Study On Optical Synthetic Aperture Images High-resolution Reconstruction Algorithms

In remote sensing observation to the earth, images with exceeding 1m spatial resolution have already been obtained successfully. In order to realize precise apperception and control in the observation, many countries have made great effort to develop higher resolution imaging sensors. High-resolution should be achieved by using an optical system with a large aperture and a long focus. However, limited by the optical material, cost, volume and weight of a mirror, a large filled-aperture system is very difficult to be manufactured and sent into orbit. Optical synthetic aperture imaging systems are composed of several smaller subapertures which are arrayed in some rules. If arrayed regularly, they are phased to form a common image field, and then a larger effective primary diameter is synthesized to obtain higher spatial resolution than that achievable with a monolithic mirror system. These systems is a new develop direction of a new generation remote sensors and make very large aperture remote sensors possible and take remote sensing observation into a revolutionary period.Optical synthetic aperture imaging systems provide a potential avenue for overcoming problems of the size and weight issues associated with deploying a large monolithic mirror system. However, compared with the monolithic mirror system, only part beam could go through the aperture, and the imaging resolution is lower. Therefore, high-resolution image reconstruction is indispensable to obtain useful remote sensing images. As a part of hardware equipments development, study in optical synthetic aperture images high-resolution reconstruction could provide technical support to manufacture hardware equipments. Study and experiment results in image reconstruction could establish a stable base for the continuing software system development, and it is of great importance for the new generation very high-resolution sensors to improve earth observation ability.Emphasis study is given on the high-resolution reconstruction of optical synthetic aperture images. The main work and innovations in the thesis are listed as follows.1 The principle, imaging model, array configuration and characteristic parameters of optical synthetic aperture system are presented, and character of modulation transfer function of the system is analyzed in detail.2 Evolution and status of the image high-resolution reconstruction technique are summarized, and classification of reconstruction algorithms is introduced. Characters and limitations of some algorithms are analyzed. Evaluation factors used as quantitative analysis criterion to estimate reconstruction effect of images are discussed. Good preparation has been done for the next step to design and realization of reconstruction algorithms. 3 A new high-resolution reconstruction method of optical synthetic aperture images based on Laplacian operator and increment Wiener filter is realized. In the Wiener filter process an effective method to regularize parameters and estimate SNR is used. Experiment results show that Laplacian operator could improve contrast of the whole image, and the increment Wiener filter could restore the image fine.4 An improved APEX algorithm is proposed and realized. The new PSF is got by weighted average to the class G PSF estimated in APEX and the PSF obtained in observation, and then SECB algorithm is used to restore images. Experiment results show that the algorithm could not only restore optical synthetic aperture images of resolution plank well, but also has good reconstruction effect to different array optical synthetic aperture images of remote sensing negative.