High precision dual-pulse dual-wavelength plasma interferometry diagnostic apparatus and method

Abstract

The application discloses a high-precision double-pulse double-wavelength plasma interference diagnosis device and method, and belongs to the field of precise diagnosis of laser plasma. The existing double-wavelength synchronous phase shift diagnosis equipment does not have an adjustable double-pulse excitation system, the time sequence is fragmented, and the measurement error is large. The application integrates a double-pulse excitation, a DG645 global time sequence control, a double-wavelength spectrometer noise reduction, a synchronous phase shift imaging and a layered algorithm processing unit; a unified time sequence linkage realizes controllable plasma excitation and synchronous detection, optical path filtering eliminates stray light interference, synchronous phase shift suppresses environmental disturbance, double-wavelength simultaneous calculation eliminates particle interference, and machine learning is combined to realize joint analysis of pulse parameters and electron density. The application deeply integrates adjustable double-pulse and double-wavelength phase shift optical paths, supports an automatic closed-loop experimental process, and significantly improves measurement accuracy and experimental efficiency, and is suitable for plasma detection such as LIBS, laser impact, inertial confinement fusion and the like.

Description

Technical Field

[0001] This invention belongs to the field of laser plasma precision diagnostic technology, and relates to a high-precision dual-pulse dual-wavelength plasma interferometry diagnostic device and method. Background Technology

[0002] The electron density and expansion evolution of plasma generated by the interaction of lasers with matter are core quantitative parameters for elucidating the microscopic interaction mechanism. Interferometric diagnostics, with its advantages of non-contact operation and high spatial resolution, has become the mainstream detection method. However, current mainstream plasma interferometric detection schemes suffer from four major drawbacks, and existing comparative patents cannot simultaneously address all of these issues: 1. Weak excitation source control capability, making it impossible to conduct research on plasma evolution mechanism: The plasma generated by traditional single-pulse laser excitation has low electron density and short duration, and can only capture instantaneous static plasma; ordinary split-type dual-pulse lasers can only coarsely adjust the pulse delay, and there is no unified timing linkage diagnostic optical path, which cannot accurately match the detection window of plasma evolution characteristic moments, making it difficult to quantitatively study the entire process of plasma enhancement, expansion and decay.

[0003] Single-frame interferometric imaging has poor anti-interference capability and large measurement phase error: Conventional single-optical-path single-frame interferograms are easily affected by laboratory environment vibration, air turbulence, and optical path drift, resulting in severe phase extraction distortion; existing synchronous phase-shifting interferometric schemes are mostly equipped with fixed single-pulse light sources and are not globally time-synchronized with adjustable dual-pulse excitation systems, making it impossible to dynamically capture transient plasmas with drastic gradient changes.

[0004] 3. Single-wavelength interferometry calculations suffer from inherent particle interference, resulting in distortion of electron density calculations: When solving for electron density using single-wavelength interferometry, neutral atoms and positive ions in the plasma will produce additional phase shifts, making it impossible to separate the phase contributions of electrons and heavy particles. Ultimately, the deviation in electron density calculations can reach more than 35%. The publicly available dual-wavelength interferometry techniques are only compatible with fixed single-pulse excitation and are not compatible with multi-pulse width, adjustable timing dual-pulse systems.

[0005] 4. The timing of excitation and diagnostic equipment is fragmented, the system integration is low, and the experimental repeatability is poor: The existing excitation optical path and the interferometric diagnostic optical path use two independent timing controllers, which have problems such as timing drift and large synchronization errors. Each multi-gradient delay and energy control experiment requires manual step-by-step calibration of the two sets of equipment, and a single debugging takes more than 3 hours. Manual parameter recording is prone to data matching errors, and the efficiency of batch mechanism research is extremely low.

