Abstract
The equation for partially coherent high-numerical-aperture scalar imaging was originally derived by Cole et al. [Jpn. J. Appl. Phys. 31, 4110 (1992)]. Here I present an alternative derivation, based on the plane-wave spectral representation of propagation, which can, at least in some respects, be viewed as more straightforward. © 2001 Optical Society of America.