A multi-mode analysis system and analysis method of CARS-LA-ICP-MS combination

Abstract

The application discloses a CARS-LA-ICP-MS combined multi-mode analysis system, which comprises a fusion optical path module, a mass spectrum analysis gas path module, a three-dimensional moving table, a CARS signal acquisition system and a computer control system; the fusion optical path module comprises a laser source, an optical parametric amplifier, an optical pulse time delay system, three dichroic mirrors, a light beam adjusting system, a galvanometer, a moving objective and a camera; the mass spectrum analysis gas path module comprises a carrier gas supply device, a multi-mode analysis sample pool and a mass spectrum analysis device; the multi-mode analysis sample pool comprises an upper cover, a lower cover and a side wall shell. The application discloses another aspect of an analysis method, which comprises initialization setting, CARS analysis, mass spectrum analysis task parameter setting, laser ablation mass spectrum analysis and data synthesis. Through coaxial optical path design and intelligent algorithm, the application realizes deep fusion of chemical imaging and element analysis, and provides a new research tool for the fields of life science, material science and the like.

Description

Technical Field

[0001] This invention belongs to the field of analytical chemistry technology, and in particular relates to a multi-mode analysis system and method using CARS-LA-ICP-MS. Background Technology

[0002] In recent years, with the rapid development of biomedicine, materials science, and micro / nano fabrication technologies, the demand for high-precision, multimodal sample detection and micro-region manipulation has been increasing. Traditional material characterization methods (such as electron microscopy and mass spectrometry), while providing information on composition or morphology, often require complex sample preparation. Furthermore, in current technologies, chemical imaging and physical processing are typically performed separately, lacking real-time feedback and dynamic control capabilities, which limits their application in precision medicine, advanced manufacturing, and other fields.

[0003] Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) has been widely used in elemental analysis of materials, especially femtosecond laser ablation technology, which is increasingly popular due to its low damage to materials and high sensitivity. However, ICP-MS cannot obtain molecular structure information, and the mass spectrometry imaging speed is relatively low, making it difficult to form large-area real-time tissue imaging like optical imaging.

[0004] Raman spectroscopy is a spectroscopic technique used to study the vibrations and rotations of molecules within matter. It provides fingerprint information about substances, making it a powerful tool for identifying and analyzing their composition. Traditional Raman spectroscopy is spontaneous and incoherent, with scattered light propagating in all directions and producing a weak signal. Coherent anti-Stokes Raman scattering (CARS) is a stimulated Raman process based on third-order nonlinear effects. It typically uses two laser pulses with different center frequencies as pump light (W). P ) and Stokes Light (W S To excite the molecular bond resonance of the sample, the frequency difference between the two laser pulses is equal to the vibrational frequency of the intrinsic vibrational mode of the molecules in the sample (W). R = W P - W S The intrinsic vibrational modes of molecules are resonantly enhanced, and this is observed in the probe light (W). PR The anti-Stokes signal (W) is generated under the action of ) AS = W P - W S + W PR ); generally, the pump light itself can also be used as the probe light, i.e., W PR = W P W AS = 2W P - WS CARS is stimulated and coherent, meaning the generated CARS signal is laser-like, highly directional (like a laser beam), and all molecules are excited synchronously, greatly enhancing the signal intensity. The CARS signal is much stronger than spontaneous Raman scattering (typically 10 times stronger). 3 Up to 10 5 Coherent anti-Stokes Raman scattering (CARS) imaging technology, with its label-free, high chemical specificity, and rapid three-dimensional imaging capabilities, offers advantages such as high sensitivity, high spatial resolution, and high data acquisition rate, making it a powerful tool for biomolecular and material composition analysis. However, when used alone, CARS can only provide information on the molecular composition and distribution of the sample, and cannot perform active intervention or elemental analysis on the target region.