[0006] Compared to the dual-wavelength + synchronous phase-shifting interferometric diagnostic optical path disclosed in patent CN118678523A, there are clear inherent shortcomings: ① It is only compatible with fixed single-pulse excitation sources and has no adjustable dual-pulse timing excitation module, so it cannot generate gradient evolution plasma; ② There is no globally unified timing control unit, and the excitation and imaging timing are independently controlled, making it impossible to accurately couple pulse delay and detection time; ③ Data processing only realizes basic phase extraction and electron density solution, and there is no algorithm for joint analysis of dual-pulse parameters and diagnostic data; ④ The optical path has no noise reduction filtering structure, and the plasma's self-luminescence will introduce stray light to interfere with the interferometric image.

[0007] In summary, existing technologies cannot simultaneously meet the four major requirements of flexible and controllable plasma excitation, interference-resistant and high-precision imaging, particle interference elimination, and end-to-end time-series coordination.

[0008] Therefore, a new high-precision dual-pulse dual-wavelength plasma interferometry diagnostic device and method are needed to solve the above problems. Summary of the Invention

[0009] The purpose of this invention is to provide a high-precision dual-pulse dual-wavelength plasma interferometry diagnostic device to solve the problems of the prior art.

[0010] The technical solution of the present invention is as follows: The high-precision dual-pulse dual-wavelength plasma interferometry diagnostic device includes: a dual-pulse excitation module, a global timing synchronization control unit, a dual-wavelength beam splitting and noise reduction module, a synchronous phase-shifting interferometric imaging module, and a data processing and computing unit; The dual-pulse excitation module includes a first pulse laser, a second pulse laser, an independent electrically driven energy attenuator, an integrating energy detector, and a beam combiner. The two pulse lasers support nanosecond-nanosecond, nanosecond-picosecond, and picosecond-picosecond pulse width combinations. The first pulse laser outputs a pre-excitation laser, and the second pulse laser outputs a main excitation laser. The two laser beams are coaxially converged on the surface of the sample under test by the beam combiner. Each laser is equipped with a closed-loop energy monitoring component to collect pulse energy in real time and provide feedback to adjust the attenuator. The global timing synchronization control unit is a DG645 high-precision digital delay generator with a delay adjustment accuracy of 1ns. Multiple synchronous output channels are electrically connected to two pulsed lasers, a diagnostic laser, and a micro-polarization array camera, respectively. The DG645 can store custom timing scripts and automatically execute the entire timing sequence of pre-pulse excitation, main pulse excitation, delay detection, and synchronous imaging, achieving drift-free linkage of the entire excitation, detection, and imaging process. The dual-wavelength beam splitting and noise reduction module includes a fundamental frequency diagnostic laser, a KDP frequency doubling crystal, a dichromatic beam splitter, and two sets of narrowband filters. The diagnostic laser outputs a 1064nm fundamental frequency laser, which is converted into a 1064nm fundamental frequency probe light and a 532nm frequency doubling probe light by the KDP crystal. The dichromatic beam splitter splits the beams into two wavelength beams, each matched with a corresponding narrowband filter to reduce noise and eliminate wavelength crosstalk. The two beams pass through the plasma region in a common path. The synchronous phase-shifting interferometric imaging module is arranged along the optical path with a Glan-Taylor prism, a polarization beam splitter, a quarter-wave plate, and a micro-polarization array camera. The two probe beams enter the polarization modulation optical path respectively, and the camera synchronously acquires two sets of interferograms, the fundamental frequency and the harmonic frequency, in a single exposure. Each set contains four original interferograms with phases that are successively different by π / 2. The data processing and computing unit incorporates an adaptive synchronous phase-shifting phase extraction program, a dual-wavelength simultaneous interference adaptive elimination model, an Abel inverse transform three-dimensional reconstruction program, and a dual-pulse parameter-electron density machine learning joint analysis model. The global timing synchronization control unit links the dual-pulse excitation module and the dual-wavelength synchronous phase-shifting imaging module to precisely match the plasma evolution time generated by the dual-pulse excitation with the detection imaging time, realizing a one-to-one coupling of excitation parameters and plasma diagnostic data. The modules do not work independently.

[0011] Furthermore, the device includes two operating modes: a dual-pulse enhanced plasma diagnostic mode and a single-pulse compatible diagnostic mode; switching to the single-pulse compatible diagnostic mode can be achieved by turning off either the first pulse laser or the second pulse laser.

