Focusing of partially coherent light in systems of large Fresnel numbers

摘要

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 [S0740-3232(97)00602-9]