Imaging through disturbing media using hybrid interferometric techniques.

Abstract

A fundamental extension of the phase conjugation imaging process is proposed and demonstrated. In the present work, the coherence of the illuminating source is reduced, leading to systems with partially coherent or even completely incoherent illumination which nevertheless retain the ability to correct distorted images. Contrary to the usual expectation, it is further found that the reduction of the imaging system aperture does not reduce the resolution in this method, and the reduction in the degree of coherence of the illumination does not diminish the efficacy of the phase conjugation process. On the contrary, this restructuring of a phase conjugation system can significantly enhance its capability to image through inhomogeneities by avoiding some of the basic limitations that previously existed. Of particular significance in the present work is a demonstration that with these techniques the previously severely limited process of one-way phase conjugation can achieve perfect aberration correction, just as in conventional two-way phase conjugation. In the system described, an object bearing wave makes only a single pass through an inhomogeneity, but is shown to behave as if a double pass had been made. The analysis treats the new system as a highly generalized phase conjugation system, which in the limit of full aperture and full coherence reduces to the case of conventional phase conjugation.