In computing and optical disc recording technologies, an optical disc
(OD) is a flat, usually circular disc which encodes binary data (bits)
in the form of pits (binary value of 0 or off, due to lack of
reflection when read) and lands (binary value of 1 or on, due to a
reflection when read) on a special material (often aluminium ) on
one of its flat surfaces. The encoding material sits atop a thicker
substrate (usually polycarbonate) which makes up the bulk of the disc
and forms a dust defocusing layer. The encoding pattern follows a
continuous, spiral path covering the entire disc surface and extending
from the innermost track to the outermost track. The data is stored on
the disc with a laser or stamping machine, and can be accessed when
the data path is illuminated with a laser diode in an optical disc
drive which spins the disc at speeds of about 200 to 4,000 RPM or
more, depending on the drive type, disc format, and the distance of
the read head from the center of the disc (inner tracks are read at a
higher disc speed). Most optical discs exhibit a characteristic
iridescence as a result of the diffraction grating formed by its
grooves. This side of the disc contains the actual data and is
typically coated with a transparent material, usually lacquer. The
reverse side of an optical disc usually has a printed label, sometimes
made of paper but often printed or stamped onto the disc itself.
Unlike the 3½-inch floppy disk, most optical discs do not have an
integrated protective casing and are therefore susceptible to data
transfer problems due to scratches, fingerprints, and other
Optical discs are usually between 7.6 and 30 cm (3 to 12 in)
in diameter, with 12 cm (4.75 in) being the most common
size. A typical disc is about 1.2 mm (0.05 in) thick, while
the track pitch (distance from the center of one track to the center
of the next) ranges from 1.6 µm (for CDs) to 320 nm (for
An optical disc is designed to support one of three recording types:
read-only (e.g.: CD and CD-ROM), recordable (write-once, e.g. CD-R),
or re-recordable (rewritable, e.g. CD-RW). Write-once optical discs
commonly have an organic dye recording layer between the substrate and
the reflective layer. Rewritable discs typically contain an alloy
recording layer composed of a phase change material, most often
AgInSbTe, an alloy of silver, indium, antimony, and tellurium.
Optical discs are most commonly used for storing music (e.g. for use
in a CD player), video (e.g. for use in a
Blu-ray player), or data and
programs for personal computers (PC). The Optical Storage Technology
Association (OSTA) promotes standardized optical storage formats.
Although optical discs are more durable than earlier audio-visual and
data storage formats, they are susceptible to environmental and
daily-use damage. Libraries and archives enact optical media
preservation procedures to ensure continued usability in the
computer's optical disc drive or corresponding disc player.
For computer data backup and physical data transfer, optical discs
such as CDs and DVDs are gradually being replaced with faster, smaller
solid-state devices, especially the USB flash drive.[citation
needed] This trend is expected to continue as USB flash drives
continue to increase in capacity and drop in price.
Additionally, music purchased or shared over the Internet has
significantly reduced the number of audio CDs sold annually.
1.5 Overview of optical types
2 Recordable and writable optical discs
5 External links
An earlier analog optical disc recorded in 1935 for Licht-Tone Orgel
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The first recorded historical use of an optical disc was in 1884 when
Alexander Graham Bell,
Chichester Bell and Charles Sumner Tainter
recorded sound on a glass disc using a beam of light.
An early optical disc system existed in 1935, named
An early analog optical disc used for video recording was invented by
David Paul Gregg in 1958 and patented in the US in 1961 and 1969.
This form of optical disc was a very early form of the
Patent 3,430,966). It is of special interest that U.S. Patent
4,893,297, filed 1989, issued 1990, generated royalty income for
Pioneer Corporation's DVA until 2007 —then encompassing the CD,
Blu-ray systems. In the early 1960s, the Music Corporation of
America bought Gregg's patents and his company, Gauss Electrophysics.
