Microscopic confocal Raman spectrometer based on galvanometer positioning

Abstract

The invention discloses a microscopic confocal Raman spectrometer based on galvanometer positioning. The microscopic confocal Raman spectrometer comprises microscopic white light illumination, an excitation light source, a galvanometer scanning element, a Raman excitation and collection module, a spectrometer light splitting detection, a sample displacement table and a data acquisition software processing module. Wide excitation wavelength coverage is realized through beam combination of multi-wavelength narrow linewidth laser, and fluorescence interference is avoided. An electric switching optical filter is used, and low wave number detection (such as 50 wave number) is met. The galvanometer scanning element has high positioning resolution (such as 50nm), and can realize rapid scanning imaging or single-point spectrum acquisition. And the white light illumination module meets the sample observation requirement. The spectrometer adopts a high luminous flux design, combines a high-sensitivity detector and a wavelength calibration algorithm, and realizes weak signal detection capability and spectrum coverage range. And the data acquisition software processing module is used for acquiring, processing, analyzing and mechanically controlling the Raman signals. According to the application example disclosed by the invention, a good result shows the advantages of feasibility, expansibility and cost performance of the method.

Description

Technical Field

[0001] The present invention relates to the field of optical technology, in particular to a microscopic confocal Raman spectrometer based on galvanometer positioning. Background Art

[0002] Raman spectroscopy is a spectroscopic technique that studies materials based on the Raman scattering phenomenon. Its advantages include non-destructive analysis and fingerprinting, and it is widely used in biomedicine, energy materials, pharmaceuticals, online analysis, archaeology, murals, jade identification, drug detection, food safety, and many other fields. A Raman spectrometer is essential for obtaining Raman spectra. However, due to the relatively weak Raman scattering effect and narrow Raman spectral peaks, higher performance requirements are placed on the instrument. Currently, most commercially available scientific research-grade Raman spectrometers are imported and relatively expensive. Furthermore, with the expansion of Raman applications, new requirements are being placed on the equipment for sensitivity, portability, and price. There is an urgent need to develop highly sensitive Raman spectrometers that are cost-effective and expandable. To this end, the present invention combines narrow-linewidth excitation light sources of different wavelengths, enabling the use of multiple excitation wavelengths. This, combined with an electrically switched filter, enhances the instrument's versatility. Furthermore, a galvanometer scanning element with high-precision positioning resolution (e.g., 50 nm) enables rapid spot scanning or positioning, enabling single-point Raman spectroscopy, multi-particle positioning, and Raman chemical imaging. The optical path design employs low-wavenumber filters to ensure the low-wavenumber performance of the Raman instrument. The spectrometer's optical splitter module can be configured with high-precision grating rotation and wavelength calibration algorithms to broaden the wavelength coverage of the Raman spectrum. The spectrometer utilizes a high-throughput design to ensure excellent imaging quality. Combined with a highly sensitive detector, it meets the requirements for detecting weak Raman scattering signals, achieving a signal-to-noise ratio of better than 10:1 for the third-order peak spectrum of silicon wafers. White light microscopy illumination is also integrated to meet the requirements of sample observation. The data acquisition software processing module is responsible for Raman signal acquisition, processing, analysis, and mechanical control. Summary of the Invention

[0003] Beneficial effects of the present invention:

[0004] The present invention provides a microscopic confocal Raman spectrometer based on galvanometer positioning. By being equipped with a multi-wavelength laser, it can meet the testing requirements of different samples and has versatility. Combined with the white light microscopic illumination function, it can perform imaging observation on the sample to be tested. The use of a galvanometer scanning element has the advantages of high precision and cost-effectiveness, and can meet the functions of single-point Raman spectroscopy, multi-particle positioning spectroscopy and Raman chemical imaging. At the same time, the use of self-made software functions can integrate data reception, display and processing, and can set functions such as spectral exposure time, spectral type and mechanical control. The microscopic confocal Raman spectrometer developed according to the present invention has the advantages of high sensitivity, high cost-effectiveness and scalability, which is conducive to the promotion of Raman spectroscopy technology and is expected to promote the independent development of domestic high-performance Raman spectrometers.

[0005] The specific technical solutions adopted in the present invention are as follows:

[0006] A microscopic confocal Raman spectrometer based on galvanometer positioning includes: a white light microscopic illumination module, an excitation light source, a galvanometer scanning element, a Raman signal excitation and collection module, a spectrometer spectroscopic detection module, a sample displacement stage and a data acquisition software processing module.

