Carbon dioxide laser beam shaping method

Abstract

The invention relates to the technical field of laser beam shaping, discloses an active test method and system for a circuit breaker, and is used for solving the problem that the self-adaptive shaping capability of a CO2 laser beam is difficult to improve by the existing method. Firstly, a stable light path is constructed, and the stability of the light path is ensured through mechanical limiting, a thermal management module and multi-stage optical alignment; then low-power calibration is carried out, a deformable mirror initial driving table is generated through a least square inversion algorithm, and a flat-topped beam reference is established; data are collected through a wavefront sensor, a high-order mode is reconstructed, the voltage of a deformable mirror is dynamically refreshed, and wavefront control and scanning motion synchronization is ensured in combination with scanning galvanometer time sequence synchronization, closed-loop control and exception handling; monitoring the temperature of the deformable mirror, starting water-cooling adjustment, and correcting the driving table to cope with the heat effect; finally, a safety system is constructed, laser power, wavefront distortion and deformable mirror stroke parameters are monitored, dry gas purging is conducted on the diffractive optical element regularly, and safety guarantee and performance verification of the whole process are achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of laser beam shaping, in particular to a carbon dioxide laser beam shaping method. BACKGROUND

[0002] The carbon dioxide laser treatment machine is a medical device based on carbon dioxide laser technology and with a wavelength of 10.6 μm, belonging to the far infrared band. Its core principle is to use the strong absorption of water molecules in tissues by laser to achieve precise cutting, vaporization or coagulation of soft tissues through thermal effect. This device is widely used in dermatology, surgery, ear-nose-throat, gynecology and other fields. With the advantages of high precision, less bleeding during operation, fast postoperative recovery and less scar formation, it is especially suitable for medical scenarios that require delicate operation and has become an important non-invasive or minimally invasive treatment tool in clinical practice. However, the host of such systems has low transmittance at 10.6 μm and insufficient power tolerance, resulting in the mid-infrared region still remaining in the low-power experimental stage. Some studies use electro-optical modulators or digital servo galvanometer synchronous power modulation to indirectly compensate for the energy density fluctuations during scanning, but due to the limitations of electrical and optical conversion efficiency, crystal aperture and driving bandwidth, it is difficult to achieve precise closed-loop control for multi-mode or pulse train waveforms, and the output uniformity still fluctuates by more than 10% with the scanning angle and power drift. Even the recent emergence of mid-infrared focusing schemes based on microlens arrays or adaptive fiber end faces still limits the synchronous control accuracy to single focal length or divergence angle adjustment, and cannot achieve spatial, temporal and polarization integrated dynamic shaping under complex working conditions.

[0003] Therefore, the prior art still lacks a method that is compact in structure, fast in response, resistant to high power, stable in operation, and capable of multi-degree-of-freedom closed-loop control. The existing method has insufficient CO2 laser beam adaptive shaping capability, which cannot meet the future demand for high power, multi-mode, and continuous adjustment of spot energy density and morphology. SUMMARY

[0004] (I) Technical problems to be solved

[0005] In view of the deficiencies of the prior art, the present application provides a carbon dioxide laser beam shaping method to solve the problem that the existing method cannot improve the CO2 laser beam adaptive shaping capability.

[0006] (II) Technical solutions

[0007] To achieve the purpose of improving the CO2 laser beam adaptive shaping capability mentioned in the background art, the present application provides the following technical solutions:

[0008] A carbon dioxide laser beam shaping method, comprising:

[0009] S1: sequentially coaxially arrange the beam expander, the diffractive optical element, the deformable mirror, the sampling wedge and the scanning galvanometer on the stable mechanical platform to construct a stable optical path;

[0010] S2: under the condition of a low-power calibration beam, measure the initial wavefront distortion by a wavefront sensor, generate an initial driving table of the deformable mirror by a least square inversion algorithm, and establish a flat-top beam reference;

[0011] S3: real-time collect wavefront data and reconstruct high-order Zernike polynomial modes, and dynamically refresh the driving voltage vector of the deformable mirror;

[0012] S4: monitor the temperature of the deformable mirror base, set a threshold for starting water cooling adjustment, and synchronously correct the focal length control vector in the driving table according to an empirical model of thermal lens effect;

[0013] S5: obtain the real-time deflection angle of the scanning galvanometer, calculate the defocus amount caused by the change of the optical path length, and pre-load a phase compensation amount in the driving voltage of the deformable mirror;

[0014] S6: input the laser power, the wavefront distortion parameter and the driving stroke data of the deformable mirror into a controller, set an emergency shutdown mechanism triggered when the parameters exceed the limit, and periodically perform dry gas blowing on the surface of the diffractive optical element.

[0015] Further, in step S2, the following is included:

[0016] Build a honeycomb platform in a constant-temperature and constant-humidity, laminar flow filtered optical room, reduce the output power of the CO2 laser to one percent of the rated power through a variable attenuator, and ensure that the sampling time stamps of each channel are consistent;

[0017] Turn off the galvanometer scanning, only keep the low-power calibration beam passing through the shaping optical path, collect at least one thousand frames of focal spot centroid data using a kHz frame rate Shack-Hartmann sensor, and convert the data into high-order Zernike coefficients online;

[0018] Apply small amplitude step bias to all execution elements of the deformable mirror in channel order, immediately record the corresponding Zernike vector after each bias, splice the Zernike vectors into a response matrix, and insert a short cooling delay between two driving operations;

[0019] Keep the low-power output running continuously for several minutes, real-time monitor the wavefront RMS and energy uniformity, when the RMS drops below the system set value and the energy uniformity significantly improves, it is considered that the reference is successfully established, if the RMS rebounds within several frames, the controller immediately switches to the safe driving table and shuts down the shutter.

[0020] Further, in step S3, the following is included:

[0021] High-speed Shack-Hartmann sensor is fixed on the sampling wedge reflection branch, and the centroid matrix of the focal spot is synchronously acquired every frame, the sensor uses high-speed CMOS to read out and completes the center positioning preprocessing at the hardware level, and the FPGA triggers the sampling uniformly;

[0022] The centroid data enters the special logic array, is first mapped into the local wavefront slope, and then is reorganized into the Zernike coefficient of 13 orders or more through the pre-stored orthogonal basis transformation table, and the edge sub-aperture with no signal-to-noise ratio is automatically removed;

[0023] The latest Zernike coefficient is sent to the control core, and the voltage increment is directly obtained by looking up the response matrix corresponding to the line generated in the static calibration stage, then the control core is vector accumulated with the baseline table saved in the previous frame, and is written into the high-resolution DAC after comparing the boundary threshold.

