Blu-ray is an optical disc format designed to display high definition video and store large amounts of data.
Blu-ray is the successor to DVD. The standard was developed collaboratively by Hitachi, LG, Matsushita (Panasonic), Pioneer, Philips, Samsung, Sharp, Sony, and Thomson. It became the default optical disk standard for HD content and optical data storage after winning a format war with HD-DVD, the format promoted by Toshiba and NEC.
The format's name comes from the fact that a blue laser reads from and writes to the disc rather than the red laser of DVD players. The blue laser has a 405 nanometer (nm) wavelength that can focus more tightly than the red lasers used for writable DVD. As a consequence, a Blu-ray disc can store much more data in the same 12 centimeter space. Like the rewritable DVD formats, Blu-ray uses phase change technology to enable repeated writing to the disc.
Blu-ray's standard storage capacity is enough to store a continuous backup copy of most people's hard drives on a single disc. Initially, the format had a 27 gigabyte (GB) single-sided capacity and 50 GB on dual-layer discs. Single-sided Blu-ray discs can store up to 13 hours of standard video data, compared to single-sided DVD's 133 minutes. In July 2008, Pioneer announced that they had found a way to increase capacity to 500 GB by creating 20-layer discs. These discs are not, however, expected to be commercially available in the near future.
Blu-ray also features data streams at 36 megabits per second (Mbps), fast enough for high quality video recording. Blu-ray discs will not play on current CD and DVD players, because those players lack the blue-violet laser required to read the discs. If the appropriate lasers are included, however, Blu-ray players can play the other two formats. Blu-ray disc players (BDPs) are available from a number of manufacturers, including Panasonic, Pioneer, Samsung and Sony. Sony's Playstation 3 also has a Blu-ray drive installed.
