrical signal.

[0007] A comparator, wherein the positive terminal of the comparator is connected to the detector to receive the monitoring electrical signal output by the detector, and the negative terminal of the comparator is connected to a preset periodic reference voltage threshold signal so that the comparator outputs a digital waveform signal containing pulse width modulation information;

[0008] an FPGA processing unit connected to the output end of the comparator, for calculating waveform reconstruction parameters in real time according to the digital waveform signal output by the comparator based on TDC digital time conversion technology, and performing waveform reconstruction based on the waveform reconstruction parameters to generate a reconstructed waveform;

[0009] a digital signal processor connected to the FPGA processing unit, for performing deviation analysis between the reconstructed waveform generated by the FPGA processing unit and the target waveform, and obtaining a deviation analysis result of a current feedback cycle;

[0010] The FPGA processing unit is also used to generate a feedback control amount according to the deviation analysis result, so as to adjust the laser based on the feedback control amount in the next feedback cycle to achieve accurate tracking of the laser output waveform to the target waveform.

[0011] Optionally, the system further comprises:

[0012] The DAC converter is connected to the FPGA processing unit to convert the feedback control quantity generated by the FPGA processing unit into an analog control signal and output it to the laser driver to adjust the pulse output parameters of the laser in the Burst mode in real time.

[0013] Optionally, the digital signal processor performs least square matching between the reconstructed waveform and the target waveform, calculates a waveform similarity index and a characteristic deviation between the reconstructed waveform and the target waveform, and implements deviation analysis.

[0014] Optionally, three parallel threads are set up inside the FPGA processing unit: TDC digital time conversion processing, waveform reconstruction and feedback control; the TDC digital time conversion processing thread is used to capture and store waveform reconstruction parameters from the digital waveform signal in real time, and the waveform reconstruction parameters include pulse width and rise / fall time; the waveform reconstruction thread is used to calculate the optical pulse shape based on the waveform reconstruction parameters and the slope of the reference voltage threshold signal, and perform waveform reconstruction; the feedback control thread is used to quantify the deviation analysis results of the current feedback cycle into multi-dimensional deviation parameters, search the preset PID parameter mapping table according to each deviation parameter to match the PID coefficient corresponding to each deviation parameter, adjust the PID algorithm according to the obtained PID coefficient combination, and generate the feedback control amount of the next feedback cycle based on the adjusted PID algorithm.

[0015] Optionally, the deviation analysis result includes one or more of rising edge slope error, peak power deviation, correlation coefficient, normalized Euclidean distance, amplitude deviation, and phase offset.

[0016] Optionally, the FPGA processing unit is also used to record historical adjustment data, which includes PID coefficient combinations and corresponding deviation convergence speeds, fit the system response model through the least squares method according to the historical adjustment data, and periodically optimize the PID coefficient combination based on the system response model.

[0017] Another aspect of the present invention provides a laser feedback adjustment method based on pulse waveform monitoring, the method comprising:

[0018] The laser output of the laser is divided into a main output beam and a monitoring beam based on a beam splitter built into the laser, and the monitoring beam is photoelectrically converted into a monitoring electrical signal based on a detector built into the laser;

[0019] Comparing the monitoring electrical signal with a preset periodic reference voltage threshold signal, and outputting a high level when the monitoring electrical signal is greater than the reference voltage threshold signal to generate a digital waveform signal containing pulse width modulation information;

[0020] Calculating waveform reconstruction parameters in real time according to the digital waveform signal based on TDC digital time conversion technology, and performing waveform reconstruction based on the waveform reconstruction parameters to generate a reconstructed waveform;

[0021] Performing deviation analysis on the reconstructed waveform and the target waveform to obtain a deviation analysis result of the current feedback cycle;

[0022] A feedback control amount is generated according to the deviation analysis result, so that the laser can be adjusted based on the feedback control amount in the next feedback cycle to achieve accurate tracking of the laser output waveform to the target waveform.