[0007] The excitation light source adopts a narrow linewidth laser as the laser light source for Raman spectrum detection.

[0008] The excitation light source can be a single wavelength laser or a multi-wavelength beam combiner to meet the testing requirements of different samples, especially for samples with fluorescence background interference.

[0009] The white light microscopic illumination module is used for imaging and observing the test sample.

[0010] The white light microscopic imaging module includes an LED lighting source (13), a lens (14), a reflector (15), a semi-reflective and semi-transparent push-pull module (10), a microscope objective lens (11), and a CCD camera (16). The light beam emitted by the LED lighting source (13) passes through the lens (14), the reflector (15), the semi-reflective and semi-transparent push-pull module (10), and the microscope objective lens (11) and is incident on the sample to be tested on the XYZ displacement sample stage (12). The reflected light of the sample to be tested passes through the microscope objective lens (11) and the semi-reflective and semi-transparent module (10) in sequence and is incident on the CCD camera (16) device to perform white light microscopic imaging observation on the sample to be tested. When white light is illuminated, it is pushed into the light path to present the microscopic image of the sample on the CCD camera; and when laser sampling is performed, it is moved out of the light path to avoid loss of Raman signals.

[0011] The Raman signal excitation and collection module comprises a laser light source (1), an optical shutter (2), a power attenuator (3), a reflector (4), a filter (5), a galvanometer (6), a lens (7), and a lens (8). The laser light source (1) emits a laser beam which sequentially passes through the power attenuator (3), the reflector (4), the filter (5), the galvanometer (6), and the microscope objective lens (11) and is incident on a sample to be tested on an XYZ displacement sample stage (12), while the Raman scattering signal of the sample to be tested returns along the original path and sequentially passes through the microscope objective lens (11), the galvanometer (6), the filter (5), the reflector (17), and the lens (18) and converges to the slit (19) of the spectroscopic module.

[0012] The power attenuation turntable (3) is composed of a combination of attenuation sheets with different transmittances, a turntable and a stepping motor, and is used to adjust the laser power in the optical path. 12 levels of laser transmittance can be selected, ranging from 0.01% to 100%.

[0013] The optical shutter (2) is used to realize the on / off operation of the laser, thereby preventing the laser from damaging the sample due to long-term irradiation.

[0014] The optical filter (5) is combined with an electric switching device to meet the switching of optical filters corresponding to different laser wavelengths. The optical filter (5) has low wave number performance, high transmittance and high cut-off depth.

[0015] The scanning element of the galvanometer module includes a galvanometer (6), a lens (7), and a lens (8), and is used to control the rapid scanning or positioning of the laser spot on the sample, and can meet the functions of single-point Raman spectroscopy, multi-particle positioning spectroscopy, and Raman chemical imaging.

[0016] The spectroscopic module includes a slit (19), a lens (20), a reflector (21), a grating (22), and a lens (23). The incident light is sequentially split by the slit (19), the lens (20), the reflector (21), and the grating (22), and then converged into a spectrum detector (24) through the lens (23). The spectrometer spectroscopic detection module splits the incident Raman scattering signal through the grating, and the split light enters the detector. The grating is equipped with a high-precision electric rotating stage and combined with a wavelength calibration function to broaden the spectral measurement range of the detector. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the device structure of the present invention.

[0018] Figure 2 This is a specific application case of the present invention: neon lamp spectrum shows the resolution of Raman spectrometer

[0019] Figure 3 This is the specific application case 2 of the present invention: silicon wafer sample demonstrates the sensitivity of Raman spectrometer

[0020] Figure 4 This is the specific application case 3 of the present invention: measuring the Raman spectrum of graphene samples

[0021] Figure 5 This is the fourth specific application case of the present invention: rapid positioning, spectrum collection and identification of microplastic particles by galvanometer DETAILED DESCRIPTION

[0022] In order to better illustrate the purpose and advantages of the present invention, the invention is further described below with reference to the accompanying drawings and examples. The specific description described below further details the purpose, technical solutions and beneficial effects of the invention; it should be understood that the following description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention; any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the scope of protection of the present invention.

