Electrically controllable multiple, active, computer-generated hologram.

The multiple, active, computer-generated hologram (MACH) is a novel device 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 nematic liquid crystal and sandwiched between two, planar indium tin oxide electrodes. Under control of a single applied voltage, the device can selectively generate any one of a number of desired, uncorrelated optical wave fronts. The device principles are discussed and experimental results presented. There is a brief discussion of the relative merits of the MACH and electrically addressed spatial light modulators.