Miniaturized laser differential confocal Raman-LIBS microscopic imaging method and device

Abstract

The invention discloses a miniaturized laser differential confocal Raman-LIBS (laser-induced breakdown spectroscopy) microscopic imaging method and device, and belongs to the technical field of microscopic spectral imaging. The device comprises a double-laser light source system for generating excitation light beams, an optical filter for separating spectral signals, a double-two-dimensional galvanometer light beam scanning system, a microscope objective, an axial scanning system, a differential confocal microscopic detection system, a mixed spectrum detection system and a computer control and display system. A double-two-dimensional micromirror scanning technology and a differential confocal microscopy technology are combined to carry out three-dimensional scanning on a sample, so that high-spatial-resolution detection of the geometrical morphology of the sample is realized; a same-light-path continuous laser and a pulse laser are respectively used as excitation light sources of Raman spectrum and laser-induced breakdown spectrum, and detection is carried out at a focal point on the surface of a sample, so that high-precision spectral information detection on the surface of the sample is realized. The sensor has the advantages of high sensitivity, multiple information, miniaturization, simple structure, wide applicability and the like, and is particularly suitable for the fields of environmental science, biomedicine, geological exploration and the like.

Description

Technical Field

[0001] This invention relates to a miniaturized laser differential confocal Raman-LIBS microscopy imaging method and device based on dual two-dimensional galvanometer scanning, belonging to the field of microscopic spectral imaging technology. Background Technology

[0002] Laser differential confocal Raman-LIBS microscopy combines three analytical techniques: reflected light / Rayleigh scattering spectroscopy, Raman spectroscopy, and laser-induced breakdown spectroscopy. Reflected light / Rayleigh spectroscopy acquires three-dimensional morphological information of the sample by measuring the intensity of reflected and Rayleigh light from the sample surface. Raman spectroscopy obtains information about molecular vibrations, crystal structure, and chemical bonds by measuring the frequency shift of scattered light from the sample. Laser-induced breakdown spectroscopy obtains information about elemental composition and concentration by heating the sample with laser pulses to create plasma. By combining reflected light / Rayleigh spectroscopy, Raman spectroscopy, and laser-induced breakdown spectroscopy, the geometric morphology, molecular structure characteristics, and elemental composition information of the sample can be obtained simultaneously, thus revealing the complex morphology and component distribution of materials. Laser differential confocal Raman-LIBS microscopy can obtain more comprehensive and accurate information in chemical analysis and has been widely applied in fields such as biomedicine, physical chemistry, materials science, environmental monitoring, food safety, drug testing, and forensic investigation.

[0003] The principle of a traditional confocal Raman-LIBS detection system is shown in the attached figure. Figure 1 As shown, the laser λ emitted from the continuous laser source C After passing through an optical system, the light is focused onto the sample surface, exciting Raman scattered light carrying information about the vibrational activity of the sample molecules. The Raman spectral signal returns along the original optical path, is filtered by a filter, and is collected by a Raman spectrometer located behind a Raman confocal pinhole. The pulsed laser source emits a laser λ... P The sample is excited by the same optical path, causing it to generate plasma and emit laser-induced breakdown spectral signals. These spectral signals are collected and detected by a LIBS spectrometer located behind a pinhole after passing through a filter. By driving a three-dimensional translation stage to move the sample under test, dual-spectral signals from different regions of the sample can be detected.

[0004] Traditional confocal Raman-LIBS detection systems suffer from the following drawbacks: To improve the signal-to-noise ratio of spectral detection, large-sized pinholes or large-core optical fibers are typically used for stray light filtering, leading to a decrease in axial resolution and spatial resolution. Furthermore, traditional dual-spectral detection systems can only detect the spectral signal of the sample and cannot acquire information about the sample surface morphology. Moreover, the use of a three-dimensional mechanical displacement stage for sample movement results in a large system size, hindering miniaturization design. These shortcomings limit the application areas and scenarios of traditional dual-spectral detection technology, restricting its further development.

[0005] To achieve miniaturization of dual-spectral detection systems, galvanometer-based beam scanning modes are widely adopted. However, galvanometer scanning systems require scanning lenses and tube mirrors to ensure the conjugate relationship between the galvanometer and the objective lens's back pupil. However, the pulsed laser beam λ... P The laser beam will converge between the scanning lens and the tube lens, causing air breakdown, which leads to energy loss of the pulsed laser and interference with the laser-induced breakdown spectral signal. Moreover, the introduction of the lens increases the spectral color difference, which is not conducive to the effective detection of the spectral signal.

[0006] In summary, existing laser-induced breakdown-Raman spectroscopy detection methods have many limitations, and how to achieve miniaturized Raman-LIBS spectroscopy detection using a simple and effective method is currently a research challenge. Summary of the Invention

[0007] To overcome the shortcomings of existing technologies, the purpose of this invention is to provide a miniaturized laser differential confocal Raman-LIBS microscopy imaging method and device, achieving in-situ spectral and multi-spectral fusion imaging with miniaturization, high spatial resolution, and high stability. This invention has significant value in fields such as deep space exploration, geological exploration, materials science, and biomedicine.

