Copying holograms.

A technique for producing many copies from one hologram is presented. This method involves using either the real or the virtual image (or both) reconstructed by a hologram as an object for a second hologram, with the undiffracted or zero-order wavefront being used as the reference beam. Such a procedure allows duplicating the first hologram without requiring close contact between the two emulsions involved. As in the recording of original holograms, a laser is used for the copying described.