[0024] Further, comprising:

[0025] The real-time calculated wavefront residual is sent to the adaptive gain module, and the residual change is observed;

[0026] Double safety protection is set in the system, and the power meter and the thermal imager are set to cross-verify and correct the effectiveness of the system;

[0027] A full hardware pipeline and a multi-level fault-tolerant logic are set, and the real-time wavefront residual is suppressed within the design threshold.

[0028] Further, in step S4, comprising:

[0029] The resistance temperature sensor is uniformly arranged at the center and the diagonal position of the deformable mirror base, and the sensor is adhered to the base through the heat-conducting insulating adhesive;

[0030] An analog signal output by each temperature sensor is collected to generate digital temperature data, and a first temperature threshold and a second temperature threshold are pre-stored in the digital temperature data;

[0031] An empirical data table of thermal lens effect stored in the programmable logic device is generated, and the data table is repaired according to the focal length correction amount corresponding to the temperature interval;

[0032] The digital temperature data is periodically read, the lookup table logic of the empirical data table of thermal lens effect is called, and the focal length correction amount obtained by the lookup table logic is written into the corresponding entry of the focal length control vector of the deformable mirror driving lookup table;

[0033] The driving vector refresh logic is synchronized with the lookup table logic, and the updated driving lookup table is written into the deformable mirror driving circuit in the same clock domain.

[0034] Further, in step S5, comprising:

[0035] Dual-axis galvanometer is equipped with absolute or incremental optical encoder respectively, the encoder is rigidly coaxial with the galvanometer axis, angle data is connected with the controller through differential serial bus and is triggered to sample in the unified clock domain of the device;

[0036] The controller pre-stores scanning geometric model parameters matched with the scanning focusing objective lens used, and maps the galvanometer deflection angle to the change of image plane position and focusing position;

[0037] The controller sets up an angle and defocus amount lookup table, which is indexed by the combined deflection angle of the galvanometer, outputs the corresponding defocus amount in an interpolation manner, and is stored in accordance with a monotonic sequence of scanning angles;

[0038] The controller sets up a defocus amount and phase compensation amount lookup table corresponding to the focal length control mode of the deformable mirror, and the lookup table is calibrated according to the controllable mode of the deformable mirror, which includes the main spherical aberration and high-order spherical aberration components related to focusing.

[0039] Further, comprising:

[0040] The controller sets up multi-source write arbitration logic to complete the accumulation and refresh of the deformable mirror drive vector in a preset priority order, and the priority order is determined by the scheduling strategy of the controller, and the timestamp alignment is completed in the same clock domain;

[0041] The deformable mirror drive circuit is jointly constituted by a digital-to-analog converter and a parallel channel driver, the controller writes the arbitrated drive vector into the digital-to-analog converter before the end of each sampling period, and generates a synchronization flag after the writing is completed;

[0042] The controller sets up angle out-of-bound and phase amplitude monitoring thresholds;

[0043] The controller sets up angle speed upper limit and angle acceleration upper limit determination logic, and the upper limit values are determined according to the galvanometer servo control characteristics;

[0044] The controller sets up an objective lens type identification field, and selects corresponding scanning geometric model and field curvature compensation parameters according to the identification;

[0045] The controller sets up a running log buffer, and outputs it to the upper computer for archiving periodically, and the recording order of the buffer is consistent with the sampling trigger order.

[0046] Further, in step S6, comprising:

[0047] Setting a high-speed analog or digital input port for connecting a thermal power type laser power meter;

[0048] Setting a data acquisition interface matched with a Shack-Hartmann wavefront sensor, and the interface is synchronized with the main clock of the device;

[0049] Setting a stroke monitoring channel connected with the feedback bus of the deformable mirror driver to form the stroke parameter of the deformable mirror and compare it with the safety threshold in the controller;

[0050] Configuring the programmable logic controller as the interlocking core, the controller reads the laser power, the wavefront distortion parameter and the stroke of the deformable mirror in turn according to a fixed scanning period, performs threshold comparison and logical OR operation, and outputs the shutdown instruction when the shutdown condition is met;

[0051] The interlocking loop meets the requirements of the laser product safety standard on environmental conditions, single-point failure and protective interlocking;

[0052] A parameterizable confirmation timer is set in the controller, which starts the delay confirmation after detecting that any monitored quantity exceeds the corresponding threshold, and outputs the shutdown signal when it is still in the over-limit state at the end of the confirmation period;

[0053] The time reference of the confirmation timer is consistent with the sampling clock.

[0054] Further, comprising:

[0055] Setting clean dry air or nitrogen as the purge medium, and configuring a filtration, pressure reduction and dew point control module;

[0056] Setting a mass flow meter and an electromagnetic valve in the purge branch, preferably using a Coriolis mass flow meter to balance the response speed and measurement accuracy;

[0057] Setting an annular or multi-point distribution nozzle circumferentially around the diffractive optical element, and a pressure switch or differential pressure switch in the gas circuit;

[0058] Setting a humidity sensor at the optical cavity or device environment, and the controller adjusts the purge cycle and duration within the set range according to the humidity data, shortens the purge interval when the humidity exceeds the set threshold, and records the humidity data and the purge event together;

[0059] Setting a running log buffer to record the laser power, wavefront distortion parameter, deformable mirror stroke, interlocking state, purge flow and dew point information at a fixed period, and long-term archive through the upper computer or database interface;

[0060] Configuring a human-machine interface to display the real-time values and thresholds of the three types of monitored quantities, and providing a manual purge button and an interlocking reset button.

[0061] Compared with the prior art, the present application provides a carbon dioxide laser beam shaping method, which has the following beneficial effects:

[0062] 1. The microcomputer electromechanical deformation mirror is matched with the Shack-Hartmann wavefront sensor of fast frame rate to form a self-adaptive loop, the MEMS deformation mirror has a mechanical response of microsecond level and an update capacity of kilohertz level, which is significantly higher than the refresh rate of the traditional low-frequency adaptive scheme, and covers the rapid aberration fluctuation caused by the galvanometer scanning; the incidence angle and the image plane position are approximately linearly corresponding; the design of the objective lens is proportional to the field point position and the incidence angle, and provides an approximately flat field image plane, maps the galvanometer angle to the defocus amount through a geometric model, and then presets the phase compensation on the DM focal length related mode, so that the consistency of the morphology and the energy distribution can be maintained during the large-angle scanning, so that the adaptive shaping ability of the CO2 laser beam is improved.