[0008] The objective of this invention is achieved through the following technical solutions.

[0009] This invention discloses a miniaturized laser differential confocal Raman-LIBS microscopy imaging method that combines differential confocal microscopy, dual-spectral detection, and dual two-dimensional galvanometer scanning techniques to achieve system miniaturization, high spatial resolution, and high stability. By continuously irradiating the sample with a laser, the reflected light is transmitted to the differential confocal microscopy detection system to measure the sample's three-dimensional morphology and perform high-precision real-time focusing, achieving highly stable three-dimensional imaging during the imaging process. The Raman scattered light generated at the sample's focal point is detected, and after Raman spectroscopy detection, a pulsed laser is used to in-situ excite the laser-induced breakdown spectral signal for further detection, achieving efficient in-situ detection at the focal point of the dual-spectral signal. The use of dual two-dimensional galvanometers in conjunction with scanning reduces the size of the scanning system and significantly suppresses the air breakdown effect caused by traditional telecentric scanning systems, achieving both high-performance imaging and miniaturization.

[0010] When only the reflected light at the sample is detected, laser differential confocal microscopy combined with dual two-dimensional galvanometer scanning technology can achieve rapid two-dimensional scanning of the sample, thereby obtaining high spatial resolution three-dimensional topography detection of the sample.

[0011] When only the Raman spectral signal of the sample is detected, differential confocal microscopy can quickly and accurately fix the focus in real time, thereby rapidly obtaining high spatial resolution Raman spectral detection of the sample.

[0012] When only the laser-induced breakdown spectral signal of the sample is detected, the pulsed laser achieves the smallest volume ablation crater at the focal point, thereby obtaining high spatial resolution laser-induced breakdown spectral detection.

[0013] When simultaneously detecting the three-dimensional morphology and multispectral information of a sample, the system can acquire complementary information of complex morphological samples in situ, accurately and stably, and realize rapid in-situ multispectral imaging detection of high spatial resolution micro-area of ​​the sample under test.

[0014] The miniaturized laser differential confocal Raman-LIBS microscopy imaging method disclosed in this invention includes the following steps:

[0015] Step 1: The continuous laser emitted by the continuous laser of the dual laser source system passes through the converging objective, the spatial light filter pinhole, and the beam expansion by the converging objective. Then, it is reflected by the beam splitter and the dichroic mirror to the two-dimensional galvanometer beam scanning system. The beam is then focused by the measuring objective onto the surface of the sample being measured, exciting Raman scattered light and reflected light.

[0016] Step 2: The signal light is collected by the measuring objective lens, and after passing through the two-dimensional galvanometer beam scanning system, it is separated by a dichroic mirror. The reflected light passes through the dichroic mirror, the beam splitter, and enters the back focal detection system and the front focal detection system. The Raman scattered light passes through the dichroic mirror and enters the laser-induced breakdown-Raman dual-spectrum measurement system.

[0017] Step 3: The pulsed laser emitted by the pulsed laser source in the dual laser source system passes through a folding mirror and a beam splitter, is reflected by a dichroic mirror and a two-dimensional galvanometer beam scanning system, and is focused by the measuring objective onto the sample to generate a laser-induced breakdown spectrum. After being collected by the measuring objective, the signal light passes sequentially through the galvanometer beam scanning system and the dichroic mirror before entering the laser-induced breakdown-Raman dual-spectrum detection system.

[0018] Furthermore, the reflected light entering the front focal detection system is focused by the first converging lens to the front focal collection pinhole located behind the focal point of the first converging lens, and is finally received by photodetector one behind the front focal collection pinhole. The reflected light entering the rear focal detection system is focused by the second converging lens to the rear focal collection pinhole located at the focal point of the first converging lens, and is finally received by photodetector two behind the rear focal collection pinhole. When the two-dimensional galvanometer beam scanning system is in a stationary state, and the axial scanning system drives the measuring objective lens to scan along the axial direction, photodetector one and photodetector two obtain the front focal axial light intensity response curve and the rear focal axial light intensity response curve, respectively. Subtracting the two yields the differential confocal axial light intensity response curve. Utilizing the strict correspondence between the zero-crossing point and the focal point of the differential confocal axial light intensity response curve, the position detection and high-precision focusing of the sample are achieved.

[0019] Furthermore, the Raman scattered light and laser-induced breakdown spectrum reaching the laser-induced breakdown-Raman dual-spectrum detection system are coupled to the fiber optic collection interface by the third converging lens, and transmitted by the fiber optic to the laser-induced breakdown-Raman dual-spectrum detector for receiving, to detect the sample Raman spectrum and laser-induced breakdown spectrum, and to obtain the sample Raman spectrum detection characteristic spectral lines and laser-induced breakdown spectrum detection characteristic spectral lines.