[0012] Furthermore, the center wavelengths of the narrowband filters are matched to 1064nm and 532nm respectively, which are used to filter out LIBS stray light generated by plasma self-luminescence and reduce background noise in the interference image.

[0013] Furthermore, the beam combiner ensures that the pre-excitation laser and the main excitation laser are completely coaxially incident on the sample, guaranteeing that the interaction regions of the pre-plasma and the main pulse completely overlap. Beneficial Effects: The high-precision dual-pulse dual-wavelength plasma interferometry diagnostic device of this invention achieves high-precision, multi-dimensional, and automated integrated plasma diagnosis through global time-series unified linkage, optical path noise reduction optimization, and hierarchical algorithm joint analysis. The core innovation of this invention is not the dual-pulse, synchronous phase-shifting, and dual-wavelength modules themselves, but rather the deep synergistic integration of these three components through time-series, optical path, and algorithmic integration, producing a superimposed technical effect that cannot be achieved by using each module individually.

[0014] The present invention also discloses a high-precision dual-pulse dual-wavelength plasma interferometry diagnostic method based on the device described above, comprising the following steps: S1: Pre-optical path background calibration, turn off all lasers, collect the fundamental and harmonic background interferograms without plasma and pre-store them to the data processing and calculation unit, and automatically subtract background noise from the measured image; S2: Dual-pulse timing coordinated excitation: DG645 calls the timing script to trigger the first pulse laser to generate pre-plasma, and after a precise delay of 1ns, triggers the second pulse laser to generate enhanced main plasma. The dual-pulse delay and real-time energy parameters of the two lasers are recorded simultaneously. The plasma state is directionally controlled by modifying the timing script to adjust the pulse interval and energy ratio. S3: Synchronous timing-triggered dual-wavelength detection: DG645 triggers the diagnostic laser at the preset plasma evolution time. The laser generates two detection beams through the KDP crystal, which are then split by a two-color beam splitter and reduced by a narrow-band filter before passing through the plasma region. S4: Synchronous phase-shifting interferometric imaging: Dual-wavelength probe light enters the polarization modulation optical path, and the micro-polarization array camera simultaneously acquires four original interferograms with a phase difference of π / 2 each in a single exposure of the fundamental frequency and the harmonic frequency. S5: Layered high-precision solution and multi-parameter joint analysis: S5.1 employs an adaptive synchronous phase-shifting algorithm to automatically adjust the phase fitting weights for the strong gradient region at the plasma edge, and extracts the two-dimensional phase distribution of the plasma under two wavelengths respectively. S5.2 runs a dual-wavelength simultaneous interference adaptive elimination model to distinguish between high and low electron density ranges, correct the phase contribution coefficients of atoms and ions, and eliminate heavy particle calculation biases. S5.3 performs an inverse Abel transform on the undisturbed phase data to reconstruct the three-dimensional electron density distribution of the plasma; S5.4 inputs the dual-pulse delay, energy parameters and electron density data into the machine learning model, and automatically outputs plasma enhancement threshold, expansion rate and decay time evolution characteristic parameters; S6: Closed-loop iterative optimization: The data processing unit automatically generates a new timing script based on the current diagnostic results, modifies the double pulse parameters, and executes steps S2 to S5 in a loop to automatically complete multi-gradient operating condition control experiments in batches.

[0015] Furthermore, in step S2, the two pulsed lasers can be configured with arbitrary pulse width combinations of nanosecond-nanosecond, nanosecond-picosecond, and picosecond-picosecond to adapt to different ultrafast and slow pulse plasma detection scenarios.

[0016] Beneficial Effects: The high-precision dual-pulse dual-wavelength plasma interferometry diagnostic method of this invention achieves high-precision, multi-dimensional, and automated integrated plasma diagnostics through global time-series unified linkage, optical path noise reduction optimization, and hierarchical algorithm joint analysis. Through deep synergistic integration of timing, optical path, and algorithms, it produces superimposed technical effects that cannot be achieved by using each module individually.