[0023] Optionally, performing deviation analysis on the reconstructed waveform and the target waveform includes:

[0024] The reconstructed waveform is matched with the target waveform by least squares, and the waveform similarity index and characteristic deviation between the reconstructed waveform and the target waveform are calculated to realize deviation analysis.

[0025] Optionally, the real-time calculation of waveform reconstruction parameters according to the digital waveform signal based on the TDC digital time conversion technology includes: capturing and storing waveform reconstruction parameters from the digital waveform signal in real time, the waveform reconstruction parameters including pulse width and rise / fall time, to implement TDC digital time conversion processing;

[0026] Reconstructing the waveform based on the waveform reconstruction parameter to generate a reconstructed waveform includes: calculating the shape of the optical pulse based on the waveform reconstruction parameter and the slope of the reference voltage threshold signal to achieve waveform reconstruction;

[0027] Generate feedback control quantity based on deviation analysis results: This includes quantifying the deviation analysis results of the current feedback cycle into multi-dimensional deviation parameters, searching the preset PID parameter mapping table according to each deviation parameter to match the PID coefficient corresponding to each deviation parameter, adjusting the PID algorithm based on the obtained PID coefficient combination, and generating the feedback control quantity for the next feedback cycle based on the adjusted PID algorithm to achieve feedback control;

[0028] The TDC digital time conversion processing, waveform reconstruction and feedback control are implemented through three parallel threads.

[0029] Optionally, the method further includes:

[0030] Record historical adjustment data, including PID coefficient combinations and corresponding deviation convergence speeds; fit the system response model using the least squares method based on the historical adjustment data, and periodically optimize the PID coefficient combination based on the system response model.

[0031] The laser feedback adjustment method and system based on pulse waveform monitoring provided by the embodiment of the invention integrate the collection optical path composed of a beam splitter and a detector into the interior of the laser, with high integration, which can improve the stability of the collection system and reduce implementation costs; further, the laser control software inside the FPGA processing unit is directly used to monitor the internal pulse waveform of the laser in real time, and a feedback control amount is generated based on the deviation analysis results between the detection results and the target waveform. In conjunction with the burst height editing function, the laser is adjusted based on the feedback control amount in the next feedback cycle to achieve accurate tracking of the laser output waveform to the target waveform. The present invention does not require human intervention, realizes the automatic feedback and real-time adjustment functions of the laser, and greatly improves the convenience of use.

[0032] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are specifically listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Various other advantages and benefits will become apparent to those skilled in the art by reading the detailed description of the preferred embodiment below. The accompanying drawings are only for the purpose of illustrating the preferred embodiment and are not to be considered as limiting the present invention. In the accompanying drawings:

[0034] Figure 1 Schematic diagram of a laser feedback adjustment system based on pulse waveform monitoring according to an embodiment of the present invention;

[0035] Figure 2 Schematic diagram of the internal software processing logic of the FPGA processing unit in an embodiment of the present invention;

[0036] Figure 3 The figure is a flow chart of a laser feedback adjustment method based on pulse waveform monitoring according to an embodiment of the present invention. DETAILED DESCRIPTION

[0037] Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0038] Those skilled in the art will understand that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by those skilled in the art in the art to which the present invention pertains. It should also be understood that terms such as those defined in common dictionaries should be understood to have meanings consistent with those in the context of the prior art and, unless specifically defined, will not be interpreted in an idealized or overly formal sense.

[0039] To address the problems in the above-mentioned background technology, the present invention provides a laser feedback adjustment method and system based on pulse waveform monitoring, which can stably and cost-effectively achieve accurate tracking of the laser output waveform to the target waveform. To clearly explain the present invention, the technical solutions in the embodiments of the present invention are further described in detail below with reference to specific embodiments in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are only intended to explain the present invention and are not intended to limit the invention.