[0005] Therefore, there is an urgent need for a system that can combine elemental analysis of LA-ICP-MS with high-sensitivity chemical imaging of CARS to achieve more complete analysis of material elements and molecular structures. Summary of the Invention

[0006] In view of this, the purpose of this invention is to propose an innovative system architecture and method that combines laser ablation inductively coupled plasma mass spectrometry and coherent anti-Stokes Raman scattering spectroscopy imaging through optical path optimization. This enables multimodal analysis of sample elemental composition and molecular structure, and can also obtain in-situ three-dimensional imaging of elemental and molecular structure composites, providing a more efficient solution for fields such as biomedicine, materials science, and micro / nano manufacturing.

[0007] To achieve the above objectives, the present invention provides a multi-mode analysis system combining CARS-LA-ICP-MS, including a fusion optical path module, a mass spectrometry analysis gas path module, a three-dimensional moving stage, a CARS signal acquisition system, and a computer control system;

[0008] The fusion optical path module includes a laser source, a CARS laser modulation module, and a common optical path module;

[0009] The laser source is configured with a fundamental frequency output mode and a frequency-doubled output mode. In the fundamental frequency output mode, the laser source sends fundamental frequency light to the CARS laser modulation module. The CARS laser modulation module converts the fundamental frequency light into a combined beam of pump light and Stokes light, which is then sent to the common optical path module through a second dichroic mirror. In the frequency-doubled output mode, the laser source directs the ablation laser through the second dichroic mirror into the common optical path module. The optical path of the common optical path module passes through the sample under test from above and enters the CARS signal acquisition system.

[0010] The mass spectrometry analysis gas path module includes a carrier gas supply device, a multimode analysis sample cell, and a mass spectrometry analysis device; the carrier gas supply device, the multimode analysis sample cell, and the mass spectrometry analysis device are connected sequentially by gas path.

[0011] The three-dimensional moving stage is provided with a mounting part having a hollow structure. The multimode analysis sample cell is fixedly installed in the mounting part and is used to hold the sample to be tested. The multimode analysis sample cell includes an upper cover, a lower cover, and a side wall shell. The upper cover and the lower cover are respectively provided with windows. The lower cover and the side wall shell are sealed together. The upper cover and the side wall shell are provided with a rotatable opening and sealing connection. The upper cover is rotated to the open state during CARS analysis and rotated to the closed and sealed state during laser ablation mass spectrometry analysis.

[0012] Preferably, the CARS laser modulation module includes an optical parametric amplifier and an optical pulse time delay system; the optical parametric amplifier converts the fundamental frequency light into pump light and Stokes light with different wavelengths, and the pump light and Stokes light form a combined beam through a first dichroic mirror; the optical pulse time delay system is used to adjust the time delay between the pulse signals of the pump light and the pulse signals of the Stokes light; the common optical path module includes a beam adjustment system, a galvanometer, a moving objective lens, and a camera; the beam adjustment system, the galvanometer, and the moving objective lens are sequentially arranged in the optical path of the common optical path module, the galvanometer is used to quickly adjust the focusing position of the laser in the horizontal direction, and the moving objective lens is used to quickly adjust the focusing position of the laser in the vertical direction; the fusion optical path module also includes a camera, the camera is used to observe the sample to be tested, and the setting optical path of the camera is merged into the optical path of the common optical path module between the galvanometer and the moving objective lens through a third dichroic mirror.

[0013] The CARS signal acquisition system is used to detect the CARS signal light generated by the sample under test and convert it into a CARS analysis signal. Preferably, the CARS signal acquisition system includes a condenser lens, a beam splitter, a photomultiplier tube, an amplifier, a data acquisition card, and a spectrometer. The condenser lens and the beam splitter are optically connected. The beam splitter is optically connected to the photomultiplier tube and the spectrometer, respectively. The photomultiplier tube, the amplifier, and the data acquisition card are sequentially signal-connected. The amplifier includes either a transimpedance amplifier or a lock-in amplifier. The CARS analysis signal includes a CARS spectral signal and a CARS imaging signal. The spectrometer is used to generate the CARS spectral signal, and the photomultiplier tube, the amplifier, and the data acquisition card are used to generate the CARS imaging signal.

[0014] Preferably, the beam conditioning system includes an attenuator, a beam expander, and a beam shaper.

[0015] Preferably, the galvanometer, the moving objective lens, and the three-dimensional moving stage are controlled by coordinate linkage to adjust the focusing position of the laser relative to the sample under test.