[0017] The present invention also discloses a computer-readable storage medium storing a computer-executable program, which, when run by a processor, performs all the steps of the high-precision dual-pulse dual-wavelength plasma interferometry diagnostic method as described above. Attached Figure Description

[0018] Appendix Figure 1 : Block diagram of the overall optical path and timing control structure of the high-precision dual-pulse dual-wavelength plasma interferometry diagnostic device of the present invention; Appendix Figure 2 The complete flowchart of the high-precision dual-pulse dual-wavelength plasma interferometry diagnostic method of this invention (including calibration, excitation, imaging, calculation, and closed-loop iteration); Explanation of reference numerals in the attached figures: 1-First pulse laser, 2-Second pulse laser, 3-Electrically powered energy attenuator, 4-Integrating energy detector, 5-Beam combiner, 6-Sample under test, 7-Plasma region, 8-DG645 digital delay generator (global timing synchronization control unit), 9-Fundamental frequency diagnostic laser, 10-KDP frequency doubling crystal, 11-Dichromatic beam splitter, 12-Narrowband filter, 13-Glan-Taylor prism, 14-Polarization beam splitter, 15-1 / 4 wave plate, 16-Micro polarization array camera, 17-Data processing and computing unit, 18-Computer-readable storage medium. Detailed Implementation

[0019] Please see Figure 1 As shown, the high-precision dual-pulse dual-wavelength plasma interferometry diagnostic device of the present invention consists of five main parts: a dual-pulse excitation module, a global timing synchronization control unit, a dual-wavelength beam splitting and noise reduction module, a synchronous phase-shifting interferometric imaging module, and a data processing and computing unit. 1. Dual-pulse excitation module It includes a first pulse laser, a second pulse laser, an independent electric energy attenuator, an integrating energy detector, and a beam combiner. The two pulse lasers support free combination of three pulse widths: nanosecond-nanosecond, nanosecond-picosecond, and picosecond-picosecond. The first pulse laser outputs a pre-excitation laser, and the second pulse laser outputs a main excitation laser. The two laser beams are coaxially converged on the surface of the sample under test by the beam combiner, ensuring that the pre-plasma and the main pulse interaction area are completely overlapped. Each laser is equipped with an independent closed-loop energy monitoring component to collect pulse energy in real time and provide feedback to adjust the attenuator, ensuring accurate and stable energy output.

[0020] 2. Global timing synchronization control unit The core component is the high-precision digital delay generator DG645, which features multiple independent synchronous output channels and a delay adjustment accuracy of 1ns. Multiple timing signals are electrically connected to the first pulse laser, the second pulse laser, the diagnostic laser in the dual-wavelength beam splitting and noise reduction module, and the micro-polarization array camera in the synchronous phase-shifting interferometric imaging module. The DG645 can store multiple sets of timing scripts and automatically execute the entire automated timing sequence of "pre-pulse excitation → delay waiting → main pulse excitation → evolution delay → dual-wavelength detection → synchronous imaging" without manual step-by-step triggering, achieving drift-free linkage of the excitation, detection, and imaging timelines.

[0021] 3. Dual-wavelength beam splitting and noise reduction module It includes a fundamental frequency diagnostic laser, a KDP frequency doubling crystal, a dichroic beam splitter, and two sets of narrowband filters. The diagnostic laser outputs a 1064nm fundamental frequency laser that is incident on the KDP crystal, simultaneously generating a 1064nm fundamental frequency probe beam and a 532nm frequency doubling probe beam. The dichroic beam splitter splits the two wavelength beams into independent optical paths, each matched with a narrowband filter corresponding to its center wavelength. This filters out stray light emitted by the plasma's own LIBS emission, and after eliminating crosstalk between the two wavelength optical paths, the two probe beams pass through the plasma region above the sample in a common path, carrying plasma phase shift information.

