This article [Opt. Eng. 53(5), 051405 (2014)] was originally published on 6 December 2013 with an error in Eqs. (1) and (9). The refractive index should be in the denominator rather than the numerator in the first term on the right hand side of these equations. The corrected equations are printed below:
The paper was corrected online on 11 July 2017.