A laser-induced plasma multidimensional measurement system

Abstract

This application discloses a multi-dimensional measurement system for laser-induced plasma, belonging to the field of laser-induced plasma measurement technology. The system includes a laser induction module, a multi-dimensional measurement module, a synchronous control and acquisition module, and a signal processing module. The laser induction module focuses a pulsed laser onto the surface of the sample to induce plasma generation. The multi-dimensional measurement module acquires the plasma's spectrum, shock wave image, radio frequency electromagnetic signal, shock wave pressure signal, and audio signal. The synchronous control and acquisition module coordinates the working timing of the laser induction module and each measurement unit to achieve time-domain synchronization. The signal processing module receives and processes various data, performs fusion analysis, and outputs multi-dimensional measurement results. This application can simultaneously acquire multi-physical field information of plasma, including spectral, electromagnetic, mechanical, and acoustic information, and is suitable for aerospace composite material testing and laser ablation damage mechanism research.

Description

Technical Field

[0001] This application relates to the field of laser-induced plasma measurement technology, and more specifically to a multi-dimensional measurement system for laser-induced plasma. Background Technology

[0002] Laser-induced plasma (LAP) is a high-temperature, high-density transient plasma formed by rapidly ionizing and vaporizing a target material through the focusing of a high-energy pulsed laser onto the target surface or interior. LAP has significant applications in materials composition analysis, laser processing, and nuclear fusion. High-precision testing of LAP is crucial for a deep understanding of plasma formation mechanisms, evolutionary patterns, and physical properties, and is also a fundamental basis for optimizing related technologies and processes. In scenarios such as advanced composite material testing in aerospace and research on laser ablation damage mechanisms, accurate plasma test data is essential for supporting material performance evaluation, process optimization, and damage control.

[0003] Currently, existing laser-induced plasma testing systems are mainly single-dimensional systems, such as systems for measuring plasma density and electron temperature. These systems focus only on the acquisition and analysis of plasma spectral characteristics, obtaining plasma emission spectra through spectrometers to achieve qualitative and quantitative analysis of material composition. However, they cannot simultaneously acquire the spatial distribution, temporal evolution, and core physical parameters of the plasma. Their single testing dimension makes it difficult to comprehensively reflect the dynamic characteristics of the plasma. Some multi-dimensional testing systems lack a unified synchronous control mechanism, resulting in time differences in test data and signal stability and testing accuracy that are insufficient for micrometer-level testing requirements. Furthermore, existing systems do not cover the testing of electromagnetic radiation characteristics, acoustic characteristics, and shock wave mechanical characteristics, failing to comprehensively characterize the spectral, shock wave, electromagnetic, acoustic, and mechanical properties of laser-induced plasma processes from multiple dimensions, thus failing to meet the needs of experimental research in related fields.

[0004] The shortcomings of existing technologies are as follows: Firstly, they offer limited testing dimensions. Existing systems mostly perform single-dimensional or dual-dimensional testing, failing to comprehensively grasp the dynamic evolution of plasma and thus unable to meet the needs of multi-physics coupled integrated research. Secondly, they have low spatiotemporal resolution. The temporal resolution is only at the microsecond level, unable to capture the nanosecond-level transient evolution details of plasma, and the spatial resolution is at the millimeter level, failing to meet the micrometer-level local feature testing requirements in aerospace composite material testing scenarios. Thirdly, they exhibit poor data correlation. Different testing modules operate independently, lacking a unified synchronous control mechanism. The time difference between laser induction and signal acquisition leads to inaccurate correspondence between spatial, temporal, spectral, electromagnetic, and acoustic data, affecting the accuracy of data analysis. Fourthly, they are cumbersome and inefficient. Most systems require manual adjustment of test positions and parameters, failing to achieve automated multi-dimensional scanning testing. The complex operation is prone to introducing human error, resulting in low testing efficiency.

[0005] Therefore, a multi-dimensional measurement system for laser-induced plasma is needed to solve the technical problems in the existing technology. Summary of the Invention

[0006] The purpose of this application is to provide a laser-induced plasma multidimensional measurement system that can solve at least one of the aforementioned technical problems. The specific solution is as follows: A laser-induced plasma multidimensional measurement system, comprising: Laser-guided module, multi-dimensional measurement module, synchronous control and acquisition module, and signal processing module; The laser induction module is used to generate pulsed laser and focus the pulsed laser onto the surface of the sample to be measured in order to induce the generation of plasma. The multi-dimensional measurement module includes: a plasma electromagnetic radiation characteristic measurement unit, a plasma shock wave mechanical characteristic measurement unit, and a plasma acoustic signal measurement unit; The plasma electromagnetic radiation characteristic measurement unit is used to acquire the radio frequency electromagnetic signals radiated outward by the plasma. The plasma shock wave mechanical property measurement unit is used to acquire the shock wave pressure signal generated by the plasma. The plasma acoustic signal measurement unit is used to acquire the audio signal generated by the plasma; The synchronous control and acquisition module is connected to the laser induction module and the multi-dimensional measurement module respectively. The synchronous control and acquisition module is used to coordinate the working timing of each measurement unit in the laser induction module and the multi-dimensional measurement module, so as to realize the time domain synchronization between the plasma generated by the laser induction module and the data acquired by the multi-dimensional measurement module. The signal processing module is connected to the multi-dimensional measurement module. The signal processing module is used to receive and process various data collected by the multi-dimensional measurement module, perform fusion analysis on the processed data, and output plasma multi-dimensional measurement results.

[0007] Furthermore, the plasma electromagnetic radiation characteristic measurement unit includes: Biconical antenna and spectrum analyzer; The biconical antenna is used to receive radio frequency electromagnetic waves radiated outward from the plasma; The spectrum analyzer is connected to the biconical antenna and is used to record the radio frequency electromagnetic radiation signal collected by the biconical antenna to obtain the spectral range and radiation intensity of the plasma radio frequency electromagnetic radiation.

[0008] Furthermore, the plasma shock wave mechanical property measurement unit includes: Piezoelectric thin film sensors and oscilloscopes; The piezoelectric thin film sensor is used to attach to the surface of the sample to be measured and to capture the shock wave pressure signal in real time; The oscilloscope is connected to the piezoelectric thin film sensor. The oscilloscope is used to record the voltage-time curve output by the piezoelectric thin film sensor and transmit the voltage-time curve to the signal processing module.

[0009] Furthermore, the plasma acoustic signal measurement unit includes: Condenser microphone and sound card; The condenser microphone is used to be aimed at the plasma generation area to record the audio pulse signal of the plasma in a non-contact manner. The sound card is connected to the condenser microphone. The sound card is used to convert the analog audio signal collected by the condenser microphone into a digital audio signal and transmit the digital audio signal to the signal processing module.