[0063] 2. The CO2 laser is prone to cause thermal lens effect during long-time operation, and the thermal-optical coefficient of the medium determines the equivalent focal shift caused by the change of the refractive index with temperature, the thermal-optical coefficient of ZnSe at 10.6 μm is positive, and the temperature rise will change the effective optical path, by arranging multiple point temperature sensors on the base, establishing an empirical data table of temperature-focal length correction amount and writing into a lookup table, the thermal phase can be pre-fed and compensated at the control level, and the influence of thermal drift on uniformity and focal depth is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0064] Figure 1 The flowchart of the CO2 laser beam shaping method is shown in the drawings. DETAILED DESCRIPTION

[0065] The technical solutions in the embodiments of the application will be described clearly and completely in combination with the drawings in the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, not all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the application.

[0066] Please refer to Figure 1 , a kind of active test method for circuit breaker is given, comprising:

[0067] S1: the beam expander, the diffractive optical element, the deformation mirror, the sampling wedge and the scanning galvanometer are coaxially arranged on the stable mechanical platform in sequence, a stable optical path is constructed, and the specific implementation is:

[0068] The system is a high-precision laser transmission and shaping device, which integrates optical, mechanical, control and thermal management multidimensional technology. The optical part adopts a three-piece Galileo beam expander to construct a 3x beam expansion system, with an entrance aperture of 6mm and an exit aperture of 18mm. The surface is coated with a dual-wavelength 9.3μm or 0.6μm AR film. After ZYGO Verifire IR interferometer detection, the wavefront distortion PV value under 10.6μm working condition is better than λ / 12, where λ represents the working wavelength of the laser, which meets the flat-top shaping requirement. The ZnSe diffraction flat-top shaper is designed with a diffraction efficiency of 95% and an anti-damage threshold of ≥15kW / cm 2 After 200W continuous light ablation test for 30 minutes, the surface is not carbonized and the transmission power attenuation is <0.3%. The 140-channel MEMS deformable mirror is scanned by a white light interferometric 3D profiler, and the initial mirror static flatness RMS is <12nm. The wedge-shaped sampling piece has a wedge angle of 2° and an outer diameter of 25.4mm. The reflective surface is coated with gold for enhancement, the sampling ratio is 2%, the working aperture is 20mm, the maximum scanning angle is ±20°, and the dynamic repeatability positioning accuracy is ±20μrad. The double-shaft Galvo mirror scanning head together constitutes the beam transmission end.

[0069] In terms of mechanical structure, the substrate adopts a 25mm thick 6061-T6 aluminum alloy honeycomb optical platform with a surface flatness of ±0.02mm. All adjustment seats are equipped with six-degree-of-freedom precision adjustment frames to ensure the initial positioning accuracy of optical elements. To suppress thermal drift, the DOE, DM and galvanometer are integrated into a 10mm thick Invar-36 modular sub-platform, which is limited by two 6mm stop positioning columns, and the installation and removal error is ≤10μm. The water cooling system uses a 6mm stainless steel corrugated pipe with a quick plug valve, which does not need to drain water when replacing the DOE or DM, and takes into account the thermal management and maintenance convenience.

[0070] The optical alignment process is implemented in stages. First, a cross target sheet is installed at the output end of the CO2 laser, and the initial positioning of the laser center is completed by combining the infrared tracer card with the silicon-based CCD coaxial observer. The input side of the beam expander is assembled concentrically with the laser flange mechanical stop. The concentricity of the four-point contact is detected by a 0-25 mm internal diameter dial gauge, with an error of ≤0.03 mm. Subsequently, a 5 mm pinhole is installed as the optical axis reference at the output side of the beam expander. The position is recorded when the intensity of the three-reflection light is lowest, achieving a straightness of the expanded optical axis of <0.02 mm / 300 mm. When the DOE is installed, it is placed on a high-precision five-phase adjustment rack. The diffraction efficiency is measured by a 100 W low-power transmission and an energy meter. After the first-order diffraction ring disappears, the DOE is locked. The far-field distribution is captured at a distance of 200 mm from the DOE exit surface using a f=200 mm Fourier lens, verifying that the flat-top spot diameter is about 14 mm and the energy uniformity is <8%. When fine-tuning the spacing between the DOE and the DM, the DM is fixed on an adjustable Z-axis translation stage and fine-tuned along the optical axis to a spacing of 50 mm. The wavefront RMS is detected by a 40×40 array Shack-Hartmann sensor, and the wavefront RMS is optimized to be minimal with an energy fluctuation of <5% in the central flat area. The spacing deviation is within ±0.2 mm. In the closed-loop state without enabling, the DM amplitude modulation zero position is calibrated by applying a +0.8 V bias to each channel to make the mirror curvature approach 0D. The PV value is adjusted to within λ / 10 by the wavefront instrument to eliminate the residual phase error of the DOE.

[0071] In the 1kW pulse power incremental test, the DOE surface temperature rise is <2℃, and the DM substrate warping is <λ / 25. In the 2kW continuous wave operation for 4 hours, the exit spot thermal distribution uniformity fluctuation is <±3%. In terms of dynamic scanning control, a 10Hz sinusoidal trajectory is loaded to the galvanometer. Under the condition of 1kHz sampling rate, the first ten Zernike coefficients are captured by the Shack-Hartmann sensor. The recursive least squares plus feedforward compensation is used by the FPGA controller to ensure that the wavefront residual σ≤λ / 18. When the scanning angle reaches ±18°, the flat-top uniformity is ≥88%. When it exceeds ±20°, the LUT-Ⅱ boundary compensation table is enabled. In the final performance verification, the radial gray level fluctuation of the glass target plate focal plane exposure is <±5% after 5 seconds. The qualified rate of 50 samples of single-point scanning and 10mm / s straight-line scanning is 100%. According to the GB / T15498-2018 standard, the full optical path is detected, and the leakage radiation is <0.25W / cm 2 , meeting the 4th level laser protection requirements.

