Production Glossary
Optical Disk
An optical disk is another name for a CD, or compact disk. The type of disk (DVD, CD, read-only, or re-writable) is determined by how the disk is formatted. Optical disks can be used for both storage and to view the contents of the disk (as with a DVD). The optical disk was instantly popular because of it’s durability and compactness. A basic CD can store up to 650 MB of data while a DVD, since it is two-sided and layered twice, can hold up to 15.9 GB of data.The standard CD is 4.724 in. in diameter, with a thickness of .0472 in. The polycarbonate disk has a layer of aluminum applied, which is then coated in lacquer. A master disk, crafted out of glass, is made in order to facilitate the making of copies. These master disks are coated in nickel to produce a mold for the disk to be formed from.
How it Works
The disk is placed into a computer or DVD player to be read. The device spins the disk and produces a laser beam that tracks a circular trail of pits that ends up in the plastic element of the disk. The pits cast light that permits the device to interpret the difference into “bits” of on/off or 1 and 0. These bits in turn produce bytes that channel the digital codes of stored data.
