Laserdisc

Laserdisc or Videodisc, optical storage device in the form of a thin, circular plastic platter that contains video and audio information. The laserdisc appeared in 1978 and was used during the 1980s and 1990s as a format for prerecorded motion pictures intended for home television viewing. The format could also contain educational information such as encyclopedias or collections of still photographs. Laserdiscs provided higher-quality video and sound than videocassettes but never achieved wide popularity. The format was superseded by the DVD (digital versatile disc), which was introduced in 1997 and went on to enjoy enormous commercial success.

The laserdisc was the about the size of a 12-in vinyl record and typically had recorded material on both sides. In the laserdisc system the original video signals were encoded as tiny elliptical depressions on a plastic disc. The information was arranged in a single long spiral, like the groove of a phonograph record. To play back the images, the track was scanned by a very narrow laser beam. Light from the laser beam, as modified by the tiny depressions, was converted back into the original patterns of electrical signals that were then fed by cable into a standard television receiver. Information-storage capability was so high that a full-length motion picture or the text of an entire encyclopedia could be stored on one disc. However, laserdiscs could only contain prerecorded material and could not be rewritten with new content.

In addition to superior picture and sound, laserdiscs were appreciated by devoted fans of motion pictures and video for bonus features such as commentaries or extra scenes, and the ability to quickly access particular content. Such bonus features were later incorporated into DVDs. The much greater success of DVDs was due in part to a more convenient physical size (the size of a compact disc), greater storage capacity (a full movie on a single side), and lower costs. In particular, the price of DVD players quickly became competitive with that of videocassette recorders. The development of DVD recorders and recordable DVDs also gave DVDs a major advantage over laserdiscs.