[0016] The computer control system is connected to the fusion optical path module, the mass spectrometry analysis gas path module, the three-dimensional moving stage, and the CARS signal acquisition system. The computer control system is used to control the multi-mode analysis system, collect CARS analysis signals and mass spectrometry analysis signals, and perform data integration processing on the CARS analysis signals and mass spectrometry analysis signals. Preferably, the computer control system includes a timing synchronization control module, which drives the positioning of the galvanometer, the switching of the laser source, the gating of the photomultiplier tube, and the signal acquisition of the mass spectrometry analysis device by generating multiple programmable timing signals.

[0017] Preferably, the wavelength of the fundamental frequency light is 1030 nm, and the wavelength of the second-harmonic light is not higher than 343 nm.

[0018] Another aspect of the present invention provides an analysis method using the aforementioned multi-mode analysis system, including initialization settings, CARS analysis, mass spectrometry analysis task parameter settings, laser ablation mass spectrometry analysis, and data synthesis;

[0019] When performing the initialization settings, set the laser source to fundamental frequency light output mode and rotate the top cover of the multimode analysis sample cell to the open state; when setting the mass spectrometry analysis task parameters, set the laser source to frequency doubling light output mode and rotate the top cover of the multimode analysis sample cell to the closed and sealed state.

[0020] Preferably, after CARS analysis, key analysis areas are obtained by image recognition of the data obtained from CARS analysis; when setting the parameters for mass spectrometry analysis, the areas that need to be laser ablated are selected based on the key analysis areas.

[0021] Preferably, during data synthesis, a feature point matching image processing algorithm based on scale-invariant feature transformation is used to perform affine transformation registration on the CARS analysis signal and the mass spectrometry analysis signal, and principal component analysis is used to obtain the correlation between the CARS analysis signal and the mass spectrometry analysis signal.

[0022] The beneficial effects of this invention are:

[0023] (1) Based on laser ablation mass spectrometry, this invention integrates coherent anti-Stokes Raman scattering spectroscopy measurement and microscopic imaging technology. The two systems share the same laser source, galvanometer system, camera, sample cell and moving stage. Through coaxial optical path design and intelligent algorithm, the deep integration of chemical imaging and elemental analysis is realized, providing a brand-new research tool for life science, materials science and other fields.

[0024] (2) This invention first performs non-destructive chemical scanning on the sample using the CARS imaging module, visualizes the distribution of specific chemical components based on molecular vibrational spectroscopy, intelligently identifies key micro-regions such as tumor areas and material defects, and uses this chemical image to precisely guide the laser ablation module, transforming traditional blind sampling into "what you see is what you get" targeted analysis;

[0025] (3) The original chemical state of the sample is fully recorded by CARS imaging, and then the target area is detected by LA-ICP-MS. Only the key analysis area can be destructively analyzed. This process preserves the integrity of the sample to the maximum extent and allows precious samples to complete the full information collection before destructive analysis. It is particularly suitable for single sample research scenarios such as clinical biopsy and cultural relic analysis, and realizes full process coverage from non-destructive screening to accurate detection.

[0026] (4) The synchronous control module based on FPGA of this invention coordinates the imaging and ablation timing with nanosecond precision and dynamically adjusts the laser parameters through a real-time feedback mechanism; the intelligent data processing platform automatically completes feature recognition, path planning and multimodal data fusion, integrating the traditional separation operation into an integrated intelligent analysis process. This design increases the system throughput by 3-5 times while ensuring the standardization and repeatability of data analysis.

