Scientists have harnessed the power of holography to store large amounts of data in a postage stamp-sized disc.
Craig Hawker, at the University of California, Santa Barbara, US, and colleagues designed photopolymers that can store up to 50 times more data than a DVD.
When the highly branched molecules polymerise, the volume change is negligible so data can be stored and retrieved accurately |
Unlike a DVD, which only uses a disc's surface, holographic data storage uses the whole volume of the disc. As a result, holography promises terabytes (1000 gigabytes) of storage capacity in a recording disc the size of a postage stamp, says Hawker. A typical DVD holds only 4.7 gigabytes.
Recently, researchers have investigated light-sensitive polymers - which are used to make the holograms seen in driving licences - for data storage. But these photopolymers shrink as the molecules polymerise during the recording process, making it difficult to accurately retrieve the recorded data.
Hawker overcame this problem by making a series of highly branched monomers. He showed that when the molecules polymerised, the volume change was much smaller than for previous photopolymers and so the shrinkage was negligible.
- Stefan Hecht, Humboldt University, Berlin, Germany
The polymer's refractive index, which is a measure of how much it reduces the speed of light passing through it, is key to increased storage capacity, explains Hawker. He is working on a system that combines a low refractive index scaffold with ultra-high refractive index monomers, which he expects to show improved results.
'This work illustrates the power of modern polymer synthesis to custom-design organic materials with advantageous properties,' says Stefan Hecht, an expert in organic functional materials at Humboldt University, Berlin, Germany. 'By fine tuning the macromolecular architecture, Hawker and co-workers have created new high performance data storage materials overcoming limitations of conventional polymer chemistry.'
Sarah Corcoran
http://www.rsc.org/Publishing/ChemTech/Volume/2009/03/polymer_data_storage.asp
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