基于CMOS APS的星敏感器光学系统参数确定

Determination of the optical system parameters for a CMOS APS based star sensor

基于CMOSAPS图象传感器的星敏感器是适应航天技术的发展而产生的新一代姿态敏感器。确定光斑形状和大小、光学系统有效通光孔径、视场和焦距等参数是进行星敏感器光学设计的前提。本文基于选定的CMOSAPS图象传感器分别对这些参数进行了分析和计算。确定光斑形状和大小的依据是,减小由于探测器像元对光斑能量分布的采样导致点扩散函数变形,从而引起的利用亚像元技术求星像中心的计算误差。光学系统的有效通光孔径与星敏感器所能探测到的极限星等有关,通过从目标辐射特性直到探测器响应的能量计算可以确定孔径的大小。确定视场和焦距首先要满足星敏感器实现全天自主星图识别所需的导航星捕获概率,其次要考虑与之相关的误差。

CMOS APS based star sensor is a new generation of attitude sensor produced to keep up with the development of aerospace technology. Determination of the optical system parameters such as the spot shape and size, the effective aperture, the field of view and the focal length is the precondition to perform optical design of the star sensor. This paper gives the analysis and the calculation of these parameters based on a selected CMOS APS. The spot shape and size are determined to minish the sub-pixel centroiding error caused by the distortion of the point spread function due to the pixel sampling effect of the CMOS APS. The effective optical aperture is related to the magnitude threshold of the stars that can be detected by the sensor. So the aperture can be determined through the energy calculation from the radiation of the objects to the response of the sensor. The determination of the field of view and the focal length needs firstly to fulfill the probability of navigation stars capture for the realization of the autonomous star recognition in the whole sky, and secondly to take the relative errors into consideration.