[0027] (5) This invention performs pixel-level registration of CARS molecular vibration information with LA-ICP-MS elemental distribution, establishes a spatial correlation model between chemical bonds and elemental content, uses SIFT feature matching algorithm to achieve accurate alignment of multimodal data, and combines principal component analysis to mine the intrinsic correlation between molecules and elements, and finally generates a comprehensive spectrum that includes both chemical structure and elemental composition, providing a panoramic view across molecular to elemental scales for the study of biological metabolism, medicine, life sciences and material composition. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a schematic diagram of the structure of the multi-mode analysis system according to an embodiment of the present invention;

[0030] Figure 2 This is a schematic diagram of the multimodal analysis sample cell according to an embodiment of the present invention;

[0031] Figure 3 This is a flowchart illustrating the analysis method according to an embodiment of the present invention. Detailed Implementation

[0032] One of the core aspects of this invention is the proposal of an innovative system architecture and method that combines laser ablation inductively coupled plasma mass spectrometry and coherent anti-Stokes Raman scattering spectroscopy imaging through optical path optimization. This enables multimodal analysis of sample elemental composition and molecular structure, and can also obtain in-situ three-dimensional imaging of elemental and molecular structure composites.

[0033] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] like Figure 1 As shown, the CARS-LA-ICP-MS system disclosed in this embodiment includes a fusion optical path module 1, a mass spectrometry analysis gas path module 2, a three-dimensional moving stage 3, a CARS signal acquisition system 4, and a computer control system 5;

[0035] The fused optical path module 1 includes a laser source 10, an optical parametric amplifier 11 (OPA), an optical pulse time delay system 12, dichroic mirrors 13a / b / c, a beam adjustment system 14, a galvanometer 15, an objective lens 16, and a camera 17. The optical path systems of CARS and laser ablation are highly integrated, sharing the laser source 10, beam adjustment system 14, galvanometer 15, objective lens 16, and camera 17.

[0036] The laser source 10 uses a picosecond or femtosecond ultrafast laser system with multi-band output as the core light source, which can output laser beams of multiple bands. The laser source 10 can output at least a fundamental frequency light (fundamental frequency light output mode) and a third-harmonic laser beam (frequency-harmonic light output mode) separately, which are used for CARS analysis and laser ablation mass spectrometry analysis, respectively.

[0037] The laser source 10 and the optical parametric amplifier 11 are optically connected. During CARS analysis, the laser outputs a fundamental frequency light with a wavelength of 1030 nm, which is converted into two beams by the optical parametric amplifier 11: one beam with a wavelength of 650-1030 nm and the other with a wavelength of 1030-2000 nm. One beam serves as the pump light for CARS analysis, and the other as the Stokes beam. Based on the sample under test, the computer control system 5 precisely controls the optical parametric amplifier 11 to ensure that the wavelengths of the output pump light and Stokes beam meet the analytical requirements. The optical pulse time delay system 12 is set in the optical path of one of the beams (this path also includes reflectors M1 / M2) to precisely control the time delay of the beam signal, ensuring that both laser pulses reach the focusing position of the sample under test simultaneously. Two beams of light are combined into a single beam by a dichroic mirror 13a, and then reflected by a dichroic mirror 13b before entering the beam conditioning system 14. The beam conditioning system 14 includes an attenuator, a beam expander, and beam shaping devices, and is responsible for precisely adjusting, expanding, and shaping the laser beam energy. After passing through the beam conditioning system 14, the combined beam is focused onto the sample under test by a galvanometer 15 and an objective lens 16. The objective lens 16 is a Z-axis movable objective lens, which can precisely focus the beam to the height of the sample under test, while the galvanometer 15 can quickly adjust the focusing position of the beam in the horizontal direction. The laser beam path for CARS analysis is directed along the Z-axis toward the sample under test (e.g., thin-layer samples such as tissue sections), and the generated CARS signal light then enters the CARS signal acquisition system 4 from below the sample.

[0038] During laser ablation analysis, the laser source 10 outputs frequency-doubled light, preferably a laser of 343 nm (third frequency) or lower wavelength as the ablation laser. The optical path of the ablation laser is from the laser source 10 through the dichroic mirror 13b into the beam adjustment system 14, and the subsequent optical path coincides with the laser optical path during CARS analysis.

[0039] The optical path and laser optical path of camera 17 are integrated through dichroic mirror 13c. Camera 17 is used to initially observe the sample surface through bright-field optical imaging and select relevant parameters such as the scanning range of the analysis task.

[0040] CARS signal acquisition system 4 includes a condenser lens 40, a beam splitter 41, a photomultiplier tube 42 (PMT), a transimpedance amplifier 43 (TIA), an acquisition card 44, and a spectrometer 45; in a preferred embodiment, the transimpedance amplifier 43 is also replaced by a lock-in amplifier.

