ELECTRICALLY CONTROLLABLE MULTIPLE, ACTIVE, COMPUTER-GENERATED HOLOGRAM

The multiple, active, computer-generated hologram (MACH) is a novel de vice combining the attributes of electrically controllable diffraction gratings and computer-generated holograms. The version discussed here consists of a surface relief transmitting structure immersed in a nem atic liquid crystal and sandwiched between two, planar indium tin oxid e electrodes. Under control of a single applied voltage, the device ca n selectively generate any one of a number of desired, uncorrelated op tical wave fronts. The device principles are discussed and experimenta l results presented. There is a brief discussion of the relative merit s of the MACH and electrically addressed spatial light modulators.