Acousto-optic gating device and laser induced breakdown spectrometer

Abstract

The present application provides an acousto-optic gating device and a laser induced breakdown spectrometer. The acousto-optic gating device includes: a detector, a delay generator, and an acousto-optic modulator, wherein the detector is used to sense a laser signal and trigger the delay generator to generate a delay based on the laser signal; the delay generator is used to control the acousto-optic modulator. The present application also provides a laser induced breakdown spectrometer including the acousto-optic gating device. The laser induced breakdown spectrometer of the present application can significantly reduce the background intensity and improve the detection sensitivity by setting an acousto-optic gating device through an acousto-optic modulator, while avoiding the use of expensive ICCDs, reducing system costs, and avoiding technical problems such as large size and harsh environmental requirements.

Description

Technical Field

[0001] The invention belongs to the field of high-sensitivity laser spectroscopy technology and applications, in particular to a laser induced breakdown spectrometer and an acousto-optic gating device used therefor. Background Art

[0002] Laser induced breakdown spectroscopy (LIBS) is an emission spectral analysis technique that uses high-energy non-resonant pulsed lasers to ablate, atomize, excite and ionize samples to generate transient plasmas. By analyzing the characteristic spectral lines of the atomic, ionic or molecular basis of the elements in its emission spectrum, quantitative analysis of the sample components is achieved. It has the advantages of rapid, simultaneous detection of multiple elements, and simple sample preparation. It can be detected in situ or online without contact, and has great application potential in industrial analysis, environmental monitoring, biomedicine and other fields. LIBS quantitative analysis relies on the spectral chemical information of the ablated plasma. When the photons of spontaneous radiation inside the plasma propagate outward, they will be absorbed by similar particles at low energy levels in their path, showing the self-absorption effect of optically thick plasma. This effect is prone to occur in major elements, which will not only reduce the spectral line intensity and broaden the line type, but also saturate the calibration curve, thereby reducing the accuracy of quantitative analysis. For example, limited by the self-absorption effect, the current typical measurement accuracy of LIBS for major elements such as Al and Mg in cement raw materials is 0.3%, which still does not meet the industry application requirement of 0.1%. Therefore, conducting research on the self-absorption mechanism of laser-induced plasma and then effectively correcting or weakening the self-absorption effect to improve the measurement accuracy is directly related to the application prospects of LIBS.

[0003] People have proposed a variety of methods to correct or weaken self-absorption. These methods mainly correct the self-absorption effect passively through plasma parameter modeling. However, due to the complexity of the interaction mechanism between laser and target and the evolution of plasma, it is inevitable that deviations will be introduced into these idealized models.

[0004] Theoretically, when the central outward radiation light does not significantly attenuate when passing through the plasma, it can be approximately regarded as an optically thin plasma. At this time, the self-absorption effect can be ignored, thereby achieving ideal measurement accuracy. Based on this principle, the self-absorption immune laser induced breakdown spectrometer (SAF-LIBS) element quantitative analysis method sets the time window for spectral acquisition according to the matching degree between the theoretical value and the measured value of the element double-line intensity ratio, directly captures the optically thin spectral line, and realizes active immunity to the self-absorption effect. However, because the plasma spectral signal within a narrow time window (~1μs) needs to be gated for exposure, and the commonly used micro-CCD spectrometer has insufficient time resolution (ms level), it can only be completed by an image intensified detector (ICCD) and a mid-step grating spectrometer, making the SAF-LIBS system costly, large in size, and demanding in the environment, making it impossible to apply in practice. Therefore, a low-cost, compact SAF-LIBS measurement device suitable for production practice is needed. Summary of the invention

[0005] The present invention provides a high-frequency acousto-optic gating SAF-LIBS and an acousto-optic gating device therefor to solve the technical problems of the current SAF-LIBS measurement device having high system cost, large volume and harsh environmental requirements.

[0006] The present application provides an acousto-optic gating device, which comprises:

[0007] detector,

[0008] Delay generator,

[0009] Acousto-optic modulator,

[0010] Wherein, the detector is used to sense the laser signal and trigger the delay generator to generate a delay based on the laser signal;

[0011] The delay generator is used to control the acousto-optic modulator.

[0012] In one embodiment, the AOM device further includes an AOM driver, and the AOM driver is electrically connected to the AOM.

[0013] The delay generator controls the AOM by inputting a radio frequency signal to the AOM driver.