[0072] S2: Under the condition of a low-power calibration beam, the initial wavefront distortion is measured by a wavefront sensor, and the least squares inversion algorithm is used to generate an initial drive table for the deformable mirror. A flat-top beam reference is established. The specific implementation is as follows:

[0073] The system operating environment needs to be strictly controlled at room temperature 22±1℃, relative humidity 40%±5%, to stabilize the air refractive index and avoid wavefront measurement drift, the air flow rate needs to be lower than 0.1m / s, and a local laminar flow hood is opened to cooperate with the HEPA filter device to reduce dust adhesion on the DOE or DM surface, and to ensure the cleanliness of the optical element and the stability of the measurement. The main test equipment includes a Shack-Hartmann wavefront sensor for real-time acquisition of Zernike coefficients, a power attenuator for stable attenuation of 2kW laser to 200W, an FPGA control board for DM voltage output and wavefront data processing, and a 3-12μm infrared thermal imager for monitoring device temperature rise. The above-mentioned devices work together to ensure the test accuracy of wavefront control, power regulation and thermal management.

[0074] The system calibration process first measures the low-power beam output and wavefront. First, turn off the galvanometer scanning function, adjust the Q-switch to continuous wave mode and turn on the water-cooled power attenuator. Confirm that the laser output is stable at 200±2W through the Ophir 10kW power meter. The unit area power of the DM gold-plated surface under an 18mm spot is only about 0.08kW / cm 2 , which is much lower than the 5kW / cm 2 damage threshold, and the Shack-Hartmann sensor can ensure a signal-to-noise ratio >60dB without additional ND filter under this power density; then introduce 2% of the energy reflected by the sampling wedge into the wavefront sensor, set the continuous sampling mode to 1kHz, and record 1024 frames of wavefront data; according to the ISO 10110-5 standard, use Zernike polynomials up to the 13th order for fast decomposition, and statistically obtain the initial wavefront distortion σ0≈0.27λ(RMS), PV≈1.03λ, which is consistent with the upper limit of λ / 4(PV) designed by the system, confirming that further compensation is needed.

[0075] On this basis, the DM initial LUT is generated through the least squares inversion algorithm. First, establish the system response matrix, load +20V positive pulses to the 140 actuators of the DM in turn, and record the corresponding Zernike response vector of each actuator by synchronously sampling 256 frames through the Shack-Hartmann sensor. Each vector contains 55 coefficients, which together form a 55x140 system matrix, denoted as A. Perform SVD decomposition on A:

[0076] A=UΣV T

[0077] Where: U is the left singular vector matrix, Σ is the singular value diagonal matrix, V T is the transpose of the right singular vector matrix; take the first 120 columns of the singular value Σ k >0.1Σmax to construct a truncated matrix The initial wavefront σ0 is processed by a low-pass filter to generate an ideal flat wavefront Wtarget≈0 with the high-order noise suppressed;

[0078] The voltage vector is solved by least square method

[0079]

[0080] Wherein: is the right singular vector matrix at time t, is the inverse matrix of the diagonal singular value matrix, U T is the transpose matrix of the left singular vector matrix, Wtarget is a target weight vector, representing the expected wavefront phase compensation amount;

[0081] And a second-order compensation term is added

[0082] Vcorr=V+αV 2

[0083] Wherein: α≈0.012V-1, determined by the piezoelectric hysteresis curve of Boston Micromachines, used to correct the nonlinear characteristics of the DM, the zero extension of Vcorr is expanded to 140 dimensions and quantified as a 14-bit DAC code value, written into the FPGA BRAM to establish "LUT-0", and the Shack-Hartmann real-time sampling data address is mapped to the DDR3 at the same time, ensuring that the LUT update and data sampling are physically aligned to avoid EMIF timing jitter. After 5 minutes of continuous operation verification, the wavefront RMS is reduced to 0.046λ, the PV is 0.18λ, and the energy uniformity is improved from 8% to 2%, meeting the starting conditions of subsequent kHz-level closed-loop control;

[0084] The SVD decomposition uses 55x140 single-precision floating-point operations, wherein the FPGA-DPU actual measurement time is 14ms; the least square inversion matrix operation is 3ms, and the total processing time is <20ms, meeting the production line rapid re-calibration requirements. The nonlinear compensation coefficient α is derived from the piezoelectric hysteresis curve of the manufacturer, and the selection of the truncation threshold considers the actual effective degrees of freedom of the DM and the low noise of the Shack-Hartmann sensor. After scanning in the range of 0.1-0.15Σmax, the corresponding value that minimizes the wavefront residual σ is selected. If the FPGA interrupt detects that the wavefront RMS is >0.15λ for 10 frames, the system will automatically fall back to the LUT-Safe mode and trigger the light shutter to shut off the laser, ensuring the safety of the equipment under abnormal conditions.

[0085] S3: Real-time acquisition of wavefront data and reconstruction of Zernike polynomial high-order modes, dynamic refresh of deformable mirror drive voltage vector, specific implementation:

[0086] The system workflow covers power ramping, scan synchronization, closed-loop control, exception handling and performance verification links. Firstly, the power ramping and thermal pre-stabilization operation is performed. The laser starts from 200W in the static calibration stage, and the power is gradually increased in steps of 500W (30s)→1kW (30s)→1.5kW (30s)→2kW (steady state). The temperature rise of the deformable mirror substrate and the surface temperature rise of the diffractive optical element are monitored in real time during the power maintaining period of each level to ensure that the temperature rise difference ΔT is less than 3℃. If the limit is exceeded, the power increase is suspended and the stabilization time of the current power level is extended. When the power rises to 2kW steady state, it continues to run for 3 minutes. The maximum warping of the DM mirror is confirmed to be less than λ / 30 by the infrared thermal imager, and the center temperature drift of the DOE is less than 1℃. At the same time, the water cooling system maintains a fixed flow rate of 8L / min. Finally, the system output power fluctuation is verified to be less than ±1.5% by the power meter, which provides a stable thermal environment for the subsequent closed-loop control.

