A multi-spectral detection system and detection method thereof

Abstract

The invention discloses a multi-spectral combined detection system and a detection method thereof. The system comprises a stimulated Brillouin scattering measurement branch and a Raman / laser induced breakdown measurement branch, which are used to detect physical information such as bulk elastic modulus and viscoelasticity and chemical information such as molecular structure and element composition of different samples. The system uses laser energy regulation combined with a zoom lens group to realize free switching between Raman spectrum and laser induced breakdown spectrum, analyzes molecular structure and element information in a first sample to be tested, obtains physical and chemical composition information of the first sample to be tested and a second sample to be tested through multi-spectral combined detection, and a computer is used to process received spectral data to obtain the content of sample elements or molecular components, and establishes a fingerprint identification database for different sample detection in combination with spectral data corresponding to different detection samples, thereby finally forming an effective method and technology for rapid detection of multiple samples.

Description

Technical Field

[0001] The present invention relates to the field of optical detection technology, and in particular to a multi-spectral combined detection system and method. Background Art

[0002] Brillouin scattering is an important research direction in laser spectroscopy. According to the physical mechanism of Brillouin scattering, when the incident laser intensity reaches or exceeds a certain threshold, an electrostrictive effect will be generated inside the medium, causing density fluctuations in the medium, thereby stimulating a "moving" sound wave field. This sound wave will scatter the incident light in a specific direction (i.e., stimulated Brillouin scattering, SBS), and the scattered light will shift in frequency due to the Doppler effect. The magnitude of the frequency shift is related to the wavelength λ of the incident light, the refractive index n of the medium, and the speed of sound υS. It has been widely used in practical applications such as material structure analysis and medium parameter measurement, and the elastic modulus can be obtained from the speed of the Brillouin sound wave and the density of the oil. However, Brillouin scattering can only detect physical properties such as the refractive index, density, and viscosity coefficient of a substance, but cannot detect the chemical composition of a substance.

[0003] Raman spectroscopy is a type of scattering spectrum. Raman spectroscopy is based on the Raman scattering effect discovered by Indian scientist CV Raman. It analyzes the scattering spectrum with a different frequency from the incident light to obtain information on molecular vibration and rotation. It can be applied to an analysis method of molecular structure and its composition. Raman spectroscopy does not damage the sample during the detection process, and the requirements for the preliminary processing of the sample are relatively low. However, Raman spectroscopy cannot detect the physical properties of the material such as the refractive index, density, viscosity coefficient, etc., nor can it analyze the elemental composition of the material.

[0004] Laser induced breakdown spectroscopy (LIBS) forms plasma by focusing a pulsed laser on the sample surface, and then analyzes the plasma emission spectrum to determine the material composition and content of the sample. LIBS is a chemical element analysis technique that can be used to evaluate the composition of each constituent element and its relative abundance. The advantages of LIBS technology include fast analysis speed (seconds), direct analysis of solid samples, and coverage of almost all elements, including light elements and non-metallic elements. However, LIBS is only suitable for analyzing the elemental composition of substances and cannot detect the molecular structure and physical properties of substances.

[0005] In order to solve the shortcomings of the above methods, the present invention proposes a multi-spectral detection system and method, which combines SBS, Raman and LIBS technologies to achieve a high degree of complementarity among the three technologies and detect samples from the perspectives of physical properties such as elastic modulus and viscoelasticity, molecular structure and elemental composition. Summary of the invention

[0006] In view of the problems and shortcomings of single spectrum detection technology, the present invention provides a multi-spectral detection system and a detection method integrating stimulated Brillouin scattering, Raman spectroscopy and laser induced breakdown spectroscopy, including a stimulated Brillouin scattering measurement branch and a Raman / laser induced breakdown spectroscopy measurement branch, which are used to detect physical information such as bulk elastic modulus and viscoelasticity and chemical information such as composition of the sample to be tested.

