Magnetic field distribution of a highly focused radially-polarized light beam

Abstract

A simple expression for the magnetic filed of a highly focused radially polarized light is derived and the incorrect results for the time averaged Poynting vector and the trapping stability for a gold particle presented in the paper "Trapping metallic Rayleigh particles with radial polarization" by Zhan (Opt. Express 12, 3377-3382 (2004)) are corrected.