A theory is developed for analyzing the structure of a focused random field in systems of large Fresnel numbers. The analysis provides a general expression for the cross-spectral density of the focused field in terms of the cross-spectral density of the random field on a spherical reference surface in the region of the diffracting aperture. The results are illustrated by considering the structure of the focal region in a field produced by focusing a partially coherent wave whose correlation function is frequently encountered in practice.
© 1997 Optical Society of America
Original Manuscript: February 5, 1996
Manuscript Accepted: September 16, 1996
Published: February 1, 1997
Weijian Wang, Ari T. Friberg, and Emil Wolf, "Focusing of partially coherent light in systems of large Fresnel numbers," J. Opt. Soc. Am. A 14, 491-496 (1997)