LA-LIBS spectral analysis system and method for regulating and controlling double-laser delay time based on electron speed feedback

Abstract

The invention belongs to the technical field of spectrums, and relates to an LA-LIBS spectral analysis system and method for regulating and controlling double-laser delay time based on electron speed feedback. Comprising a denudation laser, an LIBS laser, a sample detection table, a spectrometer and an optical fiber probe connected with the spectrometer through an optical fiber, a receiving electrode is arranged between the sample detection table and the denudation laser, and the receiving electrode is connected with a signal receiving module and a signal processing module; a real-time regulation and control mechanism based on electron speed feedback accurately solves the problem of space-time mismatch of laser and particle cloud through closed-loop control logic, firstly, a receiving electrode is used for capturing an electronic signal of high-speed movement, and the triggering time of an LIBS laser is deduced and determined based on the electronic signal; the intensity, the stability and the signal-to-noise ratio of spectral signals are remarkably improved, meanwhile, quantitative errors caused by space-time mismatch are eliminated, and the sensitivity and the accuracy of analysis are greatly improved.

Description

Technical Field

[0001] The present application belongs to the field of spectroscopy technology, and more specifically, relates to an LA-LIBS spectral analysis system and method based on electronic velocity feedback to control the delay time of dual lasers. Background Art

[0002] Laser ablation-induced breakdown spectroscopy (LA-LIBS) is an elemental analysis technique. A first laser beam ablates the sample surface, generating a rapidly expanding particle plume (containing neutral atoms, molecules, clusters, etc.). After a specific delay time (Δt), a second laser beam is focused at a specific location within the plume, exciting the neutral particles into a plasma and generating a characteristic elemental spectrum for detection. LA-LIBS has the advantage of reducing sample matrix interference and obtaining a clearer signal.

[0003] Currently, LA-LIBS generally uses a fixed delay time (Δt) to control the triggering interval between the two laser beams; this Δt value is usually set manually based on experience or preliminary tests before the experiment and remains unchanged during the analysis process.

[0004] However, the fixed Δt scheme has serious flaws. The fundamental reason is that the expansion speed of the particle plume (the core of which is the neutral particle cloud) changes dynamically, and the fixed Δt cannot sense and adapt to this change. The specific factors that cause the speed change include: Sample differences: Different materials have different optical, thermal, and mechanical properties (such as absorptivity, boiling point, and density). Even with the same laser parameters, the particle velocities produced are different.

[0005] Laser energy fluctuation: The laser's own pulse energy has inherent fluctuations, and the energy level directly affects the initial kinetic energy of the particles and the plume expansion speed.

[0006] Therefore, since Δt is fixed, the actual time when the particle cloud reaches the predetermined excitation position fluctuates with the change of velocity, resulting in: serious mismatch of excitation position, poor signal strength and stability, reduced sensitivity and reduced accuracy.

[0007] Therefore, the fixed delay control method lacks the ability to perceive the key variable (particle velocity) in real time and dynamically adapt to the environment, resulting in a spatiotemporal mismatch between the laser and the particle cloud, which seriously restricts the improvement of the analytical performance and application potential of the LA-LIBS technology. Summary of the Invention

[0008] The present invention provides an LA-LIBS spectral analysis system and method based on electronic velocity feedback to control the delay time of dual lasers. It aims to solve the technical problem that the current fixed delay control method lacks the real-time perception and dynamic adaptive adjustment capabilities of key variables, resulting in a spatiotemporal mismatch between the laser and the particle cloud.

[0009] On the one hand, the present invention provides an LA-LIBS spectral analysis system for regulating the double-laser delay time based on electronic velocity feedback, comprising an ablation laser, a LIBS laser, a sample detection stage, a spectrometer, and an optical fiber probe connected to the spectrometer through an optical fiber. A receiving electrode is arranged between the sample detection stage and the ablation laser, and the receiving electrode is connected to a signal receiving module and a signal processing module; the signal receiving module receives an electronic signal; and the signal processing module calculates and determines the trigger time of the LIBS laser based on the received electronic signal.

[0010] In the present invention, the real-time regulation mechanism based on electronic velocity feedback accurately solves the problem of spatio-temporal mismatch between the laser and the particle cloud through a closed-loop control logic. First, the receiving electrode captures the electronic signal of the high-speed movement, and the trigger time of the LIBS laser is deduced and determined based on the electronic signal, significantly improving the intensity, stability, and signal-to-noise ratio of the spectral signal. At the same time, the quantitative error caused by spatio-temporal mismatch is eliminated, greatly improving the sensitivity and accuracy of the analysis.

