Holographic Versatile Disc

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Holographic Versatile Disc
Image:HVD logo.png
Picture of an HVD by Optware
Media type Ultra-high density optical disc
Encoding MPEG-2, MPEG-4 AVC (H.264), and VC-1
Capacity theoretically up to 3.9 TB
Developed by HSD Forum
Usage Data storage,
High-definition video,
& the possiblity of ultra high definition video

Holographic Versatile Disc (HVD) is an optical disc technology that would hold up to 3.9 terabytes (TB) of information. It employs a technique known as collinear holography, whereby two lasers, one red and one green, are collimated in a single beam. The green laser reads data encoded as laser interference fringes from a holographic layer near the top of the disc while the red laser is used as the reference beam and to read servo information from a regular CD-style aluminum layer near the bottom. Servo information 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 servo information is interspersed amongst the data.

A dichroic mirror layer between the holographic data and the servo data reflects the green laser while letting the red laser pass through. This prevents interference from refraction of the 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.[1] These discs have the capacity to hold up to 3.9 terabytes (TB) of information,[2] which is approximately 5,800 times the capacity of a CD-ROM, 850 times the capacity of a DVD, 160 times the capacity of single-layer Blu-ray Discs, and about 4 times the capacity of the largest computer hard drives as of 2007. The HVD also has a transfer rate of 1 Gbit/s (125 MB/s).[3] Optware was expected to release a 200 GB disc in early June 2006, and Maxell in September 2006 with a capacity of 300 GB and transfer rate of 20 MB/s.[4] On June 28 , 2007, HVD standards have been approved and published.[5]

Contents

[edit] Technology

Holographic Versatile Disc structure 1. Green writing/reading laser (532 nm) 2. Red positioning/addressing laser (650 nm) 3. Hologram (data) 4. Polycarbon layer 5. Photopolymeric layer (data-containing layer) 6. Distance layers 7. Dichroic layer (reflecting green light) 8. Aluminium reflective layer (reflecting red light) 9. Transparent base P. PIT
Holographic Versatile Disc structure
1. Green writing/reading laser (532 nm)
2. Red positioning/addressing laser (650 nm)
3. Hologram (data)
4. Polycarbon layer
5. Photopolymeric layer (data-containing layer)
6. Distance layers
7. Dichroic layer (reflecting green light)
8. Aluminium reflective layer (reflecting red light)
9. Transparent base
P. PIT

Current optical storage saves one bit per pulse, and the HVD alliance hopes to improve this efficiency with capabilities of around 60,000 bits per pulse in an inverted, truncated cone shape that has a 200 micrometer diameter at the bottom and a 500 micrometer diameter at the top. High densities are possible by moving these closer on the tracks: 100 GB at 18 micrometers separation, 200 GB at 13 micrometers, 500 GB at 8 micrometers and a demonstrated maximum of 3.9 TB for 3 micrometer separation on a 12 cm disc.

The system uses a green laser, with an output power of 1 watt, a high power for a consumer device laser. So a major challenge of the project for widespread consumer markets is to either improve the sensitivity of the polymer used, or develop and commoditize a laser capable of higher power output and suitable for a consumer unit.[citation needed]

[edit] Storage capacity in context

  • It has been estimated that the books in the U.S. Library of Congress, the largest library in the world,[citation needed] would contain a total of about 20 terabytes if scanned in text format.[citation needed] Not including images from the books, the content could be stored with capacity to spare on six 3.9 TB discs.
  • At 15 meter resolution and 32-bit color (about the resolution found in unpopulated areas on Google Earth), a map of the land masses of Earth would occupy just over 2 TB.[citation needed]
  • Using MPEG4 ASP encoding, a 3.9 TB HVD could hold 4,600–11,900 hours of video—just over one year of uninterrupted video at usual encoding rates.[6]
  • Using typical satellite radio encoding (CT-aacPlus at 40 kbit/s), a 3.9 TB HVD could hold over 26.5 years of uninterrupted stereo audio.[citation needed]

[edit] Competing technologies

HVD is not the only technology in high-capacity, optical storage media. InPhase Technologies is developing a rival holographic format called Tapestry Media, which they claim will eventually store 1.6 TB with a data transfer rate of 120 MB/s, and several companies are developing TB-level discs based on 3D optical data storage technology. Such large optical storage capacities compete favorably with the Blu-ray Disc format. However, holographic drives are projected to initially cost around US$15,000, and a single disc around US$120–180, although prices are expected to fall steadily.[7] The market for this format is not initially the common consumer, but enterprises with very large storage needs.

[edit] The HSD Forum

The HSD Forum (formerly the HVD Alliance, & HVD FORUM) is a coalition of corporations purposed to provide an industry forum for testing and technical discussion of all aspects of HVD design and manufacturing. By cooperating, members of the Forum hope to expedite development and engender a market receptive to HVD technology.

As of February 2006, the HVD FORUM comprises these corporations:

[edit] Standards

On December 9, 2004 at its 88th General Assembly the standards body Ecma International created Technical Committee 44, dedicated to standarizing HVD formats based on Optware's technology. On June 11, 2007, TC44 published the first two HVD standards[8]: ECMA-377[9], defining a 200 GB HVD "recordable cartridge" and ECMA-378[10], defining a 100 GB HVD-ROM disc. Its next stated goals are 30 GB HVD cards and submission of these standards to the International Organization for Standardization for ISO approval.[11]

[edit] References

  1. ^ What's New (2004-08-23). Archived from the original on 2004-10-09.
  2. ^ 1 TB = 1 million MB; 1 MB = 1 million bytes
  3. ^ 1 Gbit = 1 billion bytes
  4. ^ Maxell focuses on holographic storage. CNET News.com (2005-11-28). Retrieved on 2007-05-28.
  5. ^ http://www.hvd-forum.org/news/hotnews/n20070628.html
  6. ^ Common compression rates for personal storage vary between around 780 and 2000 kbit/s. 3.9 TB equals 2000 kbit/s times 4,650 hours, or 780 kbit/s times 11,930 hours.
  7. ^ Hitachi-Maxell to Ship Holographic Storage this Year. DailyTech (2006-08-03). Retrieved on 2007-05-28.
  8. ^ Ecma releases new Holographic Information Storage Standards. Ecma press release (2007-07-04).
  9. ^ Information Interchange on Holographic Versatile Disc (HVD) Recordable Cartridges – Capacity: 200 Gbytes per Cartridge. ECMA-377.
  10. ^ Information Interchange on Read-Only Memory Holographic Versatile Disc (HVD-ROM) – Capacity: 100 Gbytes per disk. ECMA-378.
  11. ^ Ecma standardizes Holographic Information Storage. Ecma press release (2005-01-26).

[edit] See also

[edit] External links