Optical disc

"Optical media" redirects here.

Optical disc authoring
Optical disc Optical disc image Recorder hardware Authoring software Recording technologies Recording modes Packet writing
Optical media types
Laserdisc Compact Disc/CD-ROM: CD-R, CD-RW DVD: DVD-R, DVD-R DL, DVD+R, DVD+R DL, DVD-RW, DVD+RW, DVD+RW DL, DVD-RAM Blu-ray Disc: BD-R, BD-RE HD DVD: HD DVD-R
Standards
Rainbow Books File systems ISO 9660 Joliet Rock Ridge Amiga extensions to Rock Ridge El Torito Apple ISO9660 Extensions Universal Disk Format Mount Rainier

The optical lens of a compact disc drive.

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1. This article lists various types of optical discs, such as compact disc, laser disc, DVD, and so forth (in sections on 1st-gen, 2nd-gen, 3rd -gen optical discs). Please briefly mention the main feature(s) of each type of optical disc, especially in terms of what types of functions it can serve.
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An optical disc derives its name from the use of intense light, usually in the form of red or blue laser light to both write and read digital information on plastic discs. The technology became quite popular first in the digital reproduction and distribution of music in the form of compact discs (CDs), and later, as storage capacities grew, both film and video programming using digital video discs (DVDs). Beyond consumer entertainment applications, the technology is totally pervasive in personal computing and used in both application software distribution and as a data storage and transport medium worldwide.

The popularity and rate of adoption of the optical disc medium has been unparalleled in the history of consumer electronics, as the technology found its place as the superior (digital) alternative to tape-based VHS and cassette tape (analog) technology. A digital copy not only created a perfect replication of the original source but, unlike analog tape, optical discs did not deteriorate under continued use. The DVD Entertainment Group (a Los Angeles based industry trade organization) cites a group sponsored 2002 study by Ernst & Young that reported since the inception of the DVD format in 1997, software shipments reached more than 790 million units, and 35.5 million hardware players in less than five years.

How it works

The technology works by adding pits (or bumps) to the flat surface of a disc, usually along a single spiral groove. This can cover the entire recorded surface of the disc, and it is the density of the pits added to this surface that determines the all important data capacity. This differentiates between specific disc technologies in use today including CDs, DVD, (using red laser diodes) and the more recent blue laser disc technology called HD-DVD and Blu-ray.

This data is generally accessed when a special material on the disc (often aluminum) is illuminated with a laser diode. As mentioned above, various color lasers have been employed in this process including red and blue lasers. More recent developments in blue laser technology have enabled much higher capacity storage due to the higher frequency of blue light over red laser light technology.

Historical overview

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.

An acronym for Optical Disc Drives is ODD.

First-generation optical discs

<<In this and the following sections, please briefly mention the main feature(s) of each type of optical disc, especially in terms of what types of functions it can serve.>>

Optical discs were initially used for storing music and software. The Laserdisc format stored analog video, but it fought an uphill battle against VHS; other first-generation disc formats are designed to store solely digital data.

Most first-generation disc devices use an infrared laser as a read head, limiting the total capacity to, for example, 700MB for a 12cm compact disc.

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

Second-generation optical discs

Second-generation optical discs were created to store large amounts of data, including TV-quality digital video. Many, though not all, such discs use a visible light laser (usually red); the shorter wavelength allows a tighter beam, allowing the pits and lands of the disc to be smaller. In the case of the DVD format, this allows 4.7GB of storage on a standard 12cm, single-sided, single layer disc; alternately, smaller media such as the MiniDisc and DataPlay formats can have capacity approximately comparable to a much larger standard compact disc.

• Minidisc
• DVD and derivatives
  • DVD-Audio
  • DualDisc
  • Digital Video Express (DIVX)
• Super Audio CD
• Enhanced Versatile Disc
• GD-ROM
• Digital Multilayer Disk
• DataPlay
• Fluorescent Multilayer Disc
• Phase-change Dual
• Universal Media Disc

Third-generation optical discs

Major third-generation optical discs are currently in development. They are designed for holding high-definition video and sport larger capacities, enabled by the use of short-wavelength visible light lasers (blue-violet for BluRay and HD-DVD, the most common formats so far).

In practice, effective capacity for multimedia presentations can be drastically improved by using enhanced video data compression algorithms such as MPEG-4 as well.

• Currently shipping
  • Blu-ray Disc
  • HD DVD
  • Professional Disc for DATA

• In development
  • Forward Versatile Disc
  • Total HD disc
  • Versatile Multilayer Disc
  • Ultra Density Optical

Next Generation Optical Discs

The following formats are so advanced they can be considered to be ahead of current (third gen) discs. All of the following discs have the potential of over 1 terabyte of space.

• Tapestry Media
• Holographic Versatile Disc
• Protein-coated disc

References

ISBN links support NWE through referral fees

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• 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

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

Credits

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• Optical disc  ^history

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