TY - JOUR AU - H. Lin, B. Jia and M. Gu TI - Generation of an axially super-resolved quasi-spherical focal spot using an amplitude-modulated radially polarized beam JF - Optics Letters VL - 36 IS - 13 SP - 2471-2473 PY - 2011 N1 - doi: 10.1364/ol.36.002471 UR - http://dx.doi.org/10.1364/ol.36.002471