The spectrometers based on AOTF for in-situ lunar surface measurement

Abstract

Minerals such as pyroxene, plagioclase, olivine, and ilmenite, which constitute most of the lunar surface rocks with varying size and shape, have distinctive spectral characteristics in the VNIR and SWIR regions. To analyze the composition of lunar surface minerals, several spectrometers based on AOTF was developed to detect lunar surface objects and to obtain their reflectance spectra and geometric images includes the Visible and Near-IR Imaging Spectrometer(VNIS) onboard China’s Chang'E 3 and Chang’E 4 lunar rover and Lunar Mineralogical Spectrometer(LMS) onboard Chang'E 5 and Chang'E 6 lunar lander. These spectrometers, which use acoustic-optic tunable filters as dispersive components, consist of a VIS/NIR imaging spectrometer, an SWIR spectrometer, and a calibration unit with dust-proofing functionality. They are capable of synchronously acquiring the full spectra of lunar surface objects and performing in-situ calibration. This paper introduces these instruments, including their working principle, implementation, operation, and major specifications, as well as the initial scientific achievement of lunar surface exploration.