The transfer function of an annular aperture in the presence of spherical aberration and defocusing is evaluated. The technique employed is the sampling method developed in a previous paper. The Maréchal aberration-balancing theory is extended to annular apertures. Representative numerical results are discussed.
RICHARD BARAKAT and AGNES HOUSTON, "Transfer Function of an Annular Aperture in the Presence of Spherical Aberration," J. Opt. Soc. Am. 55, 538-539 (1965)