Method for designing arbitrary two-dimensional continuous phase elements

We propose a method for designing arbitrary two-dimensional continuous phas e elements. The phase anomalies that are due to amplitude zeros that occur in conventional design methods can be avoided completely with this method. Therefore the method is also useful for designing holographic elements that are free from amplitude zeros. The method is based on an iterative Fourier -transform algorithm. In the iteration process the method operates on the u nwrapped phase. Consequently, a subsequent continuation step is not needed. (C) 2000 Optical Society of America.