Iterative algorithm for determining optimal beam profiles in a three-dimensional space

A new, to our knowledge, iterative algorithm for achieving optimization of beam profiles in a three-dimensional volume is presented. The algorithm is based on examining the region of interest at discrete plane locations perpe ndicular to the propagation direction. At each such plane an intensity cons traint is imposed within a well-defined transverse spatial region of intere st, whereas the phase inside that region as well as the complex amplitude o utside the region is left unchanged from the previous iteration. Once the o ptimal solution is found, the mask that generates the desired distribution can be readily implemented with a planar diffractive optical element such a s a computer-generated hologram. Several computer simulations verified the utility of the proposed approach. (C) 1999 Optical Society of America OCIS codes: 140.3300, 090.1760.