[0020] Furthermore, the two-dimensional galvanometer beam scanning system controls two-dimensional galvanometer one to swing using the voltage waveform of two-dimensional galvanometer one and two-dimensional galvanometer two to swing using the voltage waveform of two-dimensional galvanometer two, thereby controlling the measurement beam to perform a "grating-like" scan on the surface of the sample under test. At the same time, it is equipped with a laser-induced breakdown-Raman dual-spectrum detector to obtain the laser-induced breakdown spectrum delay time sequence diagram, thereby achieving a miniaturized design and high-precision detection of the position information, Raman spectrum information, and laser-induced breakdown spectrum information of various points on the sample surface.

[0021] Furthermore, the lateral rapid scanning of the beam is achieved by controlling the tilting of two two-dimensional galvanometers through a two-dimensional galvanometer beam scanning system, and the relationship between the tilting angle of the two-dimensional galvanometers and the beam scanning angle is described.

[0022] Furthermore, by using a dual laser source system to couple continuous laser and pulsed laser in the same optical path, Raman spectroscopy and laser-induced breakdown spectroscopy excitation can be achieved with high stability and high resolution excitation detection in the same optical path and focus.

[0023] Furthermore, the laser-induced breakdown spectrum and Raman spectrum are time-division multiplexed and detected using a laser-induced breakdown-Raman dual-spectrum detection system. The spectral signal is coupled to the fiber optic collection interface through a third converging lens and transmitted by fiber optic to the laser-induced breakdown-Raman dual-spectrum detector for receiving. The Raman spectrum and laser-induced breakdown spectrum of the sample are detected to obtain the sample Raman spectrum detection characteristic spectral lines and laser-induced breakdown spectrum detection characteristic spectral lines.

[0024] Furthermore, by integrating the high-precision geometric morphology obtained by the differential confocal probe optical path, the high spatial resolution Raman spectral information obtained by the confocal Raman probe optical path, and the high spatial laser-induced breakdown spectral information, high spatial resolution "image-spectrum integration and multi-spectrum integration" imaging of the sample is achieved.

[0025] This invention discloses a miniaturized laser differential confocal Raman-LIBS microscopy imaging device for implementing the aforementioned miniaturized laser differential confocal Raman-LIBS microscopy imaging method. The miniaturized laser differential confocal Raman-LIBS microscopy imaging device disclosed in this invention includes a dual laser source system, a beam splitter, a dichroic mirror, a two-dimensional galvanometer beam scanning system, a measuring objective, an axial scanning system, a sample under test, a stage, and a beam splitter II. It also includes a laser-induced breakdown-Raman dual-spectrum detection system, a front focal detection system, a rear focal detection system, and a computer control and display system.

[0026] The dual laser source system includes a continuous laser, a converging objective, a spatial filter pinhole, a pulsed laser, a folding mirror, and a beam splitter. The converging objective, spatial filter pinhole, and beam splitter are used to expand the Raman excitation beam generated by the continuous laser to the same diameter as the pulsed laser beam. The folding mirror and beam splitter are used to combine the LIBS excitation beam generated by the pulsed laser into a single optical path.

[0027] The dual two-dimensional galvanometer beam scanning system consists of two-dimensional galvanometer one and two-dimensional galvanometer two, and is used to perform two-dimensional transverse scanning of the beam.

[0028] The laser-induced breakdown-Raman dual-spectrum detection system includes a third converging mirror, an optical fiber collection interface, an optical fiber, and a laser-induced breakdown-Raman dual-spectrum detector, used for time-division detection of laser-induced breakdown-Raman dual spectra.

[0029] The front focus detection system includes a first converging lens, a front focus collection pinhole, and a photodetector. The rear focus detection system includes a second converging lens, a rear focus collection pinhole, and a photodetector. The front and rear focus detection systems are used for microscopic topography measurement and high-precision axial focusing.

[0030] The axial scanning system is connected to the measuring objective lens and is used to drive the objective lens to perform axial displacement.

[0031] The computer control and display system is connected to the dual laser source system, the two-dimensional galvanometer beam scanning system, the axial scanning system, the laser-induced breakdown-Raman dual-spectrum detection system, the front focal detection system, and the back focal detection system. It serves as the control center of the entire measurement device, used to adjust the output power of the excitation beam and the type of the emitted beam, control the scanning frequency, scanning angle, and scanning range of the two-dimensional galvanometer, the scanning speed, scanning step, and scanning range of the axial scanning system, and process and display the acquired reflected light / Rayleigh light and laser-induced breakdown-Raman dual spectra.

[0032] In the device of this invention, the dual laser source system couples continuous laser and pulsed laser, and uses time-division control to realize the excitation and detection of sample Raman spectrum and laser-induced breakdown spectrum signals.

[0033] In the device of this invention, the dual two-dimensional galvanometer beam scanning system consists of two two-dimensional MEMS galvanometers, which cooperate to achieve telecentric scanning of the measurement beam. The two-dimensional deflection angles of the two galvanometers, the distance between them, and the distance between them and the rear pupil of the objective lens all affect the scanning angle of the measurement beam.

