ABSTRACT
The alternatives to conventional storage techniques include near-field recording, which employs near-
field coupling of light in and out of the medium and requires close proximity of the optical stylus and the
media; optically assisted magnetic recording; probe tip storage, using a large number of submicron scale
probes and direct interaction with the recording medium surface; and volumetric recording, in which the
data is recorded throughout the volume of the storage medium rather than on the surface. Holographic
data storage is a volumetric approach which, although conceived decades ago, has made recent progress
toward practicality largely through advances in the enabling technologies, such as spatial light
modulators, low-cost visible light lasers, and CCD and CMOS detectors.
