Simpsons swallowed whole by DVD of the future

A new technology capable of storing the equivalent of 100 DVDs on a single DVD-sized disc has been unveiled by researchers from London's Imperial College. The storage medium, called Multiplexed Optical Data Storage or MODS, was revealed at the Asia-Pacific Data Storage Conference 2004 in Taiwan on Monday by lecturer Dr Peter Török.

The development team said MODS can potentially store up to one terabyte (1,000 gigabytes) of data on one standard-sized disc -- enough for 472 hours of film, or every episode of the Simpsons ever made. It would also have applications in enterprise data back-up and distribution.

MODS will be laser-based like DVDs, CDs and the new BluRay system but uses much more subtle variations in the way light reflects from the discs. Where existing schemes have patterns of pits that reflect the laser as a series of ones and zeros, MODS can encode and detect over 300 variations per pit. After error correction and encoding, this leads to 10 times the data density of BluRay, currently the record holder for consumer optical storage. BluRay discs -- only available in Japan at present, with European products expected in 2005 -- can store up to 25GB per layer and can have two layers. MODS will have 250GB in each of up to four layers.

"We came up with the idea for this disk some years ago," Torok said in a statement, "but did not have the means to prove whether it worked. To do that we developed a precise method for calculating the properties of reflected light, partly due to the contribution of Peter Munro, a PhD student working with me on this project. We are using a mixture of numerical and analytical techniques that allow us to treat the scattering of light from the disk surface rigorously rather than just having to approximate it."

Products are not expected for between five and 10 years, depending on developmental funding, but the researchers are looking at using the technology in discs physically much smaller than current DVDs.

"Multiplexing and high density ODS comes in handy when manufacturers talk about miniaturisation of the disks," Torok said. "In 2002 Philips announced the development of a 3cm diameter optical disk to store up to 1GB of data. The future for the mobile device market is likely to require small diameter disks storing much information. This is where a MODS disk could really fill a niche."