Abstract

An image of a planar object obscured by a moving diffuser can be obtained if the diffuser is illuminated by a coherent plane wave and coherence measurements are made on the wave field reflected by the object back through the diffuser. The image distribution is given by the intensity that would be observed were the object illuminated directly by a plane wave and the reflected wave allowed to propagate one-half the diffuser-object distance. Improved signal-to-noise ratio is achieved if two-point illumination is coordinated with the two-point coherence measurements. Further analysis shows that (1) similar imaging can be performed even with a fixed diffuser and (2) a simpler noninterferemetric measuring system can be used if the diffuser is a pure phase screen. Partial phase conjugation associated with enhanced backscatter plays the key physical role in this process. An important aspect of the analysis is the decomposition of the object distribution into Fresnel transform components.

© 1991 Optical Society of America