[0010] Furthermore, the multi-dimensional measurement module also includes: Plasma spectroscopy measurement unit and plasma shock wave shadow imaging unit; The plasma spectral measurement unit is used to collect the emission spectral data of the plasma. The emission spectral data is used to analyze the elemental composition and content of the plasma, and to calculate the electron density and electron temperature of the plasma. The plasma shock wave shadow imaging unit is used to acquire the spatial distribution information of the plasma and the temporal evolution process of the shock wave front expansion.

[0011] Furthermore, the plasma spectroscopy measurement unit includes: Multi-channel fiber optic spectral probe arrays, fiber optic spectrometers, transient plasma spectral probes, and echelle spectrometers; The multi-channel fiber optic spectral probe array is connected to the fiber optic spectrometer to enable simultaneous measurement at multiple measurement points or simultaneous measurement of multiple spectral bands. The transient plasma spectral probe is connected to the echelle spectrometer, which is equipped with an enhanced charge-coupled device (CCD) detector. The CCD detector is used to convert optical signals into digital signals and transmit them to the signal processing module.

[0012] Furthermore, the plasma shock wave shadow imaging unit includes: Illumination laser sources, beam expanders, filter components, and enhanced charge-coupled device (CCD) cameras; The beam emitted by the illumination laser source is expanded by the beam expansion system and passes through the region where the plasma is located. After being filtered by the filter component, it is imaged onto the enhanced charge-coupled device camera, which is used to capture the shadow image of the plasma shock wave.

[0013] Furthermore, the synchronous control acquisition module includes: Digital pulse delay generator and computer; The computer links the digital pulse delay generator through a synchronous control acquisition program. The digital pulse delay generator is connected to each measurement unit in the laser induction module and the multi-dimensional measurement module, respectively. The digital pulse delay generator is used to adjust the delay time between the laser generated by the laser-induced module and the signal acquisition by each measurement unit, so as to achieve time-domain synchronization.

[0014] Furthermore, the measurement system also includes: The sample adjustment module is used to carry the sample to be measured and to adjust the position of the sample to be measured in space so that each laser pulse acts on a different position on the surface of the sample to be measured. The synchronous control acquisition module is connected to the sample adjustment module. The synchronous control acquisition module is used to coordinate the working timing of the sample adjustment module and the laser induction module to achieve spatial alignment.

[0015] Furthermore, the signal processing module is configured to perform the following processing: The radio frequency electromagnetic signal, the shock wave pressure signal, the audio signal, the emission spectrum data, and the spatial distribution information acquired by the multi-dimensional measurement module are preprocessed. The electron temperature of the plasma was calculated using the Boltzmann graphical method, and the electron density of the plasma was calculated using the Stark broadening method. Shock wave energy is calculated by combining the Sedov theory of point explosion with the shock wave front radius. The audio signal is analyzed in the frequency domain by using Fast Fourier Transform to extract the amplitude, area, and energy parameters of the audio signal. The voltage value measured by the piezoelectric thin film sensor is converted into a pressure value, and a time-pressure curve is output. The processed data are fused together to establish a multi-dimensional data correlation model and output multi-dimensional plasma measurement results.

[0016] Compared with the prior art, the above-described solutions of this application have at least the following beneficial effects: 1. This application discloses a multi-dimensional measurement system for laser-induced plasma. By setting up a plasma electromagnetic radiation characteristic measurement unit, a plasma shock wave mechanical characteristic measurement unit, a plasma acoustic signal measurement unit, a plasma spectral measurement unit, and a plasma shock wave shadow imaging unit, and integrating these five measurement units with a laser-induced module into the same system, it achieves the synchronous acquisition of laser-induced plasma radio frequency electromagnetic signals, shock wave pressure signals, audio signals, emission spectral data, and shock wave shadow images. This expands the testing dimensions from single spectral testing to multi-physics field fusion measurement of light, electricity, sound, and force, enabling a comprehensive characterization of the evolution law of laser-induced plasma.

[0017] 2. The laser-induced plasma multidimensional measurement system of this application sets up a synchronous control acquisition module connected to the laser-induced module and the multidimensional measurement module respectively. It uses a digital pulse delay generator to coordinate the working timing of the laser-induced module and each measurement unit, achieving nanosecond-level time-domain synchronization. This eliminates the time difference between the laser-induced plasma and the data acquired by each measurement unit, ensuring that the radio frequency electromagnetic signal, shock wave pressure signal, audio signal, emission spectrum data and shock wave shadow image data are accurately aligned in time, thus improving the correlation of multidimensional data and the accuracy of subsequent fusion analysis.

[0018] 3. This application discloses a laser-induced plasma multidimensional measurement system. By setting up a signal processing module to preprocess, extract characteristic parameters, and perform multi-physics field fusion analysis on various data collected by the multidimensional measurement module, a correlation model between electromagnetic radiation characteristics and plasma parameters is established. The Pearson correlation coefficient is used to quantify the correlation between spectral line intensity and audio parameters. The voltage value measured by the piezoelectric thin film sensor is converted into a pressure value and outputs a time-pressure curve. Finally, the spectral data, shock wave shadow image data, electromagnetic radiation data, acoustic signal data, and shock wave mechanical data are fused to achieve quantitative output of laser-induced plasma multidimensional measurement results. This provides comprehensive data support for the detection of advanced composite materials in aerospace and the study of laser ablation damage mechanisms. Attached Figure Description

[0019] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. It is obvious that the drawings described below are merely some embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort. In the drawings: Figure 1 This is a schematic diagram of a laser-induced plasma multidimensional measurement system provided in an embodiment of this application.

[0020] Figure 2 This is a schematic diagram of the workflow of a laser-induced plasma multidimensional measurement system provided in an embodiment of this application.

[0021] Explanation of reference numerals in the attached figures: 1. Pulsed laser source; 2. First reflecting mirror; 3. Half-wave plate; 4. Glan prism; 5. Semi-reflective mirror; 6. Energy meter; 7. Second reflecting mirror; 8. Focusing lens; 9. Plasma; 10. Sample to be measured; 11. Enhanced charge-coupled device camera; 12. Attenuator and interference filter; 13. First plano-convex lens; 14. Plano-concave lens; 15. Aperture; 16. Second plano-convex lens; 17. Illumination laser source; 18. Digital pulse delay generator; 19. Computer; 20. Piezoelectric thin film sensor; 21. Oscilloscope; 22. Biconical antenna; 23. Spectrum analyzer; 24. Multi-channel fiber optic spectral probe array; 25. Fiber optic spectrometer; 26. Transient plasma spectral probe; 27. Echelon spectrometer; 28. Condenser microphone; 29. ​​Sound card; 30. Horizontal motorized displacement stage. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this application clearer, the application will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0023] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that an article or device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such an article or device. Without further limitation, an element defined by the phrase "comprising one" does not exclude the presence of other identical elements in the article or device that includes said element.

[0024] The embodiments of this application are described in detail below with reference to the accompanying drawings.

