Study On Key Imaging Technique Of Fourier Telescopy

Fourier Telescopy, abbreviated as FT, integrates the advantages of laser activelighting and synthetic aperture imaging technique so that imaging resolution andsystem SNR are separated from each other. By the way, it is easy to expand thesystem. Using light buckets can be seen as the return signal receiving device,reducing the difficulties and costs for system research. As one of the most importantdirections of non-conventional optical imaging technique, it has a big applyingprospect in imaging and detecting the targets which are in a distant, dark and smallcondition with a high resolution. In theory, resolution is countless large, especially, ithas unique advantage in imaging and detecting GEO satellites with high resolution.On the basis of the existed research, this thesis mainly analyses and studies thefollowing aspects thoroughly:1. This thesis introduces the basic theory of FT imaging system. It states thetheoretical basis that Fourier Telescopy can be used to break through imagingdiffraction-limited, beginning from space-time encoded theory. Combining the Ttype emitter configuration mode, it gives an introduction about phase closure, andthe basic theory of eliminating the Piston phase difference has also been explained.The research on algorithms of reconstruction images has been studies and the theoryformation for the whole system has been completed as well. It has laid a theoreticalfoundation for the following research.2. Based on the fundamental theory, this thesis puts forward non-uniformspacing as launching configuration mode. Under the situation of using the emitters of the same number, it can collect the higher frequency of the target so that it will beelaborate to return to the original condition of it. From set zeros to non-uniformFourier transform (NFT) and estimating deficiency frequency, non-uniformconfiguration reconstruction algorithm has been perfect. In order to reduce samplingfrequency and import non-uniform sampling technique, it has validated thepracticability of the method combined with NFT and amplitude damping. From theanalysis, it is obvious that this method can not only decrease sampling frequency, butalso go to the same noise sensitivity with traditional Fourier Transform (FT)methods.3. As active imaging technique, it must be influenced by atmosphericdisturbance when light transmission. It can be seen from the analysis that FourierTelescopy can ignore the influence of disturbance on intensity. What is more, it’simaging system is mainly effected by2、3tilt modes when the altitude of thelaunching system is at about900m. On this basis, it has analyzed the influence ofaccuracy of tilt correction on the system.4. Having analyzed the effects of frequency errors of arbitrary two beams andthe target movement to FT system, it takes the method of all phase time shift phasedifference correcting spectrum to adjust frequency errors. Field experiment dataprocessing has been finished and the practicability also been checked. Furthermore,it has simulated the image aimed at the moving target. It is evident that this methodis not influenced by the target movement and it can be used in dealing with the datain the practical project system.5. Analyzed integrated with the theory, the experiment has been completed bothin the lab and outside. It testifies the feasibility of the system and checks thatimaging system is not influenced by down-link atmospheric disturbance. It hasoffered the reference to the practice of project system. Besides, this thesis hasstudied a lot optics delay thread and laser of high power and long coherence.