[0011] Preferably, the receiving electrode is provided with a through hole, so that the laser emitted by the ablation laser acts on the sample on the sample detection stage through the through hole.

[0012] On the other hand, the present invention provides an LA-LIBS spectral analysis method for regulating the double-laser delay time based on electronic velocity feedback. The LA-LIBS spectral analysis system for regulating the double-laser delay time based on electronic velocity feedback described in the present invention is adopted, and the method comprises the following steps: The first laser beam emitted by the ablation laser generates an electron flight time. The electron velocity is obtained by inverting the electron flight time. The flight velocity of neutral particles is deduced based on the electron velocity through a neutral particle derivation model, and the emission time of the LIBS laser is dynamically calculated based on the flight velocity of the neutral particles.

[0013] Preferably, both the ablation laser and the LIBS laser need to be triggered by a lamp pumping signal and a Q-switch signal and then trigger the laser after a predetermined delay; After the lamp pumping signal is triggered, the Q-switch signal is triggered after a predetermined delay.

[0014] Preferably, the lamp pumping signals of the ablation laser and the LIBS laser are synchronously triggered.

[0015] Preferably, after the ablation laser emits laser light, electrons hit the receiving electrode, and an electronic signal is collected through the signal receiving module. The electronic signal is transmitted to the signal processing module. Based on the signal processing module, the emission time of the LIBS laser is calculated. Based on the calculated emission time of the LIBS laser, the time interval from the lamp pump signal trigger to the Q-switch signal trigger of the LIBS laser is dynamically adjusted, thereby controlling the emission time of the LIBS laser.

[0016] Preferably, based on historical data, the total time required for the ablation laser and the LIBS laser from the lamp pump signal trigger to the Q-switch signal trigger and then to laser emission is respectively obtained, and the total time required for the ablation laser and the LIBS laser to emit is respectively obtained. Then, in combination with the flight speed of historical neutral particles, the emission time of the current LIBS laser is adjusted.

[0017] Preferably, adjusting the emission time of the current LIBS laser includes adjusting the lamp pump trigger time of the LIBS laser or adjusting the time interval from the lamp pump trigger to the Q-switch signal trigger of the LIBS laser.

[0018] Preferably, the specific steps for calculating the emission time of the LIBS laser are as follows: Collect the flight time of electrons arriving at the receiving electrode, and calculate the speed of electrons based on the distance between the receiving electrode and the laser irradiation area and the flight time. Based on the calculated speed of electrons, construct a linear model to estimate the speed of neutral particles. Then, divide the distance between the target excitation area of the second laser and the irradiation point of the first laser by the speed of neutral particles to obtain the time required for neutral particles to fly from the ablation point to the excitation area; use the time required for the neutral particles to fly from the ablation point to the excitation area as the time input for the second laser trigger control, thereby obtaining the emission time of the LIBS laser.

[0019] Preferably, the specific steps for calculating the emission time of the LIBS laser are as follows: Collect the flight time of electrons arriving at the receiving electrode, and calculate the speed of electrons based on the distance between the receiving electrode and the laser irradiation area and the flight time. Combine the laser energy transfer efficiency and the energy conservation relationship to correlate the kinetic energy of neutral particles with the electron energy, and obtain the relationship between the speed of neutral particles and the speed of electrons. Adopt an energy transfer model. Based on the distance between the target excitation area of the second laser and the irradiation point of the first laser divided by the speed of neutral particles and the relationship between the speed of neutral particles and the speed of electrons, obtain the time input for the second laser trigger control, thereby obtaining the emission time of the LIBS laser.

[0020] The beneficial effects of the present invention include: 1. By detecting the electron velocity in real time and dynamically adjusting the trigger time of the LIBS laser, it ensures that the sample is triggered at the optimal moment, significantly improving the spatio-temporal matching accuracy of the excitation, making the spectral signal more accurate and the detection result more reliable.

[0021] 2. The substrate characteristics of different samples can cause matrix effects, affecting the accuracy of spectral analysis; by feeding back the electron velocity, the system can automatically adjust the trigger time of the LIBS laser, reducing the influence of matrix effects, thereby improving the stability of the analysis result and being free from the interference of sample substrate differences.

