Abstract

A new mathematical technique for obtaining solutions to certain types of inverse propagation problem is presented. Specifically, propagation from a planar secondary source of any state of coherence is considered. It is shown how, in circumstances when contributions from evanescent waves may be neglected, the cross-spectral density function in the source plane may be determined from measurements of the cross-spectral density in any plane parallel to the source. The method, which is based on the coherent-mode propagation in spatially bandlimited wave fields,¹ is illustrated by results obtained from computer simulation. The method appears to be particularly suited to determining the mode structure of a source, e.g., a laser, from correlation measurements made at an arbitrary distance from it.

© 1987 Optical Society of America