[0022] 4. Synchronous Phase-Shifting Interferometric Imaging Module The following components are sequentially arranged along the dual-wavelength probe light path: a Glan-Taylor prism, a polarizing beam splitter prism, a quarter-wave plate, and a micro-polarization array camera. The two wavelength probe lights enter two sets of polarization modulation light paths respectively. The micro-polarization array camera can simultaneously acquire two sets of interference images, one at the fundamental frequency and the other at harmonics, in a single exposure. Each set of images contains four original interference patterns with phase differences of π / 2. Synchronous phase-shifting data acquisition can be completed in a single imaging, suppressing imaging interference caused by environmental vibrations and air turbulence.

[0023] 5. Data processing and computing unit Built-in storage medium and hierarchical algorithm program, including: adaptive synchronous phase shifting phase extraction program, dual-wavelength combined interference adaptive elimination model, Abel inverse transform three-dimensional reconstruction program, and dual-pulse parameter-electron density machine learning joint analysis model; capable of the following functions: ① accurately extracting two-dimensional phase distribution from multiple sets of interferograms; ② separating the phase contributions of electrons, neutral atoms, and positive ions, and eliminating heavy particle calculation interference; ③ reconstructing the three-dimensional electron density distribution of plasma; ④ coupling dual-pulse delay, energy control parameters and diagnostic results to model and automatically fit plasma enhancement threshold and expansion evolution characteristic parameters.

[0024] Please see Figure 2As shown, this invention also discloses a high-precision dual-pulse dual-wavelength plasma interferometry diagnostic method based on the above-mentioned device, including a pre-optical path calibration step, a dual-pulse timing-coordinated excitation step, a synchronous timing-coordinated dual-wavelength detection step, a synchronous phase-shifting multi-amplitude interferometric imaging step, a layered data solution and joint analysis step, and a closed-loop iterative optimization step. The complete process is as follows: Step S1: Front optical path background calibration All excitation and diagnostic lasers are turned off, and the micro-polarization array camera is controlled to acquire the fundamental and harmonic background interferograms in a plasma-free environment. The data is pre-stored in the data processing and computing unit, and the background noise is automatically subtracted from the subsequent measured images to eliminate the inherent stray light interference of the optical path.

[0025] Step S2: Dual-pulse timing coordinated excitation The timing synchronization control unit DG645 calls a preset timing script, outputting a first timing signal to trigger the first pulse laser to emit a pre-excitation laser, generating a pre-plasma on the surface of the sample. After a precise delay of 1 ns, it outputs a second timing signal to trigger the second pulse laser to emit a main excitation laser, which couples with the pre-plasma to generate a high-density, long-duration enhanced main plasma. Simultaneously, it acquires and stores the current dual-pulse delay and real-time energy parameters of the two lasers. The pulse interval and energy ratio can be adjusted by modifying the timing script, allowing for targeted control of the plasma electron density, duration, and spatial expansion range.

[0026] Step S3: Synchronize timing to trigger dual-wavelength detection The DG645 synchronously outputs a third timing signal, which triggers the diagnostic laser to emit a 1064nm fundamental frequency probe laser at a preset plasma evolution time. The laser incident on the KDP frequency doubling crystal generates two probe beams of 1064nm and 532nm. After being split by a two-color beam splitter and denoised by a narrowband filter, the beams pass through the plasma region in a common path, carrying plasma phase shift information.

[0027] Step S4: Synchronous phase-shifting multichannel interferometric imaging Dual-wavelength probes carrying phase information enter the polarization modulation optical path, and polarization phase modulation is completed by a Glan-Taylor prism, a polarization beam splitter, and a quarter-wave plate. The micro-polarization array camera performs a single synchronous exposure, acquiring four original interferograms with a phase difference of π / 2 for both the fundamental frequency and the harmonic frequency, and then transmitting them to the data processing and calculation unit.

[0028] Step S5: Layered high-precision electron density solution and multi-parameter joint analysis S5.1 Adaptive Phase Extraction: The adaptive synchronous phase shifting algorithm is run to automatically adjust the phase fitting weight for the strong gradient region at the plasma edge, and extract the two-dimensional phase distribution of the plasma corresponding to wavelengths of 1064nm and 532nm respectively. S5.2 Dual-wavelength interference adaptive elimination: Run the simultaneous equation model, distinguish between high and low electron density ranges to correct the phase contribution coefficients of atoms and ions, and completely eliminate the calculation bias caused by heavy particles; S5.3 Three-dimensional density reconstruction: Perform inverse Abel transformation on the phase data after removing interference, and output a three-dimensional spatial electron density distribution cloud map of the plasma; S5.4 Multi-parameter Joint Analysis: The three-dimensional data of double pulse delay, energy parameters and electron density from this experiment are input into the machine learning model, which automatically outputs evolution characteristic parameters such as plasma enhancement threshold, expansion rate and decay time.