[0022] 3. Dynamically adjusting the laser trigger time enables the laser to more effectively excite the sample, generating stronger spectral line signals, while reducing interference and noise, enhancing the signal-to-noise ratio; since each excitation is performed at the optimal time, the consistency of the results is significantly improved, enhancing the repeatability.

[0023] 4. The surface state of the sample and the fluctuations in laser energy can affect the detection result. Through a real-time feedback mechanism, the system can adapt to the fluctuations, reducing the influence brought by the fluctuations and improving the stability and reliability of the system.

[0024] 5. In a complex or dynamically changing environment, the adaptive ability of the system is particularly important. By dynamically adjusting the laser delay, the system can operate stably under different conditions, with a wider applicable range and stronger versatility. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0026] Figure 1 It is a schematic block diagram of the system provided for the embodiments of the present invention.

[0027] Figure 2 It is the trigger logic of two lasers provided for the embodiments of the present invention.

[0028] Figure 3 It is a schematic diagram of the timeline principle of two lasers provided for the embodiments of the present invention.

[0029] Explanation of the reference numerals: 1. Sample detection stage; 2. Sample; 3. LIBS laser; 4. Spectrometer; 5. Fiber optic probe; 6. Receiving electrode; 7. Ablation laser; 8. Power supply; 9. Signal receiving module; 10. Signal processing module. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0030] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clear and understandable, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0031] Embodiment 1 Referring to Figure 1 , on the one hand, the present invention provides an LA-LIBS spectral analysis system for regulating the double-laser delay time based on electronic velocity feedback, including an ablation laser 7, a LIBS laser 3, a sample detection stage 1, a spectrometer 4, and an optical fiber probe 5 connected to the spectrometer 4 through an optical fiber. It is characterized in that a receiving electrode 6 is arranged between the sample detection stage 1 and the ablation laser 7, and the receiving electrode 6 is connected with a signal receiving module 9 and a signal processing module 10; an electronic signal is received based on the signal receiving module 9; the signal processing module 10 calculates and determines the trigger time of the LIBS laser 3 based on the received electronic signal, and the receiving electrode 6 is provided with a through hole, so that the laser emitted by the ablation laser 7 acts on the sample 2 on the sample detection stage 1 through the through hole.

[0032] In this embodiment, the laser emitted by the ablation laser 7 acts on the sample 2 to generate ablation, and at this time, the generated electrons move towards the receiving electrode 6, thereby realizing the acquisition of electronic signals.

[0033] At the moment when the ablation laser hits the sample 2 to generate a particle plume, the receiving electrode 6 directly captures the high-speed moving electronic signal in the plume; due to the strong correlation between the electron movement and the expansion of the neutral particle cluster (resulting from homologous generation and coupled movement), the signal receiving module 9 obtains the precise time when the electrons reach the electrode, and this time directly reflects the instantaneous expansion speed of the front end of the particle cloud.

[0034] In the present invention, through the closed-loop control of "electron arrival time → real-time feedback of particle velocity → dynamic recalculation of delay time → immediate adjustment of laser trigger", the traditional fixed delay mode is completely replaced; whether the initial velocity of the particles changes due to the difference in the material of the sample 2 or the plume is accelerated / decelerated due to the fluctuation of the laser pulse energy, the system can sense and instantaneously correct the excitation timing in real time; through the real-time feedback of the particle velocity by the electronic signal and the dynamic self-correction of the delay time, the LA-LIBS system is endowed with the intelligent adaptation ability to resist the differences of the sample 2 and laser fluctuations, and the chronic problem of spatio-temporal mismatch caused by fixed delay is cured.

