Design Of Diffractive Membrance Imaging System With Large Aperture And Wide Band

Remote sensing imaging technology has been widely applied in the global,and the resolution of remote sensing system is directly related to the aperture of the optical system.DARPAR proposed a research plan for large aperture geostationary remote sensing satellite named MORIE(Membrane Optical Imager Real-time Exploitation).This scheme intends to use diffractive membrane primary lens to realize real-time imaging of the ground,the aperture of which is 10 meters or above.The advantage of using membrane as the primary lens is its strong engineering implementation,including low surface density,simple production process and good surface tolerance.However severe chromatic aberration caused by its diffraction brings great difficulty in optical design,and no specific design result has been provided by now.This paper adopts a HDE as the primary lens using multiband in imaging to reduce the chromatic aberration,then combines Schupmann correcting optical path to reduce more chromatic aberration,which can promote image quality.The band width of the above imaging system is 3 times and the field of view is 8 times of the MORIE.First of all,the principle of diffractive membrane imaging system is studied.The imaging principle,the dispersion and part dispersion characteristics,the primary aberration coefficient and the diffraction efficiency of diffractive lens are analyzed.Considering the difficulty of processing the diffractive membrane lens with large aperture,the design method of the primary lens is studied,then the image quality of the diffractive primary lens with the overall aperture and the spliced aperture is compared and analyzed.The way of joining the primary lens surface is determined.Secondly,due to the severe chromatic aberration of the primary diffractive lens,the following achromatic optical path is studied.The achromatic principle is derived by matrix equation,and the initial structural parameters of the imaging system are calculated.Moreover,initial structural parameters are optimized under the requirement of MOIRE and the optical design is obtained.On the basis of the above design,the final optimization result is achieved with the field of view expanded 8 times and the image quality is analyzed.Finally,in order to expand the band width of the imaging system,the principle of harmonic diffraction imaging is studied.The imaging system uses a HDE as the primary lens and selects three imaging bands with diffraction efficiency all over 90%.In ZEMAX this design can be obtained by multi-configuration.The bandwith of this final desugn is 3 times and the field of view is 8 times of the MORIE,.image quality analysis is followed.