Back قرص هولوغرافي Arabic HVD Bulgarian Holografski višenamjenski disk BS Disc Hologràfic Versàtil Catalan HVD Czech Holographic Versatile Disc German Holographic Versatile Disc Spanish Holograafiline universaalketas Estonian Holographic Versatile Disc Finnish Disque holographique polyvalent French
 | This article needs to be updated. (December 2019) |
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 An HVD by Optware | |
| Media type | Ultra-high density optical disc |
|---|---|
| Capacity | 3.9 TB[1] |
| Developed by | HSD Forum |
| Usage | Data storage, high-definition video, QHD/WQHD, possibility of Ultra HD |
| Optical discs |
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The Holographic Versatile Disc (HVD) is an optical disc technology that was expected to store up to several terabytes of data on an optical disc 10 cm or 12 cm in diameter. Its development commenced in April 2004, but it never arrived due to lack of funding. The company responsible for HVD went bankrupt in 2010.[2]
The reduced radius reduces cost and materials used. It employs a technique known as collinear holography, whereby a blue-green and red laser beam are collimated in a single beam. The blue-green laser reads data encoded as laser interference fringes from a holographic layer near the top of the disc. A red laser is used as the reference beam to read servoinformation from a regular CD-style aluminium layer near the bottom. Servoinformation is used to monitor the position of the read head over the disc, similar to the head, track, and sector information on a conventional hard disk drive. On a CD or DVD this servoinformation is interspersed among the data. A dichroic mirror layer between the holographic data and the servo data reflects the blue-green laser while letting the red laser pass through. This prevents interference from refraction of the blue-green laser off the servo data pits and is an advance over past holographic storage media, which either experienced too much interference, or lacked the servo data entirely, making them incompatible with current CD and DVD drive technology.[3]
Standards for 100 GB read-only holographic discs and 200 GB recordable cartridges were published by ECMA in 2007,[4][5] but no holographic disc product has ever appeared in the market. A number of release dates were announced, all since passed,[6] likely due to high costs of the drives and discs itself, lack of compatibility with existing or new standards, and competition from more established optical disc Blu-ray and video streaming.
- ^ Stair, Ralph; Reynolds, George (January 2015). Principles of Information Systems. ISBN 9781305482210.
- ^ "Holographic storage bites the dust". ZDNET. February 18, 2010. Retrieved January 4, 2021.
- ^ "What's New". August 23, 2004. Archived from the original on October 9, 2004.
- ^ Cite error: The named reference
ecma-377was invoked but never defined (see the help page). - ^ Cite error: The named reference
ecma-378was invoked but never defined (see the help page). - ^ "Maxell focuses on holographic storage". CNET News.com. November 28, 2005. Archived from the original on July 22, 2012. Retrieved May 28, 2007.