SURFACE-RELIEF DIFFRACTION GRATINGS RECORDED BY MULTIPLE-BEAM COHERENT PHASE EXPOSURE

Surface-relief hexagonal-array diffraction gratings have been produced by three-beam coherent exposure. Collimated light was used in an atte mpt to produce a uniform relief profile over the total area of a 7.6-c m plate coated with a positive photoresist. The resulting gratings wer e reproduced in nickel by an electroforming process and analyzed by at omic force microscopy. The topography of the gratings was found to be that predicted by theory. The results obtained show that the gratings were of uniform profile over their total area. (C) 1997 Optical Societ y of America.