基于遮光罩尺寸和镜头拉氏不变量星敏感器光学系统小型化设计

Miniaturization Design of Star Sensors Optical System Based on Baffle Size and Lens Lagrange Invariant

遮光罩尺寸和拉氏不变量是影响星敏感器体积和镜头复杂性的2个关键因素。通过推导分析极限星等与这两者的关系,研究了星敏感器光学系统的小型化设计。根据光学系统参数与星敏感器技术要求的关系,推得和分析不同极限星等时关于遮光罩尺寸和拉氏不变量的公式。结果表明随着极限星等增大,拉氏不变量单调减小,但遮光罩尺寸存在着极小值。据此优化极限星等,使得遮光罩尺寸和拉氏不变量尽可能小,实现星敏感器小型化。基于STAR1000互补金属氧化物半导体(CMOS)探测器,举例优化设计得到适于微小卫星星敏感器使用的光学系统,其极限星等5.0 MV、视场角20°×20°、入瞳直径28.2mm、长度124mm、重量约300g。

The baffle size and Lagrange invariant of star sensor are two key factors which affect its volume and lens complexity. Through derivation and analysis of the relationship between limiting star magnitude and these two factors, miniaturization of the optical system of star sensor is studied. According to the relations between its optical system parameters and technological requirements, formulae about haffle size and Lagrange invariant under various limiting magnitudes are derived and analyzed. It is shown that with the increase of limiting magnitude, the Lagrange invariant monotonically decreases, but the baffle size has minimum value. On these grounds, limiting magnitude is optimized to get as small baffle size and Lagrange invariant as possible and to facilitate its miniaturization. As an example, the optical system of a star sensor based on STAR1000 complementary metal-oxide-semiconductor transistor （CMOS） detector and suitable for microsatellite is optimally designed, with limiting magnitude, field of view, entrance pupil diameter, optical overall length, and weight of 5.0 MV, 20°× 20°, 28.2 mm, 124 mm, and about 300 g respectively.