[0087] Subsequently, the galvanometer scanning and timing synchronization operation is carried out. Firstly, the galvanometer controller loads the 8kHz sine front-trapezoidal main scan-cosine tail combined trajectory, the scanning angle is ±18°, the repetition frequency is 100Hz, the system adopts 1MHz reference clock output by FPGA, the galvanometer angle encoder, Shack-Hartmann focal plane array trigger and DM digital analog converter refresh are all synchronized to the clock, the wavefront sampling frame period Ts=1ms, the DM voltage writing delay Td=220μs, the galvanometer angle update delay Tg=70μs, and the total time difference

[0088] ΔTtotal=|Ts-Td-Tg|<0.5ms

[0089] The consistency requirement of wavefront compensation and scanning angle synchronization is met.

[0090] On this basis, the 1kHz closed-loop wavefront control algorithm is realized. Firstly, the Shack-Hartmann sensor outputs 40×40 focal spot centroid coordinates, which are processed by the FPGA DSP core in three steps, and the total time consumption is ≤120μs; the system response matrix A is pre-stored in the Block RAM t and The voltage vector calculation is completed by a 3-stage pipeline multiplication and addition array

[0091]

[0092] The operation is 72μs under the 250MHz vector clock, and then the DM is written and driven by the 14bit DAC. The closed-loop delay is composed of reconstruction, inversion and DAC and driving, and the total τ loop≈220μs, corresponding to the closed-loop cutoff frequency ≈725Hz, which can cover the 100Hz fundamental and the first 7 harmonics of the galvanometer main scanning, ensuring the timing synchronization of the wavefront control and the scanning motion;

[0093] To improve the control stability, the system introduces gain adaptive PID strategy and abnormal switching mechanism: real-time monitoring of wavefront RMS, where the threshold

[0094] σ th = λ / 12

[0095] and the CCD flatness image uniformity U(t), where the threshold

[0096] U th = 0.90

[0097] If any index is over limit for 3 frames, the adaptive PID control mode is triggered, where the PID takes σ th as the controlled quantity, sets the target σ ref = λ / 15, and the error e(t) = σ ref - σ th ; according to |e(t)|, the gain is automatically switched, when |e(t)|>0.05λ, it enters the high gain area, where K p = 1.8, K i = 12, K d = 0.002, otherwise it enters the low gain area, where K p = 0.9, K i = 6, K d = 0.001; each frame calculates

[0098] ΔV pid = K p ×e(t) + K i ×∑e(t)Δt + K d ×(de / dt)

[0099] to get the control quantity of the PID controller output, where de is the temperature difference, dt is the time difference, and de / dt is the error rate of change with time;

[0100] and is superimposed with the least squares inversion voltage V(n) and then written into the DM, balancing the convergence speed and the risk of overshoot; in the recovery time verification, under the conditions of sudden gradient disturbance of ±2° for the galvanometer and local temperature rise of 3℃ for the DOE, the system makes σ(t) fall to λ / 14 and U(t) rise to 92% within 6.3ms, meeting the design requirement that the error range is within 5-8ms;

[0101] In the security aspect, the system constructs a triple abnormality processing and safety interlocking mechanism. When σ(t) > λ / 6 lasts for 10 ms, the FPGA triggers the light shutter to shut off the laser, and the DM voltage falls back to the safety LUT, preventing the piezoelectric element from losing control, and realizing the over-limit protection. The dual-encoder incremental differential method is used to monitor the left and right axis synchronization. If the difference is > 50 μrad for 5 ms, it is determined that the step is lost, the system enters the slow stop mode and alarms, and the mirror step loss detection is realized. Through the substrate DS18B20 temperature probe monitoring, when T > 45℃, the PID amplification coefficient is automatically reduced by half and the scanning angle is limited to ≤ ± 10°, and when T > 50℃, the laser is directly shut off, ensuring the safety of the equipment and the stability of the process under abnormal conditions.

[0102] Finally, the performance verification proves the effectiveness of the system. First, the scanning angle and uniformity mapping test is carried out. The scanning angle range is 0-18°, and it is increased by 2° every time, and each angle is kept for 5 seconds. The average uniformity is > 91.6%, and the fluctuation amplitude is < ± 2%, which meets the mapping relationship requirements of scanning angle and beam uniformity. Then the long-time stability test is carried out. The maximum drift of wavefront RMS σ(t) is only 0.006λ, and the minimum uniformity is 88.7%, which is still higher than the lower limit standard of the process. Finally, the high-frequency interference simulation is carried out. The DM drive line is injected with 1 kHz, 2Vpp power noise, and the system keeps σ < λ / 11, which verifies the strong robustness of the closed-loop control to external electromagnetic disturbance.

[0103] S4: Monitor the temperature of the deformable mirror base, set the threshold value for starting water cooling adjustment, and synchronize the focal length control vector in the driving table according to the thermal lens effect empirical model. The specific implementation is:

[0104] Taking the deformable mirror thermal management as the core, three high-precision Pt1000 platinum resistors are deployed to capture the local thermal gradient in real time. The cooling unit uses the micro-channel copper base optimized by ANSYS CFD to guide away the absorbed heat through PID closed loop. The Coriolis mass flowmeter is used for precise water flow regulation, and the transmission type ZnSe sheet and InGaAs detector are used for power feedback to calculate the absorbed power. The control core is Kintex-7200T FPGA subsystem, all operations are locked to 1 MHz system clock to ensure time synchronization.

[0105] After the temperature data is sampled by 24-bit ΣΔ ADC at 2kS / s and IIR low-pass filtered, the average T DM (t) and the gradient ΔT grad (t) are calculated to diagnose the local "hot spot". Combined with the laser output and transmission power, the absorbed power is calculated through the physical model to provide input for thermal control. Based on the empirical model k T= 0.12 rad / °C is calculated and distributed to the spherical aberration and secondary spherical aberration components, and the 140-channel voltage adjustment amount is solved by the response matrix inverse, which is superimposed with the current voltage to update, the whole process is completed in single-precision floating point on the ARM side, and the time consumption is <70 μs;

[0106] When T DM > 35 °C and ΔT grad < 2 °C, the pump speed is linearly increased to 8 L / min, and the "Thermal-PID" is started, and if ΔT grad ≥ 2 °C, the acousto-optic shutter attenuates the power by 50% and alarms, and the flow and temperature rise are closed-loop controlled to target 32 °C, and the pump speed is adjusted by 50 Hz PID, and the temperature is pulled back within 2-3 seconds, and T DM > 45 °C, the laser is turned off and cooled at full speed; if the flow is < 3 L / min for 10 ms, the laser is blocked; if ΔT grad > 4 °C, the DM voltage is reset to zero; When the cumulative value is > 2 rad, forced recalibration is performed to prevent drift accumulation;

[0107] Under 2 kW working condition, the cooling is cut off for 5 seconds, and T DM rises to 36.8 °C and then returns to 32.5 °C within 0.8 seconds, and the spot uniformity is increased from the minimum of 87% to 92%; under 12-hour long-time operation The mean value is 0.024 rad, the standard deviation is 0.006 rad, the temperature is stable at 33-34 °C when scanning at ±20° and 150 Hz, and the uniformity is ≥ 90.8%, which verifies the stable control capability of the system under sudden over-temperature, long-time operation and high dynamic load.