[0041] The CARS signal light generated by the sample under test is collected by a condenser lens 40 and then split into two paths by a beam splitter 41. One path enters the spectrometer 45 for coherent anti-Stokes Raman scattering spectral measurement, forming a CARS spectral signal. The other path converts the light signal into a current signal by a photomultiplier tube 42 (with a narrowband filter to suppress non-resonant background), and amplifies it before transmitting it to a transimpedance amplifier 43. The transimpedance amplifier 43 converts the current signal into a voltage signal and amplifies it again. Finally, the acquisition card 44 performs analog-to-digital conversion, converting the acquired analog voltage signal into a digital signal and transmitting it to the computer control system 5. Through data analysis and processing, the coherent anti-Stokes Raman scattering imaging signal is acquired, forming a CARS imaging signal. Ultimately, this achieves in-situ micro-area two-dimensional or three-dimensional non-destructive imaging based on chemical bond specificity, and supports dynamic observation of biomolecules such as lipids and proteins.

[0042] The mass spectrometry analysis gas path module 2 includes a carrier gas supply device 20, a multimode analysis sample cell 21, and a mass spectrometry analysis device 22 (ICP-MS). The carrier gas supply device 20 is used to provide a stable flow rate of carrier gas such as helium, and includes devices such as gas cylinders and mass flow controllers. The carrier gas supply device 20, the multimode analysis sample cell 21, and the mass spectrometry analysis device 22 are connected sequentially via gas paths. The multimode analysis sample cell 21 is used to set the sample to be tested, and during the laser ablation analysis process, the aerosol of the sample after ablation is delivered to the mass spectrometry analysis device 22 via the carrier gas.

[0043] like Figure 2 As shown, the multimode analysis sample cell 21 of this embodiment includes an upper cover 21a, a sidewall shell 21b, and a lower cover 21c. The upper cover 21a and lower cover 21c are each provided with a double-sided coated high-transparency quartz glass window, allowing laser light to pass through. Sealing rings are provided between the upper cover 21a and the sidewall shell 21b, and between the lower cover 21c and the sidewall shell 21b, to form a sealed connection during laser ablation analysis. Since the upper cover 21a may affect the simultaneity and confocal performance of different wavelengths of laser light reaching the sample in the combined beam during CARS analysis, the upper cover 21a and the sidewall shell 21b are designed as a rotatable opening connection. During CARS analysis, rotating the upper cover 21a opens the sample, allowing the combined beam of the pump light and Stokes light to directly irradiate the sample without passing through the upper cover 21a. During laser ablation analysis, rotating the upper cover 21a closes the sample, forming a sealed structure for the entire sample cell. The sidewall housing 21b can be made of PEEK or stainless steel. One side of the sidewall housing 21b has an air inlet 21d for receiving carrier gas; the other side of the sidewall housing 21b has an air outlet 21e, which is connected to the gas path of the mass spectrometer 22.

[0044] The mass spectrometry analysis device 22 in this embodiment is a mass spectrometer based on inductively coupled plasma (ICP) technology. It uses a high-temperature plasma maintained by a radio frequency generator and a double-cone interface design to reduce matrix effects. The quadrupole mass analyzer is equipped with collision reaction cell (CRC) technology to eliminate polyatomic ion interference. The detector uses dual-channel acquisition in pulse counting and analog modes, which can achieve full elemental coverage from Li to U, with detection limits down to the ppb or ppt level. After collecting the signals acquired by the mass spectrometry analysis device 22, the computer control system 5 can resolve the continuous ion current into a single pulse signal through time-resolved analysis (TRA) mode, and finally reconstruct the elemental distribution spectrum corresponding to the CARS image space.

