Design And Research Of Optical System For Large Field Of View Dynamic Star Simulator

The precise measurement and control of spacecraft attitude is an important part for ensuring the smooth progress of space missions.Star sensors are the sensors with the highest attitude measurement accuracy and no time drift error.They are widely used in various aerospace projects.Before the star sensor is put into use,it needs to perform function testing and calibration.It is very expensive to directly perform aerospace tests,and the field star observation test is easily affected by external factors such as the environment.Therefore,it is necessary to develop measurement equipment to perform infield experiments in the ground.This type of ground test equipment is star simulator,which simulates the real star map in space and provides function detection and calibration for star sensor.In space engineering,the dynamic performance requirements of star sensors are becoming higher and higher.So it is imperative to develop a highly dynamic star simulator that can provide real and real-time changes.This article aimes at the dynamic star simulator with a large field of view,for improving star simulator's dynamic characteristics,the overall technology of a large field of view dynamic star simulator based on DMD is determined.The scheme and the main technical indicators are designed based on the DMD optical system of the large field dynamic star simulator,including the lighting system and the projection system.The influence of the stray light of the system is analyzed in combination with the opticalmechanical structure,and the stray light is suppressed and reduced.The background noise of the image improves the contrast of the star map.This article first introduces the system composition and working principle of the dynamic star simulator,analyzes and compares the performance of each star chart display device,chooses DMD as the star chart display device,and proposes a dynamic star simulation's design points and indicators of the optical system combining with the using requirements of the star sensor and the working mode of the DMD.The fly-eye lens array is used to design the illumination optical system,and the total reflection prism is used to realize the approximate coaxial arrangement of the illumination system and the projection system.The illumination uniformity of the illumination system is greater than 94%.The projection optical system employs the secondary imaging method,which solved the problems that it is difficult to achieve long working distance and system aberrations in the case of large field of view and long exit pupil distance,The projection optical system has a 60 mm exit pupil distance and a 28.6°field of view.The distortion is less than 0.045%,and the 80% of the energy is concentrated in the circle with a diameter of 8?m.Tolerance analysis was performed on the illumination optical system and the projection optical system.The tolerance range that satisfies the design arguments and processing technology is given.The stray light of the system will cause higher background noise and reduce the contrast of the simulated star map,which will affect the dynamic performance of the star simulator.So the optical-mechanical structure is integrated to perform the whole machine performance simulation and system stray light analysis at the end of this article.And the measures of controlling stray light is adopted.The energy distribution of the image plane in each state is compared,and the contrast of the simulated star map is obtained.The result proves that the design scheme in this paper is useful for suppressing the background noise,greatly improves the star map contrast,and improving the dynamic performance of large field of view star simulator.