ABSTRACT
Optical data storage has a long history dating back to the 1960s but, with the compact disk initially, it
became relevant to the consumer and industry. The success of the early laser disk indicated the
possibility of data storage based on optical phenomena and materials as an alternative to magnetic
storage. Optical storage offers reliable and removable storage media with excellent robustness and
archival lifetime and very low cost. Today, optical disk technology covers a wide variety of applications
ranging from content distribution to professional storage applications. One of the major application
areas for optical storage disks is the secondary storage of computer data in PCs and computer networks.
An optical storage system is a particularly attractive component of the data storage network because it
provides fast data access times and fair storage capacities while serving as a link between different
multimedia and computerized systems. Perhaps, the most enabling feature of optical storage is the
removability of the storage medium which allows transportation and exchange of the stored information
between desktop and laptop computers, audio, video players and recorders. In contrast to the flying
head of a hard disk drive, there are separations of a few millimetres between the recording surface and
the optical ‘head’ while active servo systems enable dynamic recording and readout from a rotating disk.
Consequently, the medium can be removed and replaced with relatively loose tolerances allowing an
optical disk to be handled in different drives.