[0025] Example 1: like Figure 1 As shown, a laser-induced plasma multidimensional measurement system includes: a laser induction module, a multidimensional measurement module, a synchronous control and acquisition module, and a signal processing module.

[0026] The laser induction module generates pulsed laser light and focuses it onto the surface of the sample 10 to induce plasma 9. The multi-dimensional measurement module includes a plasma electromagnetic radiation characteristic measurement unit, a plasma shock wave mechanical characteristic measurement unit, and a plasma acoustic signal measurement unit. The plasma electromagnetic radiation characteristic measurement unit acquires the radio frequency electromagnetic signals radiated outward by plasma 9. The plasma shock wave mechanical characteristic measurement unit acquires the shock wave pressure signals generated by plasma 9. The plasma acoustic signal measurement unit acquires the audio signals generated by plasma 9. A synchronous control and acquisition module is connected to both the laser induction module and the multi-dimensional measurement module. This module coordinates the timing of the measurement units in both modules, ensuring temporal synchronization between plasma 9 generated by the laser induction module and data acquired by the multi-dimensional measurement module. A signal processing module is connected to the multi-dimensional measurement module. This module receives and processes various data acquired by the multi-dimensional measurement module, performs fusion analysis on the processed data, and outputs the multi-dimensional measurement results of plasma 9.

[0027] The technical solution of this application integrates three key measurement dimensions—electromagnetic radiation, mechanical properties, and acoustic signals—into the same system and allows them to work simultaneously under synchronous control, overcoming the shortcomings of existing technologies such as single measurement dimensions and poor data correlation.

[0028] In this embodiment, the laser induction module includes, sequentially arranged along the optical path, a pulsed laser source 1, a first reflecting mirror 2, a half-wave plate 3, a Glan prism 4, a semi-reflective mirror 5, a second reflecting mirror 7, and a focusing mirror 8. The pulsed laser source 1 is an Nd:YAG high-energy pulsed laser with adjustable energy from 0-2000 mJ, a wavelength of 1064 nm, a pulse width of 10 ns, a repetition frequency of 10 Hz, and outputs linearly polarized nanosecond pulsed lasers with high beam quality. The laser beam diameter is 10mm. The laser energy attenuator consists of a half-wave plate 3 and a Glan prism 4, which can continuously adjust the energy from 0-100% with an accuracy of 1%. The first reflecting mirror 2 and the semi-reflective mirror 5 have the function of adjusting the beam height, and together with the second reflecting mirror 7, they can realize the laser perpendicularly irradiating the sample surface. The semi-reflective mirror 5 has a beam splitting ratio of 50:50 and is used for real-time monitoring of laser parameters. The focusing mirror 8 is a plano-convex lens with an aperture of 25.4mm and a focal length of 100mm, coated with a 1064nm anti-reflection film, with a transmittance of ≥98%, which can focus the laser into a micron-sized spot and efficiently induce the ionization and vaporization of the sample to form plasma 9.

[0029] The first reflecting mirror 2 guides the laser beam to the half-wave plate 3. The half-wave plate 3 and the Glan prism 4 form a continuously adjustable energy attenuator. By rotating the half-wave plate 3, the polarization direction of the incident light is changed, thereby adjusting the output laser energy. The splitting ratio of the semi-reflective mirror 5 is 50:50. The semi-reflective mirror 5 reflects a portion of the light to the energy meter 6 for real-time monitoring of the laser energy, while the other portion is transmitted, deflected by the second reflecting mirror 7, and finally focused by the focusing mirror 8 into a micrometer-sized spot that illuminates the surface of the sample 10 to be measured. The laser induction module can stably induce the generation of high-temperature, high-density plasma 9.

[0030] The multi-dimensional measurement module includes a plasma electromagnetic radiation characteristic measurement unit, a plasma shock wave mechanical characteristic measurement unit, a plasma acoustic signal measurement unit, a plasma spectral measurement unit, and a plasma shock wave shadow imaging unit. Each measurement unit is triggered uniformly by the synchronous control acquisition module to achieve synchronous data acquisition.

[0031] The plasma electromagnetic radiation characteristic measurement unit includes a biconical antenna 22 and a spectrum analyzer 23. In this embodiment, the detection range of the biconical antenna 22 is 3MHz to 1GHz. The aperture size of the biconical antenna 22 is 400mm × 300mm. The biconical antenna 22 is used to receive radio frequency electromagnetic waves radiated outward from the plasma 9. The biconical antenna 22 can be placed vertically or horizontally to adapt to different laser polarization directions. When the biconical antenna 22 is placed vertically, it is parallel to the X-axis; when it is placed horizontally, it is parallel to the Y-axis. When the laser beam output by the nanosecond pulse laser source 1 is vertically polarized, the polarization direction is parallel to the X-axis; when the laser beam is horizontally polarized, the polarization direction is parallel to the Y-axis.

[0032] The biconical antenna 22 is approximately 0.27m from the laser focus. For radio frequency electromagnetic waves with frequencies less than or equal to 1GHz, the detection distance satisfies the far-field reception condition for radio frequency electromagnetic waves, i.e., the reception distance r is greater than twice the square of the antenna aperture D divided by the wavelength λ. The formula is as follows: Wherein, D represents the antenna aperture, which is 200mm in this embodiment; r represents the distance between the radiation source and the antenna, which is approximately 0.27m in this embodiment; and λ represents the radiation wavelength.

[0033] In the far-field region, the spatial angular distribution of radio frequency radiation from plasma 9 is related to the distance between the receiving antenna and the radiation source. The spectrum analyzer 23 is connected to the biconical antenna 22 via a coaxial cable. The frequency range of the spectrum analyzer 23 is 9 kHz to 26.5 GHz. The spectrum analyzer 23 is used to record the radio frequency electromagnetic radiation signal collected by the biconical antenna 22, obtaining the spectral range and radiation intensity of the radio frequency electromagnetic radiation from plasma 9. The spectrum analyzer 23 converts the signal into a digital signal and transmits it to the signal processing module. The plasma electromagnetic radiation characteristic measurement unit realizes broadband, non-contact measurement of the electromagnetic radiation from plasma 9.

[0034] The technical solution of this application embodiment has that the broadband characteristics and rotatable installation method of the double-conical antenna 22 can adapt to different laser polarization states, and the installation distance that meets the far-field reception conditions ensures the accuracy of the measurement results. The wide frequency range of the spectrum analyzer 23 covers the main frequency bands of plasma 9 radio frequency radiation.

