Analytical expressions for diffraction-free beams through an opaque disk Qiulin Huang, Sebastien Coëtmellec, Fabrice Duval, Anne Louis, Herve Leblond and Marc Brunel J. Eur. Opt. Soc.-Rapid Publ., 6 (2011) 11031 Published online: 03 June 2011 DOI: 10.2971/jeos.2011.11031