American inventor James T. Russell has been credited with inventing
the first system to record a digital signal on an optical transparent
foil which is lit from behind by a high-power halogen lamp. Russell's
patent application was first filed in 1966 and he was granted a patent
in 1970. Following litigation,
Philips licensed Russell's
patents (then held by a Canadian company, Optical Recording Corp.) in
Both Gregg's and Russell's disc are floppy media read in transparent
mode, which impose serious drawbacks. In the
Netherlands in 1969,
Philips Research physicist, Pieter Kramer invented an optical
videodisc in reflective mode with a protective layer read by a focused
laser beam U.S. Patent 5,068,846, filed 1972, issued 1991. Kramer's
physical format is used in all optical discs. In 1975,
Philips and MCA
began to work together, and in 1978, commercially much too late, they
presented their long-awaited
Laserdisc in Atlanta. MCA delivered the
Philips the players. However, the presentation was a
commercial failure, and the cooperation ended.
In Japan and the U.S., Pioneer succeeded with the videodisc until the
advent of the DVD. In 1979,
Philips and Sony, in consortium,
successfully developed the audio compact disc.
In 1979, Exxon STAR Systems in Pasadena, CA built a computer
controlled WORM drive that utilized thin film coatings of Tellerium
and Selenium on a 12" diameter glass disk. The recording system
utilized blue light at 457nm to record and red light at 632.8nm to
read. STAR Systems was bought by Storage Technology Corporation (STC)
in 1981 and moved to Boulder,CO. Development of the WORM technology
was continued using 14" diameter aluminum substrates. Beta testing of
the disk drives, originally labeled the
Laser Storage Drive 2000
(LSD-2000), was only moderately successful. Many of the disks were
shipped to RCA Laboratories (now David Sarnoff Research Center) to be
used in the Library of Congress archiving efforts. The STC disks
utilized a sealed cartridge with an optical window for protection U.S.
In the late 1980s and early 1990s, Optex, Inc. of Rockville, MD, built
an erasable optical digital video disc system U.S. Patent 5,113,387
using Electron Trapping Optical Media (ETOM)U.S. Patent 5,128,849.
Although this technology was written up in Video Pro Magazine's
December 1994 issue promising "the death of the tape", it was never
In the mid-1990s, a consortium of manufacturers developed the second
generation of the optical disc, the DVD.
Magnetic disks found limited applications in storing the data in large
amount. So, there was the need of finding some more data storing
techniques. As a result, it was found that by using optical means
large data storing devices can be made which in turn gave rise to the
optical discs.The very first application of this kind was the Compact
Disc (CD) which was used in audio systems.
Philips developed the first generation of the CDs in the mid
1980s with the complete specifications for these devices. With the
help of this kind of technology the possibility of representing the
analog signal into digital signal was exploited to great level. For
this purpose the 16 bit samples of the analog signal were taken at the
rate of 44,100 samples per second. This sample rate was based on the
Nyquist rate of 40,000 samples per second required to capture the
audible frequency range to 20 kHz without aliasing, with an
additional tolerance to allow the use of less-than-perfect analog
audio pre-filters to remove any higher frequencies. The first
version of the standard allowed up to 75 minutes of music which
required 650MB of storage.
DVD disc appeared after the
CD-ROM had become widespread in
The third generation optical disc was developed in 2000–2006, and
was introduced as
Blu-ray Disc. First movies on
Blu-ray Discs were
released in June 2006.
Blu-ray eventually prevailed in a high
definition optical disc format war over a competing format, the HD
DVD. A standard
Blu-ray disc can hold about 25 GB of data, a DVD
about 4.7 GB, and a CD about 700 MB.
Comparison of various optical storage media
Initially, optical discs were used to store broadcast-quality analog
video, and later digital media such as music or computer software. The
Laserdisc format stored analog video signals for the distribution of
home video, but commercially lost to the
VHS videocassette format, due
mainly to its high cost and non-re-recordability; other
first-generation disc formats were designed only to store digital data
and were not initially capable of use as a digital video medium.
Most first-generation disc devices had an infrared laser reading head.
The minimum size of the laser spot is proportional to the wavelength
of the laser, so wavelength is a limiting factor upon the amount of
information that can be stored in a given physical area on the disc.
The infrared range is beyond the long-wavelength end of the visible
light spectrum, so it supports less density than shorter-wavelength
visible light. One example of high-density data storage capacity,
achieved with an infrared laser, is 700 MB of net user data for a
12 cm compact disc.