[0035] Embodiment 2 Referring to Figure 2As shown in the figure, a LA-LIBS spectral analysis method based on regulating the double-laser delay time by electron velocity feedback uses the LA-LIBS spectral analysis system based on regulating the double-laser delay time by electron velocity feedback of the present invention, and includes the following steps: The first laser beam emitted by the ablation laser 7 generates the electron flight time. The electron velocity is obtained by inverting the electron flight time. Based on the electron velocity, the flight velocity of neutral particles is deduced through the neutral particle derivation model, and the emission time of the LIBS laser 3 is dynamically calculated based on the flight velocity of neutral particles. As a possible implementation manner of this embodiment, the specific steps for calculating the emission time of the LIBS laser 3 are as follows: Collect the flight time of electrons arriving at the receiving electrode 6, and calculate the velocity of electrons based on the distance between the receiving electrode 6 and the laser irradiation area and the flight time; ; In the formula: L represents the distance between the receiving electrode 6 and the laser irradiation area; represents the flight time of electrons arriving at the receiving electrode 6; represents the electron velocity; Based on the calculated electron velocity, a linear model is constructed to estimate the velocity of neutral particles; ; In the formula: and represent the constants obtained by experimental calibration, which depend on laser parameters, sample 2 materials, and experimental geometries. In actual use, the parameters are determined by establishing a data model for multiple known samples 2; Then, divide the distance between the target excitation area of the second laser and the irradiation point of the first laser by the velocity of neutral particles to obtain the time required for neutral particles to fly from the ablation point to the excitation area; use the time required for the neutral particles to fly from the ablation point to the excitation area as the time input for the second laser trigger control, and then obtain the emission time of the LIBS laser 3; ; In the formula: represents the distance between the target excitation area of the second laser and the ablation point; represents the time required for neutral particles to fly from the ablation point to the excitation area; that is, the time interval between the trigger of the first laser and the trigger of the second laser.

[0036] As another possible implementation manner of this embodiment, the specific steps for calculating the emission time of the LIBS laser 3 are as follows: Collect the flight time of electrons arriving at the receiving electrode 6, and calculate the velocity of electrons based on the distance between the receiving electrode 6 and the laser irradiation area and the flight time; ; In the formula: L represents the distance between the receiving electrode 6 and the laser irradiation area; Indicates the flight time of electrons arriving at the receiving electrode 6; Indicates the electron velocity; That is, in this embodiment, a theoretical derivation path is adopted, combined with the laser energy transfer efficiency and the energy conservation relationship: Assume the energy obtained by the electron is: ; where Indicates the electron mass; Indicates the electron velocity; The kinetic energy of the neutral ion is: ; where Indicates the mass of the neutral particle; Indicates the velocity of the neutral particle; Set the energy transfer efficiency to in a single ablation event, then: ; here is an empirical value in the range of 0.1 - 0.5; ; In the formula: Indicates the distance between the target excitation region of the second laser pulse and the ablation point; Indicates the time required for the neutral particle to fly from the ablation point to the excitation region; that is, the time interval between the triggering of the first laser pulse and the triggering of the second laser pulse.

[0037] After calculating the time required from the emission of the ablation laser 7 to the emission of the LIBS laser 3, the emission time of the LIBS laser 3 can be specifically adjusted by the following method: Since the laser emissions of both the ablation laser 7 and the LIBS laser 3 require triggering by a lamp pump signal, a Q-switch signal, and then the laser emission; There is a predetermined delay between the lamp pump signal triggering and the Q-switch signal triggering, which is at the microsecond level, and the delay from the Q-switch signal triggering to the laser emission is at the nanosecond level. Therefore, in this embodiment, the nanosecond-level delay can be ignored, and only the time interval from the emission of the ablation laser 7 to the emission of the LIBS laser 3 needs to be calculated to adjust the delay between the lamp pump signal triggering and the Q-switch signal triggering. The specific steps are as follows: Since both the ablation laser 7 and the LIBS laser 3 involve delays at the microsecond level and delays at the nanosecond level, in this embodiment, the lamp pumping signals of the ablation laser 7 and the LIBS laser 3 are synchronously triggered. After the ablation laser 7 emits laser light, electrons reach the receiving electrode 6, and the electronic signal is collected through the signal receiving module 9 and transmitted to the signal processing module 10. Based on the signal processing module 10, the emission time of the LIBS laser 3 is calculated, and based on the calculated emission time of the LIBS laser 3, the time interval from the lamp pumping signal trigger of the LIBS laser 3 to the Q-switch signal trigger is dynamically adjusted, thereby controlling the emission time of the LIBS laser 3.

