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Optical storage is the storage of data on an optically readable medium. Data is recorded by making marks in a pattern that can be read back with the aid of light, usually a beam of laser light precisely focused on a spinning optical disc. An older example of optical storage that does not require the use of computers, is microform. There are other means of optically storing data and new methods are in development. An optical disc drive is a device in a computer that can read CD-ROMs or other optical discs, such as DVDs and Blu-ray discs. Optical storage differs from other data storage techniques that make use of other technologies such as magnetism, such as floppy disks and hard disks, or semiconductors, such as flash memory and RAM.
Optical storage can range from a single drive reading a single CD-ROM to multiple drives reading multiple discs such as an optical jukebox. Single CDs (compact discs) can hold around 700 MB (megabytes) and optical jukeboxes can hold much more. Single-layer DVDs can hold 4.7 GB, while dual-layered can hold 8.5 GB. This can be doubled to 9.4 GB and 17 GB by making the DVDs double sided, with readable surfaces on both sides of the disc. HD DVDs were able to store 15 GB with a single-layer and 30 GB with a dual-layer. Blu-ray discs, which won the HDTV optical format war by defeating HD DVDs, can hold 25 GB for single-layer and 50 GB for dual-layer.
It is estimated that in the year 2007, optical storage represents 27% of the world's technological capacity to store information.
- Data storage device - the broader topic of all devices that store data
- Optical jukebox
- Optical disc drive
- Optical tape - more capacity than magnetic tape but not as cost effective
- Magneto-optical drive - combines optical and magnetic technologies to store data
- Laser turntable - a device that optically reads mechanical data storage media
- Holographic Data Storage Systems - potential new optical storage technology
- 3D optical data storage - potential new optical storage technology
- Optical Storage Technology Association - industry trade association
- "The World’s Technological Capacity to Store, Communicate, and Compute Information" especially Supporting online material, Martin Hilbert and Priscila López (2011), Science (journal), 332(6025), 60-65
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