Picture of an HVD by Optware |
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| Media type | Ultra-high density optical disc |
| Encoding | MPEG-2, MPEG-4 AVC (H.264), NGVC (H.265) and VC-1 |
| Capacity | 6 TB |
| Developed by | HSD Forum |
| Usage | Data storage, High-definition video, Quad HD & the possibility of Ultra HD |
The Holographic Versatile Disc (HVD) is an optical disc technology developed between April 2004 and mid-2008 that can store up to several terabytes of data on an optical disc the same size as a CD, DVD or Blu-ray disc. It employs a technique known as collinear holography, whereby a green and red laser beam 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. 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 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]
Standards for 100 GB read-only holographic discs and 200 GB recordable cartridges were published by ECMA in 2007,[2][3] but no holographic disc product has appeared in the market. A number of release dates were announced, all since passed.[4]
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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 μm diameter at the bottom and a 500 μm diameter at the top. High densities are possible by moving these closer on the tracks: 100 GB at 18 μm separation, 200 GB at 13 μm, 500 GB at 8 μm, and most demonstrated of 5 TB for 3 μm on a 10 cm disc.
The system uses a green laser, with an output power of 1 watt which is high power for a consumer device laser. Possible solutions include improving the sensitivity of the polymer used, or developing and commoditizing a laser capable of higher power output while being suitable for a consumer unit.
HVD is not the only technology in high-capacity, optical storage media. InPhase Technologies was 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 favourably 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.[5]
The Holography System Development Forum (HSD Forum; formerly the HVD Alliance and the 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.
As of February 2011[update], the HSD Forum comprised these corporations :
On December 9, 2004 at its 88th General Assembly, the standards body Ecma International created Technical Committee 44, dedicated to standardizing HVD formats based on Optware's technology. On June 11, 2007, TC44 published the first two HVD standards:[6] ECMA-377,[2] defining a 200 GB HVD "recordable cartridge" and ECMA-378,[3] 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.[7]
New High Definition Video Technologies Road Map (2004–2010) From Maxell Corporation of America [8] shows the road map of HVD.
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