A volume holographic memory has a spinning disk comprised of photorefractive medium, object beam optics configured to direct an object beam through the outer edge of the disk, and reference beam optics configured to simultaneously direct a reference beam through the outer edge of the disk. An angle multiplexer...http://www.google.de/patents/US5966361?utm_source=gb-gplus-sharePatent US5966361 - Spinning disc volume holographic memory
