Array illumination with minimal non-uniformity based on generalized phase contrast

The generalized phase contrast method (GPC) has been previously shown to be an efficient technique for generating array illumination and is thus highly suitable for such applications as dynamic multiple beam trapping and optical micromanipulation. However, projected arrays usually exhibit intensity roll-offs that may be undesirable for some applications. We show that the uniformity of GPC-generated array illuminations can be improved using intuitive corrections to the input spatial phase modulation, by increasing or decreasing it to respectively raise or lower the intensity of the corresponding output spots to improve uniformity. This is combined with matching corrections to the phase shift introduced by the phase contrast filter. Results from numerical experiments show that the array illumination uniformity error improves from over 40% to less than 1% while maintaining the efficiency prior to implementing corrections. (c) 2008 Elsevier B.V. All rights reserved.