[0007] In order to achieve the above-mentioned object, the technical solution of the present invention is a multi-spectral combined detection system, including a stimulated Brillouin scattering detection system, a stimulated Brillouin scattering signal collection system, a Raman and laser induced breakdown spectroscopy detection system and a Raman and laser induced breakdown spectroscopy collection system;

[0008] The stimulated Brillouin scattering detection system is composed of a computer, a timing controller, a Nd:YAG solid-state laser, an energy meter, a first beam splitter, a second beam splitter, a polarization beam splitter, a half wave plate, a quarter wave plate, a first total reflection mirror, a first lens, and a second sample to be tested, wherein the first total reflection mirror, the second total reflection mirror, the half wave plate, the polarization beam splitter, the quarter wave plate, the first lens, and the second sample to be tested are on the same horizontal optical axis;

[0009] The stimulated Brillouin scattering signal acquisition system is composed of a second sample to be tested, a first lens, a second lens, a third lens, a second total reflection mirror, a quarter wave plate, a polarization beam splitter, a pinhole filter, an FP etalon, an ICCD and a computer, wherein the computer is connected to the ICCD, the timing controller is connected to the Nd:YAG solid laser and the ICCD, the second total reflection mirror, the second lens, the third lens, the pinhole filter, the FP etalon and the ICCD are in the same horizontal optical axis, and are in a different horizontal optical axis from the second sample to be tested, the first lens, the quarter wave plate and the polarization beam splitter;

[0010] The Raman / laser induced breakdown spectroscopy detection system is composed of a computer, a timing controller, a Nd:YAG solid laser, an energy meter, a first beam splitter, a second beam splitter, a zoom lens group, and a first sample to be tested, wherein the first beam splitter, the second beam splitter, the zoom lens group, and the first sample to be tested are on the same horizontal optical axis;

[0011] The Raman and laser induced breakdown spectroscopy acquisition system consists of a computer, an acquisition mirror group, an optical fiber, a spectrometer, a detector, and a first sample to be tested, wherein the outlet of the acquisition mirror group is connected to the spectrometer through the optical fiber, the detector is connected to the spectrometer, and the spectrometer is connected to the computer.

[0012] The present invention also provides a detection method for a multi-spectral combined detection system, which is implemented using the multi-spectral combined detection system. The output laser of a Nd:YAG solid laser is first divided into reflected light and transmitted light by a first beam splitter, and the reflected light irradiates an energy meter for real-time detection of laser energy; then the transmitted light is divided into two beams by a second beam splitter, the reflected light is used as Brillouin scattering excitation light, and the transmitted light is used as Raman spectrum or laser induced breakdown spectrum excitation light. The reflected light is first reflected by a first total reflection mirror and then sequentially passes through a half wave plate, a polarization beam splitter and a quarter wave plate to become circularly polarized light, and then is focused into a second sample to be tested by a first lens and stimulates stimulated Brillouin scattering. The scattered signal returns along a back direction of 180° due to its phase conjugation characteristics, and becomes vertically polarized light after passing through the first lens and the quarter wave plate again, and is reflected by the polarization beam splitter and the second total reflection mirror and sequentially passes through the second lens, a pinhole filter, a third lens, and an FP standard tool, and finally enters an ICCD signal acquisition system to generate a stimulated Brillouin scattering signal. The transmitted light enters the zoom system, and the laser focus point is adjusted to the position of the first sample to be tested. At the same time, the laser energy output by the Nd:YAG solid laser is adjusted according to the needs of the Raman spectrum and the laser induced breakdown spectrum. When the high-energy output laser is adjusted and focused, the high-energy density laser pulse excites the first sample to be tested to generate plasma, and the plasma light is collected to obtain the laser induced breakdown spectrum, which is analyzed to obtain the type and content of elements in the sample; when the low-energy output laser is switched and not focused, the low-energy density laser reacts with the first sample to be tested to generate Raman spectrum, and the molecular structure information of the first sample to be tested can be obtained. The Raman or laser induced breakdown spectrum signal is obtained by using the collection optical path, and is transmitted to the spectrometer through the optical fiber for spectrometry. The spectrum information obtained after the spectrometry is photoelectrically converted, accumulated and amplified by the detector; the computer is used to process the received spectrum data to obtain the element or molecular component content of the first sample to be tested and / or the second sample to be tested.