[0035] The plasma shock wave mechanical property measurement unit includes a piezoelectric thin film sensor 20 and an oscilloscope 21. The piezoelectric thin film sensor 20 is a PVDF piezoelectric thin film sensor. The specifications of the piezoelectric thin film sensor 20 are as follows: The thickness of the piezoelectric thin film sensor 20 is... The piezoelectric constant of the piezoelectric thin film sensor 20 is... The capacitance of the piezoelectric thin-film sensor 20 is... The surface resistance of the piezoelectric thin film sensor 20 is less than or equal to... A piezoelectric thin-film sensor 20 is attached to the back of the sample 10 to capture the laser-induced shock wave pressure signal in real time. The piezoelectric thin-film sensor 20 converts the shock wave pressure into an electrical charge signal. An oscilloscope 21 is connected in parallel with the piezoelectric thin-film sensor 20 via a signal line. The oscilloscope 21 records the voltage-time curve output by the piezoelectric thin-film sensor 20 and transmits the voltage-time curve to the signal processing module.

[0036] The plasma acoustic signal measurement unit includes a condenser microphone 28 and a sound card 29. The condenser microphone 28 employs an omnidirectional polarity mode. The condenser microphone 28 is used to align with the plasma generation area 9 to record the audio pulse signal of the plasma 9 in a non-contact manner. The sensitivity of the condenser microphone 28 is... The frequency response range is 20 Hz to 20 kHz. The condenser microphone 28 is approximately 50 cm from the point of contact with the plasma 9. The sound card 29 is connected to the condenser microphone 28 via an audio cable. The sound card 29 converts the analog audio signal acquired by the condenser microphone 28 into a digital audio signal and transmits the digital audio signal to the signal processing module. The plasma acoustic signal measurement unit avoids interference from contact sensors on the evolution of the plasma 9, and the sound card 29 has a high sampling rate, which can completely preserve the time-frequency characteristics of the audio signal.

[0037] In the technical solution of this application embodiment, the multi-dimensional measurement module further includes a plasma spectral measurement unit. The plasma spectral measurement unit is used to collect emission spectrum data of plasma 9. The emission spectrum data is used to analyze the elemental composition and content in plasma 9, and to calculate the electron density and electron temperature of plasma 9.

[0038] The plasma spectroscopy measurement unit includes a multi-channel fiber optic spectral probe array 24, a fiber optic spectrometer 25, a transient plasma spectral probe 26, and an echelle spectrometer 27. The multi-channel fiber optic spectral probe array 24 is connected to the fiber optic spectrometer 25. The multi-channel fiber optic spectral probe array 24 and the fiber optic spectrometer 25 are used to achieve simultaneous measurement at multiple measurement points or simultaneously measurement across multiple spectral bands. Steady-state spectral testing is performed before transient spectral testing to determine the spectral range of plasma 9. Simultaneous measurement at multiple test points improves the spatial resolution of the spectral measurement. The transient plasma spectral probe 26 is connected to the echelle spectrometer 27. The transient plasma spectral probe 26 uses quartz fiber, has a core diameter of 200 μm, and a numerical aperture of 0.22. One end of the transient plasma spectral probe 26 is connected to the echelle spectrometer 27, and the other end is aligned with a focusing assembly to transmit the light signal emitted by plasma 9. The focusing assembly is a plano-convex lens with a focal length of 30mm and an aperture of 40mm. It is coated with an anti-reflection film. The focusing assembly is aligned with the transient plasma spectral probe 26 to focus the light emitted by the plasma 9 onto the end face of the probe 26, thereby improving signal acquisition efficiency. The echelle spectrometer 27 is equipped with an enhanced charge-coupled device (CCD) detector. The CCD detector converts the optical signal into a digital signal and transmits it to the signal processing module.

[0039] The echelle spectrometer 27 employs a high-resolution grating spectrometer. Its wavelength measurement range is 200 nm to 1100 nm, covering the ultraviolet, visible, and near-infrared bands. The enhanced charge-coupled device (CCD) detector equipped with the echelle spectrometer 27 features time-gated functionality, enabling nanosecond-level time-resolved spectral acquisition. After steady-state spectral testing, the delay and integration gate parameters of the echelle spectrometer 27 are determined based on atomic spectral lines, ion spectral lines, and continuous background radiation intensity.

[0040] The emission spectrum data acquired by the plasma spectroscopy measurement unit is combined with the NIST atomic spectroscopy database to assign spectral lines to the experimental line spectra, which is used to accurately identify ion spectra and atomic spectra and obtain the elemental composition and concentration information of the sample 10 to be measured.

[0041] The technical solution of this application combines steady-state and transient spectral testing, which can improve spatial resolution through multi-channel arrays and achieve nanosecond-level time-resolved spectral acquisition by utilizing the time gating of enhanced charge-coupled device detectors.

[0042] The plasma shock wave shadow imaging unit includes an illumination laser source 17, a beam expander system, a filter assembly, and an enhanced charge-coupled device camera 11.

[0043] The illumination laser source 17 emits an illumination beam. The beam expanding system consists of a plano-concave lens 14 and a second plano-convex lens 16. The beam emitted by the illumination laser source 17 is expanded into collimated parallel light by the plano-concave lens 14 and the second plano-convex lens 16 in sequence. The collimated parallel light passes through the aperture 15 and illuminates the region where the plasma 9 is located. After being filtered by an attenuator and an interference filter 12, it is imaged onto the enhancement-coupled device camera 11 by the first plano-convex lens 13. The aperture 15 is used to adjust the diameter of the illumination beam to match the size of the observation area of ​​the plasma 9. The enhancement-coupled device camera 11 is used to capture the shadow image of the shock wave of the plasma 9.

[0044] The enhanced charge-coupled device (CCD) camera 11 has an adjustable gain, ranging from 1x to 1000x. The CCD camera 11 has a resolution of 1024 pixels × 1024 pixels. The exposure time of the CCD camera 11 is from 1 ns to 1 ms.

[0045] The principle of shadow imaging is as follows: When a collimated parallel beam irradiates plasma 9, the density difference in different regions of the shock wave leads to different refractive indices of the beam, thus forming a shadow image that clearly shows the boundary and shape of the shock wave. Measurements must be performed in a dimly lit environment to reduce interference from background light on the enhanced charge-coupled device camera 11.

[0046] The shadow images acquired by the plasma shock wave shadow imaging unit are used to extract the spatial distribution information of plasma 9 and the temporal evolution of shock wave wavefront expansion. The spatial resolution of the plasma shock wave shadow imaging unit reaches the micrometer level.

[0047] The technical solution of this application embodiment uses active illumination shadow imaging technology in the plasma shock wave shadow imaging unit, which is different from the method of directly photographing the self-luminous plasma. It can clearly display the shock wave front boundary, and combined with time delay control, it can obtain the evolution curve of the shock wave expansion distance over time.

