New Blu-ray DVD format uses blue-violet lasers to achieve 27 GB recording capacity
The companies that established the basic specifications for the Blu-ray Disc are: Hitachi, LG, Matsushita, Pioneer, Philips, Samsung, Sharp, Sony and Thomson. Several of the companies such as Pioneer, Sony and Philips have already demonstrated prototype Blu-ray players using violet lasers. Toshiba, which is not part of the agreement, has also demonstrated a similar player. In addition to actively promoting the new format throughout the industry, the nine companies will begin licensing the new format as soon as specifications are completed. Licensing is expected to start around spring 2002, and Blu-ray players could go on sale at the start of 2003.
Current DVD players use 650 nm red lasers, while CD players use 780 nm diodes. A number of competing formats for recordable DVD players have been introduced, including DVD-RAM, DVD-RW and DVD+RW; the Blu-ray agreement is likely to render these obsolete. The use of a 405 nm laser, in combination with a 0.85 numerical aperture (NA) field lens and other features, leads to a significant reduction in beam spot size on the surface of the disc. This boosts the recording capacity compared to conventional DVD players, which can record 4.7 GB of data on a single-sided disk. With a capacity of 27 GB, Blu-ray can record over 2 hours of digital high definition video and more than 13 hours of standard TV broadcasting. 50 GB double-layer discs are also under development. High-speed data transfer at a rate of 36 Mbit/s is also possible, sufficient to record high definition TV.
It will not be possible to play Blu-ray discs with existing DVD and CD players, since these don t contain 405 nm lasers. Blu-ray drives will need to contain 780, 650 and 405 nm lasers in order to be compatible with CD and DVD discs. At present, the only commercial source of blue-violet lasers is Nichia, although Cree and Toyoda Gosei are both making progress in this area.
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