<title>Hidden phase approaches in recovering images from coherently illuminated objects</title>

Abstract

Phase differences on a sampled grid in the pupil plane of a coherent imaging system are used in conjunction with a hidden phase approach to estimate images of coherently illuminated objects in the presence of additive Gaussian noise. The imaging system is located in the far-field with respect to the illuminated objects. Conventional least squares and minimum variance image reconstruction approaches are shown to fail because of the presence of point discontinuities in the far-field speckle pattern. Conventional phase reconstruction techniques can not properly sense the phase effects resulting from these point discontinuities or branch points. However, these conventional image reconstruction techniques can be made to work with the addition of a hidden phase term that accounts for the phase effects resulting from the branch points. The hidden phase term is added to the results of both the least squares and minimum variance phase reconstructors and the addition of the hidden phase term is shown to successfully recover the images of several types of extended objects.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.