[0014] In one embodiment, the acousto-optic gating device further includes an oscilloscope, and the oscilloscope is used to monitor the delay between the laser signal and the acousto-optic modulator.

[0015] In one embodiment, the detector is a silicon detector.

[0016] The present application also provides a laser induced breakdown spectrometer, which comprises:

[0017] a laser configured to emit a laser signal;

[0018] An optical path component, the optical path component is used to irradiate the laser signal onto the substance to be measured to generate a plasma spectrum signal, and to focus the diffracted light of the plasma spectrum signal after diffraction;

[0019] A spectrometer, used for collecting the diffracted light;

[0020] The laser induced breakdown spectrometer also includes the acousto-optic gating device of the present application.

[0021] In one embodiment, the optical path component comprises:

[0022] A reflector, used for reflecting the laser signal generated by the laser;

[0023] A polarization beam splitter, used to split the laser signal reflected by the reflector into two beams;

[0024] A concave mirror, wherein the concave mirror is used to converge the plasma spectrum signal generated by irradiating the first laser signal after polarization splitting onto the measured substance;

[0025] A first focusing mirror, used for focusing the plasma spectrum signal converged by the concave mirror;

[0026] a second focusing mirror, used to focus the diffracted light from the acousto-optic modulator of the acousto-optic gating device;

[0027] The acousto-optic modulator of the acousto-optic gating device is located between the first focusing mirror and the second focusing mirror, and is used to make the plasma spectrum signal diffract in the acousto-optic modulator.

[0028] In one embodiment, the optical path component further includes a half-wave plate, which is located between the reflector and the polarization beam splitter, so that the laser signal reflected by the reflector first enters the half-wave plate and then enters the polarization beam splitter.

[0029] In one embodiment, the laser induced breakdown spectrometer further includes an energy meter for measuring the second laser signal after polarization splitting.

[0030] In one embodiment, the concave mirror has a central hole, and the first laser signal beam that has undergone polarization splitting is irradiated onto the substance to be measured through the central hole.

[0031] In one embodiment, the laser induced breakdown spectrometer further comprises a first optical fiber, and the first optical fiber is used to transmit the plasma spectrum signal converged by the concave mirror to the first focusing mirror.

[0032] In one embodiment, the laser induced breakdown spectrometer further includes a second optical fiber, and the second optical fiber is used to transmit the diffracted light focused by the second focusing mirror to the spectrometer.

[0033] In one embodiment, the spectrometer is a grating spectrometer, in particular a micro-spectrometer.

[0034] In one embodiment, the laser induced breakdown spectrometer further includes a data processing component for processing the spectral signal collected by the spectrometer.

[0035] The laser induced breakdown spectrometer of the present application can significantly reduce the background intensity through the acousto-optic modulator by setting an acousto-optic gating device, thereby improving the detection sensitivity and avoiding the use of expensive ICCDs. While reducing system costs, it also avoids the technical problems of large size and harsh environmental requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 The schematic diagram of the structure of the laser induced breakdown spectrometer of the present application is shown.

[0037] Among them, 1-oscilloscope, 2-laser, 3-delay generator, 4-aluminum-coated reflector, 5-half-wave plate, 6-polarization splitter prism, 7-energy meter, 8-concave mirror with middle hole, 9-stepping rotation stage, 10-AOM driver, 11-first focusing mirror, 12-acoustic-optic modulator (AOM), 13-second focusing mirror, 14-spectrometer, 15-computer, 16-detector, 17-blade, 21-first optical fiber, 22-second optical fiber.

[0038] Figure 2 The operating timing scheme when the AOM is used as an optical gate switch for laser-induced breakdown spectroscopy is shown.

[0039] Figure 3 The spectrum of the aluminum alloy sample plasma obtained by the laser induced breakdown spectrometer of the above embodiment of the present application (using the embodiment LIBS) and the spectrum of the aluminum alloy sample plasma obtained by using the traditional LIBS system (using the traditional LIBS) are shown.

[0040] Figure 4 The Boltzmann plane diagram of the Al atomic spectral line before and after self-absorption correction and obtained by the device of the present invention is shown (before self-absorption correction means data before self-absorption correction using a traditional LIBS system, after self-absorption correction means data after self-absorption correction using a traditional LIBS system, and using embodiment LIBS means data obtained using the laser induced breakdown spectrometer of the above embodiment of the present application).

[0041] Figure 5 Shown is a schematic diagram of the structure of traditional LIBS. DETAILED DESCRIPTION

[0042] The technical solution of the present invention is further described below according to specific embodiments. The protection scope of the present invention is not limited to the following embodiments, which are listed only for illustrative purposes and do not limit the present invention in any way.

