Due to a publisher oversight, this article [J. Biomed. Opt. 13, 050507 (2008)] was originally published online on 9 October 2008 with an error in Sec. 3.

In the sentence that reads “In the experiments, the fluorescent dye was excited with continuous-width laser light...” the phrase “continuous-width” has been changed to “continuous-wave.” All online versions of the article were corrected on 18 November 2008.