[0048] In the technical solution of this application embodiment, the synchronous control and acquisition module includes a digital pulse delay generator 18 and a computer 19. The digital pulse delay generator 18 adopts a DG645 signal delay generator. The computer 19 has a built-in synchronous control and acquisition program. The computer 19 links the digital pulse delay generator 18 through the synchronous control and acquisition program. The digital pulse delay generator 18 is connected to the nanosecond pulse laser source 1 in the laser induction module and each measurement unit in the multi-dimensional measurement module through trigger lines. The digital pulse delay generator 18 is used to adjust the delay time between the laser generated by the laser induction module and the signal acquisition by each measurement unit to achieve time-domain synchronization. In specific operation, the synchronous control and acquisition module pre-stores the control timing program and sets the time nodes for laser induction, sample scanning, signal acquisition, and data transmission. The digital pulse delay generator 18 adjusts the delay interval between laser induction and signal acquisition to ensure that at the moment the laser acts on the sample 10 to be measured to generate plasma 9, each measurement unit of the multi-dimensional measurement module synchronously starts signal acquisition to achieve time-domain synchronization of multiple detection methods. The calibration accuracy of the digital pulse delay generator 18 reaches 1 nanosecond.

[0049] In the technical solution of this application embodiment, the synchronous control acquisition module takes the digital pulse delay generator 18 as the core and provides multiple independent and adjustable low jitter trigger pulses to ensure that all measurement units start synchronously or in a preset delay sequence under the action of the same laser pulse, thereby eliminating the time difference of data acquisition and ensuring the spatiotemporal correlation of multi-dimensional data.

[0050] In the technical solution of this application embodiment, a laser-induced plasma multidimensional measurement system further includes a sample adjustment module. The sample adjustment module is used to carry the sample 10 to be measured and to adjust the position of the sample 10 in space, so that each laser pulse acts on a different position on the surface of the sample 10. The sample adjustment module includes a horizontal electric displacement stage 30 and a three-dimensional sample stage. The horizontal electric displacement stage 30 is used to move the sample 10 along the X and Y axes in the horizontal plane. The positioning accuracy of the horizontal electric displacement stage 30 is [insert accuracy here]. The repeatability accuracy is The horizontal electric displacement stage 30 supports single-motion and uniform-speed motion modes and can work in conjunction with the laser induction module and the multi-dimensional measurement module. The three-dimensional sample stage is used to adjust the focus and tilt angle of the sample 10 in the vertical Z-axis direction. The computer 19 in the synchronous control acquisition module is connected to the sample adjustment module. The computer 19 coordinates the working timing of the sample adjustment module and the laser induction module through the synchronous control acquisition program to achieve spatial alignment, that is, to ensure that the laser focus point is consistent with the detection spatial position of each measurement unit.

[0051] The sample adjustment module, through an automated precision displacement stage, ensures that each laser pulse acts on the fresh surface of the sample, avoiding errors caused by repeated ablation. At the same time, in conjunction with synchronous control, it can realize automated scanning tests, greatly improving testing efficiency and repeatability.

[0052] The technical solution of this application embodiment provides a detailed description of the specific processing flow of the signal processing module. The signal processing module is implemented by a computer 19 and its internal data processing software. The signal processing module is configured to perform the following processes: First, the signal processing module preprocesses the radio frequency electromagnetic signals, shock wave pressure signals, audio signals, emission spectrum data, and spatial distribution information acquired by the multi-dimensional measurement module. Preprocessing includes calibration, noise reduction, and singular value removal. Preprocessing can be performed using existing technical solutions, depending on the specific circumstances; the technical solutions in this application embodiment are not limited in this regard.

[0053] Next, the signal processing module combines the NIST atomic spectroscopy database to assign spectral lines to the experimental line spectra, accurately identify ion spectra and atomic spectra, and obtain the elemental composition and concentration information of the sample 10 to be measured.

[0054] The signal processing module calculates the electron temperature of plasma 9 using the Boltzmann graphical method. The module analyzes the intensity ratio of spectral lines of the same element in different excited states in the emission spectrum of plasma 9, and calculates the electron temperature using the Boltzmann equation. The specific expression is: in, Indicates the intensity of characteristic spectral lines; Indicates the center wavelength; Indicates the probability of a jump; Indicates degeneracy; Indicates the energy of the upper energy level; represents Boltzmann constant; T represents electron density; h represents Planck constant; c represents speed of light; F represents experimental parameters, including factors such as instrument receiving efficiency; Indicates element concentration; This represents the partition function.

[0055] The signal processing module calculates the electron density of plasma 9 using the Stark broadening method. The module fits the characteristic spectral lines using the Lorentz function to obtain the full width at half maximum (FWHM) of the spectral lines, and then calculates the electron density using the Stark broadening formula. The expression for the calculation formula is as follows: in, The Stark full width at half maximum (FWHM) of the characteristic spectral line is obtained by fitting the characteristic spectral line with the Lorentz function. The value represents the Stark broadening factor, which is an intrinsic constant of the corresponding characteristic spectral line at a specific plasma temperature. The value can be found in the literature. Represents electron density, with a calculation range of The calculation accuracy is .

[0056] The signal processing module combines the shock wave shadow image with the Sedov theory of point explosion to calculate the relevant physical parameters of the shock wave. The signal processing module obtains the wavefront radius from the shock wave shadow image, expressed as: in, R Indicates the radius of the shock wave front; E Indicates the energy of the shock wave; ρ denoted by , where represents the atmospheric density before the shock wave; k represents the dimensionless integral constant related to the shock wave process, with a value close to 1. t Indicates the delay time.

[0057] The signal processing module sequentially performs baseline correction, detrending processing, and smoothing filtering on the electromagnetic radiation signal of plasma 9 to improve the signal-to-noise ratio.

[0058] The signal processing module extracts three key characteristic parameters—center frequency, peak intensity, and spectral bandwidth—from the processed spectral data. Each parameter characterizes the plasma 9 properties as follows: Center frequency, corresponding to the intrinsic frequency of the collective electron oscillation in plasma 9, is used to quantitatively invert the electron density and satisfies the following expression: in, Indicates the center frequency of plasma characteristic 9. Indicates electron density; The higher, The larger.

[0059] Peak intensity characterizes the total ionization degree of plasma and the total number of instantaneous free electrons. The higher the intensity, the higher the ionization efficiency of the sample. Combined with the time-series curve, it can reflect the electron recombination decay rate.

[0060] The spectral bandwidth characterizes the spatial gradient and uniformity of plasma 9 electron density; the wider the bandwidth, the greater the difference between the high-density core and the low-density peripheral region, and the more uneven the ionization distribution; the bandwidth narrows synchronously when plasma 9 expands and recombines.

[0061] The signal processing module establishes a correlation model between electromagnetic radiation characteristics and plasma 9 parameters by comparing experimental data under different laser energy conditions, ultimately enabling the characterization and analysis of electromagnetic radiation patterns during the evolution of plasma 9.

[0062] The signal processing module performs time-domain and frequency-domain analysis on the audio signal. Time-domain analysis extracts three key parameters: amplitude, area, and energy. Frequency-domain analysis uses a Fast Fourier Transform algorithm to obtain the spectral data. (Audio area...) and audio energy The expression for the calculation formula is: in, x ( t () represents the time function of audio signal strength; , This indicates the time period of the audio signal that is covered before the first echo.

