The past 10 years have seen the optical storage business go from
non-existent to a rapidly growing business offering a diversity of
products with enhanced storage capacities, such as disks (128 megabytes
to 20 gigabytes), tape (50 gigabytes to 1 terabyte), and card
(4 megabytes). Two of the major attractions of optical storage systems
are their ability to store large amounts of information in a reasonably
small volume and their long storage times ( years). Although the
existing media are planar, there is considerable research into
three-dimensional (and even four-dimensional) optical storage systems.
These will be treated separately for the purposes of this technology
introduction.