[0108] S5: The real-time defocusing amount caused by the change in the optical path length is calculated based on the deflection angle of the scanning galvanometer, and a phase compensation amount is preloaded in the deformable mirror driving voltage, and a specific embodiment is as follows:

[0109] At the hardware level, each of the two-axis galvanometers is configured with a 16-bit photoelectric encoder, and the angle data (θL, θR) sampling and debouncing are completed within the first 0.1 ms of each 1 ms time slot through the LVDS bus, ensuring dynamic response and timeliness. The optical path length L from the center of the galvanometer to the workpiece focal plane is measured by a target when the product is shipped and is solidified to the EEPROM of the FPGA, providing a reference for subsequent control. For phase compensation requirements, two linear interpolation lookup tables LUTΔf and are pre-generated to cover the defocusing amount Δf and the DM phase increment The data is stored in the FPGA's BRAM using a page-based cache, achieving a lookup time of <10μs and supporting fast phase compensation. Based on precise timing control, the dual-axis angles are synchronously sampled and the average value θ is calculated at T0 = 0μs. If the difference is >25μrad, an "axis deviation" event is triggered. Subsequently, at T0+20μs and T0+40μs, the linear interpolation lookup table is consulted to obtain Δf and Δt, respectively. T0+60μs will Write the compensation amount into the temporary register in a ratio of 70% spherical aberration channel and 30% secondary spherical aberration channel. Accumulate the compensation amount to the current DM voltage vector and write it into the DAC at T0+90μs. Finally, broadcast the "compensation complete" flag at T0+340μs. During the process, the galvanometer needs to maintain a forward angle of more than 0.16ms to achieve a DM galvanometer wavefront synchronization time of <0.5ms.

[0110] To ensure control stability and equipment safety, the system has established a hierarchical safety mechanism, including angular velocity protection when the rate of change of θ is >1500 deg / s. 2 Pause feedforward and retain only closed-loop control; phase and amplitude protection is checked every frame. If the absolute value exceeds the limit, the scanning angle will be reduced by 50% and a "phase overflow" message will be displayed. Synchronization monitoring compares the DM completion flag with the galvanometer timestamp. If the difference is greater than 0.8ms and there are 3 consecutive abnormal frames, resynchronization will be triggered. After 3 failures, the laser will be turned off.

[0111] In terms of status observation, the linear CCD records the grayscale of the scanned lines and calculates the uniformity in real time on the workpiece plane. When the uniformity is less than 90% and fails to meet the standard for 5 consecutive frames, the parameter self-check is triggered, and the LUT accuracy is verified by scanning angle by angle. At the same time, all key data are packaged into 1kHz log frames and support operation and maintenance traceability.

[0112] The debugging and verification results show that the uniformity is ≥93% in static angle verification; the uniformity is at least 92.1% in dynamic scanning verification, with a focus drift of <±10μm. In the error tolerance assessment, even... Introducing ±10% random deviation, the closed-loop control can still maintain uniformity ≥90%, verifying the fault tolerance capability of the feedforward and closed-loop dual-layer structure.

[0113] S6: Input the laser power, wavefront distortion parameters, and deformable mirror drive stroke data into the controller, set an emergency shutdown mechanism to be triggered when parameters exceed limits, and periodically purge the surface of the diffractive optical element with dry gas. Specifically:

[0114] The system constructs a complete safety system from hardware monitoring, logic control, environment protection to abnormal handling around the whole process of laser processing, and realizes long-term tracing and analysis through data archiving. At the hardware configuration level, special monitoring channels are designed for laser power, wavefront quality and actuator state key parameters. Laser power is captured in real time at a rate of 10 kS / s by InGaAs power meter installed 200 mm behind the 4% reflective sampling sheet at the laser outlet. Wavefront RMS is monitored by 40x40 sub-aperture Shack-Hartmann wavefront instrument in the sampling wedge 2% reflective light path, and 1 kS / s rate ensures beam shaping quality; DM stroke relies on the built-in 14-bit displacement sensor of BOS-DM140 driver to detect the state of piezoelectric ceramic; PLC master station scans the interlocking logic with a 1ms cycle, and the Q-Switch shutdown line is configured with a 24V optical isolation relay to ensure that the light can be turned off in an emergency;

[0115] The interlocking logic realizes multi-parameter cooperative protection through the ladder diagram. By setting the upper limit of power to 2.3kW, the lower limit to 1.6kW, the upper limit of wavefront RMS to λ / 10, and the upper limit of DM stroke to 90% full scale, the thresholds are set. Then, PLC reads three channel data every 1ms and compares them. If any parameter exceeds the limit, the corresponding alarm bit is set. After OR logic, a comprehensive alarm signal ALM is formed. After ALM is triggered, a 10ms delay timer is started. If the fault is not eliminated, the Q-Switch is turned off, the safety lock is set, and the message is sent.

[0116] After the operator eliminates the fault and resets the alarm, the three parameters must return to the safe area, the DM stroke must be less than 70% of the full scale, and the wavefront RMS must be less than λ / 12 for 3s. Only then will HMI light up the open light button.

[0117] To ensure the dryness of the DOE optical element, an oil-free air compressor and a refrigeration dryer are configured as the air source. The flow is controlled by a mass flow meter and a FKM sealed electromagnetic valve. The annular microporous nozzle uniformly covers the substrate. PLC automatically executes 60s purge every 8 hours. When the environmental humidity is greater than 60%, the cycle is shortened to 4 hours and a prompt is given. Manual immediate purge can bypass the timer, and the 8-hour cycle is automatically reloaded after operation. PLC sends power, wavefront, stroke and event code to InfluxDB at 10ms intervals. Each purge records timestamp, flow, duration, RH to DOE_PURGE table. Daily 00:00 generates a daily report of safe operation, which includes running time, ALM trigger statistics, last purge time, parameter extreme value and mean value, providing full-process tracing and long-term data support for operation and maintenance analysis.

