Efficient method for evaluation of the diffraction efficiency upper bound of diffractive phase elements

The theoretical diffraction efficiency upper limit of diffractive phase ele ments (DPE's) with finite apertures is investigated. A successful numerical method of evaluating the efficiency upper bound of DPE's is proposed. The method includes a hybrid optimization procedure that combines a genetic alg orithm with the conjugate gradient method. This efficient global optimizati on technique can also be used to design DPE's. Simulation computations are detailed for rotationally symmetric beam shaping in which a Gaussian profil e laser beam is converted into a uniform beam. Numerical results demonstrat e that the estimated diffraction efficiency upper bound is consistent with the design results. (C) 2000 Optical Society of America OCIS codes: 050.197 0, 050.1940.