This article [Opt. Eng. 51, 026001 (2012)] was originally published on 1 March 2012 with numerous typesetting errors in mathematical characters throughout the paper. The corrected paper was reposted online in its entirety on 21 March 2012. The article appears correctly in print.
Any readers who downloaded this paper between 1 March and 12 March 2012 and would like a corrected version of the paper should contact the SPIE editorial office at firstname.lastname@example.org.