[0118] The scheme of the embodiment firstly constructs a stable optical path, coaxially sets the beam expander, the diffractive optical element, the deformable mirror, the sampling wedge and the scanning galvanometer on the stable mechanical platform, ensures the stability of the optical path through mechanical limiting, thermal management module and multi-stage optical alignment, including initial positioning, optical axis straightness calibration, diffraction efficiency verification; then performs low-power calibration, measures the initial wavefront distortion under the low-power beam, generates the initial driving table of the deformable mirror through the least square inversion algorithm, and establishes the flat-top beam reference; in the real-time control stage, the wavefront sensor collects data and reconstructs high-order modes, dynamically refreshes the voltage of the deformable mirror, combines the timing synchronization, closed-loop control and abnormal processing of the scanning galvanometer, and ensures the synchronization of wavefront control and scanning motion; at the same time, the temperature of the deformable mirror is monitored, the water cooling adjustment is started and the driving table is corrected to cope with the thermal effect; the defocus amount is calculated according to the real-time angle of the galvanometer, and the phase compensation is preloaded to the deformable mirror; finally, a safety system is constructed, the key parameters of laser power, wavefront distortion and deformable mirror stroke are monitored, the emergency shutdown is triggered when the limit is exceeded, and the diffractive optical element is periodically blown by dry gas to realize the safety guarantee and performance verification of the whole process.

[0119] The above embodiments can be realized wholly or partially by software, hardware, firmware or any combination thereof. When realized by software, the above embodiments can be realized wholly or partially in the form of a computer program product. The computer program product includes one or more computer instructions or computer programs. When the computer instructions or computer programs are loaded or executed on a computer, the processes or functions described in the embodiments of the present application are wholly or partially generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network or other programmable devices. The computer instructions can be stored in a computer-readable storage medium or transferred from one computer-readable storage medium to another, for example, the computer instructions can be transferred from one website, computer, server or data center to another through wireless or wired transmission; the wired transmission includes optical fiber, twisted pair, coaxial cable, etc.; the wireless transmission includes infrared, microwave, etc. The computer-readable storage medium can be any available medium accessible by a computer or a data storage device such as a server, data center, etc. containing one or more available medium collections. The available medium can be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium. The semiconductor medium can be a solid-state disk.

[0120] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working process of the above-described system, device and module can refer to the corresponding process in the foregoing method embodiments, which will not be described here.

[0121] In several embodiments provided in the present application, it should be understood that the disclosed system, device and method can be implemented in other manners. For example, the division of the above-described device embodiment is merely an example, and there can be other division manners. For example, the modules or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the displayed or discussed mutual couplings or direct couplings or communication connections can be indirect couplings or communication connections through some interfaces, devices or modules, and can be in electrical, mechanical or other forms.

[0122] The modules illustrated as separated components can or can not be physically separated, and the components illustrated as modules can or can not be physical modules, and can be located in one place, or can be distributed on a plurality of network modules. Some or all of the modules can be selected according to actual needs to achieve the purpose of the embodiment.

[0123] In addition, each functional module in each embodiment of the present application can be integrated into a processing module, or each module can be physically present alone, or two or more modules can be integrated into one module.

[0124] If the functions are realized in the form of software function modules and sold or used as independent products, they can be stored in a computer readable storage medium. Based on this understanding, the technical solutions of the present application essentially or the parts of the technical solutions that make contributions to the prior art or the parts of the technical solutions can be embodied in the form of a software product. The computer software product is stored in a storage medium, and includes several instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in each embodiment of the present application. The foregoing storage medium includes: 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 program codes that can be stored in the medium.

[0125] The above description is merely a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art can easily think of changes or replacements within the technical scope disclosed in the present application, and all should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

[0126] Finally: the above only for the preferred embodiments of the present application, and not for limiting the present application, any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application, should be included in the scope of protection of the present application.

Claims

1. A method for shaping a carbon dioxide laser beam, characterized in that, Includes the following steps: S1: The beam expander, diffractive optical element, deformable mirror, sampling wedge and scanning galvanometer are sequentially and coaxially set on a stable mechanical platform to construct a stable optical path; S2: Under low-power calibration beam conditions, the initial wavefront distortion is measured by a wavefront sensor, and the initial driving table of the deformable mirror is generated by the least squares inversion algorithm to establish the flat-top beam reference. S3: Real-time acquisition of wavefront data and reconstruction of Zernike polynomial higher-order modes, dynamically refreshing the deformable mirror driving voltage vector; S4: Monitor the temperature of the deformable mirror base, set the threshold for initiating water cooling regulation, and synchronously correct the focal length control vector in the drive table based on the thermal lens effect empirical model. S5: Obtain the real-time deflection angle of the scanning galvanometer, calculate the defocusing amount caused by the change in optical path length, and preload the phase compensation amount into the deformable mirror driving voltage. S6: Connect the laser power, wavefront distortion parameters, and deformable mirror drive stroke data to the controller, set the emergency shutdown mechanism to be triggered when the parameters exceed the limit, and periodically purge the surface of the diffractive optical element with dry gas.

2. The carbon dioxide laser beam shaping method according to claim 1, characterized in that, Step S2 includes: A honeycomb platform was built in an optical room with constant temperature and humidity and laminar flow filtration. The output power of the CO2 laser was reduced to one percent of the rated power by a variable attenuator, while ensuring that the sampling timestamps of each channel were consistent. With the galvanometer scanning turned off, only the low-power calibration beam was allowed to pass through the shaping optical path. At least a thousand frames of focal spot centroid data were acquired using a Shack-Hartmann sensor with a kHz frame rate, and then converted into high-order Zernike coefficients online. Apply small-amplitude step bias to all the actuators of the deformable mirror in channel order. Record the corresponding Zernike vector immediately after each bias and combine them into a response matrix. Insert a short cooling delay between two drives. The system operates at low power output for several minutes, monitoring the wavefront RMS and energy uniformity in real time. When the RMS drops below the system set value and the energy uniformity significantly improves, the baseline is considered to have been successfully established. If the RMS rebounds within a few frames, the controller immediately switches to the safety drive and shuts off the shutter.