[0038] See Figure 3 As shown, it should be noted here that the time from the lamp pumping signal trigger of the ablation laser 7 to the emission of the ablation laser 7 is less than the time from the lamp pumping signal trigger of the LIBS laser 3 to the Q-switch signal trigger; when the time interval required from the emission of the ablation laser 7 to the emission of the LIBS laser 3 is calculated, the time interval needs to be used to dynamically adjust the time from the lamp pumping trigger to the Q-switch signal trigger; since the lamp pumping signals of the ablation laser 7 and the LIBS laser 3 are synchronously triggered, only after obtaining the time interval required from the emission of the ablation laser 7 to the emission of the LIBS laser, the time interval is used to adjust the trigger time of the lamp pumping signal to the Q-switch signal of the LIBS laser 3; for example: ; Where: t3 represents the adjustment amount of the delay from the lamp pumping signal to the Q-switch signal trigger of the LIBS laser 3; t2 represents the time interval from the Q-switch signal to the emission of the LIBS laser 3; t1 represents the time interval required from the emission of the ablation laser to the emission of the LIBS laser.

[0039] For the above two calculation methods, since the time interval from the Q-switch signal to the emission of the LIBS laser is at the nanosecond level, it can be ignored at the microsecond level; of course, for the sake of accuracy, it can also be taken into account.

[0040] It should be noted that t3 represents the adjustment amount. Since the time from the lamp pumping signal trigger of the ablation laser 7 to the emission of the ablation laser 7 is less than the time from the lamp pumping signal trigger of the LIBS laser 3 to the Q-switch signal trigger, and since the lamp pumping signals of the two are synchronously triggered, when the laser of the ablation laser 7 is triggered, at this time, the LIBS laser 3 is in the time interval from the lamp pumping trigger to the Q-switch signal trigger. At this time, only the emission time point of the ablation laser 7 needs to be recorded, and by adding the obtained time interval to this time node, the dynamic adjustment of the trigger time node of the LIBS laser 3 can be achieved.

[0041] Embodiment 3 Based on historical data, obtain the total time required for the ablation laser 7 and the LIBS laser 3 from the lamp pumping signal trigger to the Q-switch signal trigger and then to laser emission respectively, and obtain the total time required for the ablation laser 7 and the LIBS laser 3 to emit respectively. Then, adjust the emission time of the current LIBS laser 3 in combination with the flight speed of historical neutral particles.

[0042] It should be noted that in this embodiment, the lamp pumping signals of the ablation laser 7 and the LIBS laser 3 are also synchronously triggered. Secondly, the total time required for the ablation laser 7 and the LIBS laser 3 to emit is obtained through historical data, so the time difference between the emissions of the two lasers is obtained. By combining the time interval from the emission of the ablation laser 7 to the emission of the LIBS laser 3, the adjustment amount of the delay from the lamp pumping signal trigger to the Q-switch signal trigger of the LIBS laser 3 can be obtained. Based on the above, it can be seen that the difference between this embodiment 3 and this embodiment 2 lies only in the different ways of obtaining the adjustment amount.

[0043] Embodiment 4 In the technical solution of Embodiment 3, the emission time of the LIBS laser 3 can be controlled not only by adjusting the time interval from the lamp pumping trigger to the Q-switch signal trigger of the LIBS laser 3, but also by adjusting the lamp pumping trigger time of the current LIBS laser 3. That is, in this Embodiment 4, the lamp pumping triggers of the LIBS laser 3 and the ablation laser 7 are asynchronous. Secondly, this Embodiment 4 also uses historical data to obtain the total time required for the two lasers from the lamp pumping signal to laser emission. Based on the total time of the two lasers, the emission time interval of the two lasers is obtained. Then, through this time interval and the time interval from the emission of the ablation laser 7 calculated historically to the emission of the LIBS laser 3, the lamp pumping trigger time of the current LIBS laser 3 can be adjusted.

[0044] For Embodiment 4, the average value of historical data can be taken to obtain the average time interval for calculation. That is, the total time of the two lasers can obtain the emission time interval of the two lasers. Multiple sets of historical data can be used to take the average value, and the time interval from the emission of the ablation laser 7 calculated historically to the emission of the LIBS laser 3 also extracts the average value using multiple sets of historical data.

[0045] The above are only the preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present application shall be included within the protection scope of the present application.

Claims

1. An LA-LIBS spectral analysis system for regulating the double-laser delay time based on electron velocity feedback, comprising an ablation laser, a LIBS laser, a sample detection stage, a spectrometer, and an optical fiber probe connected to the spectrometer through an optical fiber, characterized in that, A receiving electrode is arranged between the sample detection stage and the ablation laser, and the receiving electrode is connected with a signal receiving module and a signal processing module; The signal receiving module receives electronic signals; the signal processing module calculates and determines the trigger time of the LIBS laser based on the received electronic signals.

