Imaging Characteristics And Aberration Suppression Of Large F/# Optical System Based On Wavefront Coding

High resolution target imaging is of great significance in the field of astronomy,space target surveillance,aviation and so on.Due to the limitation of the wavelength and system aperture,the angular resolution of traditional system can only be improved by enlarging the system aperture for a certain working wavelength.Currently,the contradiction between the increasingly high resolution system and large diameter machining process and cost is becoming more and more obvious.Compared with the large aperture optical system,although the large F/# optical system has low resolution,with the development of computer technology and advanced optical processing technology,the combination of new optical imaging technology and image processing technology can also get high quality image.Moreover,the large F/# optical system has the characteristics of small diameter,easy processing,light weight and good post processing capacity,which is one of the trends of the optical system.However,the incensement of system aperture is limited by the high costs of the system processing and alignment.In order to realize the simple alignment and high resolution of the large F/# system,the wavefront coding(WFC)technique is proposed.The main contents are as follows:1.Analyzing the requirements on the large F/# system for the telescope system,a novel WFC technique was proposed to solve the two problem of large F/# system: low resolution and difficult alignment.2.The basic principle of WFC technology and the traditional image restoration algorithm was demonstrated.Later,Wiener filter and wavelet de-noising image restoration algorithm,based on the characteristics of the WFC imaging system,was applied to achieve high resolution imaging system.3.According to the design principle of reflective optical system,four systems including Cassegrain,Gregory,on and off-axis three mirror optical systems with F/37,focal length 3700 mm,diameter 100 mm and visible light were designed,while each secondary mirror of the four systems was encoded.Later,error analysis simulation was compared between traditional system and WFC system,as well as the image restoration,which resulted that the WFC technology can successfully reduce the difficulty of processing,improve the alignment tolerance and enhance the resolution of the optical system.4.Based on the built experimental platform of F/37 optical system,imaging experiments using the traditional F/37 system and the proposed WFC system were carried out respectively.The resolution was greatly improved by WFC technology,which resulted by the comparisons between the traditional image and the reconstructed image of WFC system with Wiener filter and wavelet de-noising algorithm.