Multiple object-beam holograms

A multiple object-beam holography is proposed, where a two-dimensional rectangular amplitude grating and a phase plate of matrix form placed at the frequency plane of the grating constitute the main parts of a speckle-free periodic illumination system of continuous tone transparencies. Demonstration experiments are made, where the number of diffracted orders of the grating, the ratio of the widths of transparent and opaque zones of the grating, the retardation of each matrix zone of the phase plate and the distance between planes of the image of the grating and a transparency are taken as variables.