大口径折反式星敏感器光学系统的光路设计

Optical Path Design for Catadioptric Star Sensor with Large Aperture

为提高星敏感器探测极限星等的能力,采用改进型卡塞格林系统、光阑校正球面透镜组和视场校正球面透镜组相结合的结构,设计了一种光谱范围为450~950nm、半视场为1.4°、入瞳直径为250mm、焦距为425mm,且能够矫正像散、场曲和畸变的大口径折反式星敏感器光学系统.基于像差理论的系统初始结构参数计算和Zemax软件光线追迹的优化设计,光学系统的次镜遮拦比为0.43,成像点80%的能量集中在30μm内,最大畸变为0.081%,光学传递函数在奈奎斯特频率34lp/mm处大于0.75,最大倍率色差为1.138μm,满足星敏感器对成像的要求.对光学系统进行公差分析,在20次蒙特卡罗分析结果中,第13个结构的绩效函数最好,为4.97516μm,第20个结构的绩效函数最差,达到7.79957μm.通过对20次蒙特卡罗结构的绩效函数分析,所选定的公差值能够很好地满足光学系统性能基本要求,为加工和安装过程中的误差提供依据.

In order to improve the ability of the star sensor to detect limited magnitude,a combination of the improved Cassegrain system,aperture-corrected spherical lens group and field-of-view corrected spherical lens group is adopted to design an optical system of a large aperture catadioptric star sensor capable of correcting astigmatism,field curvature and distortion,with the spectral range of 450~950 nm,the semifield of 1.4°,an entrance pupil diameter of 250 mm and the focal length of 425 mm.According to the calculation of the initial structure parameters of the system based on the aberration theory and the optimization design of Ray tracing in Zemax software,the blocking ratio of the secondary mirror of the optical system reaches 0.43,the energy concentration of the imaging point is 80%within 30μm,and the maximum distortion is 0.081%.The modulation transfer function is greater than 0.75 at a Nyquist frequency of 34 lp/mm,and the maximum magnification chromatic aberration is 1.138μm,which meets the imaging requirements of star sensor pairs.Through the tolerance analysis of optical system,in the 20 Monte Carlo analysis results,the best structure is the 13th structure with the performance function of 4.97516μm,the worst structure is the 20th structure with the performance function of 7.79957μm.Through the performance function analysis of 20 times Monte Carlo structure,the selected tolerance value can well meet the basic requirements of optical system performance,and provide the basis for the errors in the process of processing and installation.