Spherical aberration effects in lens-axicon doublets: theoretical study.

Effects of spherical aberrations in converging and diverging lens-axicon doublets are investigated. Intensity profiles are obtained in the line and ring focal regions by numerically solving the Fresnel-Kirchhoff integral. Comparisons with aberration-free computations show that higher peak irradiances occur for the converging doublet when spherical aberrations are included. Results are presented for axicons with small apex angles in lens-axicon combinations illuminated by collimated Gaussian 1.064-mum laser beams.