3. The carbon dioxide laser beam shaping method according to claim 1, characterized in that, Step S3 includes: The high-speed Shack-Hartmann sensor is fixed on the sampling wedge reflection branch, and the focal spot centroid matrix is ​​acquired synchronously every frame. The sensor uses high-speed CMOS readout and performs center positioning preprocessing at the hardware level, and the sampling is triggered by a unified FPGA clock. The centroid data enters a dedicated logic array, is first mapped to the local wavefront slope, and then reconstituted into Zernike coefficients of order 13 or higher through a pre-stored orthogonal basis transformation table. The system automatically removes sub-apertures with no signal-to-noise ratio at the edges. The latest Zernike coefficients are fed into the control core, and the voltage increment is obtained by directly looking up the corresponding row of the response matrix generated in the static calibration stage. Then, the control core performs vector accumulation with the baseline table saved in the previous frame, and writes it into the high-resolution DAC after comparing the boundary threshold.

4. The carbon dioxide laser beam shaping method according to claim 3, characterized in that, include: The wavefront residuals calculated in real time are fed into the adaptive gain module, and the changes in the residuals are observed. The system incorporates dual security measures, and the power meter and thermal imager are configured as a cross-validation system for calibration effectiveness. The system incorporates a fully hardware pipeline and multi-level fault tolerance, while keeping the real-time wavefront residual within the design threshold.

5. The method for shaping a carbon dioxide laser beam according to claim 1, characterized in that, Step S4 includes: The resistance temperature sensors are evenly distributed in the center and diagonal positions of the deformable mirror base, and the sensors are bonded to the base with thermally conductive insulating adhesive. The system collects analog signals output from each temperature sensor and generates digital temperature data, and pre-stores the first and second temperature thresholds within the digital temperature data. Generate an empirical data table of thermal lensing effect stored inside the programmable logic device, and repair the data table according to the focal length correction amount corresponding to the temperature range; The system periodically reads digital temperature data, calls the lookup logic of the thermal lensing effect empirical data table, and writes the focal length correction obtained from the lookup logic into the corresponding entry of the focal length control vector in the deformable mirror drive lookup table. The driving vector refresh logic is synchronized with the lookup table logic, and the updated driving lookup table is written to the deformable mirror driving circuit within the same clock domain.

6. The carbon dioxide laser beam shaping method according to claim 1, characterized in that, Step S5 includes: The dual-axis galvanometers are equipped with either absolute or incremental photoelectric encoders. The encoders are rigidly coaxially mounted with the galvanometer shafts. The angle data is connected to the controller via a differential serial bus and is triggered for sampling within the unified clock domain of the device. The controller pre-stores scanning geometry model parameters that match the scanning focusing objective lens used, and maps the galvanometer deflection angle to the change between the image plane position and the focusing position; The controller sets up an angle and defocus lookup table, using the galvanometer composite deflection angle as the index, outputs the corresponding defocus amount in an interpolated manner, and stores it according to the monotonic sequence of scanning angles; The controller sets up lookup tables for defocus and phase compensation, which correspond one-to-one with the focal length control modes of the deformable lens. The lookup tables are calibrated according to the controllable modes of the deformable lens, which include the principal spherical aberration and higher-order spherical aberration components related to focus.

7. The carbon dioxide laser beam shaping method according to claim 6, characterized in that, include: The controller is configured with multi-source write arbitration logic to sequentially accumulate and refresh the deformable mirror drive vector according to a preset priority order. The priority order is determined by the controller's scheduling strategy, and timestamp alignment is completed within the same clock domain. The deformable mirror drive circuit is composed of a digital-to-analog converter and a parallel channel driver. Before the end of each sampling period, the controller writes the arbitrated drive vector into the digital-to-analog converter and generates a synchronization flag after the writing is completed. The controller is set with thresholds for angle overshoot and phase amplitude monitoring. The controller sets the upper limit for angular velocity and the upper limit for angular acceleration, and the upper limit value is determined based on the galvanometer servo control characteristics. The controller sets the objective type identifier field and selects the corresponding scanning geometry model and field curvature compensation parameters based on the identifier; The controller sets up a running log buffer and periodically outputs it to the host computer for archiving. The recording order in the buffer is consistent with the sampling trigger order.

8. The method for shaping a carbon dioxide laser beam according to claim 1, characterized in that, Step S6 includes: Set up a high-speed analog or digital input port for connecting a thermal power laser power meter; A data acquisition interface is provided to be compatible with the Shack-Hartmann wavefront sensor, and the interface is synchronized with the device's master clock. Set up a stroke monitoring channel connected to the feedback bus of the deformable mirror driver to generate deformable mirror stroke parameters and compare them with safety thresholds in the controller; A programmable logic controller is configured as the interlocking core. The controller reads the laser power, wavefront distortion parameters and deformable mirror travel sequentially according to a fixed scanning cycle, performs threshold comparison and logical OR operation, and outputs a shutdown command when the shutdown condition is met. The interlocking circuit meets the requirements of laser product safety standards regarding environmental conditions, single-point failures, and protective interlocking. A parameterizable confirmation timer is set inside the controller. When any monitored quantity is detected to exceed the corresponding threshold, a delayed confirmation is initiated, and a shutdown signal is output when the state is still in the over-limit state at the end of the confirmation period. The time base of the confirmation timer is consistent with the sampling clock.

9. A method for shaping a carbon dioxide laser beam according to claim 8, characterized in that, include: Clean, dry air or nitrogen is used as the purging medium, and a filtration, pressure reduction, and dew point control module is configured. Mass flow meters and solenoid valves are installed in the purging branch. Coriolis mass flow meters are preferred to balance response speed and measurement accuracy. An annular or multi-point distribution nozzle is arranged circumferentially on the diffractive optical element, and a pressure switch or differential pressure switch is installed in the gas path. A humidity sensor is installed in the optical cavity or equipment environment. The controller adjusts the purging cycle and duration within a set range based on the humidity data, and shortens the purging interval when the humidity exceeds the set threshold. The humidity data and purging events are recorded together. Set up an operation log buffer to record laser power, wavefront distortion parameters, deformable mirror travel, interlock status, purge flow and dew point information at fixed intervals, and archive them for a long time through a host computer or database interface. The human-machine interface is configured to display the real-time values ​​and thresholds of the three types of monitoring quantities, and provides a manual purging button and an interlock reset button.

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