[0040] Figure 1The schematic diagram of a laser feedback adjustment system based on pulse waveform monitoring in an embodiment of the present invention is shown. The embodiment of the present invention provides a laser feedback adjustment system based on pulse waveform monitoring, including a beam splitter 10, a detector 20, a comparator 30, an FPGA processing unit 40, and a digital signal processor 50. The beam splitter 10 and the detector 20 are built into the laser to form a monitoring beam collection optical path integrated into the system, resulting in high integration and good system stability. The beam splitter 10 divides the laser output by the laser into a main output beam and a monitoring beam. The detector 20 can be a high-speed detector, which is used to receive and collect the monitoring beam split by the beam splitter 10 and perform photoelectric conversion processing to obtain a monitoring electrical signal. The output end of the detector 20 is connected to the positive end of the comparator 30 to connect the monitoring electrical signal output by the detector to the positive end of the comparator 30. The negative end of the comparator 30 is connected to the FPGA processing unit 40 to access a pre-configured periodic reference voltage threshold signal. The comparator compares the two input signals in real time. When the positive end input signal is greater than the negative end reference voltage threshold, it outputs a high level and adopts a hysteresis comparison design to prevent signal jitter. Finally, it outputs a digital waveform signal containing pulse width modulation (PWM) information. The waveform envelope can accurately reflect the time domain characteristics of the laser pulse, and at the same time outputs a zero-crossing detection signal as a time reference. The output of the comparator 30 is connected to an FPGA processing unit 40. The FPGA processing unit 40 is configured to calculate waveform reconstruction parameters for optical pulse reconstruction in real time based on the digital waveform signal output by the comparator 30 and the zero-crossing detection signal using TDC digital time conversion technology. The waveform reconstruction algorithm is then used to reconstruct the waveform based on the waveform reconstruction parameters to generate a reconstructed waveform, thereby restoring the original optical pulse shape. A digital signal processor 50 is connected to the FPGA processing unit 40 to perform deviation analysis between the reconstructed waveform generated by the FPGA processing unit 40 and the target waveform, obtaining a deviation analysis result for the current feedback cycle and returning the deviation analysis result to the FPGA processing unit 40 for the FPGA processing unit 40 to generate a feedback control variable based on the deviation analysis result. The feedback control variable is then used to adjust the laser in the next feedback cycle to ensure that the laser output waveform accurately tracks the target waveform.

[0041] The present invention uses a comparator with a hysteresis comparison design to prevent signal jitter, so that the final output digital waveform signal can accurately reflect the time domain characteristics of the laser pulse. It not only achieves high-resolution and wide-range pulse waveform capture, but also realizes automatic feedback of pulse height without the need for external detector calibration.

[0042] Specifically, the beam splitter 10 may be a 90:10 ratio beam splitter, wherein the main output beam accounts for 90% of the total output and the monitoring beam accounts for 10% of the total output. The detector 20 is implemented as a high-speed detector.

[0043] Furthermore, the reference voltage threshold signal can be updated and optimized according to the adjusted laser output waveform to ensure that the waveform envelope output by the comparator can accurately reflect the time domain characteristics of the laser pulse.

[0044] In this embodiment, the digital waveform signal output by the comparator 30 is transmitted to the FPGA processing unit. The FPGA processing unit performs high-precision time measurement based on time-to-digital conversion (TDC) technology, and uses an interpolation algorithm to improve the time resolution to the picosecond level. The waveform reconstruction algorithm restores the original optical pulse shape and calculates key parameters such as pulse width and rise / fall time in real time. In a specific example, the specific implementation method for calculating waveform reconstruction parameters based on TDC digital time conversion technology is as follows: the optical pulse waveform reconstruction parameters are calculated based on signal input and triggering mechanisms. Specifically, the start signal (Start) is triggered by the edge of the digital waveform output by the comparator when the optical pulse arrives (such as a rising edge), and the stop signal (Stop) is triggered by the zero-crossing detection signal (i.e., when the optical pulse energy decays to zero). By measuring the time interval (TimeInterval) between the "start-stop" signals, the width or phase information of the optical pulse is directly corresponding.

[0045] In this embodiment, to ensure high-precision control and stability of the laser feedback regulation system, each feedback cycle is shorter than the laser pulse interval, preferably less than or equal to 1 / 10 of the laser pulse interval. Specifically, tasks such as signal acquisition, algorithm calculation, and drive response must be completed within the laser pulse interval. Using a 10:1 cycle ratio (for example, a 100ns pulse must be processed within 10ns) allows the system to execute multiple feedback regulation cycles within a single pulse interval, ensuring real-time response.