[0029] Step S6: Closed-loop iterative optimization (automated control experiment) The data processing unit automatically generates a new set of timing scripts based on the current electron density results, modifies the double pulse delay / energy parameters, and automatically cycles through steps S2 to S5 to complete batch multi-gradient operating condition control experiments. There is no need for manual repeated equipment adjustments, and all experimental parameters and diagnostic data are automatically bound and stored one by one.

[0030] 3.2.3 Computer-readable storage media matching scheme A computer-readable storage medium stores a computer-executable program, which, when run on a processor, executes all the steps of the high-precision dual-pulse dual-wavelength plasma interferometry diagnostic method described in S1 to S6.

[0031] The present invention can achieve the following beneficial effects: 1. Dual noise reduction and anti-interference, significantly improving measurement accuracy: At the hardware level, synchronous phase-shifting technology acquires four phase difference interferograms in a single acquisition, suppressing interference from environmental vibrations and air turbulence. A wavelength-matched narrowband filter is added to the optical path to filter out stray light emitted by the plasma itself. At the algorithm level, dual-wavelength simultaneous equations eliminate inherent phase interference from neutral atoms and positive ions. Measured data: Under the same vibration conditions, the phase error of traditional single-frame interferometry is 21%, while the phase error of this invention is <1.2%; the electron density calculation deviation of the single-wavelength scheme is 35%, while the calculation deviation of this invention is <4%.

[0032] 2. The dimensions of plasma modulation have been comprehensively expanded, and the ability to study mechanisms has been significantly enhanced: The dual-pulse module supports three types of pulse width combinations, and the pulse delay and output energy are fully adjustable in a closed loop, enabling the controllable generation of plasmas with different densities, durations, and expansion scales. Combined with a machine learning joint analysis model, it can quantitatively analyze the complete dynamic physical mechanisms of plasma enhancement, expansion, and decay, breaking through the limitations of traditional single-pulse devices that can only observe static plasmas. It is suitable for various mechanism research scenarios such as LIBS, laser shock, and fusion plasma.

[0033] 3. Global time-series integration significantly improves experimental efficiency and repeatability: Using the DG645 as the sole timing core, this invention achieves drift-free synchronous linkage across the entire excitation, detection, and imaging chain, accompanied by automated timing scripts and closed-loop iterative processes. Traditionally, manual operation of a single multi-gradient control experiment using separate equipment takes 8 hours, while this invention's automatic operation takes only 1 hour, reducing equipment debugging time from 3 hours to 15 minutes. All parameters and measurement data are automatically bound and stored, eliminating manual recording and matching errors, resulting in strong experimental repeatability and consistency.

[0034] 4. Multi-mode compatibility and strong device versatility: The system supports two working modes: ① dual-pulse enhanced plasma diagnostic mode; ② one pulse laser can be turned off, compatible with traditional single-pulse plasma detection mode, making it a dual-purpose machine and reducing the procurement cost of laboratory equipment; the pulse width combination and dual-wavelength optical path can be adapted to diverse plasma detection scenarios such as laser micromachining, inertial confinement fusion, and thin film deposition.

[0035] 5. Layered algorithm collaborative innovation possesses independent software protection value. It features a unique three-layer algorithm: adaptive phase extraction, dual-wavelength adaptive interference elimination, and pulse parameter machine learning analysis. Unlike existing patent-based solution programs, it can independently achieve software-level rights protection through storage medium claims, resulting in higher patent commercial licensing and transfer value.

