Design of Optical System for Small Long-Life Star Sensor

In order to realize a high-precision and continuous working function of a star sensors, we propose a new optical system design.Considering the difficulty of the manufacturing process, the entire optical system uses a complicated Petzval structure.In this paper, the key design elements of the optical system applied for star sensors are presented and the most important performance parameters are given.The ground test results show that the system can maintain excellent detection performance on a near-surface atmospheric platform.This study provides an optical system design scheme for a high-precision and continuous operating star sensor, as well as the theoretical basis for future in-atmosphere and continuous star detection technology.

Conclusions

The star sensor designed in this paper has the characteristics of high precision and continuous performance,and is mainly used on near-surface platforms in the atmosphere.According to the advantages of long life,large field of view,large relative aperture,good optical performance and light weight,two schemes of aspheric design and global design were proposed.Considering the difficulty of the process,the complicated Petzval optical structure (global design) was finally adopted.At the same time,high refractive index and low dispersion materials were selected to greatly reduce the optical aberration.In addition,silicon dioxide with good compactness was selected as the outermost film material,and a multi-layer broadband anti-reflection film system was adopted,so that the transmittance of the optical system is greater than 83%.In this optical system,the diameter of the speckle is small,the energy is concentrated,the color deviation,and the absolute distortion are small.At the beginning of the design,the entire lens was guaranteed to have no vignetting in the 0.8 field of view.In order to reduce the influence of ghosting,the transmittance of the key lens surface was improved,thereby improving the comprehensive imaging capability of the entire optical system.According to the simulation results of ZE-MAX,the tolerance and temperature variation characteristics of the optical system are within the required range.After precision machining and assembly,the optical performance of the star sensor was tested at room temperature.The ground test results show that the center wavelength of the optical system is 0.62μm,the receiving spectral range is 0.47-0.75μm,and the transmittance is greater or equal to 80%.The color deviation was less than or equal to 2.9μm.Under normal temperature and pressure and in 0.8 field of view,the diameter of dispersion spot with 80%energy concentration is 16-34μm,and the absolute distortion was no more than 1.5μm.Its excellent optical properties remain within the application requirements in the atmospheric environments with large temperature variations.