Holographic multiple imaging: successive simplifications of principles of realization

By a suitable change in the distribution of n point sources giving rise to an interferogram, gratings can be obtained for image multiplication by a factor n(n - 1), instead of conventional point holograms, yielding n - 1 images. As n = 3 or 2, the diffraction rate can be improved by bleaching the interferograms. Moreover such an operation allows to make use of the central image as well as spurious images related to non linearities of the photographic emulsion.