title: Focal shifts in diffracted converging electromagnetic waves. II. Rayleigh theory.
abstract: Part II of this study is an application of the Rayleigh vector diffraction integrals to an investigation of the effect of focal shifts in converging spherical waves diffracted in systems of arbitrary relative aperture. The results are compared numerically with those obtained in Part I [J. Opt. Soc. Am. A 22, 68 (2005)] from the Kirchhoff vector diffraction theory. The effect of the numerical aperture (NA) on focal shifts can be considered in two regions: When NA < or = 0.5 the system behaves like an paraxial system, and the Fresnel number is the dominant factor. When 0.5 < NA < or = 0.9 the absolute value of the relative focal shift decreases with increasing value of NA.
authors.affiliation: yajun_li@yahoo.com
authors.forename: Yajun
authors.initials: Y
authors.lastname: Li