Optical discs are CDs that can be formatted as DVDs, CDs, read-only or rewritable. They are compact, lightweight, rugged and digital, and replaced vinyl records, cassettes, video tapes and floppy disks. The technology is based on light, and a laser beam follows a spiraling trail of holes and lands in the plastic material of the disc. Optical discs are increasingly used for data storage such as backup and archiving, and can be purchased in many formats.
An optical disc is a compact disc or CD. Formatting it will determine whether it is a DVD, CD, read-only or rewritable. They replaced vinyl records, cassettes, video tapes and floppy disks.
Optical disc has become the preferred medium for music, movies and software programs due to its many advantages. Compact, lightweight, rugged and digital, they also provide as little as 650 megabytes (MB) of data storage. A double-layer, double-sided DVD can hold up to 15.9 gigabytes (GB) of data.
This form of media is so called because its technology is based on light. As the disc spins, a laser beam follows a spiraling trail of holes and lands in the plastic material of the disc. Pits reflect light differently than earths, while a device translates the reflective difference into “on/off” bits or 1s and 0s. The bits form bytes that carry the digital code of data stored on the optical disc.
A standard optical disc measures 4.724 inches (120 mm) in diameter and 0.0472 inches (1.2 mm) thick. It is made of polycarbonate with a reflective layer of aluminum, coated with lacquer. The main disc is made of glass. Nickel stencils are produced by the master glassmaker and used in an injection molding machine to “stamp” or produce multiple copies for distribution. If the disc is double layered, there will be stencils for each layer, after which the two layers need to be glued together. A double-sided disc requires different stencils for each side, as well as each layer.
Despite digital music, movies and photographs, optical disc is increasingly being used for data storage such as backup and archiving. Instant file access and the ability to use a built-in DVD player make it a superior choice over legacy tape backup drives for the average computer user.
A blank optical disc can be purchased in many formats. The least expensive will be an audio CD, as these are single-sided, single-layered, and non-rewritable. DVDs are more expensive, with a double-sided, dual-layer disc being the most expensive. Before buying this type, please make sure your DVD player can handle the format. Blank discs are available almost everywhere music, DVD movies and computers are sold, including discount department stores.
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