BLU-RAY DISC

A Blu-ray Disc (also called BD) is a high-density optical disc format for the storage of digital information, including high-definition video.

The name Blu-ray Disc is derived from the blue-violet laser used to read and write this type of disc. Because of its shorter wavelength (405 nm), substantially more data can be stored on a Blu-ray Disc than on the DVD format, which uses a red (650 nm) laser. A single layer Blu-ray Disc can store 25 gigabytes (GB), over five times the size of a single layer DVD at 4.7 GB. A dual layer Blu-ray Disc can store 50 GB, almost 6 times the size of a dual layer DVD at 8.5 GB.

Blu-ray was developed by the Blu-ray Disc Association, a group of leading consumer electronics companies. The standard is covered by several patents belonging to different companies. As of March 2007, a joint licensing agreement for all the relevant patents has not yet been finalized.

As of 2 October 2007, 336 titles have been released on Blu-ray Disc in the United States (32 of these titles have since been discontinued). Since January 2007, new releases on dual layer disc have represented about half of all new releases approximately 75 titles and 2.5 mm discs. As of 9 October 2007, 179 titles have been released in Japan, with 55 titles planned for release.

The Blu-ray standard is currently in a format war with its rival, HD DVD (which also uses a blue-violet laser), to determine which (if either) of the two formats will become the leading carrier for high-definition content to consumers.

info : wikip