We introduce the so-called moment expansion of a defocused image as a tool for analyzing and improving the depth of focus in optical imaging. It is shown that a number of previously noted defocus phenomena can be readily derived or explained in terms of moment expansion. Some potential applications of the moment expansion to phase-shifting mask and pupil filter design for optical lithography are also briefly noted.
© 1995 Optical Society of America
Original Manuscript: May 15, 1995
Published: September 15, 1995
Yao-Ting Wang, Y. C. Pati, and Thomas Kailath, "Depth of focus and the moment expansion," Opt. Lett. 20, 1841-1843 (1995)