We all the know about the blu-ray disc that’s out now with its astounding storage capactity(n price :P) But this isn’t all. There are still a few things round the corner that are expected to get bigger than your HDD

The Holographic Versatile Disc (HVD) is an optical disc technology that, in the future, may hold up to 3.9 terabytes (TB) of information, although the current maximum is 250GB. 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. The HVD also has a transfer rate of 1 Gbit/s (125 MB/s).


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.

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 possibility of ultra high definition video

Competing Technologies

In addition to HDV, other proprietary standards are making advances optical disk technology. Other players exist, such as those made by Hitachi Maxell Ltd and InPhase Technologies. Tapestry Media – a holographic format patented by InPhase Technologies – having a storage capacity of 1.6TB and a data transfer rate of 120 MB/s is one such device, while similar a 300 GB disks with a data transfer rate of 20 Mbit/s is in the pipeline for Hitachi Maxell Ltd.

HVD Capacity

* The entire US Library of Congress can be stored on six HVDs, assuming that every book has been scanned in the text format. The Library of Congress is the largest in the world and contains over 130 million items.
* The pictures of every landmass on Earth – like the ones shown in Google Earth – can be stored on two HVDs.
* With MPEG4 ASP encoding, a 3.9 TB HVD can hold anywhere between 4,600-11,900 hours of video, which is enough for non-stop playing for a year.

HVD Adoption

The biggest challenge for HVD will be in establishing itself in the commercial market, which as of now seems to be a distant dream, given its higher cost margins. It is anticipated that a single HVD, when commercially available, may cost anywhere between $100-120 (by 2006 year’s end), and the reader will be priced anywhere in the range of $10,000 to $15,000. However, like anything else associated with technology, the price will soon fall as R&DD costs are recouped and competitions lowers profit margins.