2. The LA-LIBS spectral analysis system for regulating the double-laser delay time based on electronic velocity feedback according to claim 1, wherein The receiving electrode is provided with a through hole, so that the laser emitted by the ablation laser acts on the sample on the sample detection stage through the through hole.

3. LA-LIBS spectral analysis method for regulating the double-laser delay time based on electron velocity feedback, characterized in that Using the LA-LIBS spectral analysis system for regulating the double-laser delay time based on electron velocity feedback according to claim 1 or 2, comprising the following steps: The first laser beam emitted by the ablation laser generates an electron flight time. The electron velocity is obtained by inverting the electron flight time. Based on the electron velocity, the flight velocity of neutral particles is deduced through a neutral particle derivation model, and the emission time of the LIBS laser is dynamically calculated based on the flight velocity of neutral particles.

4. The LA-LIBS spectral analysis method for regulating the double-laser delay time based on electronic velocity feedback according to claim 3, wherein, Both the ablation laser and the LIBS laser need to be triggered by a lamp pumping signal and a Q-switch signal and then trigger the laser after a predetermined delay; After the lamp pumping signal is triggered, the Q-switch signal is triggered after a predetermined delay.

5. The LA-LIBS spectral analysis method for regulating the double-laser delay time based on electronic velocity feedback according to claim 4, characterized in that The lamp pumping signals of the ablation laser and the LIBS laser are synchronously triggered.

6. The LA-LIBS spectral analysis method for regulating the double-laser delay time based on electronic velocity feedback according to claim 4, wherein After the ablation laser emits laser, electrons hit the receiving electrode. The electronic signals are collected through the signal receiving module, and the electronic signals are transmitted to the signal processing module. The emission time of the LIBS laser is calculated based on the signal processing module. Based on the calculated emission time of the LIBS laser, the time interval from the lamp pumping signal trigger to the Q-switch signal trigger of the LIBS laser is dynamically adjusted, thereby controlling the emission time of the LIBS laser.

7. The LA-LIBS spectral analysis method for regulating the double-laser delay time based on electronic velocity feedback according to claim 4, wherein Based on historical data, the total time required for the ablation laser and the LIBS laser from the lamp pumping signal trigger to the Q-switch signal trigger and then to the laser emission is respectively obtained, and the total time required for the ablation laser and the LIBS laser to emit is respectively obtained. Then, the emission time of the current LIBS laser is adjusted in combination with the flight velocity of historical neutral particles.

8. The LA-LIBS spectral analysis method for regulating the double-laser delay time based on electronic velocity feedback according to claim 7, wherein Adjusting the emission time of the current LIBS laser includes adjusting the lamp pumping trigger time of the LIBS laser or adjusting the time interval from the lamp pumping trigger to the Q-switch signal trigger of the LIBS laser.

9. The LA-LIBS spectral analysis method for regulating the double-laser delay time based on electronic velocity feedback according to any one of claims 3 to 8, characterized in that The specific steps for calculating the emission time of the LIBS laser are as follows: Collect the flight time of electrons arriving at the receiving electrode, and calculate the velocity of electrons based on the distance between the receiving electrode and the laser irradiation area and the flight time; Construct a linear model based on the calculated electron velocity to estimate the velocity of neutral particles; Then, divide the distance between the target excitation area of the second laser and the irradiation point of the first laser by the velocity of neutral particles to obtain the time required for neutral particles to fly from the ablation point to the excitation area; use the time required for the neutral particles to fly from the ablation point to the excitation area as the time input for the second laser trigger control, and thus obtain the emission time of the LIBS laser.

10. The LA-LIBS spectral analysis method for regulating the double-laser delay time based on electronic velocity feedback according to any one of claims 3 to 8, characterized in that, The specific steps for calculating the emission time of the LIBS laser are as follows: Collect the flight time of the collected electrons arriving at the receiving electrode, and calculate the velocity of the electrons based on the distance between the receiving electrode and the laser irradiation area and the flight time; Combine the laser energy transfer efficiency and the energy conservation relationship to correlate the kinetic energy of neutral particles with the electron energy, and obtain the relationship between the velocity of neutral particles and the electron velocity; Adopt an energy transfer model, and based on the distance between the target excitation area of the second laser and the irradiation point of the first laser divided by the velocity of neutral particles and the relationship between the velocity of neutral particles and the electron velocity, obtain the time input for the second laser trigger control, and further obtain the emission time of the LIBS laser.

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