Optical disc

From Encyclopedia Jr, free information reference for Kids

The optical lens of a compact disc drive.

In computing, sound reproduction, and video, an optical disc is a flat, circular, usually polycarbonate disc whereon data is stored in the form of pits (or bumps) within a flat surface. This data is generally accessed when a special material on the disc (often aluminum) is illuminated with a laser diode. The pits distort the reflected laser light.

David Paul Gregg developed an analog optical disc for recording video and patented it in 1961 and 1969 (U.S. patent 3,430,966). Of special interest is U.S. Patent # 4,893,297, first filed in 1968 and issued in 1990, so that it will be a source of royalty income for Pioneer’s DVA until 2007. It encompasses systems such as CD, DVD, and even Blu-ray Disc. Gregg's company, Gauss Electrophysics, was acquired, along with Gregg's patents, by MCA in the early 1960s.

Parallel, and probably inspired by the developments in the U.S., a small group of physicists started their first optical videodisc experiments at Philips Research in Eindhoven, The Netherlands in 1969. In 1975, Philips and MCA decided to join forces. In 1978, much too late, the long waited laserdisc was introduced in Atlanta. MCA delivered the discs and Philips the players. It turned out to be a total technical and commercial failure, and quite soon the Philips/MCA cooperation came to an end. In Japan and the U.S., Pioneer has been successful with the videodisc until the advent of DVD.

Philips and Sony formed a consortium in 1979 to develop a digital audio disc, which resulted in the very successful introduction of the compact disc in 1983.

The promotion of standardised optical storage is undertaken by the Optical Storage Technology Association (OSTA).

The information on an optical disc is stored sequentially on a continuous spiral track from the innermost track to the outermost track.

[edit] First-generation optical discs

Optical discs were initially used for storing music and software. The Laserdisc format stored analog video, but it fought an uphill battle against VHS.

• Compact disc (CD)
• Laserdisc
• Magneto-optical disc

[edit] Second-generation optical discs

Second-generation optical discs were created to store large amounts of data, including TV-quality digital video.

• Minidisc
• Digital Versatile Disc (DVD)
• Digital Multilayer Disk
• Digital Video Express
• Fluorescent Multilayer Disc
• GD-ROM
• Phase-change Dual
• Universal Media Disc

[edit] Third-generation optical discs

Major third-generation optical discs are currently in development. They will be optimal for storing high-definition video and extremely large video games.

• Blu-ray Disc
• Enhanced Versatile Disc
• Forward Versatile Disc
• Holographic Versatile Disc
• HD DVD
• Ultra Density Optical
• Professional Disc for DATA
• Versatile Multilayer Disc

[edit] Optical discs in development

• Protein-coated disc

[edit] References

• http://web.mit.edu/invent/iow/russell.html
• http://seattletimes.nwsource.com/html/businesstechnology/2002103322_cdman29.html
• http://inventors.about.com/library/inventors/blopticaldisk.htm

[edit] External links

• Optical Storage Technology Association
• The Authoritative Blu-ray Disc (BD) FAQ by Hugh Bennett
• The Authoritative HD DVD FAQ by Hugh Bennett
• Understanding Recordable & Rewritable DVD by Hugh Bennett
• Understanding CD-R & CD-RW by Hugh Bennett