Simulation And Analysis Of The High-order Diffraction Of Light Of Diffractive Membrane Optical Imaging System

High resolution geostationary orbit remote sensing satellite has become a new competitive field for aerospace giants.American Membrane Optical Imaging Real-time Exploitation(MOIRE)project has been put into operation since 2010,competing with others seriously,and is still being prepared for launch.In December 2015,China successfully launched the historic high-resolution 4 satellite.This is the world's first geostationary orbit optical remote sensing satellite,which not only greatly improves China's ability to monitor space,but also marks China's first place in this important space race.The paper first expounds the background of this study,and on this basis leads to the purpose and significance of this study-to analyze and effectively suppress the high-order diffraction light of the membrane diffraction imaging system,and to avoid or reduce its influence on the performance of the system.Secondly,the paper introduces the development history of the membrane diffraction imaging system,and expounds the main problems in the past research work-mainly the study of the imaging light of the main mirror,and the effect of the high-order diffractive light on the imaging system has not been fully considered.Based on the above issues,a complete optical imaging system using diffractive optical elements as primary mirror and correction mirror is introduced in this paper.In addition,the diffraction efficiency of the high-order diffractive beam of step diffraction element is quantitatively derived and the analytical solution is given.At the same time,the imaging characteristics and high-order diffraction characteristics of diffractive optical elements used in the system are analyzed.Based on the above analysis,the high-order diffracted stray light of diffractive optical elements is effectively suppressed.The stray light caused by other systems,solar radiation and mirrors is also analyzed and effectively suppressed.An important work of the paper is to implement the method of importing non diffractive optical elements from Zemax to ASAP and the direct design of diffractive optical elements in ASAP.At the same time,it realizes the simulation of the whole system in ASAP.Another important work of this paper is to realize the simulation of diffractive light at all levels in the same system,that is to design different diffraction gradation in different rings and the more finer the band is divided,the better the simulation results are.When using this method to simulate,the boundary conditions must be considered,that is,the two inner and outer edge loops need to set specific girdle to meet the needs of stray light analysis.Specifically,the inner edge ring should be set to second level of diffractive light,and the outer rim must be set as first order diffractive light.