Computer generated holograms: iterative and Coordinate transform interconnects

The computer generated hologram (CGH) may be used to produce an optical fan out. This fan out element is a fundamental unit in all parallel optical computing architectures. Optical fan out may be accomplished using optically produced holograms in a computer controlled scheme. The CGH allows for totally flexible and precise control of beam directions and intensity. These digital holograms model the optical holographic method and produce a complex output pattern which must be rendered at a usable size. The holograms presented are all directly fabricated at a usable size for optical reconstruction at 633 nm. A custom built optical plotter has been constructed with gray level capability which can write structure down to 3 μm. The low diffraction efficiency associated with amplitude transmission CGHs may be overcome by holographic copying into volume materials to form computer originated holographic optical elements (COHOES). The authors overview the optical plotter and presents two methods of synthesising suitable phase only CGH to implement optical fan out