[0034] In the device of the present invention, the hybrid spectral detection system can share a fiber optic spectrometer to detect Raman spectroscopy and laser-induced breakdown spectroscopy, and use a transmission fiber to transmit the spectral signal to the spectrometer for dual-spectral time-division detection.

[0035] Beneficial effects:

[0036] 1. The miniaturized laser differential confocal Raman-LIBS microscopic imaging method and device disclosed in this invention achieves telecentric scanning of high-energy pulse beams by scanning dual laser beams with two two-dimensional galvanometers, which greatly reduces the size of the optical system and improves the miniaturization and integration of the system.

[0037] 2. The miniaturized laser differential confocal Raman-LIBS microscopy imaging method and apparatus disclosed in this invention utilizes a second two-dimensional galvanometer to adjust the beam to ensure that the spot at the rear pupil of the objective lens remains stationary. This eliminates the need for heavy scanning lenses and tubes in traditional beam scanning systems, avoiding the problem of premature convergence of the pulsed laser between the two and breaking down the air. This greatly improves the excitation efficiency of the laser-induced breakdown spectrum and also avoids the spectral signal interference caused by air breakdown.

[0038] 3. The miniaturized laser differential confocal Raman-LIBS microscopy imaging method and device disclosed in this invention integrates high axial resolution laser differential confocal microscopy technology and laser-induced breakdown-Raman spectroscopy detection technology. It can utilize the characteristic that the zero-crossing point of the high axial resolution laser differential confocal axial response curve precisely corresponds to the focal point of the measuring objective lens to achieve precise focusing of the sample under test, and simultaneously acquire the geometric position and Raman spectral signal of the sample. At the same time, it utilizes the characteristic that the focal points of the pulsed laser and the continuous laser in this device coincide in the same optical path to acquire the laser-induced breakdown spectral signal of the sample in situ at the focal point, which greatly improves the performance of traditional laser-induced breakdown-Raman spectroscopy detection technology.

[0039] 4. The miniaturized laser differential confocal Raman-LIBS microscopy imaging method and device disclosed in this invention combines Rayleigh / reflected light, laser-induced breakdown spectrum, and Raman spectral signals to simultaneously measure geometric morphology, elemental composition, and molecular vibrational distribution information.

[0040] 5. The miniaturized laser differential confocal Raman-LIBS microscopy imaging method and device disclosed in this invention, while achieving the above-mentioned beneficial effects, has the advantages of wide applicability. The device is small in size, light in weight, highly integrated and simple in structure, and can be applied to field testing and laboratory settings. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of the traditional laser confocal Raman-LIBS spectral imaging method.

[0042] Figure 2 This is a schematic diagram of the miniaturized laser differential confocal Raman-LIBS microscopic imaging measurement method of the present invention, i.e., the abstract figure;

[0043] Figure 3 This is a schematic diagram of the miniaturized laser differential confocal Raman-LIBS microscopic imaging measurement method and device of the present invention, i.e., a diagram used in an embodiment;

[0044] Figure 4 This is a system timing control diagram according to an embodiment of the present invention;

[0045] Among them, 1-Dual laser source system, 2-Continuous laser, 3-Converging objective, 4-Spatial light filter pinhole, 5-Converging objective, 6-Pulsed laser, 7-Reflecting mirror, 8-Beam splitter, 9-Beam splitter one, 10-Dichroic mirror, 11-Dual two-dimensional galvanometer beam scanning system, 12-Two-dimensional galvanometer one, 13-Two-dimensional galvanometer two, 14-Microscopic objective, 15-Axial scanning system, 16-Sample under test, 17-Stage, 18-Beam splitter two, 19-Front focus detection system, 20-First converging objective, 21-Front focus collection pinhole, 22-Photodetector one, 23-Back focus detection system, 24-Second converging objective, 25-Back focus collection pinhole, 26-Photodetector two, 27-Laser-induced breakdown-Raman dual-spectrum detection system, 28-Third converging objective, 29-Fiber optic collection interface, 30 - Fiber optic cable, 31-Laser-induced breakdown-Raman dual-spectral detector, 32-Front focal axis light intensity response curve, 33-Front focal axis light intensity response curve, 34-Differential confocal axis light intensity response curve, 35-Laser-induced breakdown spectral detection characteristic lines, 36-Raman spectral detection characteristic lines, 37-Computer control and display system, 38-Beam splitter, 39-Raman spectral detection system, 40-Fourth converging mirror, 41-Raman spectral collection pinhole, 42-Raman spectral detector, 43-Laser-induced breakdown spectral detection system, 44-Fifth converging mirror, 45-Laser-induced breakdown spectral collection pinhole, 46-Laser-induced breakdown spectral detector, 47-Raster scanning grid diagram, 48-Two-dimensional galvanometer first control voltage, 49-Two-dimensional galvanometer second control voltage, 50-Laser-induced breakdown spectral delay time series diagram. Detailed Implementation

[0046] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0047] Example 1

[0048] This embodiment utilizes two two-dimensional galvanometers in conjunction with deflection to achieve two-dimensional scanning of pulsed and continuous lasers; combined with differential confocal microscopy imaging technology, it images the geometric morphology, elemental composition, and molecular structure distribution of the sample under test, achieving a high-precision, highly integrated, and miniaturized system design. (See attached image) Figure 2 This is a schematic diagram of the miniaturized laser differential confocal Raman-LIBS microscopy imaging method based on dual two-dimensional galvanometer scanning according to the present invention.