[0046] The laser feedback adjustment system based on pulse waveform monitoring provided by the present invention integrates an acquisition optical path consisting of a beam splitter and a detector into the interior of the laser, thereby achieving high integration, improving the stability of the acquisition system, and reducing implementation costs. Furthermore, the laser control software within the FPGA processing unit directly monitors the internal pulse waveform of the laser in real time, and generates a feedback control amount based on the deviation analysis results between the detection results and the target waveform. In conjunction with the burst height editing function, the laser is adjusted based on the feedback control amount in the next feedback cycle to achieve accurate tracking of the laser output waveform to the target waveform.

[0047] This method replaces the conventional method of using high-speed photodetectors and high-bandwidth oscilloscopes to acquire ultrafast laser output light pulses. It offers high stability and low cost. The acquisition clock is synchronized with the laser's mode-locked seed and the laser pulse phase, resulting in low waveform phase noise. This method directly acquires the laser's internal waveform in real time through the laser control software built into the FPGA processing unit. Combined with the burst height editing function, this method eliminates the need for manual intervention, enabling automatic feedback and real-time adjustment of the laser, significantly improving ease of use.

[0048] In one embodiment of the present invention, the system further includes a DAC converter 60, which is connected to the FPGA processing unit 40 and is used to convert the feedback control quantity generated by the FPGA processing unit into an analog control signal and output it to the laser driver to adjust the pulse output parameters of the laser in the Burst mode in real time.

[0049] The laser feedback regulation system of an embodiment of the present invention uses closed-loop control to perform dynamic adjustment. The feedback control quantity in the digital mode is converted into an analog control signal through DAC conversion and then output to the laser driver. The pulse parameters in the Burst mode, including pulse amplitude, repetition frequency and duty cycle, are adjusted in real time. The power output stage uses feedforward compensation to improve the response speed, further achieving accurate tracking of the output waveform with the target waveform.

[0050] In one embodiment of the present invention, the digital signal processor 50 performs least square matching between the reconstructed waveform and the target waveform, calculates the waveform similarity index and characteristic deviation between the reconstructed waveform and the target waveform, and implements deviation analysis.

[0051] In a specific example, a digital signal processor (DSP) can be integrated into the FPGA processing unit, and the digital signal processor (DSP) performs deviation comparison analysis, specifically by performing least square matching between the reconstructed waveform and the target model, calculating the waveform similarity index and characteristic deviation, so that the FPGA processing unit can generate feedback control quantity through an adaptive PID algorithm. Furthermore, predictive compensation control can be performed considering system delay. Among them, the deviation analysis results include one or more of the rising edge slope error, peak power deviation, correlation coefficient, normalized Euclidean distance, amplitude deviation, and phase offset. The waveform similarity index includes indicators such as the correlation coefficient and the normalized Euclidean distance, and the characteristic deviation includes parameters such as the rising edge slope error, peak power deviation, amplitude deviation, and phase offset.

[0052] In one embodiment of the present invention, the FPGA processing unit 40 internally includes three parallel threads: TDC digital time conversion processing, waveform reconstruction, and feedback control. These threads are synchronized using a parallel pipeline. Specifically, the TDC digital time conversion processing thread is used to capture waveform reconstruction parameters from the digital waveform signal in real time and store them in a ring buffer. The waveform reconstruction parameters include pulse width and rise / fall time. The waveform reconstruction thread is used to calculate the optical pulse shape based on the slope of the waveform reconstruction parameters and the reference voltage threshold signal (k = \Delta V / \Delta tk = ΔV / Δt) and perform waveform reconstruction. The feedback control thread is used to quantify the deviation analysis results of the current feedback cycle into multidimensional deviation parameters, search a preset PID parameter mapping table for each deviation parameter to match the corresponding PID coefficient, adjust the PID algorithm based on the obtained PID coefficient combination, and generate the feedback control variable for the next feedback cycle based on the adjusted PID algorithm. The PID parameter mapping table includes the corresponding relationship between each deviation parameter and the PID coefficient. For example, if the rising edge is too slow based on the rising edge slope error, the corresponding item in the PID parameter mapping table is to increase the differential term weight.