[0063] The signal processing module uses the Pearson correlation coefficient to quantify the linear correlation between spectral line intensity and audio amplitude, audio area, and audio energy. The generation of laser-induced plasma audio signals is closely related to laser power density, and different materials have different plasma excitation thresholds.

[0064] The signal processing module converts the voltage value measured by the piezoelectric thin-film sensor 20 into a pressure value and outputs a time-pressure curve. The relationship between the charge Q generated by the piezoelectric thin-film sensor 20 after being subjected to shock wave pressure and the voltage value U measured by the oscilloscope 21 satisfies the following expression: Where C represents the capacitance of the piezoelectric thin film sensor 20, and in the technical solution of this application embodiment, C is taken as a value of .

[0065] The relationship between shock wave pressure σ and charge Q satisfies the following expression: Where A represents the effective working area of ​​the piezoelectric thin film sensor 20; d represents the piezoelectric strain constant.

[0066] Substituting the parameters of the piezoelectric thin-film sensor 20, the expression for the pressure conversion formula is obtained: The signal processing module fuses the processed spectral data, shock wave shadow image data, electromagnetic radiation data, acoustic signal data, and shock wave mechanical data to establish a multi-dimensional data correlation model, enabling synchronous data analysis and quantitative characterization of the laser-induced plasma 9. The signal processing module outputs multi-dimensional measurement results for plasma 9, including a spatiotemporally resolved shock wave image, spectrum, electromagnetic spectrum, audio signal graph, and shock wave pressure curve. The module also supports data storage and export in Excel and TXT formats.

[0067] Multi-dimensional data fusion analysis shows that the peak value of plasma 9 radio frequency electromagnetic radiation and the peak value of electron density have time synchronization characteristics, and the timing of their peak occurrence is highly consistent; the energy of shock wave acoustic signal and the amplitude of shock wave pressure have strong correlation characteristics; the electron temperature obtained by spectral calculation shows a positive correlation trend with the energy of shock wave.

[0068] In the technical solution of this application embodiment, the signal processing module integrates a variety of physical parameter inversion algorithms, which can extract key physical quantities such as electron temperature, electron density, shock wave energy, and pressure time history from the original measurement data, and reveal the intrinsic relationship between various physical fields through a multi-dimensional data fusion model.

[0069] Example 2: like Figure 2 As shown, the workflow of a laser-induced plasma multidimensional measurement system is as follows: S1. Sample Installation and Debugging. Fix the sample 10 to be measured on the horizontal electric displacement stage 30 of the sample adjustment module. Control the movement of the horizontal electric displacement stage 30 via computer 19 to align the target position of the sample with the focused spot of the laser-induced module. Install and debug the plasma electromagnetic radiation characteristic measurement unit, plasma acoustic signal measurement unit, plasma shock wave mechanical characteristic measurement unit, plasma spectrum measurement unit, and plasma shock wave shadow imaging unit. Adjust the position of the biconical antenna 22 to ensure that the antenna is approximately 0.27m away from the laser focus, meeting the far-field reception conditions. Calibrate the frequency range and sensitivity of the spectrum analyzer 23. Fix the condenser microphone 28 approximately 50cm away from the point of action of the plasma 9 and couple it to the sound card 29, calibrating the microphone sensitivity. Attach the piezoelectric thin film sensor 20 to the back of the sample 10 to be measured, ensuring a tight fit without looseness. Adjust the positions of the illumination laser source 17, beam expander system, and enhanced charge-coupled device camera 11 to ensure clear acquisition of the shock wave shadow image of the plasma 9. Throughout the debugging process, ensure that there is no mutual interference between the measurement units and that signal transmission is normal.

[0070] S2. Laser Parameter and Test Parameter Settings. Connect the synchronous control acquisition module via computer 19 and enter the parameter setting interface. Set the relevant parameters of the laser induction module: adjust the energy of the nanosecond pulse laser source 1 to the set value, fix the wavelength at 1064nm, and adjust the laser focusing spot position. Set the test parameters of each measurement unit of the multi-dimensional measurement module: set the wavelength range, acquisition speed, and enhanced charge-coupled device (CCD) detector gain for the echelle spectrometer 27, and optimize the spectral delay and integration gate width through the digital pulse delay generator 18; set the resolution, exposure time, and imaging gain for the enhanced CCD camera 11, and adjust the attenuation and filter parameters in conjunction with the illumination laser optical path, and adjust the illumination beam diameter through the aperture 15 to match the observation area; set the detection frequency band, center frequency, and sweep width parameters for the biconical antenna 22 and the spectrum analyzer 23 to ensure effective acquisition of far-field electromagnetic signals; set the matching sampling rate and acquisition range for the condenser microphone 28 and the sound card 29; set the sampling rate for the piezoelectric thin film sensor 20 and the oscilloscope 21. Configure the horizontal electric displacement stage 30 with positioning accuracy, step distance, and motion mode. After setting all parameters, save the parameter configuration for future repeated testing.

[0071] S3. Synchronous Control Parameter Calibration. Computer 19 links digital pulse delay generator 18 through synchronous control acquisition program. Digital pulse delay generator 18 adjusts the delay time between nanosecond pulse laser source 1 and signal acquisition of each measurement unit, achieving a calibration accuracy of 1 nanosecond. Nanosecond pulse laser source 1 is activated to emit a single pulse laser, synchronously triggering plasma shock wave shadow imaging unit, plasma spectrum measurement unit, plasma electromagnetic radiation characteristic measurement unit, plasma acoustic signal measurement unit, and plasma shock wave mechanical characteristic measurement unit. This ensures that at the instant the laser acts on the sample 10 to generate plasma 9, each measurement unit synchronously starts signal acquisition without time difference. Repeat calibration 3 to 5 times to ensure timing stability. The detection position of each measurement unit is calibrated. After calibration, the installation position parameters of each measurement unit are recorded, and the brackets of each measurement unit are fixed to prevent positional shifts during measurement. Simultaneously, the collaborative working parameters of synchronous control acquisition module and sample adjustment module are calibrated to ensure that the movement of horizontal electric displacement stage 30 matches the timing of laser induction and signal acquisition, laying the foundation for subsequent automated scanning measurement.

[0072] S4. Laser-induced plasma 9 is generated. After parameter calibration, the laser induction module is activated. The nanosecond pulse laser source 1 emits high-energy pulsed laser according to the set parameters. The laser energy is adjusted by the attenuator composed of half-wave plate 3 and Glan prism 4, the propagation direction is changed by the first reflecting mirror 2 and the second reflecting mirror 7, and finally focused on the target test position on the surface of the sample 10 by the focusing mirror 8. The laser energy is concentrated on the surface of the sample 10, causing the surface material of the sample 10 to be rapidly ionized and vaporized, forming a high-temperature, high-density transient plasma 9. The energy meter 6 monitors the laser energy in real time. During the measurement process, the horizontal electric displacement stage 30 of the sample adjustment module is translated in two dimensions in the X and Y directions to ensure that each laser pulse corresponds to a new action position on the surface of the sample 10, avoiding repeated ablation that could damage the sample surface.