[0049] The miniaturized laser differential confocal Raman-LIBS microscopy imaging method disclosed in this embodiment is implemented through the following steps:

[0050] The continuous laser emitted by the continuous laser 2 of the dual laser source system 1 is expanded by the converging objective 3, the spatial light filter pinhole 4, and the converging objective 5. It is then reflected by the dichroic mirror 10 through beam splitters 8 and 9 to the two-dimensional galvanometer beam scanning system 11. The beam is then focused onto the surface of the sample 16 by the measuring objective 14, exciting Raman scattered light and reflected light carrying molecular vibration information. The Raman scattered light and reflected light are collected by the measuring objective 14 and separated by the dichroic mirror 10 after passing through the two-dimensional galvanometer beam scanning system 11. The reflected light passes through the dichroic mirror 10, beam splitters 9 and 18, and enters the back focus detection system 23 and the front focus detection system 19; the Raman scattered light passes through the dichroic mirror 10 and enters the laser-induced breakdown-Raman dual-spectrum measurement system 27. The pulsed laser 6 of the dual laser source system 1 emits pulsed laser light, which passes through the folding mirror 7 and the beam splitter 8, and is reflected by the dichroic mirror 10 and the two-dimensional galvanometer beam scanning system 11. The pulsed laser light is then focused onto the sample 16 under test by the measuring objective lens 14 to generate a laser-induced breakdown spectrum. After being collected by the measuring objective lens 14, the generated laser-induced breakdown spectrum passes sequentially through the galvanometer beam scanning system 11 and the dichroic mirror 10, and then enters the laser-induced breakdown-Raman dual-spectrum detection system 27.

[0051] The reflected light entering the front focal detection system 19 is focused by the first converging lens 20 onto the front focal collection pinhole 21 located at the focal point of the first converging lens 20, and is finally received by the photodetector 22 behind the front focal collection pinhole 21. Similarly, the reflected light entering the rear focal detection system 23 is focused by the second converging lens 24 onto the rear focal collection pinhole 25 located at the focal point of the first converging lens 24, and is finally received by the photodetector 26 behind the rear focal collection pinhole 25.

[0052] When the two-dimensional galvanometer beam scanning system is stationary, and the axial scanning system 15 drives the measuring objective lens 14 to scan along the axial direction, due to the presence of the front focal collection pinhole 21 and the rear focal pinhole 25, photodetector 1 22 and photodetector 26 respectively obtain the front focal axial light intensity response curve 32 and the rear focal axial light intensity response curve 33 of the sample 16 under test. Subtracting these two curves yields the differential confocal axial response curve 34. The zero-crossing point of the differential confocal axial response curve 34 highly corresponds to the focal point position of the sample, achieving sample position detection and high-precision focusing. Subsequently, Raman scattered light at the focal point is collected, and simultaneously, a high-energy pulsed laser is used for in-situ excitation and collection of the laser-induced breakdown spectrum.

[0053] The Raman scattered light and laser-induced breakdown spectrum arriving at the laser-induced breakdown-Raman dual-spectrum detection system 27 are coupled to the fiber optic collection interface 29 by the third converging lens 28, and transmitted by the fiber optic cable 30 to the laser-induced breakdown-Raman dual-spectrum detector 31 for receiving. This allows for the detection of the sample's Raman spectrum and laser-induced breakdown spectrum, yielding the sample's Raman spectral detection characteristic line 36 and laser-induced breakdown spectral detection characteristic line 35. By fusing the high-precision geometric topography information obtained from the differential confocal detection optical path with the high spatial resolution Raman and laser-induced breakdown spectral information obtained from the laser-induced breakdown-Raman dual-spectrum detection optical path, high spatial resolution "image-spectrum fusion, multi-spectrum fusion" imaging is achieved.

[0054] Specifically, the two-dimensional galvanometer beam scanning system 11 consists of a first two-dimensional galvanometer 12 and a second two-dimensional galvanometer 13. The two two-dimensional galvanometers work together to control the beam to reach the back pupil of the objective lens at different scanning angles, thus completing a two-dimensional scan of the sample surface. This enables a miniaturized design and high-precision detection of the positional information, Raman spectral information, and laser-induced breakdown spectral information of various points on the sample surface.

