An error was made in calculating the complex electric field vector for the diffracted beams. We have corrected the error and repeated the optimization to achieve a phase mask design bearing the same result. The overall approach remains unchanged.
© 2008 Optical Society of America
In the article  we used a genetic algorithm to design a phase mask that produces a hexagonal array of helices in photoresist. The algorithm relies on the repeated calculation of the complex electric field vector, Ẽ, for each diffracted beam. We recently discovered that our calculations applied a spurious rotation to Ẽ, affecting the interference pattern that is formed. Consequently, the design shown in Fig.1 and Fig. 3 does not produce the intended target structure. We have corrected the error and rerun the optimization using the procedure outlined in the paper . The revised design obtains an enhanced fitness, F, of 94% and is shown along with the resultant structure in Fig. 1 below. The new polarization angles ψ and χ are 0.57 and 6.21 radians respectively. The thickness, h, of the grating layer is now 640 nm. The contrast (V) of the intensity distribution has decreased somewhat to 6.56. However, we believe the effective two-photon contrast, V eff=43.0, is more than sufficient for proper transfer into SU-8 photoresist.
1. J. W. Rinne, S. Gupta, and P. Wiltzius, “Inverse design for phase mask lithography,” Opt. Express 16, 663–670 (2008), http://www.opticsinfobase.org/abstract.cfm?URI=oe-16-2-663. [CrossRef] [PubMed]