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CN-122016761-A - Large-light-spot in-situ Raman detection device based on expansion matching

CN122016761ACN 122016761 ACN122016761 ACN 122016761ACN-122016761-A

Abstract

The invention discloses a large-light-spot in-situ Raman detection device based on expansion matching, which mainly comprises a laser light guide-in unit, a light beam collimation unit, a light beam splitting unit, a focusing objective lens and a signal collection unit, wherein the signal collection unit also comprises a signal filtering unit, a signal coupling lens and a shape conversion optical fiber assembly, and lasers with different wavelengths and spectrometers with different measuring ranges are in butt joint through a modularized interface to realize collimation, reflection splitting, light spot projection, diffuse emission focusing, filtering, conversion and the like of light beams. The invention starts from the angles of thermal damage resistance and high flux macroscopic sampling, generates flat-top large light spots through the excitation light paths matched with specific parameters, realizes the collection of the light paths and the expansion of the slit of the matched spectrometer by utilizing the cross section shape conversion fiber bundles, can realize the 'mild' excitation of the large light spots, prevent the sample burning, and can couple the 'lossless' scattered light with a large area into the slit of the spectrometer.

Inventors

  • ZHU MINGHUI
  • CAO LIANJIE
  • LI YUE

Assignees

  • 南通谱迅智能科技有限公司

Dates

Publication Date
20260512
Application Date
20260310

Claims (10)

  1. 1. A large-light-spot in-situ Raman detection device based on expansion matching is characterized by sequentially comprising the following components along the transmission direction of an optical path A laser light guiding unit composed of a laser interface and a transmission optical fiber, which generates an excitation light beam with a certain cross-sectional area; A beam collimation unit which collimates the excitation beam generated by the laser introduction unit; A beam splitting unit that performs reflection splitting on the collimated excitation beam; A focusing objective lens which collects and projects the light beam to the surface of the sample to form a macroscopic excitation light spot; And the signal collecting unit filters, collects and converts scattered light generated by the sample and enters the spectrometer.
  2. 2. The large-spot in-situ Raman detection device based on expansion matching of claim 1 is characterized in that the diameter of a spot projected to the surface of a sample is 50-200 μm; The transmission optical fiber is a multimode optical fiber with the core diameter more than or equal to 100 mu m; the NA numerical aperture of the focusing objective is >0.5.
  3. 3. The large-spot in-situ Raman detection device based on expansion matching of claim 2, wherein the high photon density is ensured and the thermal power density per unit area is reduced by matching the ratio of the core diameter of the transmission fiber, the focal length of the beam collimation unit and the focal length of the focusing objective lens.
  4. 4. The large-spot in-situ Raman detection device based on expansion matching of claim 1, wherein the signal collection unit comprises The signal filtering unit is a long-pass filter and used for filtering Rayleigh scattered light; The signal coupling lens is a focusing lens and focuses the filtered diffuse reflection light; a shape-changing optical fiber assembly that converts the focused transmitted light spot into a line shape.
  5. 5. The large-spot in-situ Raman detection device based on expansion matching of claim 4, wherein the shape-changing optical fiber assembly comprises a light incident end and a light emergent end, the light incident end of the shape-changing optical fiber assembly is formed by closely arranging a plurality of optical fibers into a round shape or a polygonal shape, and the light emergent end of the shape-changing optical fiber assembly rearranges the optical fibers into a linear array.
  6. 6. The large-spot in-situ Raman detection device based on expansion matching of claim 5, wherein the light incident end of the shape-changing optical fiber assembly is arranged at the focal plane of the signal coupling lens and used for receiving the converged scattered light, and the arrangement direction of the light emergent end of the shape-changing optical fiber assembly is parallel to the incident slit of the Ji Guangpu instrument and used for coupling and butt joint of the spectrometer.
  7. 7. The expansion matching-based large-spot in-situ Raman detection device according to claim 5, wherein the imaging size of the reflected light generated by the sample at the light incident end of the shape-changing optical fiber assembly is not larger than the effective receiving diameter of the light incident end by amplifying the magnification of the signal coupling lens.
  8. 8. The large-spot in-situ Raman detection device based on expansion matching of claim 6, wherein the total height of the optical fiber array at the light emitting end of the shape-changing optical fiber assembly is smaller than the effective photosensitive height of the spectrometer detector.
  9. 9. The large-spot in-situ Raman detection apparatus based on expansion matching of claim 1, further comprising a rotating optical wedge or dynamic scanning mechanism disposed in the collimating optical path for driving the excitation light spot to perform high-speed circumferential scanning on the sample surface to increase the effective sampling area and reduce the local heat accumulation.
  10. 10. The large-spot in-situ Raman detection device based on expansion matching of claim 1 is characterized in that the detection device is integrally packaged in a modularized mode to be connected with lasers with different wavelengths and spectrometers with different measuring ranges.