[0023] like Figure 1 As shown. The present embodiment discloses a structure of a microscopic confocal Raman spectrometer based on galvanometer positioning, in which the numbers are as follows: laser light source (1), optical shutter (2), power attenuator (3), reflector (4), filter (5), galvanometer (6), lens (7), lens (8), reflector (9), semi-reflective and semi-transparent push-pull module (10), microscope objective (11), XYZ translation stage (12), LED light (13), lens (14), reflector (15), CCD camera (16), reflector (17), lens (18), slit (19), lens (20), reflector (21), grating (22), lens (23), and spectrum detector (24).

[0024] The working method of a microscopic confocal Raman spectrometer based on galvanometer positioning disclosed in this embodiment is as follows:

[0025] First, push in the semi-reflective and semi-transparent push-pull module (10) and adjust the microscopic focus through the white light microscopic illumination module. By adjusting the XYZ displacement stage, the image of the sample focus is clear. According to the resolution and spectrum acquisition range, select the appropriate parameters of the spectrometer spectrometer system (such as slit, grating lines, readout rate, etc.). According to the detection requirements of the sample, select the appropriate wavelength excitation light source (1), and adjust the appropriate laser power in combination with the power attenuator (3). At this time, the corresponding laser passes through the reflector (4), filter (5), galvanometer (6), and microscope objective (15) in sequence and is incident on the sample to be tested on the XYZ displacement sample stage (16). If it is a single-point acquisition, adjust the XYZ displacement sample stage (16) or galvanometer (6) so that the sample to be tested is located under the laser spot and Raman spectrum acquisition can be performed. If Raman scanning chemical imaging is required, scanning can be performed by setting the area scanned by the galvanometer. If it is necessary to locate and collect spectra of specific microscopic particle samples, the particle coordinates can be recorded with the mouse, and the galvanometer can focus the light spot on each particle in turn to complete the automatic collection of Raman spectra, which can greatly improve the test efficiency.

[0026] Example 1

[0027] In this embodiment, a microscopic confocal Raman spectrometer based on galvanometer positioning of the present invention is used, with a grating line of 1200 g / mm and a spectrometer focal length of 100 mm, and its spectral resolution is tested in combination with a homemade neon lamp calibration light source. Figure 2 The spectral measurement results show that the spectrometer implemented according to the present invention has excellent spectral resolution (0.1 nm / pixel). In subsequent specific implementations, the spectral resolution and spectral coverage can be further adjusted by changing the focal length of the spectrometer.

[0028] Example 2

[0029] In this embodiment, a microscopic confocal Raman spectrometer based on galvanometer positioning of the present invention is used to test the Raman spectrum of a silicon wafer. Figure 3 The test results are shown in Figure 2. The test conditions employed a laser wavelength of 532nm, a laser power of 6mW, an exposure time of 1s (10s for the third-order peak), an integration time of 1, and a 100×NA=0.8 lens. It can be seen that the spectra of the first- and second-order peaks of the silicon wafer are clear, and the third-order peak signal of the silicon wafer is visible even at a low excitation power of 6mW and a short exposure time of 10s, demonstrating that the galvanometer-based confocal Raman spectrometer implemented in accordance with the present invention has excellent sensitivity.

[0030] Example 3

[0031] In this embodiment, a microscopic confocal Raman spectrometer based on galvanometer positioning of the present invention is used, and the sample is a thin layer of graphene. The test results are shown in FIG. Figure 4 The test conditions employed a laser wavelength of 532 nm, a laser power of 6 mW, an integration time of 8 seconds, an integration count of 1, and a 100×NA = 0.8 lens. The spectra show the Raman signal of the silicon wafer substrate and the Raman spectrum of the graphene sample, demonstrating that the galvanometer-based confocal Raman spectrometer implemented in accordance with the present invention can meet the testing requirements of a variety of samples.

[0032] Example 4

[0033] In this embodiment, a microscopic confocal Raman spectrometer based on galvanometer positioning of the present invention is used, and the sample is plastic particles. The test results are shown in FIG. Figure 5 . The test conditions are 633nm, power 3mW, integration time 3s, lens 50×NA=0.8. By obtaining the (x, y) coordinates of different microplastics in the microscope through the mouse and calculating and converting them into the control voltage (Vx, Vy) required to drive the galvanometer, it is possible to automatically realize the fixed-point spectrum acquisition of the light spot of all microplastic particles in the field of view, which can greatly improve the experimental efficiency of microplastic particle detection; combined with the deep learning algorithm, a large number of microplastic particles can be qualitatively and quantitatively analyzed for their chemical composition, realizing efficient digital detection of microplastic particles. Due to the fast scanning speed of the galvanometer, Raman chemical imaging tests can also be carried out, such as obtaining component distribution information on tablets.

