[The Research of Spatial Heterodyne Raman Spectroscopy with Standoff Detection]

Spatial heterodyne Raman spectroscopy (SHRS) is a new type of Raman spectroscopic detection technique with characteristics of high optical throughout, high spectral resolution, and no moving parts. SHRS is very suitable for the planetary exploration missions, which can be used to the analysis of minerals and find the biomarkers maybe exist on the surface of planetary. The authors have applied the technique to the standoff Raman spectroscopic detection, analyzed the main characteristics, including spectral resolution, bandpass and signal to noise (SNR), of standoff SHRS and proved it through experiments. The basic theory of standoff SHRS has been described briefly while a breadboard has been designed, built and calibrated. On the basis, the Raman spectra of some inorganic solids, organic liquids and some natural minerals have been achieved at a distance of 10 m, the SNR of the breadboard has been estimated. Due to the poor adjustment and the defects of the optical elements, the breadboard is far away from an ideal system. But the results show that the SNR is better than 5 for most of the main Raman peaks of the samples, which can meet the basic requirement of clear positive detection of typical Raman peaks and the feasibility of standoff SHRS has been proved. SHRS can overcome the main defects of dispersive grating Raman spectrometers and Fourier transform Raman spectrometers and it has a great application prospect on the detection and analysis of the planetary surface. The work of the authors can prove the potentiality of SHRS on standoff detection and can provide reference for the engineering realization of standoff SHRS.