Researches Of The Phase Diversity Wave-front Reconstruction Techniques And Its Application In The High Resolution Image Restoration

As the existence of atmospheric turbulence, when the electromagnetic wave passes through the atmosphere, its amplitude and phase will produce a random fluctuation(wave front distortion) if satisfy the near field approximate condition, and as a result leading to astronomical image quality degradationl. Over the past 20 years, new high-resolution imaging methods have been proposed to overcome this natural limitation. They can be divided into two main kinds: One kind is active pre-detection compensation, like Adaptive Optics. It detects wave-front by wave-front sensor, and controls the deformation of the mirror to compensate the distorted wave front in real-time in order to correct the atmosphere. The other kind is passive post-detection compensation. For example, the Speckle Interferometry, which reconstruct the power spectrum of by a number of short exposure images and presently widely used image reconstruction technique, which based on wave front sensing methods.Phase diversity, discussed in this paper is a passive post-detection compensation method. It is based on GS algorithm and Misell algorithm, on the foundation of phase reconstruction technology, combined with image restoration technique, with the precondition that does not require the processing speed, phase retrieval problem from intensity measurements and the target image reconstruction method. Compared with other image restoration techniques, the most important advantage is that it can not only reconstruct the target image, but also can solve the phase distribution of the pupil.Firstly, This paper starts with the mathematical module of the astronomical image reconstruction, and then introduces introduced the relevant information of atmospheric model, the reason for using speckle image to reconstruct the astronomical images, and the physical model of the imaging system. Secondly introduced are three wave front sensors widely used in adaptive optics presently, and the typical image reconstruction techniques in the image reconstruction domain. At the third part of this paper, using rigorous mathematical method to derive the principle of phase retrieval problem from intensity measurements, then GS algorithm, Misell algorithm and Phase diversity method are introduced detailedly. At the fourth part of this paper, using Phase diversity method, we realized (realize) the wave front reconstruction and image reconstruction of single and double star, and also show detailed experiment steps and the final results of experiment. At the end of this paper,â… outlined the work plan of the future.