Abstract
Multilevel phase holograms can be obtained from the combination of two binary phase-only holograms set up in a fractional joint Talbot configuration. Among possible solutions, the quarter-Talbot location is of particular interest because it permits the generation of four-level phase holograms from the combination of two binary {0, pi} phase holograms. At the same time recent advances in electrically addressed ferroelectric liquid-crystal spatial light modulators for producing binary pure phase-only holograms make possible the implementation of programmable high-diffraction-efficiency computer-generated holograms. An extension of computer generation of holograms is proposed that includes spatial constraints related to the fractional Talbot effect.