[0053] Figure 2 FIG. 1 is a diagram showing the internal software processing logic of the FPGA processing unit in an embodiment of the present invention. Figure 2 As shown, the target waveform is preloaded for subsequent deviation analysis, and a periodically cyclic reference voltage threshold signal is initialized and configured. The reference voltage threshold signal is converted from digital to analog by a DAC converter and then connected to the negative terminal of the comparator. The digital waveform signal output by the comparator is monitored. When a pulse is detected, the timestamp is collected to calculate the waveform reconstruction parameters, and the current pulse waveform is reconstructed. The reconstructed waveform is analyzed for deviation with the target waveform by DSP to obtain the deviation analysis result of the current feedback cycle. Then, a feedback control amount is generated based on the deviation analysis result to adjust the laser based on the feedback control amount in the next feedback cycle to achieve accurate tracking of the laser output waveform with the target waveform. Furthermore, the reference voltage threshold signal is optimized based on the adjusted laser output waveform to ensure that the waveform envelope output by the comparator can accurately reflect the time domain characteristics of the laser pulse.

[0054] Specifically, when making feedback decisions and executions, the feedback control thread quantifies the deviation analysis results between the reconstructed waveform and the target waveform into multi-dimensional deviation parameters, such as the rising edge slope error and peak power deviation, and then quickly matches the PID coefficients corresponding to each deviation parameter through a table lookup method.

[0055] In one embodiment of the present invention, the FPGA processing unit 40 is further configured to record historical adjustment data, including PID coefficient combinations and corresponding deviation convergence rates, fit the system response model using the least squares method based on the historical adjustment data, and periodically optimize the PID coefficient combinations based on the system response model. Specifically, the present invention records historical adjustment data (such as PID parameters and error convergence rate) after each feedback adjustment cycle, and then uses the least squares method to fit the system response model to achieve periodic optimization of the PID coefficients. In a specific example, the PID coefficients are periodically optimized to perform 10^6 feedback adjustments per cycle, and then the optimal proportional coefficients kP, kI, and kD are recalculated based on the obtained system response model.

[0056] In one embodiment of the present invention, a deep reinforcement learning (DRL) algorithm is employed to achieve self-optimization of PID dynamic parameters. Specifically, using deviation analysis results and error convergence rate as input, an actor-critic network (e.g., the DDPG algorithm) outputs the PID coefficient tuning values ​​ΔKp, ΔKi, and ΔKd in real time, achieving PID coefficient optimization and effectively improving system response speed.

[0057] In other embodiments of the present invention, a machine learning algorithm may be used instead of the PID adaptive adjustment algorithm to handle more complex waveform nonlinear correction requirements.

[0058] The laser feedback regulation system based on pulse waveform monitoring provided by the present invention can also automatically adjust the control strategy by setting priority weights (such as accuracy priority / speed priority) to achieve multi-objective trade-offs. In one specific example, if the user sets the priority weight to accuracy priority, the TDC sampling time can be extended to 2ns resolution, sacrificing 10% throughput. In another specific example, if the user sets the priority weight to speed priority, the pulse interpolation prediction algorithm can be enabled, skipping some reconstruction steps and quickly achieving feedback regulation.

[0059] Figure 3 FIG. 1 is a flow chart of a laser feedback adjustment method based on pulse waveform monitoring according to an embodiment of the present invention. Figure 3 As shown, the laser feedback adjustment method based on pulse waveform monitoring proposed in an embodiment of the present invention includes the following steps:

[0060] S11, splitting the laser output by the laser into a main output beam and a monitoring beam based on a beam splitter built into the laser, and performing photoelectric conversion on the monitoring beam to obtain a monitoring electrical signal based on a detector built into the laser;

[0061] S12, comparing the monitoring electrical signal with a preset periodic reference voltage threshold signal, and outputting a high level when the monitoring electrical signal is greater than the reference voltage threshold signal to generate a digital waveform signal containing pulse width modulation information;

