Harry RAMENAH,^1,2 Poul BERTRAND² and Patrick MEYRUEIS¹

¹Laboratoire des Systèmes Photoniques, Boulevard Sebastien Brant France, 67400 Illkirch, ²Imagine Technologies Company, 115 chemin du Geffrier, 93190 Ollioules, France

(Received June 5, 1995; Accepted September 12, 1995)

Two thousand images of resolution 512×512 pixels as a regular matrix pattern of 10×10 elements are stored, where each element is angularly multiplexed 20 times in a 25 μm thickness of dichromated gelatin emulsion without cross-talk effect. The surface area of the matrix is 1 cm². We show good concordance of the angular selectivity between the experimental result and theory. The diffraction efficiency of each 20 multiplexed images is measured and has nearly the same value. Examples of reconstructed images for multiple applications are given, for example, storage of 160,000 images on a 3"1/2 floppy disc format, which is about 100 min of black and white film. Application can be made to automobile cartography and storage of X-ray images as well as weather forecast images. Colored diffractive images are also possible and are illustrated.

Key words : holography, holographic storage, page oriented memories, data storage, associative memories, angular multiplexing, cross-talk, multiple gratings