[0045] The three-dimensional moving stage 3 is positioned on the optical path from the fusion optical path module 1 to the CARS signal acquisition system 4, and has nanometer-level moving accuracy, i.e., position resolution less than 10 nm. A hollow sample cell mounting section is located at the center of the three-dimensional moving stage 3 for fixing the multimode analysis sample cell 21. When performing CARS analysis or laser ablation mass spectrometry analysis independently, the multimode analysis sample cell 21 can be removed and replaced with the corresponding CARS sample cell or laser ablation cell. Since the size of the selected analytical task area of ​​the sample may exceed the scanning range of the galvanometer 15, the computer control system 5 has coordinate linkage for the orientation control of the three-dimensional moving stage 3, the galvanometer 15, and the objective lens 16. Through the cooperation of the three-dimensional moving stage 3, the galvanometer 15, and the objective lens 16, a large-scale three-dimensional high-speed scan is achieved. For example, if the analytical task area is divided into several sub-regions, each sub-region being within the scanning range of the galvanometer 15, then the galvanometer 15 and objective lens 16 are used for high-speed scanning and focusing within the sub-region. Then, the three-dimensional moving stage 3 performs high-precision three-dimensional movement to switch to the next sub-region. When performing multimodal analysis using CARS-LA-ICP-MS, a large-scale CARS imaging can be used as a guide. Image recognition processing methods can be used to identify key analytical areas, such as tumor areas in tissue sections or defect areas in material sections. Then, local laser ablation mass spectrometry analysis is performed on these key analytical areas. Local analysis, compared to comprehensive laser ablation mass spectrometry imaging of the entire analytical task area, can shorten analysis time and improve analysis efficiency.

[0046] The computer control system 5 is connected to the fusion optical path module 1, the mass spectrometry analysis gas path module 2, the three-dimensional moving stage 3, and the CARS signal acquisition system 4. The computer control system 5 includes a computer used to control the operation of each module and collect and integrate the data signals acquired by the mass spectrometry analysis device 22 and the CARS signal acquisition system 4. In order to ensure the timing synchronization of each part of the system during operation, the computer control system 5 in this embodiment is also equipped with a timing synchronization control module with FPGA as the control core. The FPGA generates multiple programmable timing signals through a 100 MHz reference clock to drive the positioning of the galvanometer 15, the switching of the laser source 10, the gating of the photomultiplier tube 42, and the signal acquisition of the mass spectrometry analysis device 22, respectively. The galvanometer 15 monitors the deflection angle in real time through a position comparator, triggers the ablation laser when the scanning trajectory reaches the preset coordinates, and eliminates the equipment response difference through nanosecond-level delay compensation (accuracy ±2 ns) to ensure that the spatial registration error between the CARS imaging pixels and the LA-ICP-MS ablation pits is small. At the same time, it supports real-time feedback mode to dynamically adjust the ablation parameters according to the CARS signal intensity.

[0047] Based on the above system, the analysis method of CARS-LA-ICP-MS combined in this embodiment includes the following steps:

[0048] S1: Initialization settings: Turn on the device power and start the laser source 10; place the sample to be tested in the multimode analysis sample cell 21, and then install and fix it in the center of the three-dimensional moving stage 3, with the upper cover 21a of the multimode analysis sample cell 21 in the open state; select the sample scanning area through the camera, set the scanning task and related working parameters; set the output mode of the laser source 10 to the fundamental frequency light output mode;

[0049] S2: CARS Analysis: Laser source 10 outputs a fundamental frequency light of 1030 nm, which is used by optical parametric amplifier 11 to generate pump light and Stokes light according to instructions. The output wavelengths of the two beams are adjustable preset values. After the two beams are combined, the energy is adjusted, the beam is expanded and shaped, and then focused on the sample to be tested. Through the linkage of three-dimensional moving stage 3, galvanometer 15 and objective lens 16, the combined beam is used to perform three-dimensional high-speed scanning of the sample to be tested, generating CARS analysis signals, including CARS spectral signals and CARS imaging signals. The CARS analysis signals are then transmitted to computer control system 5.

[0050] S3: Image Recognition: The computer control system 5 intelligently recognizes the CARS imaging signal and generates key analysis areas, such as tumor areas, material defect areas, etc. When performing comprehensive mass spectrometry imaging analysis on the scanned area, the key analysis area can also be simply set to the entire area of ​​the sample scanned area in step S1. The specific method of image recognition can be set by those skilled in the art according to actual needs and with reference to existing relevant technical documents, and will not be elaborated here.

