DESIGN AND FABRICATION OF COMPUTER-GENERATED BEAM-SHAPING HOLOGRAMS

For the design of computer-generated holograms reconstructing certain intensity patterns with phase freedom, we use an object-oriented appro ach. The given intensity pattern is decomposed into elementary objects for which appropriate phase-only hologram functions can be constructe d. The total hologram function is found by the subsequent superpositio n of its constituents, with a relative amplitude and phase weighting f or each of them. Thus, the degrees of freedom are dramatically reduced compared with those of sampling approaches. The design algorithm allo ws us to compensate on the one hand for the intensity and phase distri bution of the impinging laser beam and on the other hand for the shape of the hologram aperture. We report on the computer-aided design of s uch holograms, as well as their fabrication through the use of laser l ithography and reactive ion etching. Optical reconstructions are shown . (C) 1996 Optical Society of America