[0062] S13, calculating waveform reconstruction parameters in real time according to the digital waveform signal based on TDC digital time conversion technology, and performing waveform reconstruction based on the waveform reconstruction parameters to generate a reconstructed waveform;

[0063] S14, performing deviation analysis on the reconstructed waveform and the target waveform to obtain a deviation analysis result of the current feedback cycle;

[0064] S15. Generate a feedback control amount according to the deviation analysis result, so as to adjust the laser based on the feedback control amount in the next feedback cycle to achieve accurate tracking of the laser output waveform to the target waveform.

[0065] The laser feedback adjustment method based on pulse waveform monitoring provided by the present invention integrates an acquisition optical path composed of a beam splitter and a detector into the interior of the laser, with high integration, which can improve the stability of the acquisition system and reduce implementation costs. Furthermore, the laser control software inside the FPGA processing unit directly monitors the internal pulse waveform of the laser in real time, and generates a feedback control amount based on the deviation analysis result between the detection result and the target waveform. In combination with the burst height editing function, the laser is adjusted based on the feedback control amount in the next feedback cycle to achieve accurate tracking of the laser output waveform to the target waveform. The present invention does not require human intervention, realizes the automatic feedback and real-time adjustment functions of the laser, and greatly improves the convenience of use.

[0066] In one embodiment of the present invention, the method further includes converting the feedback control variable into an analog control signal and outputting it to the laser driver to adjust the pulse output parameters of the laser in burst mode in real time. The present invention utilizes closed-loop control to perform dynamic adjustment. Specifically, the digital feedback control variable is converted into an analog control signal through DAC conversion and then output to the laser driver. Burst mode pulse parameters, including pulse amplitude, repetition frequency, and duty cycle, are adjusted in real time. Feedforward compensation is employed in the power output stage to improve response speed, further enabling the output waveform to accurately track the target waveform.

[0067] In one embodiment of the present invention, the step S13 of calculating the waveform reconstruction parameters in real time according to the digital waveform signal based on the TDC digital time conversion technology specifically includes the following steps (not shown in the drawings):

[0068] S131, capturing waveform reconstruction parameters from the digital waveform signal in real time, the waveform reconstruction parameters including pulse width and rise / fall time, and storing them in a ring buffer to implement TDC digital time conversion processing;

[0069] S132, reconstructing the waveform based on the waveform reconstruction parameter to generate a reconstructed waveform includes: calculating the light pulse shape based on the waveform reconstruction parameter and the slope of the reference voltage threshold signal to achieve waveform reconstruction;

[0070] S133. Generating a feedback control variable based on the deviation analysis result: This includes quantifying the deviation analysis result of the current feedback cycle into multi-dimensional deviation parameters, searching a preset PID parameter mapping table according to each deviation parameter to match the PID coefficient corresponding to each deviation parameter, adjusting the PID algorithm according to the obtained PID coefficient combination, and generating the feedback control variable for the next feedback cycle based on the adjusted PID algorithm to implement feedback control;

[0071] The TDC digital time conversion processing, waveform reconstruction and feedback control are implemented through three parallel threads, so as to achieve parallel synchronization by adopting a parallel pipeline method.

[0072] In one embodiment of the present invention, step S14 of performing deviation analysis on the reconstructed waveform and the target waveform specifically includes: performing least square matching on the reconstructed waveform and the target waveform, calculating the waveform similarity index and characteristic deviation between the reconstructed waveform and the target waveform, and realizing deviation analysis.

[0073] In a specific example, a digital signal processor (DSP) can be integrated into the FPGA processing unit, and the digital signal processor (DSP) performs deviation comparison analysis, specifically by performing least square matching between the reconstructed waveform and the target model, calculating the waveform similarity index and characteristic deviation, so that the FPGA processing unit can generate feedback control quantity through an adaptive PID algorithm. Furthermore, predictive compensation control can be performed considering system delay. Among them, the deviation analysis results include one or more of the rising edge slope error, peak power deviation, correlation coefficient, normalized Euclidean distance, amplitude deviation, and phase offset. The waveform similarity index includes indicators such as the correlation coefficient and the normalized Euclidean distance, and the characteristic deviation includes parameters such as the rising edge slope error, peak power deviation, amplitude deviation, and phase offset.