[0036] Example 1: Nanosecond-nanosecond dual-pulse LIBS plasma diagnostics

[0037] Device selection: two 1064nm nanosecond pulsed lasers, DG645 digital delay generator, KDP frequency doubling crystal, and micro-polarization array camera; Timing script parameters: First pre-pulse energy 30mJ, DG645 pulse interval set to 200ns to trigger the second main pulse (energy 80mJ); plasma evolution delay of 500ns to trigger the 1064nm diagnostic laser; Test results: Compared with the single-pulse diagnostic solution of patent CN118678523A, the peak plasma electron density is increased by 78%, and the relative error of electron density measurement is reduced from 32% to 3.7%; the automatic completion of 10 sets of control experiments with different pulse intervals takes only 50 minutes without manual intervention.

[0038] Example 2: Nanosecond-Picosecond Dual-Pulse Laser Shock Enhanced Plasma Diagnostics

[0039] Device selection: First 1064nm nanosecond laser, second 1030nm picosecond laser; Timing script parameters: nanosecond pre-pulse energy 50mJ, pulse interval 150ns triggering picosecond main pulse, evolution delay 300ns to start dual-wavelength detection; Test results: It can accurately capture the ultrafast plasma expansion process induced by picosecond pulses, clearly distinguish the differences in plasma temperature rise and density enhancement brought about by nanosecond and picosecond pulses respectively, and realize the quantitative study of ultrafast evolution mechanism that cannot be completed by traditional single-pulse equipment.

Claims

1. A high-precision dual-pulse dual-wavelength plasma interferometry diagnostic device, characterized in that, include: Dual-pulse excitation module, global timing synchronization control unit, dual-wavelength beam splitting and noise reduction module, synchronous phase-shifting interferometric imaging module, and data processing and computing unit; The dual-pulse excitation module includes a first pulse laser, a second pulse laser, an independent electrically driven energy attenuator, an integrating energy detector, and a beam combiner. The two pulse lasers support nanosecond-nanosecond, nanosecond-picosecond, and picosecond-picosecond pulse width combinations. The first pulse laser outputs a pre-excitation laser, and the second pulse laser outputs a main excitation laser. The two laser beams are coaxially converged on the surface of the sample under test by the beam combiner. Each laser is equipped with a closed-loop energy monitoring component to collect pulse energy in real time and provide feedback to adjust the attenuator. The global timing synchronization control unit is a DG645 high-precision digital delay generator with a delay adjustment accuracy of 1ns. Multiple synchronous output channels are electrically connected to two pulsed lasers, a diagnostic laser, and a micro-polarization array camera, respectively. The DG645 can store custom timing scripts and automatically execute the entire timing sequence of pre-pulse excitation, main pulse excitation, delay detection, and synchronous imaging, achieving drift-free linkage of the entire excitation, detection, and imaging process. The dual-wavelength beam splitting and noise reduction module includes a fundamental frequency diagnostic laser, a KDP frequency doubling crystal, a dichromatic beam splitter, and two sets of narrowband filters. The diagnostic laser outputs a 1064nm fundamental frequency laser, which is converted into a 1064nm fundamental frequency probe light and a 532nm frequency doubling probe light by the KDP crystal. The dichromatic beam splitter splits the beam into two wavelength beams, each matched with a corresponding narrowband filter to reduce noise and eliminate wavelength crosstalk. The two beams pass through the plasma region in a common path. The synchronous phase-shifting interferometric imaging module is arranged along the optical path with a Glan-Taylor prism, a polarization beam splitter, a quarter-wave plate, and a micro-polarization array camera. The two probe beams enter the polarization modulation optical path respectively, and the camera synchronously acquires two sets of interferograms, the fundamental frequency and the harmonic frequency, in a single exposure. Each set contains four original interferograms with phases that are successively different by π / 2. The data processing and computing unit incorporates an adaptive synchronous phase-shifting phase extraction program, a dual-wavelength simultaneous interference adaptive elimination model, an Abel inverse transform three-dimensional reconstruction program, and a dual-pulse parameter-electron density machine learning joint analysis model. The global timing synchronization control unit links the dual-pulse excitation module and the dual-wavelength synchronous phase-shifting imaging module to precisely match the plasma evolution time generated by the dual-pulse excitation with the detection imaging time, realizing a one-to-one coupling of excitation parameters and plasma diagnostic data. The modules do not work independently.

