基于非球面的大相对孔径微型星敏感器镜头设计

Lens design of micro star sensor with large aperture based on aspheric surface

星敏感器是卫星上精度最高的姿态测量仪器,其通过对恒星成像与识别来确定卫星的三轴姿态,主要由光学系统、电子学系统和信息处理系统组成。传统卫星上高精度星敏感器的体积重量较大,难以满足蓬勃发展的微纳卫星的任务需求,成为限制微纳卫星定位精度的主要障碍。相对于电子学微型化、集成化和信息处理技术的飞速发展,光学系统成为星敏感器小型化的瓶颈。提出一种基于非球面大相对孔径微小型光学系统设计方法,仅用5片镜片,即可实现焦距25 mm,相对孔径1/1. 3,17°全视场角,在奈奎斯特频率处MTF优于0. 5,采用选取相对部分色散系数相同或接近、色散系数相差较大的玻璃组合的方法,有效校正了500~880 nm宽光谱色差,并实现了全视场畸变≤0. 013%。引用此技术设计纳型星敏感器镜头焦距25 mm,重量仅为15 g,降低到国内纳型星敏感器镜头的1/5。结果表明,光学系统经测试畸变等指标,满足角秒级星点中心确定的要求,为高精度纳型星敏感器提供了核心保障。

The star sensor is the most accurate attitude measure instrument on the satellite.It determines the three-axis attitude of the satellite by imaging and recognizing stars.It is mainly consisted of optical system,electronic system and information processing system.Star sensor on the conventional satellite has large weight and volume,which is difficult to meet the mission requirements of the booming micro-nano satellite.It has become a major obstacle which limits the accuracy of micro-nano satellite positioning.Compared with the rapid development of electronic miniaturization,integration and information processing technology,the optical system has become the bottleneck of star sensor miniaturization.To solve this problem,this paper proposes a large relative aperture micro-small optical system based on aspherical 1/1.3,which can realize 17°full field of view with 5 lenses.MTF is better than 0.5 at the Nyquist frequency point.The glass combination with the same partial or close dispersion coefficient and large difference of dispersion coefficient is selected.It is effective to correct the wide spectral chromatic aberration from 500~880 nm,which can achieve full field distortion≤0.013%.This technology can help design the nano-star sensor lens with a focal length of 25 mm.Its weight is 15 g,which is only 1/5 of the domestic nano-star sensor lens.Experimental results show that the optical system can meet the requirements determined by the angular secondlevel star point center after distortion and other indicators test.It provides one kind of core guarantee for realizing the high precision nano-star sensor.