[0074] In one embodiment of the present invention, the method further includes a step of periodically optimizing the PID coefficients, specifically including: recording historical adjustment data, the historical adjustment data including PID coefficient combinations and corresponding deviation convergence speeds; fitting a system response model using a least squares method according to the historical adjustment data, and periodically optimizing the PID coefficient combinations based on the system response model.

[0075] Specifically, the present invention records historical adjustment data (such as PID parameters and error convergence rate) after each feedback adjustment cycle. It then uses the least squares method to fit the system response model to achieve periodic optimization of the PID coefficients. In one specific example, the PID coefficients are periodically optimized, performing 10^6 feedback adjustments per cycle. The optimal proportional coefficients (kP, kI, and kD) are then recalculated based on the resulting system response model.

[0076] In one embodiment of the present invention, a deep reinforcement learning (DRL) algorithm is employed to achieve self-optimization of PID dynamic parameters. Specifically, using deviation analysis results and error convergence rate as input, an actor-critic network (e.g., the DDPG algorithm) outputs the PID coefficient tuning values ​​ΔKp, ΔKi, and ΔKd in real time, achieving PID coefficient optimization and effectively improving system response speed.

[0077] The laser feedback adjustment method and system based on pulse waveform monitoring provided by the embodiments of the present invention achieve high-precision control of laser output by using a beam splitter and detector to convert optical to electrical signals, a comparator to implement time encoding, and real-time digital reconstruction of the pulse waveform and closed-loop feedback through laser control software within the FPGA processing unit. By synergizing high-speed signal processing with real-time feedback, the present invention ensures that the output waveform closely tracks the target model without manual intervention, achieving automatic feedback and real-time adjustment of the laser, greatly improving its ease of use.

[0078] Furthermore, those skilled in the art will appreciate that although some embodiments herein include certain features included in other embodiments but not other features, combinations of features from different embodiments are intended to be within the scope of the present invention and to form different embodiments. For example, any of the claimed embodiments may be used in any combination.

[0079] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A laser feedback adjustment system based on pulse waveform monitoring, characterized in that: The system comprises: The beam splitter and detector are built into the laser. The beam splitter splits the laser output into a main output beam and a monitoring beam. The detector collects the monitoring beam and performs photoelectric conversion to obtain a monitoring electrical signal. A comparator, wherein the positive terminal of the comparator is connected to the detector to receive the monitoring electrical signal output by the detector, and the negative terminal of the comparator is connected to a preset periodic reference voltage threshold signal so that the comparator outputs a digital waveform signal containing pulse width modulation information; an FPGA processing unit connected to the output end of the comparator, for calculating waveform reconstruction parameters in real time according to the digital waveform signal output by the comparator based on TDC digital time conversion technology, and performing waveform reconstruction based on the waveform reconstruction parameters to generate a reconstructed waveform; a digital signal processor connected to the FPGA processing unit, for performing deviation analysis between the reconstructed waveform generated by the FPGA processing unit and the target waveform, and obtaining a deviation analysis result of a current feedback cycle; The FPGA processing unit is also used to generate a feedback control amount according to the deviation analysis result, so as to adjust the laser based on the feedback control amount in the next feedback cycle to achieve accurate tracking of the laser output waveform to the target waveform.

2. The system according to claim 1, wherein: The system further comprises: The DAC converter is connected to the FPGA processing unit to convert the feedback control quantity generated by the FPGA processing unit into an analog control signal and output it to the laser driver to adjust the pulse output parameters of the laser in the Burst mode in real time.

3. The system according to claim 1, wherein: The digital signal processor performs least square matching between the reconstructed waveform and the target waveform, calculates the waveform similarity index and characteristic deviation between the reconstructed waveform and the target waveform, and realizes deviation analysis.

