Blu-ray Disc

The name Blu-ray is derived from the blue-violet laser used to read and write this type of disc. On a Blu-ray its shorter wavelength (450 nm) can be stored more data than on the common DVD format, which uses a red , 650 nm laser. In comparison to HD DVD, which also uses a blue laser, Blu-ray Disc has more information capacity per layer (currently 25 GB, but test media is up to 33 GB).

Blu-ray also known as Blu-ray Disc is the name of a next-generation optical disc format jointly developed by the Blu-ray Disc Association, a group of the world's leading consumer electronics, personal computer and media manufacturers (including Apple, Dell, Hitachi, HP, JVC, LG, Mitsubishi, Panasonic, Pioneer, Philips, Samsung, Sharp, Sony, TDK and Thomson).

The format was developed to enable recording, rewriting and playback of high-definition video (HD), as well as storing large amounts of data.

The format offers more than five times the storage capacity of traditional DVDs. This extra capacity combined with the use of advanced video and audio codecs will offer consumers an unprecedented HD experience.

While current optical disc technologies such as DVD, DVD±R, DVD±RW, and DVD-RAM rely on a red laser to read and write data, the new format uses a blue-violet laser instead, hence the name Blu-ray.

Despite the different type of lasers used, Blu-ray products can easily be made backwards compatible with CDs and DVDs through the use of a BD/DVD/CD compatible optical pickup unit.

The benefit of using a blue-violet laser (405nm) is that it has a shorter wavelength than a red laser (650nm), which makes it possible to focus the laser spot with even greater precision. This allows data to be packed more tightly and stored in less space, so it's possible to fit more data on the disc even though it's the same size as a CD/DVD. This together with the change of numerical aperture to 0.85 is what enables Blu-ray Discs to hold 25GB/50GB.

Blu-ray is currently supported by more than 180 of the world's leading consumer electronics, personal computer, recording media, video game and music companies. The format also has broad support from the major movie studios as a successor to today's DVD format.