Dissertation > Excellent graduate degree dissertation topics show

Study of Imaging Capacity of Multi-aperture Imaging System

Author: ZhouZhiWei
Tutor: WangDaYong
School: Beijing University of Technology
Course: Optical Engineering
Keywords: optical multi-aperture imaging system atmospheric turbulence co-phase error wavefront sensing
CLC: TH751
Type: PhD thesis
Year: 2013
Downloads: 28
Quote: 0
Read: Download Dissertation

Abstract

Since the exploration of outer space became more and more wider, the quest forhigher angular resolution of astronomy telescopes was much more urgent. However,the high angular resolution of telescopes leads to manufacture large reflective mirror.The cost of building a large aperture telescope increases rapidly, sometimes such largeaperture telescope is even impossible to be built by present technology. The difficultyof manufacturing large aperture telescopes contradicts with the quest for high angularresolution telescopes. The optical multi-aperture imaging system is proposed to solvethe contradiction.Optical multi-aperture imaging system was inspired by synthetic aperture radar.After decades research, the optical multi-aperture imaging system is being examined ina laboratory. Several test-beds have been built for engineering problem study. Theoptical multi-aperture imaging system forms an image of object by only one exposure,so it is suitable for fast change observation, such as space vehicle, satellites, and so on.Also the optical multi-aperture imaging system is able to be deployed in outer space formilitary surveillance. The development of optical multi-aperture imaging system iswide. At present, the research about optical multi-aperture imaging system is stillenthusiastic.This thesis study on three aspects about the improvement of imaging capacity ofoptical multi-aperture imaging system. The three aspects include the noise effect onrestored image within the point spread function, the improvement of restored imagequality of optical multi-aperture imaging system in the presence of atmosphericturbulence, and the co-phase error detection. By theoretical analysis, numericalsimulation and optical experiments, lots of data were obtained and several conclusionwere given. The major work was as follow:1. Based upon the theory of incoherent diffraction-limited imaging system, asimplified model of optical multi-aperture imaging systems was presented. Accordingto the simple model, the imaging performance of optical multi-aperture imaging systemwas analyzed. Meanwhile, the image quality evaluation criterion was discussed. Thealgorithm of image restoration was given, and the image quality of restored picutre andblurring image were examined by image quality evaluation criterion. The model aboutco-phase error and fundamental knowledge about atmospheric turbulence were introduced.2. The theoretical analysis about the noise effect within the point spread functionand optical transfer function was done. The numerical simulation and opticalexperiments both demonstrated that the noise contained within point spread functionand optical transfer function depressed the restored image quality. The point spreadfunction and optical transfer function calculated by array configuration restored imageperfectly, and was capable of replacing the point spread function and optical transferfunction obtained by experiment which contains noise.3. The random phase screen was added in exit pupil function of optical multi-aperture imaging system to simulate the effect of atmospheric turbulence. A multiframeblind deconvolution algorithm based on total variation was proposed to restore theimage of optical multi-aperture imaging system in the presence of atmospheric ofturbulence. The validity of this algorithm were proved by numerical simulation andoptical experiment.4. The co-phase error was added in exit pupil function of optical multi-apertureimaging system. The optical transfer function with co-phase error was analyzed todemonstrate the effect of co-phase error. The wavefront sensing method by digitalholography was examined and applied in optical multi-aperture imaging system. Theprocess of phase reconstruction of the exit pupil function was deduced and simulatedby numerical method. The phase of the exit pupil function was reconstructedsuccessfully, and co-phase error is able to be detected by analysis of phase informationabout exit pupil function. The optical experiment result was given.

Related Dissertations

CLC: > Industrial Technology > Machinery and Instrument Industry > Instruments, meters > Astronomical instruments > Telescope
© 2012 www.DissertationTopic.Net Mobile