A multilayer optical disk system, which includes an optical disk unit having a number of connected optical disks. A number of light sources, such as diode lasers, are used to provide a number of light beams of different wavelengths. A wavelength multiplexer combines the light beams into a single beam...http://www.google.co.uk/patents/US5526338?utm_source=gb-gplus-sharePatent US5526338 - Method and apparatus for storage and retrieval with multilayer optical disks
