Design Of Telecentric Beam Path Lens For Star Sensor With Binary Optics

The star sensor is an opto-electronic instrument used to provide the absolute three-axis attitude of spacecrafts utilizing star observations, which has the most highly accuracy in the optical attitude sensors. The star lights are captured by the lens system and imaged on the detector. As the star pattern recognition and the attitude estimation are based on the angular positions of the viewed stars, the image quality of the lens system is crucial for the measurement accuracy of star sensor.This paper focuses on the key issues of the lens system design in the development of high accuracy star sensor. It includes the following parts: At first, aberrations of the optical lens are analyzed, which introduced position error for star sensor. The analysis shows that the aberration can be divided into three parts, i.e., the aberrance of the principal ray, the coma of the lens and the effects of the stellar spectrums.Based on this analysis, an initial lens of Petzval configuration is achieved by PW method. And then, the telecentric beam path structure is introduced to rectify the aberrance of the principal ray and the coma. Finally, the chromatic aberrantion is rectified by the binary optics to reduce the effect of the stellar spectrums without adding any other elements. The simulation in ZEMAX showed that the position error introduced by this optical lens is less than 2".