长焦距无热化星敏感器光学系统设计

Optical system design of star sensor with long focal length and athermalization

光学系统是自主导航星敏感器实现恒星光信号收集以及高精度姿态测量的核心组件。以高精度星敏感器光学系统为研究对象,分析了影响光学系统探测不同色温恒星精度的机理,恒星色温及环境温度变化引起的质心漂移量误差通过后期标定抑制的难度大,需要在光学设计阶段进行控制;建立了光学系统设计波长权重计算模型及分配方法;在性能评价方面,除了常规的能量集中度、畸变以及非对称像差之外,提出采用恒星色温质心漂移量以及温度变化质心漂移量作为精度评价的主要指标。根据应用需求设计了一款基于航天卫星平台的长焦距星敏感器光学系统,焦距为95 mm,相对孔径为F/2.4,视场角为8°×8°,探测光谱范围为450~1 000 nm,3×3像元内能量集中度大于85%。基于常规玻璃材料校正了超宽谱段长焦距光学系统的倍率色差,全视场倍率色差不超过0.9μm。精度分析结果表明:2 600~9 800 K范围内不同色温恒星的质心漂移量小于0.36μm;在工作温度0~40℃范围内,焦距变化量小于2.7μm,温度变化引起的质心漂移量小于0.45μm。

Optical system is the core component of autonomous navigation star sensor to realize the collection of star light and high-precision attitude measurement.In this paper,the optical system of high precision star sensor was taken as the research object,the influence mechanism of the accuracy of optical system for detecting different color temperature stars were studied and analyzed.It is difficult to suppress the centroid drift caused by the changes of star color temperature and ambient temperature through later calibration,which needs to be controlled under the stage of optical design.The calculation model and allocation method of optical system design wavelength weight were established,and the performance evaluation was carried out.In addition to the conventional energy concentration,distortion and asymmetric aberrations,the centroid drift of star color temperature and ambient temperature change were proposed as the main index of accuracy evaluation.According to the application requirements,a long focal star sensor optical system based on space satellite platform was designed,with the focal length of 95 mm,the relative aperture of f 2.4,the field view of 8°×8°,the spectrum range of 450-1000 nm,and the energy concentration of more than 85%in 3×3 pixels.Based on the regular glass materials,the lateral color aberration of the optical system was corrected under ultra-wide spectral range and long focal.The lateral color aberration of the full field was less than 0.9μm;The results of accuracy analysis show that the accuracy of centroid position is less than 0.36μm in the range of 2600-9800 K,and the change of focal length is less than 2.7μm in the range of 0-40℃,and the accuracy of centroid position caused by temperature is less than 0.45μm.