Design and manufacturing of a highly integrated optical module for Tianwen-1 probe's landing LiDAR

Abstract

In this study, a highly-integrated optical module based on micro-electromechanical system (MEMS) mirror, glass with low thermal expansion coefficient, a higher-order aspheric lens with high refractive index and two position-optimized optical filters is proposed. The Mars exploration mission requirements and the non-coaxial optical path of the optical module are discussed, while the relationship between the signal-to-noise ratio (SNR) and the detection distance, as well as between the scanning field of view(FOV)and the entrance pupil diameter, is given. The transmitting module consisting of a scanning device and angle magnifier has a temperature range of −20 °C to +40 °C, and a good reliability at 1800 g@4000 Hz. The receiving module using two ZnS lenses and two narrow-band filters with bandwidths of 22 and 10 nm has an f number of 0.55, a back working distance of 3.24 mm and a normalized energy collection efficiency at the edge of the FOV of 72.8%. The presented optical module has a Ø30°FOV, 120 m detection distance and 2 mrad angular resolution, and has been successfully applied to Tianwen-1 Probe's landing LiDAR.