Holographic video disk: an alternative approach to optical video disks.

Optical video disks employing time sequential coding are superior to mechanical video disks because of their noncontact reproducing capability. One drawback in the optical systems is the necessity of precise focusing and tracking adjustments. To solve this problem, an alternative approach, using a holographic technique that makes it possible to store a frame of information in a specified area redundantly, is proposed. A design concept and experiments relating to the breakthroughs are described. A combination of random phase sampling holography and coherently superimposing holography makes it possible to store color-encoded images sufficient for about a 30-min motion picture on a disk of 300 mm in diameter. A sound recording technique suitable for the holographic video disk, constituting one-dimensional hologram-type, pulse-coded-modulation signals, is proposed.