[0013] The beneficial effects of the present invention include: being able to simultaneously detect the physical properties and chemical composition of different samples, such as elastic modulus and viscoelasticity, and the like, and being able to freely switch between Raman spectroscopy and laser induced breakdown spectroscopy by utilizing laser energy regulation in combination with a zoom lens group, analyzing the molecular structure and element information in the first sample to be tested, obtaining the physical and chemical composition information of the first sample to be tested and the second sample to be tested by multi-spectral joint detection, and a computer being used to process the received spectral data to obtain the content of sample elements or molecular components, and establishing a fingerprint identification database for different sample detection in combination with the spectral data corresponding to different detection samples, thereby finally forming an effective method and technology for rapid detection of multiple samples. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is the principle diagram of the detection system of the present invention;

[0015] exist Figure 1 In the figure, 001-Nd:YAG solid laser, 002A-first beam splitter, 002B-second beam splitter, 003-zoom lens group, 004A-first sample to be tested, 005-collection lens group, 006-optical fiber, 007-spectrometer, 008-detector, 009A-first total reflection mirror, 010-half wave plate, 011-polarization beam splitter, 012-quarter wave plate, 013A-first lens, 004B-second sample to be tested, 009B-second total reflection mirror, 013B-second lens, 014-pinhole filter, 013C-third lens, 015-FP etalon, 016-ICCD, 017-timing controller, 018-energy meter, 019-computer. DETAILED DESCRIPTION

[0016] exist Figure 1A multi-spectral detection system and a detection method thereof are provided. In the stimulated Brillouin scattering detection system, a computer 019 is connected to an ICCD 016, a timing controller 017 is connected to an Nd:YAG solid laser 001 and an ICCD 016, and a first total reflection mirror 009A, a half wave plate 010, a polarization beam splitter 011, a quarter wave plate 012, a lens 013A and a second sample to be tested 004B are on the same horizontal optical axis. Computer 019 starts timing controller 017 to control Nd:YAG solid laser 001 pulse width of 10ns, Nd:YAG solid laser 001 outputs 532nm vertical polarized light, which is divided into two beams by first beam splitter 002A, energy meter 018 receives reflected light for energy detection, transmitted light passes through second beam splitter 002B, reflected light passes through first total reflection mirror 009A, and then passes through half wave plate 010 to become 532nm horizontal polarized light, and is incident at Brewster angle through polarization beam splitter 011 (polarization beam splitter 011 surface coating, high transmittance to horizontal polarized light), and then passes through quarter wave plate 012 to convert horizontal polarized light into circular polarized light. Laser is focused by first lens 013A and injected into second sample to be tested 004B. In the stimulated Brillouin scattering signal acquisition system, the second total reflection mirror 009B, the second lens 013B, the pinhole filter 014, the third lens 013C, the FP etalon 015 and the ICCD 016 are on the same horizontal optical axis. The second sample to be tested 004B, the first lens 013A, the quarter wave plate 012 and the polarization beam splitter 011 are on another horizontal optical axis. After the stimulated Brillouin scattering signal of the second sample to be tested 004B passes through the first lens 013A and the quarter wave plate 012 in the direction 180° back to the incident light, the stimulated Brillouin scattering signal becomes a vertical polarization signal, which is reflected by the polarization beam splitter 011 and the second total reflection mirror 009B and then passes through the second lens 013B, and is collimated by the pinhole filter 014 and the FP etalon 015. The stimulated Brillouin scattering signal is collected by the ICCD 016 and transmitted to the computer 019. In the Raman / laser induced breakdown spectroscopy detection system, the computer 019 is connected to the spectrometer 007, the spectrometer 007 is connected to the timing controller 017, and the first beam splitter 002A, the zoom lens group 003 and the first sample to be tested 004A are on the same horizontal optical axis. The computer 019 starts the timing controller 017 to control the pulse width of the Nd:YAG solid laser 001 to be 10ns, and the Nd:YAG solid laser 001 outputs 532nm laser. When performing Raman spectrum detection, it switches to low-energy output laser, which is divided into two beams by the first beam splitter 002A. The energy meter 018 receives the reflected light for energy detection. After the transmitted light passes through the second beam splitter 002B, the zoom lens group 003 adjusts the transmitted light to the surface of the first sample to be tested 004A to be in a non-focused state, and the low-energy density laser acts on the first sample to be tested 004A to generate a Raman signal.When performing laser induced breakdown spectroscopy detection, the high energy output laser is switched and split into two beams by the first beam splitter 002A. The energy meter 018 receives the reflected light for energy detection. After the transmitted light passes through the second beam splitter 002B, the zoom lens group 003 adjusts the transmitted light to the surface of the first sample to be tested 004A to be in a focused state. The high energy density laser pulse excites the first sample to be tested 004A to generate plasma. In the Raman / laser induced breakdown spectroscopy acquisition system, the outlet of the acquisition lens group 005 is connected to the spectrometer 007 through the optical fiber 006, and the detector 008 is connected to the spectrometer 007. The spectrometer 007 is connected to the computer 019. After the Raman signal and the laser induced breakdown signal are collected by the acquisition lens group 005, they are transmitted to the spectrometer 007 through the optical fiber 006 for splitting. The spectrum information obtained after splitting is photoelectrically converted, accumulated and amplified by the detector 008; the computer 019 is used to process and analyze the received spectrum data.

