Research On Configuration Optimization And Image Restoration Of Space Optical Synthetic Aperture Imaging

Synthetic aperture technology is an effective way to realize high-resolution imaging with multiple small apertures.With the increasing demand for observation resolution in frontier space science research,optical synthetic aperture technology is also applied to the observation of exoplanets,black holes and other deep space exploration fields.Deep space exploration needs higher resolution and contrast because of its large spatial scale and dim target.For example,in order to distinguish the target celestial bodies that are 60 light-years away from the solar system,an optical telescope with an angular resolution of 0.01 angular seconds is needed.When the mid infrared band is used,the equivalent aperture of the telescope needs to reach 200 meters.However,due to the constraints of processing capacity and rocket carrying capacity,the size and number of subaperture of array are limited.It is difficult for traditional configuration methods to achieve such a large equivalent aperture.Scanning synthetic aperture imaging technology is needed.The determination of scanning mode and scanning times is the key problem.Too few scanning times will lead to the loss of frequency domain information in the middle and high frequency parts,resulting in serious image degradation and irrecoverable.Too many scans will increase the complexity of the system and reduce the accuracy of sub aperture cooperative control.In order to obtain high-quality images and reduce the number of scans,this paper studies the array selection and configuration optimization of optical synthetic aperture.The main research contents are as follows:1.The introduction of the basic theory of optical synthetic aperture imaging.The relationship among optical transfer function,point spread function and modulation transfer function,as well as some important characteristic indexes and imaging performance evaluation indexes are introduced in detail.2.The scanning synthetic aperture imaging technology based on rotation and growth baseline is proposed to meet the aperture requirements.The initial array was scanned with rotation and growth baseline in a certain step,and each scanning point was observed for a period of time,until the configuration composed of all scanning points realized full coverage of 200 m aperture in the pupil plane,and all observation information was integrated for image restoration.3.The scanning configuration adopts the central symmetrical scanning point position arrangement,a configuration optimization method based on the middle and high frequency boundary circle search is proposed to solve the problem of high frequency information loss of traditional configuration,which can reduce the number of scanning and obtain high system performance.4.Optimization of filter parameters with correlation coefficient and PSNR,and the Wiener filter algorithm is improved.It enhances the anti noise ability of the algorithm,and realizes high-quality image restoration under low computational complexity.5.The direct blind deconvolution algorithm is improved by weighting the ideal and the estimated point spread function.Implement the correction of system transfer function,at the same time,it has high robustness to noise interference.The experimental results show that,after optimization,the number of scans of the initial Golay3 array with a 4-meter aperture is reduced from 131 to 81,and the image quality is greatly improved.It shows that the optimization effect of the configuration optimization method is obvious,and the improved algorithm has obvious improvement effect,which can meet the needs of exoplanet exploration.