2. The high-precision dual-pulse dual-wavelength plasma interferometry diagnostic device according to claim 1, characterized in that: The device includes two operating modes: a dual-pulse enhanced plasma diagnostic mode and a single-pulse compatible diagnostic mode; switching to the single-pulse compatible diagnostic mode can be achieved by turning off the first pulse laser or the second pulse laser.

3. The high-precision dual-pulse dual-wavelength plasma interferometry diagnostic device according to claim 1, characterized in that: The narrowband filter has center wavelengths matched to 1064nm and 532nm, respectively, to filter out LIBS stray light generated by plasma self-luminescence and reduce background noise in the interference image.

4. The high-precision dual-pulse dual-wavelength plasma interferometry diagnostic device according to claim 1, characterized in that: The beam combiner ensures that the pre-excitation laser and the main excitation laser are coaxially incident on the sample, guaranteeing that the interaction regions of the pre-plasma and the main pulse completely overlap.

5. A high-precision dual-pulse dual-wavelength plasma interferometry diagnostic method based on the device described in any one of claims 1 to 4, characterized in that, Includes the following steps: S1: Pre-optical path background calibration, turn off all lasers, collect the fundamental and harmonic background interferograms without plasma and pre-store them to the data processing and calculation unit, and automatically subtract background noise from the measured image; S2: Dual-pulse timing coordinated excitation: DG645 calls the timing script to trigger the first pulse laser to generate pre-plasma, and after a precise delay of 1ns, triggers the second pulse laser to generate enhanced main plasma. The dual-pulse delay and real-time energy parameters of the two lasers are recorded simultaneously. The plasma state is directionally controlled by modifying the timing script to adjust the pulse interval and energy ratio. S3: Synchronous timing-triggered dual-wavelength detection: DG645 triggers the diagnostic laser at the preset plasma evolution time. The laser generates two detection beams through the KDP crystal, which are then split by a two-color beam splitter and reduced by a narrow-band filter before passing through the plasma region. S4: Synchronous phase-shifting interferometric imaging: Dual-wavelength probe light enters the polarization modulation optical path, and the micro-polarization array camera simultaneously acquires four original interferograms with a phase difference of π / 2 each in a single exposure of the fundamental frequency and the harmonic frequency. S5: Layered high-precision solution and multi-parameter joint analysis: S5.1 employs an adaptive synchronous phase-shifting algorithm to automatically adjust the phase fitting weights for the strong gradient region at the plasma edge, and extracts the two-dimensional phase distribution of the plasma under two wavelengths respectively. S5.2 runs a dual-wavelength simultaneous interference adaptive elimination model to distinguish between high and low electron density ranges, correct the phase contribution coefficients of atoms and ions, and eliminate heavy particle calculation biases. S5.3 performs an inverse Abel transform on the undisturbed phase data to reconstruct the three-dimensional electron density distribution of the plasma; S5.4 inputs the dual-pulse delay, energy parameters and electron density data into the machine learning model, and automatically outputs plasma enhancement threshold, expansion rate and decay time evolution characteristic parameters; S6: Closed-loop iterative optimization: The data processing unit automatically generates a new timing script based on the current diagnostic results, modifies the double pulse parameters, and executes steps S2 to S5 in a loop to automatically complete multi-gradient operating condition control experiments in batches.

6. The high-precision dual-pulse dual-wavelength plasma interferometry diagnostic method according to claim 5, characterized in that: In step S2, the two pulsed lasers can be selected to have arbitrary pulse width combinations of nanosecond-nanosecond, nanosecond-picosecond, and picosecond-picosecond to adapt to different ultrafast and slow pulse plasma detection scenarios.

7. A computer-readable storage medium, characterized in that: The storage medium stores a computer-executable program, which, when run by a processor, executes all the steps of the high-precision dual-pulse dual-wavelength plasma interferometry diagnostic method as described in claim 5 or 6.

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