[0017] Action process and operation steps: Computer 019 and timing controller 017 control Nd:YAG solid laser 001 to output 532nm single longitudinal mode vertical polarized light, which first passes through the first beam splitter 002A, and the reflected light is received by energy meter 018 for detecting laser energy. The transmitted light passes through the second beam splitter 002B and then the reflected light is reflected by the first total reflection mirror 009A and then passes through the half wave plate 010 to become 532nm horizontal polarized light, and is incident at the Brewster angle through the polarization beam splitter 011 (surface coated, high transmittance to horizontal polarized light), and then passes through the quarter wave plate 012 to convert the horizontal polarized light into circularly polarized light. The laser is focused by the first lens 013A and injected into the second sample to be tested 004B to stimulate stimulated Brillouin scattering. The scattered signal returns along the back direction (180°) due to its phase conjugation characteristics, and becomes vertically polarized light after passing through the first lens 013A and the quarter-wave plate 012 again, and is reflected by the polarization beam splitter 011 and the second total reflection mirror 009B to the stimulated Brillouin scattering signal acquisition system composed of the second lens 013B, the pinhole filter 014, the third lens 013C, the FP etalon 015 and the ICCD 016. After the spectral signal is subjected to signal processing techniques such as denoising and de-broadening, the stimulated Brillouin scattering frequency shift and line width information can be obtained.

[0018] Computer 019 starts timing controller 017 to control Nd:YAG solid laser 001 pulse width to 10ns, Nd:YAG solid laser 001 outputs 532nm laser, when Raman spectrum detection is performed, low energy output laser is switched, and it is divided into two beams by first beam splitter 002A, energy meter 018 receives reflected light for energy detection, and after the transmitted light passes through second beam splitter 002B, when the transmitted light passes through zoom lens group 003 and is in non-focusing state, low energy density laser acts on first sample to be tested 004A to generate Raman signal. Raman signal is collected by collection lens group 005 and transmitted to spectrometer 007 through optical fiber 006 for spectral splitting, and the spectral information obtained after spectral splitting is photoelectrically converted, accumulated and amplified by detector 008; computer 019 is used to process and analyze the received spectral data, and can accurately obtain the molecular structure composition and content information of first sample to be tested 004A. When performing laser induced breakdown spectroscopy detection, the Nd:YAG solid laser is adjusted to output high-energy laser, which is divided into two beams by the first beam splitter 002A. The energy meter 018 receives the reflected light for energy detection. After the transmitted light passes through the second beam splitter 002B, when the transmitted light passes through the zoom lens group 003 and is in a focused state, the high-energy density laser pulse excites the first sample to be tested 004A to generate plasma. The plasma light is collected by the collection lens group 005 and transmitted to the spectrometer 007 through the optical fiber 006 for splitting. The spectrum information obtained after splitting is photoelectrically converted, accumulated and amplified by the detector 008; the computer 019 is used to process and analyze the received spectrum data, and the element composition and content information of the first sample to be tested 004A can be obtained.