[0043] like Figure 1 As shown, the present application provides a laser induced breakdown spectrometer, which includes:

[0044] A laser 2, wherein the laser 2 is configured to emit a laser signal;

[0045] An optical path component, the optical path component is used to irradiate the laser signal onto the substance to be measured to generate a plasma spectrum signal, and to focus the diffracted light of the plasma spectrum signal after diffraction;

[0046] A spectrometer 14, used for collecting the focused diffracted light;

[0047] The laser induced breakdown spectrometer also includes an acousto-optic gating device.

[0048] The various parts of the laser induced breakdown spectrometer are described below.

[0049] The laser induced breakdown spectrometer includes a laser 2, which is configured to emit a laser signal. In one embodiment, an AUT-ONDA DPSS laser can be selected, with an excitation wavelength of 1064 nm, a maximum single pulse energy of 800 μJ, a pulse width of 2 to 10 ns, and a repetition frequency of 1 Hz to 100 kHz.

[0050] The device described in the present invention mainly includes two parts: one part is a LIBS device, including a laser 2, an optical path component and a spectrometer 14, etc., which uses laser to excite the sample to generate plasma, and the generated plasma is transmitted to the spectrometer 14 (micro-spectrometer) through the optical path component to obtain the plasma spectrum for spectral analysis; the other part is an acousto-optic gating device.

[0051] First, combine Figure 1 The acousto-optic gating device used in the laser-induced breakdown spectroscopy is described.

[0052] like Figure 1 The acousto-optic gating device comprises:

[0053] Detector 16,

[0054] Delay generator 3,

[0055] Acousto-optic modulator (AOM) 12,

[0056] Wherein, the detector 16 is used to sense the laser signal and trigger the delay generator 3 to generate a delay based on the laser signal;

[0057] The delay generator 3 is used to control the AOM 12 .

[0058] In the acousto-optic gating device, after the detector 16 senses the laser signal, it will generate a high level, and use the high level to trigger the delay generator 3 to generate a delay. In one embodiment, the detector is a silicon detector. In the present application, the detector 16 is used to detect the laser signal in the optical path component passing through the reflector 4.

[0059] In the acousto-optic gating device, the delay generator 3 can output a TTL signal consistent with the pulse laser frequency, which is used to control the acousto-optic modulator 12. In one embodiment, the acousto-optic gating device further includes an acousto-optic modulator driver 10, which is electrically connected to the acousto-optic modulator 12. The delay generator 3 can output a TTL signal consistent with the pulse laser frequency, which is used as the radio frequency input of the acousto-optic modulator driver 10, thereby realizing the control of the acousto-optic modulator 12.

[0060] In one embodiment, the acousto-optic gating device further includes an oscilloscope 1, which is used to monitor the Q switch inside the laser 2 (not shown, the Q switch is an internal device of the laser and is used to control the generation of pulsed laser), the laser signal and the delay between the acousto-optic modulator 12. The oscilloscope 1 can be electrically connected to the laser 1, the spectrometer 14 and the delay generator 3 respectively.

[0061] In the acousto-optic gating device, the silicon detector 16 is used to measure the laser pulse width and the laser emission time, and simultaneously trigger the delay generator 3 for timing and the spectrometer 14 for exposure. The delay generator 3 is used to control the delay between the laser pulse and the acousto-optic modulator 12 and the first-order diffraction gating, and the gating duration depends on the pulse width of the acousto-optic modulator driver 10 triggered by the delay generator 3 and the gate rise time of the acousto-optic modulator 12. The oscilloscope 1 is used to monitor the delay between the Q switch and the laser pulse, and the gate rise of the acousto-optic modulator 12.

[0062] The switch for gated control of laser induced breakdown spectrometer should meet the following requirements: 1. The typical delay time between the laser pulse and the optical thin time window is several hundred nanoseconds, and the opening time of the switch should be less than 100ns; 2. The typical plasma lifetime is 10μs, and the optical shutter frequency of the switch should be less than 100kHz; 3. The typical optical thin time window is 0.5-1.2μs, and the gate duration of the switch should be less than 1.2μs. As an acousto-optic switch device with bias frequency modulation, the principle of the acousto-optic modulator is to use an electroacoustic transducer to convert the modulation signal into an ultrasonic field of the same frequency, and then form a Bragg grating with a changing refractive index in the acousto-optic medium, so that diffracted light of different orders is emitted in different directions. The opening time of the acousto-optic modulator is 30-80ns, the operating frequency is kHz-MHz, and the trigger drive pulse width is 1μs. These performance parameters all meet the above requirements. Therefore, the acousto-optic modulator can serve as an optical gated switch for laser induced breakdown spectrometer.

