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Optical disc

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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 environmental problems

Optical discs are usually between 76 and 30 cm 3 to 12 in in diameter, with 12 cm 475 in being the most common size A typical disc is about 12 mm 005 in thick, while the track pitch distance from the center of one track to the center of the next ranges from 16 µm for CDs to 320 nm for Blu-ray discs

An optical disc is designed to support one of three recording types: read-only eg: CD and CD-ROM, recordable write-once, eg CD-R, or re-recordable rewritable, eg 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 eg for use in a CD player, video eg 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 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

Contents

  • 1 History
    • 11 First-generation
    • 12 Second-generation
    • 13 Third-generation
    • 14 Fourth-generation
    • 15 Overview of optical types
  • 2 Recordable and writable optical discs
  • 3 Specifications
  • 4 References
  • 5 External links

History

An earlier analog optical disc recorded in 1935 for Licht-Tone Orgel sampling organ

The first recorded historical use of an optical disc was in the 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 Lichttonorgel

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 DVD US Patent 3,430,966 It is of special interest that US Patent 4,893,297, filed 1989, issued 1990, generated royalty income for Pioneer Corporation's DVA until 2007 —then encompassing the CD, DVD, and 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, Sony and Philips licensed Russell's patents then held by a Canadian company, Optical Recording Corp in the 1980s

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 US 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 discs and Philips the players However, the presentation was a commercial failure, and the cooperation ended

In Japan and the US, 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 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 discsThe very first application of this kind was the Compact Disc CD which was used in audio systems

Sony and 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

The DVD disc appeared after the CD-ROM had become widespread in society

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 47 GB, and a CD about 700 MB

Comparison of various optical storage media

First-generation

Initially, optical discs were used to store music and 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 CLV, 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
  • LaserDisc
  • GD-ROM
  • Phase-change Dual
  • Double Density Compact Disc DDCD
  • Magneto-optical disc
  • MiniDisc

Second-generation

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 47 GB storage on a standard 12 cm, single-sided, single-layer disc; alternatively, smaller media, such as the DataPlay format, can have capacity comparable to that of the larger, standard compact 12 cm disc

  • DVD and derivatives
    • DVD-Audio
    • DualDisc
    • Digital Video Express DIVX
  • Nintendo GameCube Game Disc miniDVD derivative
  • Wii Optical Disc DVD derivative
  • Super Audio CD
  • Enhanced Versatile Disc
  • DataPlay
  • Universal Media Disc
  • Ultra Density Optical

Third-generation

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 DVD uses 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 H264/MPEG-4 AVC and VC-1

  • Blu-ray Disc up to 400 GB - experimental
  • Wii U Optical Disc 25 GB per layer
  • HD DVD discontinued disc format, up to 51 GB triple layer
  • CBHD a derivative of the discontinued disc format HD DVD
  • HD VMD
  • Digital Multilayer Disk
  • Fluorescent Multilayer Disc
  • Forward Versatile Disc

Fourth-generation

The following formats go beyond the current third-generation discs and have the potential to hold more than one terabyte 1 TB of data:

  • Archival Disc
  • Holographic Versatile Disc
  • LS-R
  • Protein-coated disc

Overview of optical types

Name Capacity Experimental Years
Laserdisc LD 03GB 1971-2001
Compact Disc CD 07-09GB 1981-today
MiniDisc MD 014GB 1989-today
Magneto Optical Disc MOD 01-167GB 1990-today
Digital Versatile Disc DVD 47-17GB 1995-today
LIMDOW Laser Intensity Modulation Direct OverWrite 26GB 10GB 1996-today
GD-ROM 12GB 1997-today
Fluorescent Multilayer Disc 50-140GB 1998-2003
Versatile Multilayer Disc VMD 5-20GB 100GB 1999-2010
Ultra Density Optical UDO 30-60GB 2000-today
FVD FVD 54-15GB 2001-today
Enhanced Versatile Disc EVD DVD 2002-2004
HD DVD 15-51GB 1TB 2002-2008
Blu-ray Disc BD 25GB
50GB
100GB BDXL
128GB BDXL
400GB 2002-today
Professional Disc for Data PDD 23GB 2003-2006
Digital Multilayer Disk 22-32GB 2004-2007
Multiplexed Optical Data Storage MODS-Disc 250GB-1TB 2004-today
Universal Media Disc UMD 09-18GB 2004-2014
Holographic Versatile Disc HVD 60TB 2004-today
Protein-coated Disc PCD 50TB 2005-today
M-DISC 4·7GB DVD format
25GB Blu-ray format
50GB Blu-ray format
100GB BDXL format
2009-today
Archival Disc 03-1TB 2014-today
Notes
  1. ^ Prototypes and theoretical values
  2. ^ Years from known start of development till end of sales or development

Recordable and writable optical discs

Main article: 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 CD-R and DVD-R are "Write once read many", while CD-RW and 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

