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17 Jun 2002
An optical disk that holds 27.4 gigabytes of data - enough to store four hours of high-definition video - uses a violet laser. The system was demonstrated by Pioneer Electronics Corp at the Japan Electronics Show earlier this month, using a 405 nanometre violet laser developed by Nichia Chemical Industries.
Pioneer plans to use this system for the next generation of DVD videos. The prototype has a two-layer structure like the current 8.54 gigabyte DVDs. The violet laser reads a very small track pitch, allowing more data to be stored than on current disks. Pioneer's system divides the laser beam into three, with the central beam giving the signal and the other two beams cancelling interference from adjacent tracks.
Nichia started to market the first violet semiconductor laser, with a power of 5 milliwatts, at the start of October 1999.
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