[0055] Specifically, the laser-induced breakdown-Raman dual-spectrum detection system 27 enables time-division multiplexing detection of Raman and laser-induced breakdown spectra, and uses optical fiber 30 to transmit the spectral signal generated by the sample to the laser-induced breakdown-Raman spectrometer 31. This achieves miniaturization and integration.

[0056] In particular, the present invention can rapidly achieve high spatial resolution three-dimensional morphology detection of a sample by using only the continuous laser 2 of the light source system 1 as the excitation source and only detecting the reflected light at the sample; when only the continuous laser 2 of the light source system 1 is used and only the Raman spectral signal of the sample is detected, high spatial resolution Raman spectral detection of the sample can be achieved; when the pulsed laser 2 of the light source system is used as the excitation source to detect the laser-induced breakdown spectral signal of the sample, high spatial resolution laser-induced breakdown spectral detection can be achieved.

[0057] Example 2

[0058] In this embodiment, the continuous laser 2 in the dual laser source is a 532nm semiconductor laser, the pulsed laser 6 is a 532nm nanosecond pulsed laser, the two two-dimensional galvanometers in the dual two-dimensional galvanometer beam scanning system 11 are both two-dimensional MEMS scanning mirrors, the dichroic mirror 10 is a notch filter, and the laser-induced breakdown-Raman dual-spectrum detector 27 is a miniaturized fiber optic spectrometer.

[0059] Appendix Figure 3 This is a schematic diagram of a miniaturized laser differential confocal Raman-LIBS microscopic imaging detection method and device according to an embodiment of the present invention. The specific detection process is shown below:

[0060] The laser emitted from the continuous laser 2 of the dual laser source system 1 is converged by the converging objective 3 and enters the spatial light filter pinhole 4. It is then collimated and expanded by the collimating lens 5 to generate a parallel excitation beam. The laser emitted from the pulsed laser 6 is reflected by the folding mirror 7 to the beam splitter 8, where it couples with the expanded continuous laser beam into the same optical path. First, the continuous laser excitation beam passes through the beam splitter 9 and is reflected by the Notch Filter 10 and the dual two-dimensional galvanometer beam scanning system 11. The beam is then focused onto the surface of the sample 16 by the measuring objective 14, exciting Raman scattered light and reflected / Rayleigh scattered light carrying the molecular vibrational information parameters of the sample 16. After Raman scattering detection, the pulsed laser 6 in the same optical path acts as the excitation source for laser-induced breakdown spectroscopy, generating a high-energy pulsed laser that in-situ excites the sample 16 to produce plasma at the focal point of the measuring objective 14.

[0061] The system controls the deflection of two two-dimensional MEMS galvanometers in the two-dimensional galvanometer scanning system 11 via a driving voltage, thereby obtaining scanning beams at different angles. Combined with an axial actuator, scanning the surface of the sample 16 yields a three-dimensional spectral distribution image of the region of interest. The functional relationship between the MEMS galvanometer deflection angle and the beam scanning angle is determined using geometric parameters.

[0062]

[0063] Where, α x α y These are the deflection angles of the scanning beam in the orthogonal X and Y directions, δ. x1 δ y1 δ x2 δ y2 d represents the deflection angles of the two two-dimensional galvanometers in the X and Y directions, respectively; d is the distance between the center points of the two two-dimensional galvanometers; and l is the distance between the center of the two-dimensional galvanometer 13 and the rear pupil of the measuring objective lens 14.

[0064] The galvanometer scanning system is controlled based on the above formula and the corresponding relationship between the galvanometer tilt angle and the driving voltage. (Appendix) Figure 4 The system's grid scanning process is demonstrated. In the grid scan diagram 47, a single dot represents a equidistant measurement site on the sample surface, and 16×5 black dots enclosed by rectangles represent the measurement sites. Arrows between the sites indicate the scanning order of the grid distribution. The scanning process is completed by providing control voltage waveform 48 to 2D galvanometer 12 and control voltage waveform 49 to 2D galvanometer 23. The scanning motion is divided into two directions: a fast axis and a slow axis. The slow axis rotates once for every one cycle of the fast axis scan. The return and outward strokes use symmetrical waveforms, allowing two scans to be completed in one cycle, thus improving the scanning speed.

[0065] Raman scattered light, laser-induced breakdown spectrum and reflected light / Rayli scattered light at various positions on the sample 16 are collected by the measuring objective lens 14 and split into two beams by the Notch Filter 10. One beam, reflected by the Notch Filter 10, reaches the confocal detection system 18, and the other beam passes through the Notch Filter 10 and enters the laser-induced breakdown-Raman dual-spectrum detection system 27.

