Study On The Principles And Co-phasing Error Of Optical Sparse Aperture System

The resolution of the imaging system is limited by the optical diffraction effect. The quest for higher angular resolution in astronomy and earth observation will inevitably lead to larger and larger apertures. Unfortunately, limited by the fabrication technology, cost, volume and weight of monolithic mirrors, a large aperture system is very difficult to be manufactured and implemented. Efforts are ongoing to break through the physical limits to the diameter of conventional filled aperture telescope. Optical sparse aperture system is a particular array synthesized by several small filled imaging systems. It can be designed to obtain high resolution in astronomical object imaging and is one of the hot research topics in high resolution imaging field at present.This dissertation summarized the academic and experimental research on sparse aperture imaging technique.The background of this technique, including the development status both at home and abroad, was introduced at first. We also discussed fringe interferometry technique, and compared their characteristics. The issue studied in this dissertation was put forward.Then, a diffraction-limited incoherent imaging model was proposed and the theory of optical sparse aperture imaging system was described. The Point Spread Function (PSF) and the Modulation Transfer Function (MTF) formulas were given out. The typical configurations and the characteristics of the systems were introduced. The MTFs of the systems were related to the array configurations of sparse apertures. The cut-off spatial frequency was got higher at the cost of the loss of mid-spatial frequency.Maximal and minimum fill factors were presented, with the examples of Annulus, Tri-Arm and Golay configurations. The performances of the systems were analyzed and compared under different circumstances, such as the aperture configurations and the fill factors. The computer imaging simulations were done for these systems. Different kinds of criterions were used to evaluate the imaging quality.Furthermore, co-phasing errors which would degrade the performance of sparse aperture imaging system were analyzed. Criterions were given out to evaluate the degradation. The co-phasing error analysis and computer imaging simulation were done for typical array configurations.A simple laboratory verification experiment was performed after theoretical studies.Finally, the contents in this dissertation were summarized, and the work that could be done in the future was put forward.