[0051] S4: Mass spectrometry analysis task parameter settings: Manually or automatically select the laser ablation area according to the key analysis area and set the corresponding working parameters so that the laser ablation area covers each key analysis area; adjust the laser source 10 to the frequency doubling light output mode and output the ablation laser; rotate the top cover 21a to the closed and sealed state; In a preferred embodiment, the CARS signal intensity is affected by factors such as the absorbance of the medium in the sample micro-region, so the relevant working parameters of the ablation laser can be dynamically adjusted according to the CARS signal intensity. For example, in areas with low CARS signal intensity, the ablation laser power is adjusted to a higher value.

[0052] S5: Laser ablation mass spectrometry analysis: After energy adjustment, beam expansion and shaping, the ablation laser is focused on the surface of the sample to be tested, causing the sample to be ablated to form an aerosol. The aerosol formed by the sample is efficiently transported to the mass spectrometry analysis device 22 through the gas path for analysis and detection. Through the linkage of the three-dimensional moving stage 3, galvanometer 15 and objective lens 16, the ablation laser achieves three-dimensional high-speed scanning of the sample to be tested, generating a mass spectrometry analysis signal.

[0053] S6: Data Synthesis: The computer control system 5 collects CARS analysis signals and mass spectrometry analysis signals, processes the data through the data fusion processing module, and finally generates a comprehensive spectrum with spatial information that simultaneously contains chemical structure and elemental composition.

[0054] In this embodiment, when the computer control system 5 collects and integrates the data signals acquired by the mass spectrometry analysis device 22 and the CARS signal acquisition system 4, it can perform affine transformation registration of the CARS image and the LA-ICP-MS elemental map based on the SIFT (Scale-Invariant Feature Transform) feature point matching image processing algorithm. Principal component analysis (PCA) and hierarchical clustering are used to explore the intrinsic correlation between molecular vibrational spectra and elemental content. A multimodal visualization engine is developed to achieve the overlay display and three-dimensional reconstruction of chemical molecule-element data. It supports the automatic generation of a comprehensive analysis report containing spectral features, elements, element ratios, and correlation coefficients by arbitrarily defining regions of interest (ROIs) in the fused image, ultimately establishing a multivariate database of "molecular structure-elemental distribution-spatial location." Those skilled in the art can also use other commonly used data analysis methods to match and integrate the data from the CARS image and the LA-ICP-MS elemental map to establish a multimodal fused spectral database.

[0055] When performing CARS analysis or laser ablation mass spectrometry analysis alone, the multimode analysis sample cell 21 can still be used, or a corresponding single-purpose sample cell can be used, which is installed in the center of the three-dimensional moving stage 3 and the corresponding analysis task can be performed.

[0056] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A multi-modal analytical system for CARS-LA-ICP-MS, characterized in that, The system comprises a fusion optical path module, a mass spectrometry gas path module, a three-dimensional moving stage, a CARS signal acquisition system and a computer control system. The fusion optical path module comprises a laser source, a CARS laser modulation module and a common optical path module. The laser source is provided with a fundamental frequency light output mode and a frequency-doubled light output mode; in the fundamental frequency light output mode, the laser source sends fundamental frequency light to the CARS laser modulation module, the CARS laser modulation module converts the fundamental frequency light into combined light of pump light and Stokes light, and then sends the combined light to the common optical path module through a second dichroic mirror; in the frequency-doubled light output mode, the laser source sends ablation laser to the common optical path module through the second dichroic mirror; the optical path of the common optical path module passes through the setting position of the sample to be measured from above and enters the CARS signal acquisition system. The mass spectrometry gas path module comprises a carrier gas supply device, a multi-mode analysis sample cell and a mass spectrometry device; the carrier gas supply device, the multi-mode analysis sample cell and the mass spectrometry device are sequentially connected in gas path. The three-dimensional moving stage is provided with a mounting part with a hollow structure, and the multi-mode analysis sample cell is fixedly installed on the mounting part, and the multi-mode analysis sample cell is used for setting the sample to be measured; the multi-mode analysis sample cell comprises an upper cover, a lower cover and a side wall shell; the upper cover and the lower cover are respectively provided with window pieces, the lower cover and the side wall shell are sealingly connected, and the upper cover and the side wall shell are sealingly connected in a rotatable open cover mode; the upper cover is rotated to an open state during CARS analysis, and is rotated to a closed sealing state during laser ablation mass spectrometry analysis. The CARS laser modulation module comprises an optical parametric amplifier and an optical pulse time delay system; the optical parametric amplifier converts the fundamental frequency light into pump light and Stokes light with different wavelengths, and the pump light and the Stokes light form combined light through a first dichroic mirror; the optical pulse time delay system is used for adjusting the time delay between the pulse signals of the pump light and the pulse signals of the Stokes light. The common optical path module comprises a beam adjustment system, a galvanometer and a moving objective lens; the beam adjustment system, the galvanometer and the moving objective lens are sequentially arranged on the optical path of the common optical path module, the galvanometer is used for quickly adjusting the focusing position of the laser in the horizontal direction, and the moving objective lens is used for quickly adjusting the focusing position of the laser in the vertical direction. The fusion optical path module further comprises a camera, the camera is used for observing the sample to be measured, and the setting optical path of the camera is merged into the optical path of the common optical path module between the galvanometer and the moving objective lens through a third dichroic mirror.

