Research On Inversion Recovery Method Of Space Diffraction Membrane Imaging System

With the increasing demand of high-quality image for high-orbit surveillance,the optical imaging system that embodies large aperture,light weight and low cost is in urgent need.The diffractive membrane optical imaging system has been an important development trend for large aperture and light weight space telescope.As a result,image degradation of diffraction imaging system is severer than the conventional ones: the system Modulation Transfer Function(MTF)and Signal to Noise Ratio(SNR)has more prominent degradation as well as exists serious space-variant characteristic over fields of view.Besides,the quantization error and space stress-thermal environment will lead to the further degradation.It may be difficult to meet the interpretation requirements of the target scene information.Therefore,it is necessary to restore the original scenery information according to image degradation characteristics and subsequent image processing.However,related investigations on physics-based diffractive imaging degradation characteristics and corresponding image restoration methods are less studied.Aiming at this problem,the imaging degradation characteristics of diffractive membrane optical imaging system are explored in this paper,and then a new inversion recovery method is put forward for multi-objective improvement,after that algorithm is verified through experiments.The main works and achievements are as follows:(1)The imaging degradation characteristics of diffractive membrane optical imaging system are explored.According to the mechanism of diffractive membrane imagery,the models of degradation processes including blurring,sampling,conversion and random noise are established.And focuses on the analysis for such image quality problems as poor MTF,serious space variation and low contrast.On this basic,the image quality degradation model of diffraction membrane imaging system is established to characterize the effects of image chains,diffractive optical and membrane deformation,which can provide scientific basis for the research on image inversion recovery method.(2)The image inversion recovery method of diffraction membrane imaging system based on multi-objective improvement is proposed.On the basic of imaging degradation characteristics,a new regularization model with multiple prior constraints is established based on regularization frame and block idea,according to multi-objective improvement including MTF and SNR improving,background radiation removal,edge and texture preserving as well as artifact suppressing.Moreover,the efficient solving method of the model is investigated aiming at the problems of multi-variable estimation,multi-norm coexistence and multi-regularizing parameter optimization.Then the new image inversion recovery method based on multi-objective improvement is proposed.(3)The performance of the proposed method is verified.The proposed inversion recovery method is verified according to digital simulation experiment and ground semi-physical experiment.Experimentally,the proposed algorithm demonstrates its capacity to achieve multi-objective improvement including MTF enhancing,background radiation removal,noise and artifact suppressing as well as image’s detail preserving,and produce satisfactory visual quality.This can provide scientific basis for applications and possesses potential application prospects on future space applications of diffractive membrane imaging technology.