4. The system according to claim 1, wherein: The FPGA processing unit is internally provided with three parallel threads: TDC digital time conversion processing, waveform reconstruction, and feedback control. The TDC digital time conversion processing thread is used to capture and store waveform reconstruction parameters from the digital waveform signal in real time. The waveform reconstruction parameters include pulse width and rise / fall time. The waveform reconstruction thread is used to calculate the optical pulse shape based on the waveform reconstruction parameters and the slope of the reference voltage threshold signal, and perform waveform reconstruction. The feedback control thread is used to quantify the deviation analysis results of the current feedback cycle into multi-dimensional deviation parameters, search the preset PID parameter mapping table according to each deviation parameter to match the PID coefficient corresponding to each deviation parameter, adjust the PID algorithm according to the obtained PID coefficient combination, and generate the feedback control amount of the next feedback cycle based on the adjusted PID algorithm.

5. The system according to claim 4, characterized in that The deviation analysis result includes one or more of rising edge slope error, peak power deviation, correlation coefficient, normalized Euclidean distance, amplitude deviation, and phase offset.

6. The system according to claim 4, characterized in that The FPGA processing unit is also used to record historical adjustment data, which includes PID coefficient combinations and corresponding deviation convergence speeds. The system response model is fitted using the least squares method based on the historical adjustment data, and the PID coefficient combination is periodically optimized based on the system response model.

7. A laser feedback adjustment method based on pulse waveform monitoring, characterized in that: The method comprises: The laser output of the laser is divided into a main output beam and a monitoring beam based on a beam splitter built into the laser, and the monitoring beam is photoelectrically converted into a monitoring electrical signal based on a detector built into the laser; Comparing the monitoring electrical signal with a preset periodic reference voltage threshold signal, and outputting a high level when the monitoring electrical signal is greater than the reference voltage threshold signal to generate a digital waveform signal containing pulse width modulation information; Calculating waveform reconstruction parameters in real time according to the digital waveform signal based on TDC digital time conversion technology, and performing waveform reconstruction based on the waveform reconstruction parameters to generate a reconstructed waveform; Performing deviation analysis on the reconstructed waveform and the target waveform to obtain a deviation analysis result of the current feedback cycle; A feedback control amount is generated according to the deviation analysis result, so that the laser can be adjusted based on the feedback control amount in the next feedback cycle to achieve accurate tracking of the laser output waveform to the target waveform.

8. The method according to claim 7, characterized in that The performing deviation analysis on the reconstructed waveform and the target waveform includes: The reconstructed waveform is matched with the target waveform by least squares, and the waveform similarity index and characteristic deviation between the reconstructed waveform and the target waveform are calculated to realize deviation analysis.

9. The method according to claim 7, characterized in that The real-time calculation of waveform reconstruction parameters according to the digital waveform signal based on the TDC digital time conversion technology includes: capturing and storing waveform reconstruction parameters from the digital waveform signal in real time, the waveform reconstruction parameters including pulse width and rise / fall time, and implementing TDC digital time conversion processing; Reconstructing the waveform based on the waveform reconstruction parameter to generate a reconstructed waveform includes: calculating the shape of the optical pulse based on the waveform reconstruction parameter and the slope of the reference voltage threshold signal to achieve waveform reconstruction; Generate feedback control quantity based on deviation analysis results: This includes quantifying the deviation analysis results of the current feedback cycle into multi-dimensional deviation parameters, searching the preset PID parameter mapping table according to each deviation parameter to match the PID coefficient corresponding to each deviation parameter, adjusting the PID algorithm based on the obtained PID coefficient combination, and generating the feedback control quantity for the next feedback cycle based on the adjusted PID algorithm to achieve feedback control; The TDC digital time conversion processing, waveform reconstruction and feedback control are implemented through three parallel threads.

10. The method according to claim 9, characterized in that The method further comprises: Record historical adjustment data, including PID coefficient combinations and corresponding deviation convergence speeds; fit the system response model using the least squares method based on the historical adjustment data, and periodically optimize the PID coefficient combination based on the system response model.

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