Research On Key Optical Technology Of Dynamic Star Simulator

The Dynamic Star Simulator is used to simulate realistic star scenarios and is an important piece of equipment for testing and calibrating star sensitive instruments.During the hardware-in-the-loop(HWIL)simulation test,the star simulator and the star sensor are mounted together on a flight simulation turntable.In order to maintain the pupils overlap,the star simulator is required to have a very long exit distance.Based on this problem,we propose a Liquid Crystal on Silicon(LCoS)based optical engine for the star simulator,focusing on the overall system design,the projection system design and the illumination system design.In addition,the performance of the star simulator is evaluated and analysed in this paper.The research work can be summarised as follows.According to the test requirements,the main performance parameters of the system are analysed and the key optical components are discussed.The overall design requirements of the star simulator are finally determined and the main design specifications are given.(1)The design method of the illumination system is investigated.The design concept of the illumination system is clarified,and a Compound Parabolic Concentrator(CPC)is used for the secondary distribution of the energy of the Light-Emitting Diode(LED)light source.The telescopic system structure and the introduction of a fly’s-eye lens for beam shaping further improve the illumination uniformity and energy utilisation.The results of the illumination system design were evaluated by means of a non-sequential ray tracing method and the illumination uniformity was better than 95%,meeting the requirements of the star simulator.(2)The design method of the projection system is studied.The projection system is characterised by small aberrations and an extremely long exit pupil distance.The design is optimised using an Elfer eyepiece as the initial structure to achieve an ultra-long parallel light output of 1250 mm.In addition,the results of the projection system design are analysed and evaluated by means of sequential ray tracing.It is demonstrated that the aberration of the projection system is less than 1%,the geometric energy concentration of each field of view is greater than 80% within one image element size,the Modulation Transfer Function(MTF)is greater than 0.4 at 61 lp/mm,and the aberration is well corrected to meet the requirements of star point image quality for HWIL simulation tests.(3)The performance of the ultra-long exit distance star simulator is tested.The actual evaluation methods of the main parameters such as the magnitude simulation accuracy and the interstellar angular distance are discussed,and the test data are analyzed and calculated,and the system star point coordinate data are corrected according to the calculation results.The results demonstrated that the accuracy of the magnitude simulation reached ±0.1Mv,the error of star point position was less than 30″,and the error of interstellar angular distance was less than 15″,which proved that the star simulator met the design index requirements and could be used for the ground semiphysical simulation test of the star sensor.