A novel method of optical data storage could soon be used to hold a terabyte of data on a disk the size of a normal DVD, say researchers at Imperial College London, UK.

Information is encoded on a normal DVD in the form of microscopic indents on the surface of the disk. The presence or absence of an indent corresponds to a binary piece of information – a ‘1’ or a ‘0’. Indents are detected by beaming light onto a disk with a laser and measuring the amount of light that bounces back.

Using tracks embedded at several depths within a disk, it is possible to store more data on the highest capacity disks. Multilayer DVDs hold about 16 gigabytes of data, which equals about 8 hours of high quality video.

But the researchers realised that the polarity of light might also be used to encode information. They developed a type of disk that incorporates angled ridges within the pits in order to subtly alter the polarity of the light that gets reflected. This can be used to store 10 times’ more data than is currently possible, they say.

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