Study Of Raman Spectrum Technique For Material Detection On Mars Surface

Raman spectroscopy is one of the important means of components identification, it has the characteristics of peak spectrum, wide detection range and small region detection. Based on the background of the Martian surface material’s detection, this paper compared Raman spectrometer technology with other techniques, such as visible-near infrared spectrometer, M?ssbauer spectrometer and X- ray fluorescence spectrometric technique which were ever used in the Martian surface material detection,and expatiated the characteristic of Raman spectrometer. The paper combined RLS and SHERLOC which will be used for Raman spectroscopy of Mars exploration, pointed out the feasibility of Raman spectroscopy in Mars exploration area.This paper considered the difficult questions of Raman spectrometer, and solved two key problems of remote Raman spectrometer based on Mars surface detection. The first key problem was the design of Casey Green telescope system: primary and secondary mirrors with parabolic, the secondary mirror was mobile, the entrance pupil diameter 200 mm, distance 1.5-2.5m. Second key problem was writing the pretreatment algorithm—wavelet transform and polynomial fitting algorithm,which respectively used for high frequency noise deducting and fluorescence background deducting.Wavelet transform using the ’sym5’ wavelet basis function for the 5 layer wavelet decomposition, and soft threshold denoising in signal reconstruction. The key point of polynomial fitting was derivative for the high frequency noise deducted, using the derivative in the vicinity of 0 points about ±10 to fitting polynomial,do some times circularly, this polynomial fitting result was more accurate. Then deducted background fluorescence from the denoising spectrum, and obtained final Raman spectra.In order to verify the performance of the remote Raman spectro meter and validate its feasibility for the Martian surface material detection, this paper selected four kinds of materials—calcite, olivine, pyroxene and hematite,which have been detected on the surface of Mars, and a kind of organic matter—glucose.Detected some samples using remote Raman spectroscopy in the different distances, pretreated the spectrum with the wavelet transform and the polynomial fitting algorithm, analyzed the final data by spectral analysis, got more reliable results, and verified the performance of theinstrument.