Claims

1. A multi-spectral combined detection system, comprising a stimulated Brillouin scattering measurement branch and a Raman / laser induced breakdown measurement branch, characterized in that: Including stimulated Brillouin scattering detection system, stimulated Brillouin scattering signal acquisition system, Raman and laser induced breakdown spectroscopy detection system and Raman and laser induced breakdown spectroscopy acquisition system; The stimulated Brillouin scattering detection system is composed of a computer, a timing controller, a Nd:YAG solid-state laser, an energy meter, a first beam splitter, a second beam splitter, a polarization beam splitter, a half wave plate, a quarter wave plate, a first total reflection mirror, a first lens, and a second sample to be tested, wherein the first total reflection mirror, the second total reflection mirror, the half wave plate, the polarization beam splitter, the quarter wave plate, the first lens, and the second sample to be tested are on the same horizontal optical axis; The stimulated Brillouin scattering signal acquisition system is composed of a second sample to be tested, a first lens, a second lens, a third lens, a second total reflection mirror, a quarter wave plate, a polarization beam splitter, a pinhole filter, an FP etalon, an ICCD and a computer, wherein the computer is connected to the ICCD, the timing controller is connected to the Nd:YAG solid laser and the ICCD, the second total reflection mirror, the second lens, the third lens, the pinhole filter, the FP etalon and the ICCD are in the same horizontal optical axis, and are in a different horizontal optical axis from the second sample to be tested, the first lens, the quarter wave plate and the polarization beam splitter; The Raman / laser induced breakdown spectroscopy detection system is composed of a computer, a timing controller, a Nd:YAG solid laser, an energy meter, a first beam splitter, a second beam splitter, a zoom lens group, and a first sample to be tested, wherein the first beam splitter, the second beam splitter, the zoom lens group, and the first sample to be tested are on the same horizontal optical axis; The Raman and laser induced breakdown spectroscopy acquisition system consists of a computer, an acquisition mirror group, an optical fiber, a spectrometer, a detector, and a first sample to be tested, wherein the outlet of the acquisition mirror group is connected to the spectrometer through the optical fiber, the detector is connected to the spectrometer, and the spectrometer is connected to the computer.

2. A detection method of a multi-spectral detection system, characterized in that: The multi-spectral detection system described in claim 1 is used to realize that the output laser of the Nd:YAG solid laser is first divided into reflected light and transmitted light by a first beam splitter, and the reflected light irradiates an energy meter for real-time detection of laser energy; then the transmitted light is further divided into two beams by a second beam splitter, the reflected light is used as Brillouin scattering excitation light, and the transmitted light is used as Raman spectrum or laser induced breakdown spectrum excitation light, the reflected light is first reflected by a first total reflection mirror, and then successively passes through a half wave plate, a polarization beam splitter and a quarter wave plate to become circularly polarized light, and then is focused to the second sample to be tested by a first lens and stimulates stimulated Brillouin scattering, the scattered signal is returned along the back direction of 180° due to its phase conjugate characteristic, and becomes vertically polarized light after passing through the first lens and the quarter wave plate again, and is reflected by the polarization beam splitter and the second total reflection mirror, and successively passes through the second lens, the pinhole filter, the third lens, the FP standard tool, and finally enters the ICCD signal acquisition system to generate stimulated Brillouin scattering signal, and the transmitted light is reflected by the polarization beam splitter and the second total reflection mirror. Light enters the zoom system, and the laser focus is adjusted to the position of the first sample to be tested. At the same time, the laser energy output by the Nd:YAG solid laser is adjusted according to the needs of Raman spectrum and laser induced breakdown spectrum. When the high-energy output laser is adjusted and focused, the high-energy density laser pulse excites the first sample to be tested to generate plasma, and the plasma light is collected to obtain the laser induced breakdown spectrum, which is analyzed to obtain the type and content of elements in the sample; when the low-energy output laser is switched and not focused, the low-energy density laser reacts with the first sample to be tested to generate Raman spectrum, and the molecular structure information of the first sample to be tested can be obtained. The Raman or laser induced breakdown spectrum signal is obtained by using the collection optical path, and is transmitted to the spectrometer through the optical fiber for spectrometry. The spectrum information obtained after the spectrometry is photoelectrically converted, accumulated and amplified by the detector; the computer is used to process the received spectrum data to obtain the element or molecular component content of the first sample to be tested and / or the second sample to be tested.

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