A storage device that records binary information in the form of holograms, which are produced (as interference patterns) on photographic or photochromic media by means of laser beams, and are read by means of low-power laser beams. The advantage of a hologram is the way in which the image is dispersed over the recording surface so that dust or scratches do not totally obscure data though they may reduce the contrast. Several projects have attempted to apply this technology but none have yet been commercially successful.