Other factors that affect data storage density include: the existence
of multiple layers of data on the disc, the method of rotation
Constant linear velocity
Constant linear velocity (CLV),
Constant angular velocity
Constant angular velocity (CAV), or
zoned-CAV), the composition of lands and pits, and how much margin is
unused is at the center and the edge of the disc.
Compact Disc (CD) and derivatives
Video CD (VCD)
Super Video CD
Compact Disc (DDCD)
Write Once Read Many (WORM)
Second-generation optical discs were for storing great amounts of
data, including broadcast-quality digital video. Such discs usually
are read with a visible-light laser (usually red); the shorter
wavelength and greater numerical aperture allow a narrower light
beam, permitting smaller pits and lands in the disc. In the DVD
format, this allows 4.7 GB storage on a standard 12 cm,
single-sided, single-layer disc; alternatively, smaller media, such as
DataPlay format, can have capacity comparable to that of the
larger, standard compact 12 cm disc.
DVD and derivatives
Digital Video Express (DIVX)
Nintendo GameCube Game Disc (mini
Wii Optical Disc (
Super Audio CD
Enhanced Versatile Disc
Universal Media Disc
Ultra Density Optical
Third-generation optical discs are in development, meant for
distributing high-definition video and support greater data storage
capacities, accomplished with short-wavelength visible-light lasers
and greater numerical apertures.
Blu-ray Disc and HD
blue-violet lasers and focusing optics of greater aperture, for use
with discs with smaller pits and lands, thereby greater data storage
capacity per layer. In practice, the effective multimedia
presentation capacity is improved with enhanced video data compression
codecs such as
H.264/MPEG-4 AVC and VC-1.
Blu-ray Disc (up to 400 GB - experimental)
Wii U Optical Disc (25 GB per layer)
DVD (discontinued disc format, up to 51 GB triple layer)
CBHD (a derivative of the discontinued disc format HD DVD)
Digital Multilayer Disk
Fluorescent Multilayer Disc
Forward Versatile Disc
The following formats go beyond the current third-generation discs and
have the potential to hold more than one terabyte (1 TB) of data
and meant for distributing Ultra HD video :
Holographic Versatile Disc
Ultra HD Blu-ray
Stacked Volumetric Optical Disc
Overview of optical types
Write Once Read Many Disk (WORM)
Compact Disc (CD)
Electron Trapping Optical Memory (ETOM)
Magneto Optical Disc (MOD)
Digital Versatile Disc (DVD)
Laser Intensity Modulation Direct OverWrite)
Fluorescent Multilayer Disc
Versatile Multilayer Disc
Versatile Multilayer Disc (VMD)
Ultra Density Optical (UDO)
Enhanced Versatile Disc (EVD)
1 TB
Blu-ray Disc (BD)
128 GB (BDXL)
Professional Disc for Data (PDD)
Digital Multilayer Disk
Multiplexed Optical Data Storage (MODS-Disc)
250 GB–1 TB
Universal Media Disc
Universal Media Disc (UMD)
Holographic Versatile Disc
Holographic Versatile Disc (HVD)
Protein-coated Disc (PCD)
4.7 GB (
25 GB (
50 GB (
100 GB (BDXL format) 
Ultra HD Blu-ray
^ Prototypes and theoretical values.
^ Years from (known) start of development till end of sales or
Recordable and writable optical discs
Optical disc recording technologies
There are numerous formats of optical direct to disk recording devices
on the market, all of which are based on using a laser to change the
reflectivity of the digital recording medium in order to duplicate the
effects of the pits and lands created when a commercial optical disc
is pressed. Formats such as
DVD-R are "Write once read many",
DVD-RW are rewritable, more like a magnetic recording
hard disk drive (HDD). Media technologies vary,
M-DISC uses a
different recording technique & media versus
DVD-R and BD-R.
Base (1×) and (current) maximum speeds by generation
Capacity and nomenclature
CD–ROM 74 min
CD–ROM 80 min
DVD–R (2.0), +R, –RW, +RW
DVD-R, +R, –RW, +RW
^ Adedeji, Dr. Adewole. "COMBATING PIRACY THROUGH OPTICAL DISC PLANT
REGULATION IN NIGERIA: PROSPECTS AND CHALLENGES" (PDF).