[0073] S5. Synchronous Acquisition of Multi-Dimensional Measurement Data. Simultaneously with the generation of laser-induced plasma 9, the synchronous control acquisition module triggers all measurement units in the multi-dimensional measurement module, initiating synchronous acquisition. The biconical antenna 22 and spectrum analyzer 23 acquire electromagnetic radiation signals. The piezoelectric thin-film sensor 20 and oscilloscope 21 acquire shock wave pressure signals. The condenser microphone 28 and sound card 29 acquire audio signals. The multi-channel fiber optic spectral probe array 24 and fiber optic spectrometer 25, along with the transient plasma spectral probe 26 and echelle spectrometer 27, acquire emission spectra. The illumination laser source 17 and enhanced charge-coupled device camera 11 acquire shock wave shadow images.

[0074] All measurement units include: a plasma electromagnetic radiation characteristics measurement unit, a plasma shock wave mechanical characteristics measurement unit, a plasma acoustic signal measurement unit, a plasma spectral measurement unit, and a plasma shock wave shadow imaging unit. Data acquisition begins simultaneously to ensure the stability and accuracy of multi-dimensional data.

[0075] S6. Data Processing and Result Output. After receiving all multi-dimensional raw measurement data, the signal processing module initiates the signal processing flow. The module calibrates the spectral data, shock wave shadow image data, electromagnetic signals, acoustic signals, and mechanical signals, correcting measurement errors. It employs a multi-dimensional data fusion algorithm to fuse the five types of data, establishing a multi-dimensional data correlation model for synchronous data analysis. The module performs curve fitting on the time evolution data, generating time evolution curves for plasma density, electron temperature, electromagnetic signals, acoustic signals, and mechanical signals. It performs qualitative and quantitative elemental analysis on the spectral data, assigning spectral lines using the NIST atomic spectral database and outputting elemental composition and content reports. It performs spectral analysis on the electromagnetic signals, outputting an electromagnetic radiation spectrum and characteristic parameters. It performs time-domain and frequency-domain analysis on the acoustic signals, extracting amplitude, area, and energy parameters, and quantifying the linear correlation between spectral line intensity and audio parameters using the Pearson correlation coefficient. Finally, it analyzes the mechanical signals, outputting pressure-time curves. After all processing is completed, the computer 19's display terminal displays the working status of each module, measurement parameters, and processing results in real time, and supports storing and exporting the measurement results in Excel and TXT formats.

[0076] S7. Measurement Completed. After all measurements are completed, first shut down the laser induction module to stop laser emission. Then shut down all measurement units of the multi-dimensional measurement module to stop signal acquisition. Remove the sample 10 to be measured and clean the horizontal electric displacement stage 30 to avoid residual impurities affecting subsequent measurements. Shut down the synchronous control acquisition module, signal processing module, and sample adjustment module, and save all measurement data and parameter configurations. Check the status of each device, turn off the power, tidy up the measuring instruments and experimental site, and complete the entire measurement process.

[0077] The laser-induced plasma multidimensional measurement system in this application embodiment performs laser-induced plasma multidimensional measurements on carbon fiber composite materials. The measurement results are as follows: The electromagnetic radiation spectrum obtained by the plasma electromagnetic radiation characteristic measurement unit ranges from 10MHz to 800MHz, and the radiation intensity increases with increasing laser energy. The received electromagnetic signal intensity is highest when the biconical antenna 22 is placed vertically and the laser is vertically polarized. Meeting the far-field reception conditions, when the antenna is 0.27m away from the laser focus, the spectrum data recorded by the spectrum analyzer 23, after baseline correction and filtering, yields a center frequency of 150MHz and a peak intensity of -65dBm. The pressure peak value obtained by the plasma shock wave mechanical characteristic measurement unit ranges from 5MPa to 20MPa, and the pressure pulse width is approximately 200ns. The specifications of the piezoelectric thin film sensor 20 are as follows: With a thickness of 30μm and a capacitance of 390pF, the voltage-time curve recorded by oscilloscope 21 was obtained using the formula... The converted time-pressure curve shows that the shock wave pressure reaches its peak approximately 100 ns after laser emission. The main frequency of the audio signal acquired by the plasma acoustic signal measurement unit is concentrated between 1 kHz and 10 kHz, and the acoustic signal energy is positively correlated with the laser energy. When the condenser microphone 28 is 50 cm away from the plasma 9 point of action, the audio signal shows no saturation distortion. The sound card 29 has a sampling rate of 192 kHz. Fast Fourier transform analysis shows that the audio signal energy increases with increasing laser energy. Pearson correlation coefficient calculation shows that the correlation coefficient between spectral line intensity and audio energy is 0.89. The electron temperature calculated by the plasma spectral measurement unit is 8000 K to 15000 K, and the electron density is... to Steady-state spectroscopy was completed before transient spectroscopy, clarifying the main spectral range of plasma 9. The enhanced charge-coupled device detector gate width of the echelle spectrometer 27 was set to 50 ns, with a delay of 100 ns, achieving the optimal signal-to-noise ratio. The shock wavefront expansion radius acquired by the plasma shock wave shadow imaging unit varied with the delay time according to... The calculated shock wave energy shows a linear correlation with the laser energy, exhibiting a regular growth pattern. The experiment was conducted in a low-light environment with an exposure time of 10 ns and a gain of 500 times for the enhanced charge-coupled device (CCD) camera 11, clearly obtaining the shock wave contour image with a spatial resolution down to the micrometer level. Multi-dimensional data fusion analysis shows that the peak value of the plasma 9 radio frequency electromagnetic radiation and the peak value of the electron density exhibit temporal synchronization characteristics, with their peak occurrence times highly consistent. The shock wave acoustic signal energy and the shock wave pressure amplitude show a strong correlation, and the electron temperature calculated from the spectrum shows a positive correlation with the shock wave energy. These results verify the feasibility and effectiveness of the technical solution in this application.

[0078] The laser-induced plasma multi-dimensional measurement system provided in this application includes a laser induction module, a multi-dimensional measurement module, a synchronous control and acquisition module, and a signal processing module. The technical solution integrates a plasma electromagnetic radiation characteristic measurement unit, a plasma shock wave mechanical characteristic measurement unit, a plasma acoustic signal measurement unit, a plasma spectral measurement unit, and a plasma shock wave shadow imaging unit with the laser induction module into the same system. This achieves simultaneous measurement of multiple physical fields, including 9-frequency electromagnetic signals, shock wave pressure signals, audio signals, emission spectral data, and shock wave shadow images of laser-induced plasma, overcoming the limitation of existing technologies with only one testing dimension.

