OPTICAL INFORMATION STORAGE AND RETRIEVAL

摘要

This invention provides for an information storage device that features at least one layer (14-28) containing a plurality of information storage zones (12) with the device being configured so that the electromagnetic reflection properties of the storage zones are individually alterable to one of at least four different reflective states. These states reflect one of at least two possible electromagnetic waves (38-42) having different characteristics, so as to store at least two bits of information at the storage zone. The Invention also provides a writer for storing information on the information storage device, a method of storing information on the information storage device, an information retriever for retrieving information from the information storage device, and a method of retrieving information from the information storage device.