ELECTROMAGNETIC DIFFRACTION OF LIGHT FOCUSED THROUGH A PLANAR INTERFACE BETWEEN MATERIALS OF MISMATCHED REFRACTIVE-INDEXES - STRUCTURE OF THE ELECTROMAGNETIC-FIELD .2.

We consider the electromagnetic diffraction occurring when light is fo cused by a lens without spherical aberration through a planar interfac e between materials of mismatched refractive indices, which focusing p roduces spherical aberration. By means of a rigorous vectorial electro magnetic treatment developed previously for this problem by Torok et a l. [J. Opt. Soc. Am. A 12, 325 (1995)], the time-averaged electric ene rgy density distributions in the region of the focused probe are numer ically evaluated for air-glass and air-silicon interfaces as functions of lens numerical aperture and probe depth. Strehl intensity, lateral and axial sizes, and axial location of the probe are shown to be regu lar functions for low numerical apertures and probe depths but irregul ar functions for high numerical apertures and probe depths. An explana tion to account for these occurrences is presented that also explains some previous experimental results of confocal microscopy. (C) 1996 Op tical Society of America.