^ Kinoshita, edited by Shuichi (2013). "6.5.2 Diffraction Grating".
Pattern formations and oscillatory phenomena (Online-Ausg. ed.).
Waltham: Elsevier. p. 240. ISBN 978-0-12-397014-5. Retrieved
8 October 2014. CS1 maint: Extra text: authors list (link)
^ Cornwall, Malcolm G (January 1993). "CD means Colourful
Diffraction". Physics Education. 28 (1): 12–14.
doi:10.1088/0031-9120/28/1/002. Retrieved 8 October 2014.
^ Guides/Storage/CD-R/CD-RW – PC Technology Guide.
Pctechguide.com (1999-02-22). Retrieved on 2011-10-09.
^ Avadhanulu, M. N. (2001). An Introduction to Lasers Theory and
Applications. S. Chand Publishing. ISBN 9788121920711.
^ Milster, Tom D. "Optical Data Storage". The Pennsylvania State
University. CiteSeerX 10.1.1.92.6992 .
^ Dudley, Brier (2004-11-29). "Scientist's invention was let go for a
song". The Seattle Times. Retrieved 2014-07-24.
^ "INVENTOR AND PHYSICIST JAMES RUSSELL '53 WILL RECEIVE VOLLUM AWARD
AT REED'S CONVOCATION" (Press release). Reed College public affairs
office. 2000. Retrieved 2014-07-24.
^ "Inventor of the Week - James T. Russell - The Compact Disc". MIT.
December 1999. Archived from the original on April 17, 2003.
^ HAWAN KIM, SUNG. "June 2004" (PDF). Massachusetts Institute of
^ Hass, J. Introduction to Computer Music, Indiana University CECM
(retrieved 8 October 2014), Volume One, Chapter Five: Digital
^ DRAWBAUGH, BEN. "HD
Blu-ray movies released on June 20th
2006". Engadget International Editions.
^ a b Format War Update:
Blu-ray Wins Over HD DVD.
Crutchfieldadvisor.com. Retrieved on 2011-10-09.
^ "Optical Carriers" (PDF).
Blu-ray disc hits 400GB across 16-layers".
^ "Pioneer's 400 GB
Blu-ray Disc". www.gizmag.com.
^ 100 GB Disc
^ "LG BH14NS40 14x
Blu-ray Disc ReWriter". CDRinfo.com.
^ "DVD, Book A – Physical parameters". MPEG. Retrieved
DVD in Detail" (PDF). Cinram. 27 November 2000. Archived from the
original on October 29, 2008. CS1 maint: Unfit url (link)
Wikimedia Commons has media related to Optical discs.
"Inventor of the Week Archive: The Digital Compact Disc".
Massachusetts Institute of Technology. December 1999. Archived from
the original on 2008-06-19. Retrieved 2007-07-13.
Dudley, Brier (November 29, 2004). "Scientist's invention was let go
for a song". The Seattle Times. Retrieved 2007-07-13.
"David Gregg and the Optical Disk". About.com. Retrieved
Byers, Fred R. (2003). "Care and Handling of CDs and DVDs — A Guide
for Librarians and Archivists" (PDF). National Institute of Standards
Romeyn, Jacob. "50th-anniversary -of-the-optical-disc".
"Optical Storage Technology Association".
O'Kelly, Terence. "Reference Guide for Optical Media" (PDF). Memorex
"The history of ideas "the optical disc as a "unique" carrier of
information in the systems management". European Society of the
History of Science.
"Thomson-CSF's transmissive videodisc".
"Know Your Digital Storage Media: a guide to the most common types of
digital storage media found in archives". USA: University of Texas at
Optical storage media
BD-R XL (2010)
BD-RE XL (2010)
DVD+R DL (2004)
DVD-R DL (2005)
Compact disc (1982)
Optical tape (20th century)
Optical disc (20th century)
Magneto-optic Kerr effect
Magneto-optic Kerr effect (1877)
MO disc (1980s)
Laser turntable (1986)