LASER-BEAM APODIZER UTILIZING GRADIENT-INDEX OPTICAL EFFECTS IN CHOLESTERIC LIQUID-CRYSTALS

The fabrication of laser beam apodizers (or soft apertures) with large clear apertures using cholesteric liquid crystals is described. A soft edge profile is achieved by filling a cell with two separate cholesteric liquid crystal mixtures with different selective reflection bands. The fluidlike property of liquid crystals allows them to mix at the interface. In this overlap region, the reflectivity changes as a function of position. This concept is applied to the fabrication of two devices: (1) a one-dimensional beam apodizer with a clear aperture that can be mechanically adjusted by sliding two complementary devices relative to each other and (2) a circular beam apodizer.