[0066] The reflected light and Rayleigh scattered light entering the front focal detection system 19 are focused by the first converging lens 20 to the front focal collection pinhole 21 located behind the focal point of the first converging lens 20, and then received by photodetector 1 22. Similarly, the reflected light and Rayleigh scattered light reflected by the beam splitter 18 into the rear focal detection system 23 are focused by the second converging lens 24 to the rear focal collection pinhole 25 located in front of the focal point of the second converging lens 24, and then received by photodetector 26. Photodetector 1 22 and photodetector 26 transmit the output light intensity to the computer control and display system 37, and then subtract the acquired front focal axial light intensity response curve 32 and rear focal light intensity response curve 33 to obtain the differential axial light intensity response curve 34 of the sample, realizing the position detection and high-precision focusing of the sample. After that, the Raman scattered light at the focal position is collected. After the Raman spectrum acquisition is completed, the pulsed laser 6 and the dual-spectrum detector 31 complete the spectral acquisition according to the laser-induced breakdown spectrum timing 50. It achieves high-speed synchronization of two-dimensional scanning with dual galvanometers, light source, and spectrometer data acquisition.

[0067] Raman scattered light and laser-induced breakdown spectrum pass through Notch Filter 10 and reach the laser-induced breakdown-Raman dual-spectrum detection system 27. A third converging lens 28 is coupled to the fiber optic collection interface 29, and the light is transmitted via fiber optic 30 to the laser-induced breakdown-Raman dual-spectrum detector 31 for receiving. This system detects the sample's Raman and laser-induced breakdown spectra, obtaining the sample's Raman spectral detection characteristic lines 36 and 35, which are then transmitted to the computer control and display system 37, enabling sample Raman spectral detection and display. By fusing the high-precision geometric topography obtained from the differential confocal detection optical path with the high spatial resolution Raman spectral information and laser-induced breakdown spectral information obtained from the related confocal Raman optical path, high spatial resolution "image-spectrum fusion, multi-spectrum fusion" imaging is achieved.

[0068] The specific embodiments of the present invention have been described above with reference to the accompanying drawings. However, these descriptions should not be construed as limiting the scope of the present invention. The scope of protection of the present invention is defined by the appended claims. Any modifications made based on the claims of the present invention are within the scope of protection of the present invention.

Claims

1. A miniaturized laser differential confocal Raman-LIBS microscopic imaging method, characterized in that: It comprises the following steps: Step one, the continuous laser emitted by the continuous laser (2) of the double laser source system (1) is expanded by the converging objective lens (3), the spatial light filtering pinhole (4) and the converging objective lens (5), and then is reflected by the dichroic mirror (10) to the two-dimensional galvanometer beam scanning system (11) through the beam splitters (8) and (9), is converged to the surface of the measured sample (16) by the measuring objective lens (14), and excites the Raman scattering light and the reflected light; Step two, the signal light is collected by the measuring objective lens (14), is separated by the dichroic mirror (10) after the two-dimensional galvanometer beam scanning system (11), wherein the reflected light enters the front focal detection system (19) and the back focal detection system (23) through the dichroic mirror (10), the beam splitter (9) and (18); the Raman scattering light enters the laser-induced breakdown-Raman dual-spectrum detection system (27) through the dichroic mirror; Step three, the pulsed laser emitted by the pulsed laser (6) of the double laser source system (1) is reflected by the dichroic mirror (10) and the two-dimensional galvanometer beam scanning system (11) after passing through the fold mirror (7) and the beam splitter (8), is converged to the measured sample (16) by the measuring objective lens (14) to generate the laser-induced breakdown spectrum; the signal light is collected by the measuring objective lens (14), and then enters the laser-induced breakdown-Raman dual-spectrum detection system (27) in sequence through the galvanometer beam scanning system (11) and the dichroic mirror (10).

2. The method of claim 1, wherein: The reflected light entering the front focal detection system (19) is focused to the front focal collection pinhole (21) located after the focal point of the first converging lens (20) by the first converging lens (20), and is finally received by the photodetector one (22) after the front focal collection pinhole (21); the reflected light entering the back focal detection system (23) is focused to the back focal collection pinhole (25) located at the focal point of the first converging lens (24) by the second converging lens (24), and is finally received by the photodetector two (26) after the back focal collection pinhole (25); when the two-dimensional galvanometer beam scanning system (11) is in a static state and the axial scanning system (15) drives the measuring objective lens (14) to scan along the axial direction, the photodetector one (22) and the photodetector two (26) obtain the front focal axial light intensity response curve (32) and the back focal axial light intensity response curve (33) respectively, and the differential confocal axial light intensity response curve (34) is obtained by subtracting the two curves, and the position detection and high-precision focusing of the sample are realized by using the relationship that the zero-crossing point of the differential confocal axial light intensity response curve and the focal point strictly correspond.

3. The method of claim 1, wherein: The Raman scattering light and the laser-induced breakdown spectrum reaching the laser-induced breakdown-Raman dual-spectrum detection system (27) are coupled to the optical fiber collection interface (29) by the third converging lens (28), are transmitted to the laser-induced breakdown-Raman dual-spectrum detector (31) by the optical fiber (30), and the sample Raman spectrum and the laser-induced breakdown spectrum detection are performed to obtain the sample Raman spectrum detection characteristic spectrum (36) and the laser-induced breakdown spectrum detection characteristic spectrum (35) of the sample.

