Efficient optimization of diffractive optical elements based on rigorous diffraction models

An efficient optimization strategy for the design of diffractive optical el ements that is based on rigorous diffraction theory is described. The optim ization algorithm combines diffraction models of different degrees of accur acy and computational complexity. A fast design algorithm for diffractive o ptical elements is used to yield estimates of the optimum surface profile b ased on paraxial diffraction theory. These estimates are subsequently evalu ated with a rigorous diffraction model. This scheme allows one to minimize the need to compute diffraction effects rigorously, while providing accurat e design. We discuss potential applications of this scheme as well as detai ls of an implementation based on a modified Gerchberg-Saxton algorithm and the finite-difference time-domain method. Illustrative examples are provide d in which we use the algorithm to design Fourier array illuminators. (C) 2 001 Optical Society of America.