Claims

1. A microscopic confocal Raman spectrometer based on galvanometer positioning, characterized in that: include: White light microscope illumination module, excitation light source, galvanometer scanning element, Raman signal excitation and collection module, spectrometer spectroscopic detection module, sample displacement stage and data acquisition software processing module.

2. The microscopic confocal Raman spectrometer based on galvanometer positioning according to claim 1, characterized in that: The excitation light source uses a narrow linewidth laser as the laser light source for Raman spectroscopy detection. The excitation light source can be a single wavelength laser or a multi-wavelength beam combination to meet the testing requirements of different samples, especially for samples with fluorescence background interference.

3. The microscopic confocal Raman spectrometer based on galvanometer positioning according to claim 1, characterized in that: The white light microscopic illumination module is used for imaging and observing the test sample.

4. The microscopic confocal Raman spectrometer based on galvanometer positioning according to claim 4, characterized in that: The white light microscopic imaging module includes an LED lighting source (13), a lens (14), a reflector (15), a semi-reflective and semi-transparent push-pull module (10), a microscope objective lens (11), and a CCD camera (16). The light beam emitted by the LED lighting source (13) passes through the lens (14), the reflector (15), the semi-reflective and semi-transparent push-pull module (10), and the microscope objective lens (11) and is incident on the sample to be tested on the XYZ displacement sample stage (12). The reflected light of the sample to be tested passes through the microscope objective lens (11) and the semi-reflective and semi-transparent module (10) in sequence and is incident on the CCD camera (16) device to perform white light microscopic imaging observation on the sample to be tested. When white light is illuminated, it is pushed into the light path to present the microscopic image of the sample on the CCD camera; and when laser sampling is performed, it is moved out of the light path to avoid loss of Raman signals.

5. The microscopic confocal Raman spectrometer based on galvanometer positioning according to claim 1, characterized in that: The Raman signal excitation and collection module comprises a laser light source (1), an optical shutter (2), a power attenuator (3), a reflector (4), a filter (5), a galvanometer (6), a lens (7), and a lens (8). The laser light source (1) emits a laser beam which sequentially passes through the power attenuator (3), the reflector (4), the filter (5), the galvanometer (6), and the microscope objective lens (11) and is incident on a sample to be tested on an XYZ displacement sample stage (12), while the Raman scattering signal of the sample to be tested returns along the original path and sequentially passes through the microscope objective lens (11), the galvanometer (6), the filter (5), the reflector (17), and the lens (18) and converges to the slit (19) of the spectroscopic module.

6. The Raman signal excitation and collection module according to claim 6, characterized in that: The power attenuation turntable (3) is composed of a combination of attenuation sheets with different transmittances, a turntable and a stepping motor, and is used to adjust the laser power in the optical path. 12 levels of laser transmittance can be selected, ranging from 0.01% to 100%.

7. The Raman signal excitation and collection module according to claim 6, characterized in that: The optical shutter (2) is used to realize the on / off operation of the laser, thereby preventing the laser from damaging the sample due to long-term irradiation.

8. The Raman signal excitation and collection module according to claim 6, characterized in that: The optical filter (5) is combined with an electric switching device to meet the switching of optical filters corresponding to different laser wavelengths. The optical filter (5) has low wave number performance, high transmittance and high cut-off depth.

9. The micro-Raman spectrometer based on galvanometer positioning according to claim 1, characterized in that: The scanning element of the galvanometer module comprises a galvanometer (6), a lens (7), and a lens (8). It is used to control the rapid scanning or positioning of the laser spot on the sample, and can meet the functions of single-point Raman spectroscopy, multi-particle positioning spectroscopy and Raman chemical imaging.

10. The portable micro-confocal Raman spectrometer based on galvanometer positioning according to claim 1, characterized in that: The spectroscopic module includes a slit (19), a lens (20), a reflector (21), a grating (22), and a lens (23). The incident light is sequentially split by the slit (19), the lens (20), the reflector (21), and the grating (22), and then converged into a spectrum detector (24) through the lens (23). The spectrometer spectroscopic detection module splits the incident Raman scattering signal through the grating, and the split light enters the detector. The grating is equipped with a high-precision electric rotating stage and combined with a wavelength calibration function to broaden the spectral measurement range of the detector.

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