4. The method of claim 1, wherein: The two-dimensional galvanometer light beam scanning system (11) controls the two-dimensional galvanometer one (12) to deflect with the two-dimensional galvanometer one voltage waveform (48), and controls the two-dimensional galvanometer two (13) to deflect with the two-dimensional galvanometer two voltage waveform (49), controls the measurement light beam to perform "raster scanning" (47) on the surface of the measured sample (16), and meanwhile, the laser-induced breakdown-Raman dual-spectrum detector is used to realize the high-precision detection of the position information, the Raman spectrum information and the laser-induced breakdown spectrum information of each point on the sample surface.

5. The method of claim 1, wherein: The two-dimensional galvanometer light beam scanning system (11) controls the deflection of the two two-dimensional galvanometers to realize the transverse rapid scanning of the light beam, and describes the relationship between the deflection angle of the two-dimensional galvanometer and the scanning angle of the light beam.

6. The method of claim 1, wherein: The two laser light source system (1) is used for coupling the continuous laser and the pulsed laser in the same light path, so that the Raman spectrum and the laser-induced breakdown spectrum are excited in the same light path and the same focal point, and high-stability and high-resolution excitation detection is realized.

7. The method of claim 1, wherein: The laser-induced breakdown-Raman dual-spectrum detection system (27) is used for realizing the time-division multiplexing detection of the laser-induced breakdown spectrum and the Raman spectrum, the spectral signal is coupled to the optical fiber collection interface (29) through the third converging lens (28), is transmitted to the laser-induced breakdown-Raman dual-spectrum detector (31) by the optical fiber (30), and the sample Raman spectrum and the laser-induced breakdown spectrum are detected, so that the sample Raman spectrum detection characteristic spectrum (36) and the laser-induced breakdown spectrum detection characteristic spectrum (35) of the sample are obtained.

8. The method of claim 1, wherein: The high-precision geometric appearance obtained by the differential confocal detection light path and the high-spatial-resolution Raman spectrum information and high-spatial-resolution laser-induced breakdown spectrum information obtained by the confocal Raman detection light path are fused, so that the "graph and spectrum integration, multi-spectrum integration" imaging of the sample with high spatial resolution is realized.

9. Apparatus for implementing the method of any one of claims 1 to 8, characterized in that: The two laser light source system (1), the beam splitter (9), the dichroic mirror (10), the two-dimensional galvanometer light beam scanning system (11), the measurement objective lens (14), the axial scanning system (15), the measured sample (16), the object table (17) and the beam splitter two (18), the laser-induced breakdown-Raman dual-spectrum detection system (27), the front focal detection system (19), the rear focal detection system (23) and the computer control and display system (37) are included. The two laser light source system (1) includes a continuous laser (2), a converging objective lens (3), a spatial light filtering pinhole (4) and a converging objective lens (5), a pulsed laser (6), a return mirror (7) and a beam splitter (8); the converging objective lens (3), the spatial light filtering pinhole (4) and the converging objective lens (5) are used for expanding the Raman excitation light beam generated by the continuous laser (2) to the same diameter as the pulsed laser beam; the return mirror (7) and the beam splitter (8) are used for merging the LIBS excitation light beam generated by the pulsed laser (6) into the same light path; The two-dimensional galvanometer light beam scanning system (11) is composed of the two-dimensional galvanometer one (12) and the two-dimensional galvanometer two (13), and is used for performing two-dimensional transverse scanning of the light beam. The laser-induced breakdown-Raman dual-spectrum detection system (27) comprises a third converging lens (28), a fiber collection interface (29), a fiber (30) and a laser-induced breakdown-Raman dual-spectrum detector (31) for laser-induced breakdown-Raman dual-spectrum time-sharing detection; The front focal detection system (19) comprises a first converging lens (20), a front focal collection pinhole (21) and a photoelectric detector I (22), and the rear focal detection system (23) comprises a second converging lens (24), a rear focal collection pinhole (25) and a photoelectric detector II (26), the front focal detection system (19) and the rear focal detection system (23) are used for microscopic topography measurement and high-precision axial focusing; The axial scanning system (15) is connected with the measurement objective lens and is used for driving the objective lens to perform axial displacement; The computer control and display system (37) is connected with the dual-laser light source system (1), the two-dimensional galvanometer light beam scanning system (11), the axial scanning system (15), the laser-induced breakdown-Raman dual-spectrum detection system (27), the front focal detection system (19) and the rear focal detection system (23), is the control center of the whole measuring device, is used for adjusting the output power of the excitation light beam and the type of the outgoing light beam, controlling the scanning frequency, the scanning angle and the scanning range of the two-dimensional galvanometer, the scanning speed, the scanning step and the scanning range of the axial scanning system, and processing the collected reflected light / Rayleigh light and laser-induced breakdown-Raman dual-spectrum and displaying the results.

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