Abstract

Iterative algorithms such as projections onto constraint sets (POCS) are successful in designing continuous phase structures but have a stagnation problem in designing quantized phase structures. The fewer quantization levels used, the easier the iterations stagnate. The performance of the iterative algorithms can be improved by a number of techniques. An iterative interlacing approach that explores the property of subfields separated in space and combats the residual quantization error stepwise has a superior performance over the regular POCS method. We introduce an extension of this new method, particularly for four levels of phase quantization. Experimental results indicate that this modified iterative interlacing approach reduces the reconstruction error even further compared with a direct quantized phase design. Recent implementations with the e-beam and the reactive ion-etching technologies are also discussed.

© 1992 Optical Society of America