2. The multi-modal analysis system of claim 1, wherein, The CARS signal acquisition system comprises a condenser lens, a beam splitter, a photomultiplier tube, an amplifier, an acquisition card and a spectrometer; the condenser lens and the beam splitter are connected in optical path; the beam splitter is connected in optical path with the photomultiplier tube and the spectrometer respectively, the photomultiplier tube, the amplifier and the acquisition card are sequentially connected in signal; the amplifier comprises one of a transimpedance amplifier or a lock-in amplifier; the CARS analysis signal comprises a CARS spectral signal and a CARS imaging signal, the spectrometer is used for generating the CARS spectral signal, and the photomultiplier tube, the amplifier and the acquisition card are used for generating the CARS imaging signal.

3. The multi-modal analysis system of claim 1, wherein, The light beam adjusting system comprises an attenuator, a beam expander and a beam shaper.

4. The multi-modal analysis system of claim 1, wherein, The galvanometer, the moving objective lens and the three-dimensional moving stage are connected through a coordinate linkage control mode to adjust the focusing position of the laser relative to the sample to be measured.

5. The multi-modal analysis system of claim 1, wherein, The computer control system is connected with the fusion light path module, the mass spectrum analysis gas path module, the three-dimensional moving stage and the CARS signal acquisition system, respectively, and is used for controlling the multi-mode analysis system, collecting CARS analysis signals and mass spectrum analysis signals, and performing data integration processing on the CARS analysis signals and the mass spectrum analysis signals.

6. The multi-modal analysis system of claim 1, wherein, The wavelength of the fundamental light is 1030 nm, and the wavelength of the frequency-doubled light is not higher than 343 nm.

7. An analytical method of CARS-LA-ICP-MS combination, characterized in that, The multi-mode analysis system is used for analysis; The analysis method comprises initialization setting, CARS analysis, mass spectrum analysis task parameter setting, laser ablation mass spectrum analysis and data synthesis. In the initialization setting, the laser source is set to the fundamental light output mode, and the upper cover of the multi-mode analysis sample pool is rotated to the open state; in the mass spectrum analysis task parameter setting, the laser source is set to the frequency-doubled light output mode, and the upper cover of the multi-mode analysis sample pool is rotated to the closed and sealed state.

8. The analysis method according to claim 7, characterized in that, After the CARS analysis, the key analysis region is obtained by image recognition of the data obtained by the CARS analysis; in the mass spectrum analysis task parameter setting, the region to be ablated by the laser is selected according to the key analysis region.

9. The analysis method according to claim 7, characterized in that, In the data synthesis, a feature point matching image processing algorithm based on scale invariant feature transformation is used to perform affine transformation registration on the CARS analysis signals and the mass spectrum analysis signals, and principal component analysis is used to obtain the correlation of the CARS analysis signals and the mass spectrum analysis signals.

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