[0063] Introducing an acousto-optic modulator into a laser-induced breakdown spectrometer can enable the optically thick fluorescence outside the time window to undergo zero-order diffraction in the acousto-optic modulator and directly exit along the original direction, while enabling the optically thin fluorescence within the time window to undergo first-order diffraction and deflect out to the spectrometer, thus realizing gated spectral acquisition.

[0064] Taking the AOM as the optical gating switch of the laser-induced breakdown spectrometer, the timing scheme is shown in Figure 2 . At t = 0, the laser pulse is emitted. After being detected by the detector 16, it triggers the delay generator 3 to start timing on one hand and triggers the spectrometer 14 to start a 10-ms exposure on the other hand, while forming a transient plasma. In the time period 0 < t < td, the AOM outputs the plasma fluorescence with zero-order diffraction. Among them, at t = (td - tr), the delay generator outputs a pulse with a pulse width of 1 μs to trigger the AOM. At t = td, the Bragg grating inside the AOM is formed. In the time period td < t < (td + tw), which belongs to the optically thin time window, the AOM outputs the plasma fluorescence with first-order diffraction to the miniature spectrometer. At t = (td + tw), the trigger pulse ends, and the AOM switches to zero-order diffraction. Until the next laser pulse is emitted, one cycle is completed. The above is repeated until t = 10 ms, the spectrometer completes one exposure and outputs a spectrum, which is the integrated spectrum of the optically thin fluorescence of all plasmas within 10 ms. Until the number of output spectra reaches the preset value, the device stops running.

[0065] For the laser-induced breakdown spectrometer of the present application, the optical path assembly includes:

[0066] The mirror 4 is used to reflect the laser signal generated by the laser 2;

[0067] The polarization beam splitter 6 is used to divide the laser signal reflected by the mirror 4 into two beams;

[0068] The concave mirror 8 is used to converge the plasma spectral signal generated by irradiating the first beam of laser signal after polarization beam splitting onto the measured substance;

[0069] The first focusing mirror 11 is used to focus the plasma spectral signal converged by the concave mirror 8;

[0070] The second focusing mirror 13 is used to focus the diffracted light from the acousto-optic modulator 12 of the acousto-optic gating device;

[0071] Among them, the acousto-optic modulator 12 of the acousto-optic gating device is located between the first focusing mirror 11 and the second focusing mirror 13 and is used to diffract the plasma spectral signal within the acousto-optic modulator 12.

[0072] In one embodiment, the reflector 4 may be an aluminum-coated mirror.

[0073] In one embodiment, the optical path component further includes a half-wave plate 5, and the half-wave plate 5 is located between the reflector 4 and the polarization beam splitter 6, so that the laser signal reflected by the reflector 4 first enters the half-wave plate 5 and then enters the polarization beam splitter 6. In one embodiment, the laser induced breakdown spectrometer further includes an energy meter 7 for measuring the second laser signal after polarization splitting. The polarization beam splitter 6 divides the laser signal entering therein into two beams, the first beam irradiates the plasma spectrum signal generated by the measured substance, and the second beam is monitored by the energy meter 7 for real-time power monitoring.

[0074] In one embodiment, the concave mirror 8 has a central hole, and the first laser signal beam that has undergone polarization splitting is irradiated onto the substance to be measured through the central hole.

[0075] In one embodiment, the laser induced breakdown spectrometer further comprises a stepping rotating stage 9 for placing a sample. The sample is located on the optical path of the first polarization split laser signal, so that the first polarization split laser signal can irradiate the measured substance to generate a plasma spectrum signal.

[0076] In one embodiment, the laser induced breakdown spectrometer further includes a first optical fiber 21, which is used to transmit the plasma spectrum signal converged by the concave mirror 8 to the first focusing mirror 11, and is focused at the Bragg angle to the AOM 12 for diffraction via the first focusing mirror 11. In the AOM 12, zero-order diffraction light and first-order diffraction light are generated, wherein the zero-order diffraction light is blocked by the blade 17 after being emitted horizontally, and the first-order diffraction light is focused by the second focusing mirror 13. In one embodiment, the laser induced breakdown spectrometer further includes a second optical fiber 22, which transmits the diffraction light focused by the second focusing mirror 13 to the spectrometer 14.