Description

Large-light-spot in-situ Raman detection device based on expansion matching Technical Field The invention relates to the technical field of spectrum detection, in particular to a large-light-spot in-situ Raman detection device based on expansion matching. Background The Raman spectrum technology refers to a fluorescence inhibition method by combining physics and mathematics, two light sources with known micro wavelength difference are used for respectively exciting a sample, corresponding original Raman spectra are acquired, and the baselines of the existing spectra are aligned through pretreatment steps such as normalization, reconstruction, baseline correction and the like. From the viewpoint of mathematical processing, the difference process can be regarded as convolution operation of the raman spectrum and the square wave function, and finally, the actual raman spectrum is reconstructed by deconvolution. When a sample is excited by two laser light sources with similar wavelengths, the spectrum shape of a fluorescence signal is not shifted along with the tiny change of the excitation wavelength, the position of a Raman characteristic peak is correspondingly shifted due to the change of the excitation wavelength, and the original spectrum obtained by the excitation of the two light sources is subjected to subtraction processing based on the physical characteristic, so that the fluorescence background interference can be effectively subtracted, and the high-quality differential Raman spectrum is obtained. The differential Raman spectrum can effectively resist interference of fluorescent background and ambient light, the characteristic of detection signal-to-noise ratio of Raman characteristic signals is obviously improved, when detection activities are carried out under complex field illumination conditions such as outdoor sunlight environment, detection targets are subjected to primary screening, interference peaks are filtered, pure Raman characteristic peaks are reserved, and on the premise of ensuring measurement accuracy, light source power can be greatly reduced, so that the reliability and spectral error correction capability of the system are improved. The Raman spectrum technology has the advantages of no need of special pretreatment, high efficiency, no damage, small water interference, sharp and clear spectrum peak, low detection limit, good reproducibility and wide application in the fields of material science, chemical catalysis and the like. Raman spectroscopy is a powerful tool for analyzing molecular structures of substances, and has obvious defects in the existing detection technology in the applications of in-situ characterization of catalysts, detection of dark powder and the like: 1. thermal damage problem Conventional micro raman spectrometers focus the laser light to a very small spot (typically 2 μm) in order to pursue spatial resolution. The extremely high Power Density (Power Density) causes instantaneous local overheating, burning or phase change of dark or strong-absorbance samples (such as carbon deposition catalysts, iron oxides and the like), and cannot acquire real material information. 2. Sampling is poor in representativeness The micrometer scale spot can only detect a single particle, and for heterogeneous mixed powder samples, single point data lacks statistical representation, requiring time-consuming multi-point scanning. Contradiction of "large spot" and "high flux To solve the above problems, the prior art attempts to enlarge the spot (macroscopic raman). However, according to the principle of conservation of etendue (Etendue), a large light spot means a large light emitting area. When imaged at a spectrometer slit, the spot size is much larger than the slit width (typically 25 um), resulting in >80% of the raman signal being blocked by the slit and the system sensitivity is very low. Thus, there is a need for a high throughput probe device that can achieve both "gentle" excitation of large spots to prevent sample burn-out and "lossless" coupling of large areas of scattered light into the spectrometer slit. Disclosure of Invention Aiming at the defects existing in the prior art, the invention aims to provide a large-light-spot in-situ Raman detection device based on expansion matching, which solves one or more problems. In order to achieve the above purpose, the present invention provides the following technical solutions: Large-light-spot in-situ Raman detection device based on expansion matching and sequentially comprising along optical path transmission direction A laser light guiding unit composed of a laser interface and a transmission optical fiber, which generates an excitation light beam with a certain cross-sectional area; A beam collimation unit which collimates the excitation beam generated by the laser introduction unit; A beam splitting unit that performs reflection splitting on the collimated excitation beam; A focusing objective lens which collects and