Design And Analysis Of Membrane Difffractive Imaging System

With the advancement of space technology,space remote sensing technology has been developing rapidly in recent years.The use of space optical remote sensing system has achieved remarkable results in many applications,such as meteorological observation,astronomical observation,natural resource exploration and military reconnaissance.In order to get more detailed information on the ground,the spatial resolution of optical system needs further improvement.A higher angular resolution is required when the orbit height is constant.However,under the constraint of the fluctuation characteristics of light,the angular resolution of the optical system is determined by the system aperture and the working wavelength.Under the premise of determining the working band,we can only enlarge the aperture of the system so as to improve the system's ability to distinguish details.The traditional optical systems are restricted by factors such as volume,weight,material,processing and launching ability,thus can not realize space high resolution imaging system.The combination of membrane and diffraction is one of the feasible ways to achieve large aperture and high resolution in space.On the basis of the principle of diffraction imaging,the exploration of system scheme design and the analysis of system imaging quality are carried out in this paper,which provide the technical scheme and feasibility analysis for the space application of the membrane diffraction technology.Based on the scalar diffraction theory,the optical characteristics of the diffractive imaging system are analyzed,such as the focal power,the diffraction efficiency,the chromatic aberration and so on.Based on the multistage phase grating,the diffraction efficiency of the diffractive optical element is modeled and the imaging characteristics of the diffractive optical element are established.On this basis,the influence of the diffraction efficiency on the MTF is established.In the end,the chromatic aberration characteristics of the diffraction imaging system are analyzed,and a correction method using the Schupmann achromatic model is put forward,and the parameter relation of the Schupmann model is deduced.Then the membrane diffraction imaging system is designed according to the Schupmann achromatic model.First,the segmented membrane diffractive lens of the system is designed.Then the initial structure of the system is designed,and the parameters are given.Finally,the design parameters of the system are optimized.Finally,the image quality of the membrane diffraction imaging system designed in this paper is analyzed by using the image quality analysis model and method established in this paper.The tolerance analysis of the designed membrane diffraction imagingsystem is carried out.The tolerance including the diffractive objective,the adjustment error of the diffractive objective and the rear lens group,and the splicing error of the diffractive objective are analyzed.On the basis of in-depth analysis of the imaging characteristics of the membrane diffractive optical system,a large aperture space membrane diffractive optical system with high imaging quality is designed,and the imaging quality and tolerance of the system are analyzed.The analysis results show that the model and method established in this paper can be used to support the imaging characteristics analysis and system optimization design of the membrane diffractive optical system.The system designed in this paper can meet the application of space large aperture optical information acquisition and processing.The relevant models and design results can provide references for the design and application of the space membrane diffractive optical system.