Optical Recording: Optical storage systems consist of a drive unit and a storage medium in a rotating disk form. In general the disks are pre-formatted using grooves and lands (tracks) to enable the positioning of an optical pick-up and recording head to access the information on the disk. Under the influence of a focused laser beam emanating from the optical head, information is recorded on the media as a change in the material characteristics, often using a thermally induced effect. To record a bit, a small spot is generated on the media modulating the phase, intensity, polarization, or reflectivity of a readout optical beam which is subsequently detected by a detector in the optical head.
Advantage of DVD over CD player:
1. Capacity is more
Disadvantage of DVD over CD- expensive