Specifications

Base 1× and current maximum speeds by generation
Generation Base Max
Mbit/s Mbit/s ×
1st CD 117 656 56×
2nd DVD 1057 2536 24×
3rd BD 36 504 14×
Capacity and nomenclature
Designation Sides Layers
total
Diameter Capacity
cm GB
BD SS SL 1 1 8 78
BD SS DL 1 2 8 156
BD SS SL 1 1 12 25
BD SS DL 1 2 12 50
BD SS TL 1 3 12 100
BD SS QL 1 4 12 128
CD–ROM 74 min SS SL 1 1 12 0682
CD–ROM 80 min SS SL 1 1 12 0737
CD–ROM SS SL 1 1 8 0194
DDCD–ROM SS SL 1 1 12 1364
DDCD–ROM SS SL 1 1 8 0387
DVD–1 SS SL 1 1 8 146
DVD–2 SS DL 1 2 8 266
DVD–3 DS SL 2 2 8 292
DVD–4 DS DL 2 4 8 532
DVD–5 SS SL 1 1 12 470
DVD–9 SS DL 1 2 12 854
DVD–10 DS SL 2 2 12 940
DVD–14 DS DL/SL 2 3 12 1324
DVD–18 DS DL 2 4 12 1708
DVD–R 10 SS SL 1 1 12 395
DVD–R 20, +R, –RW, +RW SS SL 1 1 12 47
DVD-R, +R, –RW, +RW DS SL 2 2 12 940
DVD–RAM SS SL 1 1 8 146
DVD–RAM DS SL 2 2 8 265
DVD–RAM 10 SS SL 1 1 12 258
DVD–RAM 20 SS SL 1 1 12 470
DVD–RAM 10 DS SL 2 2 12 516
DVD–RAM 20 DS SL 2 2 12 940

References

  1. ^ Adedeji, Dr Adewole "COMBATING PIRACY THROUGH OPTICAL DISC PLANT REGULATION IN NIGERIA: PROSPECTS AND CHALLENGES" PDF 
  2. ^ Kinoshita, edited by Shuichi 2013 "652 Diffraction Grating" Pattern formations and oscillatory phenomena Online-Ausg ed Waltham: Elsevier p 240 ISBN 978-0-12-397014-5 Retrieved 8 October 2014 
  3. ^ Cornwall, Malcolm G January 1993 "CD means Colourful Diffraction" Physics Education 28 1: 12–14 doi:101088/0031-9120/28/1/002 Retrieved 8 October 2014 
  4. ^ Guides/Storage/CD-R/CD-RW – PC Technology Guide Pctechguidecom 1999-02-22 Retrieved on 2011-10-09
  5. ^ http://newsdesksiedu/releases/playback-130-year-old-sounds-revealed
  6. ^ Milster, Tom D "Optical Data Storage" The Pennsylvania State University CiteSeerX 1011926992 
  7. ^ Dudley, Brier 2004-11-29 "Scientist's invention was let go for a song" The Seattle Times Retrieved 2014-07-24 
  8. ^ "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 
  9. ^ "Inventor of the Week - James T Russell - The Compact Disc" MIT December 1999 Archived from the original on April 17, 2003 
  10. ^ HAWAN KIM, SUNG "June 2004" PDF Massachusetts Institute of Technology 
  11. ^ Hass, J Introduction to Computer Music, Indiana University CECM retrieved 8 October 2014, Volume One, Chapter Five: Digital Audio
  12. ^ DRAWBAUGH, BEN "HD DVD and Blu-ray movies released on June 20th 2006" Engadget International Editions 
  13. ^ a b Format War Update: Blu-ray Wins Over HD DVD Crutchfieldadvisorcom Retrieved on 2011-10-09
  14. ^ "Optical Carriers" PDF 
  15. ^ "Pioneer's Blu-ray disc hits 400GB across 16-layers" wwwengadgetcom 2008-07-07 
  16. ^ "Pioneer's 400 GB Blu-ray Disc" wwwgizmagcom 
  17. ^ 100 GB Disc
  18. ^ "LG BH14NS40 14x Blu-ray Disc ReWriter" CDRinfocom 
  19. ^ "DVD, Book A – Physical parameters" MPEG Retrieved 2011-10-09 
  20. ^ "DVD in Detail" PDF Cinram 27 November 2000 Archived from the original on October 29, 2008  CS1 maint: Unfit url link

External links

  • "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" Aboutcom Retrieved 2007-07-13 
  • Byers, Fred R 2003 "Care and Handling of CDs and DVDs — A Guide for Librarians and Archivists" PDF National Institute of Standards and Technology 
  • Romeyn, Jacob "50th-anniversary -of-the-optical-disc" 
  • "Optical Storage Technology Association" 
  • O'Kelly, Terence "Reference Guide for Optical Media" PDF Memorex Inc 
  • "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 San Antonio 

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