[0077] In one embodiment, the spectrometer 14 is a grating spectrometer, in particular a micro spectrometer. The micro spectrometer used is also a grating spectrometer, which is a substitute for a medium-sized grating spectrometer. Compared with a medium-sized grating spectrometer, a micro spectrometer is smaller in size, cheaper in price, and more conducive to industrial applications.

[0078] In one embodiment, the laser induced breakdown spectrometer further includes a data processing component 15 for processing the spectral signal collected by the spectrometer 14 and performing data analysis. The data processing component can be a computer, and the signal output end of the spectrometer 14 is connected to the signal input end of the computer 15 for receiving and analyzing the spectral signal.

[0079] In one embodiment, the following accessories are selected to construct the laser induced breakdown spectrometer of the embodiment of the present application:

[0080] AUT-ONDA DPSS laser, excitation wavelength 1064nm, maximum single pulse energy 800μJ, pulse width 2~10ns, repetition frequency 1Hz~100kHz; the acousto-optic modulator (AOM) model used is 1206C, transmission band is 360~448nm, separation angle is 9.4~12.8mrad, rise time is 30ns, diffraction efficiency>85%; DG535 delay generator is selected, time resolution is 5ps, trigger pulse width is 1μs; the micro-fiber spectrometer model used is Ava Spec-ULS4096 is a cross-asymmetric Czerny-Turner structure with a 1200 line / mm grating, a wavelength range of 340-480nm, and an average spectral resolution of 0.12nm. The DET10A / M fast silicon detector is selected, with a response band of 200-1100nm and a response time of 1ns. The selected off-axis parabolic mirror with a central hole (concave mirror with a central hole) is coated with a UV-enhanced aluminum film, with an average reflectivity of more than 90% at 200-450nm and 1064nm, and a reflection focal length of 101.6mm.

[0081] The laser induced breakdown spectrometer of the present application works as follows: a laser pulse beam is generated by a laser 2, and after being reflected by a reflector 4, it is divided into two beams by a half-wave plate 5 and a polarization beam splitter 6, one of which goes to an energy meter 7, and the other converges on the sample surface located on a stepping rotary table 9 to generate a plasma fluorescence signal; the fluorescence radiated by the plasma is reflected by a concave mirror 8 and converged to the first optical fiber 21, and then focused by a first focusing mirror 11 at a Bragg angle to the AOM 12 for diffraction, and its zero-order diffraction light is horizontally emitted and blocked by a blade 17, and the first-order diffraction light is converged by a second focusing mirror 13 to the second optical fiber 22 and enters the miniature spectrometer 14; the signal output end of the miniature spectrometer 14 is connected to the signal input end of a computer 15.

[0082] Figure 3 The spectrum of the aluminum alloy sample plasma passing through the laser induced breakdown spectrometer of the above embodiment of the present application (using the embodiment LIBS) is shown. The content of each element in the aluminum alloy is: Al 93.72%, Mg 4.58%, Cr 0.16%, Fe0.41%, and the delay time is set to 400ns.

[0083] Figure 3 The spectrum of the aluminum alloy sample plasma obtained using the conventional LIBS system is also shown (using the conventional LIBS). Figure 5As shown, it includes a Nd:YAG laser 201, a laser beam amplifier 202, a half-wave plate 203 and a polarization beam splitter 204. The pulsed laser output from the Nd:YAG laser 201 is collimated and expanded by the laser beam amplifier 202 and then divided into two beams by the half-wave plate 203 and the polarization beam splitter 204. The vertical light is used by a laser power meter 205 for real-time power monitoring. The horizontal light is incident on the sample surface on the sample stage 209 after passing through a lens 208. The fluorescence that excites and forms plasma is collected by an optical fiber 211 and transmitted to a grating spectrometer 212 for spectrometry. The spectrum is detected by an image-intensified CCD (ICCD) 210 and input into a computer 213 for data processing.

[0084] for Figure 3 The signal in the image is normalized by taking the intensity of the Al I 396.15nm line as the highest intensity. It can be seen that the background intensity is significantly reduced within the transmission band of the AOM.

