The Analysis of Implement of SiPM in LDRI System

LDRI system stands for Laser Dynamic Range Imager. It has been used in STS-114 mission in 2005 as the main sensors to realize an on-orbit inspection of the thermal protection system which covers the Orbiter spacecraft. The basic of LDRI is phase discrimination and the key technology is the realization of optoelectronic mixing (OEM) using ICCD. Unfortunately, 2 main drawbacks arise from the usage of ICCD, including the high voltage (~2000V) of PMT drivers and the difficulties in high voltage modulations. SiPM is a rather novel detector which has the similar performances as PMT does but only requires a driving voltage of about 30V. Recently, the SiPM based OEM has been proved and this implies the implement of SiPM in LDRI system. In this paper, the basic of LDRI and SiPM are summerized and some theoretical analysis and simulations are made to verify the feasibility of implement of SiPM in LDRI system. The results show that SiPM is capable of realizing phase discrimination regardless of the high driving voltage and difficulties in modulations. The mean range error is found to be no more than 0.4mm within a range of 5m and an average incident power of 6nW.