Stimulated Raman hyperspectral combined detection device and method

Abstract

The invention provides a stimulated Raman hyperspectral combined detection device and method. The method comprises the steps: S1, generating two beams of pulse lasers with different frequencies, carrying out frequency coding on one beam of pulse laser, selecting laser signals with different preset frequencies, and selecting a single laser signal with a fixed frequency for the other beam of pulse laser; and S2, carrying out time synchronization and space synchronization on the laser signals with different preset frequencies and the laser signals with fixed frequencies, simultaneously focusing the signals on a test sample, and jointly exciting stimulated Raman spectrum signals of the test sample. The number of detection times required in the invention is far less than the number of spectrumchannels of the Raman spectrum so that a detection speed of the current stimulated Raman spectrum analysis technology in wide-spectrum and high-resolution spectrum analysis application can be greatlyimproved.

Description

technical field [0001] The invention relates to the technical field of spectral analysis, in particular to a stimulated Raman hyperspectral combined detection device and method. Background technique [0002] Stimulated Raman spectroscopy technology is a non-scale sensitive detection technology that uses the nonlinear interaction between laser and matter to achieve Raman signal enhancement. This technology is not affected by non-resonant background noise, and its spectral information is completely consistent with spontaneous Raman spectroscopy. However, the signal intensity can be enhanced by three to five orders of magnitude compared with the spontaneous Raman spectrum, and the signal intensity of the stimulated Raman spectrum is proportional to the molecular concentration, which can realize quantitative measurement. Stimulated Raman uses two beams of ultrafast lasers synchronized in time and space as excitation light, one beam with a higher frequency is the pump light, and ...

AI Technical Summary

Problems solved by technology

The laser frequency tuning method mainly relies on tuning the output frequency of the laser to realize the wavelength tuning of the Raman spectrum detection spectrum, but the frequency tuning speed of the existing laser is slow, resulting in a slow spectrum detection speed

The femtosecond pulse shaping method disperses the wide-spectrum femtosecond pulse in the Fourier plane, extracts the preset frequency components through the movable slit, and then excites the subject together with another fixed-frequency narrow-spectrum pulse. Stimulated Raman spectral signals to achieve high-resolution stimulated Raman detection, but in this method, most of the pulse energy does not participate in the stimulated Raman process, the limited laser power cannot be effectively used, and the detection signal-to-noise ratio is limited

The spectral focusing method uses the same dispersion medium to linearly chirp the pump light pulse and the Stokes light pulse. During the pulse duration, a stable frequency difference is formed between the pump light pulse and the Stokes light pulse. Through The time delay line changes the time interval between the pump light pulse and the Stokes pulse to realize the Raman vibration frequency selection. This method makes most of the energy in the pulse participate in the excitation of the stimulated Raman spectrum signal, and the energy utilization rate is relatively low. High, but the spectral resolution of this method is relatively low due to the linear chirp matching problem and the presence of higher-order chirps

Moreover, the detectors in the above three methods can only detect Raman spectra of a single frequency in one detection. For the detection of Raman spectra with N Raman frequency shifts, that is, spectral channels, N spectral scans are required. Wide-spectrum, high-resolution stimulated Raman detection requires a large number of scanning detections, which greatly increases the detection time

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