[0085] Test Case

[0086] After pure KBr and Al2O3 dry powders were uniformly mixed, a pressed sample with an Al content of 13% ± 0.04% was prepared under a pressure of 30MPa. The self-absorption coefficients of four Al atomic spectral lines, Al I 308.21nm, Al I 309.27nm, Al I394.40nm and Al I 396.15nm, were obtained using a traditional LIBS system. After correction, the integrated intensity without self-absorption effect is obtained. At the same time, the laser induced breakdown spectrometer of the above embodiment of the present application was also used for measurement.

[0087] Figure 4 The Boltzmann plane diagrams obtained from the 13% pressed tablets before and after self-absorption correction and the device of the present invention are compared (before self-absorption correction means the data before self-absorption correction using the traditional LIBS system, after self-absorption correction means the data after self-absorption correction using the traditional LIBS system, and using example LIBS means the data obtained using the laser induced breakdown spectrometer of the above example of the present application). It can be seen that before self-absorption correction, the points are very scattered, and the linear correlation coefficient R 2 =0.95. After calibration and when the laser induced breakdown spectrometer of the present application is used through AOM, these points coincide better with the corresponding straight line fitting line, and the slope is closer, R 2 Both reached 0.99.

[0088] Those skilled in the art should note that the embodiments described in the present invention are merely exemplary, and various other substitutions, changes and improvements may be made within the scope of the present invention. Therefore, the present invention is not limited to the above embodiments, but only to the claims.

Claims

1. An acousto-optic gating device, comprising: detector, Delay generator, Acousto-optic modulator, an AOM driver, the AOM driver being electrically connected to the AOM; Wherein, the detector is used to sense the laser signal and trigger the delay generator to generate a delay based on the laser signal; The delay generator controls the AOM by inputting a radio frequency signal to the AOM driver.

2. The acousto-optic gating device according to claim 1, wherein: The acousto-optic gating device further includes an oscilloscope, which is used to monitor the delay between the laser signal and the acousto-optic modulator.

3. The acousto-optic gating device according to claim 1, wherein: The detector is a silicon detector.

4. A laser induced breakdown spectrometer, comprising: a laser configured to emit a laser signal; An optical path component, the optical path component is used to irradiate the laser signal onto the substance to be measured to generate a plasma spectrum signal, and to focus the diffracted light of the plasma spectrum signal after diffraction; A spectrometer, used for collecting the diffracted light; The laser induced breakdown spectrometer further comprises the acousto-optic gating device according to any one of claims 1 to 3.

5. The laser induced breakdown spectrometer according to claim 4, wherein: The optical path component comprises: A reflector, used for reflecting the laser signal generated by the laser; A polarization beam splitter, used to split the laser signal reflected by the reflector into two beams; A concave mirror, wherein the concave mirror is used to converge the plasma spectrum signal generated by irradiating the first laser signal after polarization splitting onto the measured substance; A first focusing mirror, used for focusing the plasma spectrum signal converged by the concave mirror; a second focusing mirror, used to focus the diffracted light from the acousto-optic modulator of the acousto-optic gating device; The acousto-optic modulator of the acousto-optic gating device is located between the first focusing mirror and the second focusing mirror, and is used to make the plasma spectrum signal diffract in the acousto-optic modulator.

6. The laser induced breakdown spectrometer according to claim 5, wherein: The optical path component also includes a half-wave plate, which is located between the reflector and the polarization beam splitter, so that the laser signal reflected by the reflector first enters the half-wave plate and then enters the polarization beam splitter.

7. The laser induced breakdown spectrometer according to claim 4, wherein: The laser induced breakdown spectrometer further comprises an energy meter for measuring the second laser signal after polarization splitting.

8. The laser induced breakdown spectrometer according to claim 5, wherein: The concave mirror has a central hole, and the first laser signal after polarization splitting irradiates the measured object through the central hole.

9. The laser induced breakdown spectrometer according to claim 5, wherein: The laser induced breakdown spectrometer further includes a first optical fiber, which is used to transmit the plasma spectrum signal focused by the concave mirror to the first focusing mirror.

10. The laser induced breakdown spectrometer according to claim 5, wherein: The laser induced breakdown spectrometer further includes a second optical fiber, and the second optical fiber is used to transmit the diffracted light focused by the second focusing mirror to the spectrometer.

11. The laser induced breakdown spectrometer according to claim 4, wherein: The spectrometer is a grating spectrometer.

12. The laser induced breakdown spectrometer according to claim 11, wherein: The spectrometer is a miniature spectrometer.

13. The laser induced breakdown spectrometer according to claim 4, wherein: The laser induced breakdown spectrometer also includes a data processing component for processing the spectral signal collected by the spectrometer.

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