Research On Optical System Of Micro Raman Spectrometer For Lunar Surface Material Detection

Raman spectroscopy is known as the "fingerprint spectrum" for the detection of material components.It has a wide detection range,no need to deal with samples,sharp Raman peaks,strong analytical and processing ability,and is one of the important analytical methods for the detection of material components.Under the background of lunar surface material detection,this paper analyzes some advantages of Raman spectroscopy technology in lunar surface material detection,and analyzes the feasibility of Raman spectroscopy technology in lunar surface material detection according to the previous research of using Raman spectroscopy technology to analyze lunar return samples.In this paper,based on the comprehensive consideration of the existing Raman spectroscopy technology,and according to the actual detection situation of the lunar surface,we mainly study the Raman spectrometer probe optical system and spectrometer spectroscopic system for the detection of lunar surface materials.The probe is composed of two parts: the laser convergence system and the Raman scattering light collection system.The numerical aperture of the laser convergence system is matched with that of the optical fiber.The dot plot is used as the evaluation index of the system performance.The root mean square radius of the dot plot in each field of view is less than the radius of the Airy spot.The system has good concentrating ability.The collection system adopts the telephoto optical structure,and the object square value of the system is lower The aperture is 0.4,which can collect the Raman scattering light effectively.The root mean square radius of the point column diagram at zero field of view and(0,0.05mm)field of view is 2.566 μm and2.933 μm respectively,which is smaller than the Elli radius and the radius is 10 μm,and 90% of the light energy is concentrated in the surrounding circle with radius of 10μm.In the design of the optical system of the spectrometer,the diffraction characteristics of blazed grating are analyzed.The optical system of Raman spectrometer is designed by using transmission grating.The total length of the system is less than 12 cm,the object square numerical aperture is 0.22,and the system resolution is better than 0.2nm in the spectral range of 532～782nm.In order to verify the performance of Raman spectrometer and analyze the feasibility of its application in lunar surface material detection,several mineral samples,quartz,olivine,augite,diopside and plagioclase,which have been detected on the lunar surface,are selected as the experimental samples to be tested.These minerals are detected by Raman spectrometer,and the original Raman signals are analyzed by software Finally,the final data is compared with the database and the spectral analysis is carried out.The results are more reliable,which preliminarily verifies the performance and feasibility of the system.