[0079] By connecting a synchronous control acquisition module to both the laser-induced plasma module and the multi-dimensional measurement module, the working timing of each measurement unit in both modules is unified and coordinated. This achieves nanosecond-level time-domain synchronization between the plasma generated by the laser-induced plasma module and the data acquired by the multi-dimensional measurement module, eliminating the time difference in multi-dimensional data acquisition and ensuring accurate correlation between spectral, electromagnetic, mechanical, and acoustic data. A signal processing module receives and processes the radio frequency electromagnetic signals, shock wave pressure signals, audio signals, emission spectral data, and spatial distribution information acquired by the multi-dimensional measurement module. The processed data are then fused and analyzed to establish a multi-dimensional data correlation model, enabling a comprehensive quantitative characterization of the laser-induced plasma evolution process. This provides reliable multi-physics test data support for the detection of advanced aerospace composite materials and the study of laser ablation damage mechanisms.

[0080] Finally, it should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the systems or apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple, and relevant parts can be referred to the method section.

[0081] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A multi-dimensional measurement system for laser-induced plasma, characterized in that, include: Laser-guided module, multi-dimensional measurement module, synchronous control and acquisition module, and signal processing module; The laser induction module is used to generate pulsed laser and focus the pulsed laser onto the surface of the sample to be measured in order to induce the generation of plasma. The multi-dimensional measurement module includes: a plasma electromagnetic radiation characteristic measurement unit, a plasma shock wave mechanical characteristic measurement unit, and a plasma acoustic signal measurement unit; The plasma electromagnetic radiation characteristic measurement unit is used to acquire the radio frequency electromagnetic signals radiated outward by the plasma. The plasma shock wave mechanical property measurement unit is used to acquire the shock wave pressure signal generated by the plasma. The plasma acoustic signal measurement unit is used to acquire the audio signal generated by the plasma; The synchronous control and acquisition module is connected to the laser induction module and the multi-dimensional measurement module respectively. The synchronous control and acquisition module is used to coordinate the working timing of each measurement unit in the laser induction module and the multi-dimensional measurement module, so as to realize the time domain synchronization between the plasma generated by the laser induction module and the data acquired by the multi-dimensional measurement module. The signal processing module is connected to the multi-dimensional measurement module. The signal processing module is used to receive and process various data collected by the multi-dimensional measurement module, perform fusion analysis on the processed data, and output plasma multi-dimensional measurement results.

2. The measurement system according to claim 1, characterized in that, The plasma electromagnetic radiation characteristic measurement unit includes: Biconical antenna and spectrum analyzer; The biconical antenna is used to receive radio frequency electromagnetic waves radiated outward from the plasma; The spectrum analyzer is connected to the biconical antenna and is used to record the radio frequency electromagnetic radiation signal collected by the biconical antenna to obtain the spectral range and radiation intensity of the plasma radio frequency electromagnetic radiation.

3. The measurement system according to claim 1, characterized in that, The plasma shock wave mechanical property measurement unit includes: Piezoelectric thin film sensors and oscilloscopes; The piezoelectric thin film sensor is used to attach to the surface of the sample to be measured and to capture the shock wave pressure signal in real time; The oscilloscope is connected to the piezoelectric thin film sensor. The oscilloscope is used to record the voltage-time curve output by the piezoelectric thin film sensor and transmit the voltage-time curve to the signal processing module.

4. The measurement system according to claim 1, characterized in that, The plasma acoustic signal measurement unit includes: Condenser microphone and sound card; The condenser microphone is used to be aimed at the plasma generation area to record the audio pulse signal of the plasma in a non-contact manner. The sound card is connected to the condenser microphone. The sound card is used to convert the analog audio signal collected by the condenser microphone into a digital audio signal and transmit the digital audio signal to the signal processing module.

5. The measurement system according to claim 1, characterized in that, The multi-dimensional measurement module also includes: Plasma spectroscopy measurement unit and plasma shock wave shadow imaging unit; The plasma spectral measurement unit is used to collect the emission spectral data of the plasma. The emission spectral data is used to analyze the elemental composition and content of the plasma, and to calculate the electron density and electron temperature of the plasma. The plasma shock wave shadow imaging unit is used to acquire the spatial distribution information of the plasma and the temporal evolution process of the shock wave front expansion.

6. The measurement system according to claim 5, characterized in that, The plasma spectroscopy measurement unit includes: Multi-channel fiber optic spectral probe arrays, fiber optic spectrometers, transient plasma spectral probes, and echelle spectrometers; The multi-channel fiber optic spectral probe array is connected to the fiber optic spectrometer to enable simultaneous measurement at multiple measurement points or simultaneous measurement of multiple spectral bands. The transient plasma spectral probe is connected to the echelle spectrometer, which is equipped with an enhanced charge-coupled device (CCD) detector. The CCD detector is used to convert optical signals into digital signals and transmit them to the signal processing module.

7. The measurement system according to claim 5, characterized in that, The plasma shock wave shadow imaging unit includes: Illumination laser sources, beam expanders, filter components, and enhanced charge-coupled device (CCD) cameras; The beam emitted by the illumination laser source is expanded by the beam expansion system and passes through the region where the plasma is located. After being filtered by the filter component, it is imaged onto the enhanced charge-coupled device camera, which is used to capture the shadow image of the plasma shock wave.

8. The measurement system according to claim 1, characterized in that, The synchronous control acquisition module includes: Digital pulse delay generator and computer; The computer links the digital pulse delay generator through a synchronous control acquisition program. The digital pulse delay generator is connected to each measurement unit in the laser induction module and the multi-dimensional measurement module, respectively. The digital pulse delay generator is used to adjust the delay time between the laser generated by the laser-induced module and the signal acquisition by each measurement unit, so as to achieve time-domain synchronization.

9. The measurement system according to claim 1, characterized in that, The measurement system also includes: The sample adjustment module is used to carry the sample to be measured and to adjust the position of the sample to be measured in space so that each laser pulse acts on a different position on the surface of the sample to be measured. The synchronous control acquisition module is connected to the sample adjustment module. The synchronous control acquisition module is used to coordinate the working timing of the sample adjustment module and the laser induction module to achieve spatial alignment.

10. The measurement system according to claim 1, characterized in that, The signal processing module is configured to perform the following processing: The radio frequency electromagnetic signal, the shock wave pressure signal, the audio signal, the emission spectrum data, and the spatial distribution information acquired by the multi-dimensional measurement module are preprocessed. The electron temperature of the plasma was calculated using the Boltzmann graphical method, and the electron density of the plasma was calculated using the Stark broadening method. Shock wave energy is calculated by combining the Sedov theory of point explosion with the shock wave front radius. The audio signal is analyzed in the frequency domain by using Fast Fourier Transform to extract the amplitude, area, and energy parameters of the audio signal. The voltage value measured by the piezoelectric thin film sensor is converted into a pressure value, and a time-pressure curve is output. The processed data are fused together to establish a multi-dimensional data correlation model and output multi-dimensional plasma measurement results.

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