Blu-ray Disc (also known as Blu-ray or BD) is an optical disc storage medium designed by Sony to supersede the standard DVD format. Its main uses are high-definition video and data storage with 50GB per disc. The disc has the same physical dimensions as standard DVDs and CDs.

The name Blu-ray Disc is derived from the blue laser (violet-colored) used to read and write to this type of disc. In part because of the shorter wavelength (405 nanometres), substantially more data (almost 6 times more) can be stored on a Blu-ray Disc than on a standard DVD, which uses a red (650 nm) laser.

During the format war over high-definition optical discs, Blu-ray Disc competed with the HD DVD format. In February 2008, Toshiba—the main company supporting HD DVD— ceded and effectively ended the format war.

Blu-ray Disc is developed by the Blu-ray Disc Association, a group representing makers of consumer electronics, computer hardware, and motion pictures. As of January 2009, more than 890 Blu-ray disc titles are available in Australia, 720 in Japan, 1,140 in the United Kingdom, and 1,500 in the United States.

History

Commercial HDTV sets began to appear in the consumer market around 1998, but there was no commonly-accepted, inexpensive way to record or play HD content. In fact, there was no medium with the storage required to accommodate HD codecs, except JVC's Digital VHS and Sony's HDCAM. Nevertheless, it was well known that using lasers with shorter wavelengths would enable optical storage with higher density. When Shuji Nakamura invented practical blue laser diodes, it was a sensation, although a lengthy patent lawsuit delayed commercial introduction.

Origins

SONY started two projects applying the new diodes: UDO (Ultra Density Optical) and DVR Blue (together with Pioneer), a format of rewritable discs which would eventually become Blu-ray Disc (more specifically, BD-RE). The core technologies of the formats are essentially similar.

The first DVR Blue prototypes were unveiled at the CEATEC exhibition in October 2000. Because the Blu-ray Disc standard places the data recording layer close to the surface of the disc, early discs were susceptible to contamination and scratches and had to be enclosed in plastic cartridges for protection. On February 19, 2002, the project was officially announced as Blu-ray, and the Blu-ray Disc Founders was founded by the nine initial members.

The first consumer devices were in stores on April 10, 2003. This device was the Sony BDZ-S77; a BD-RE recorder that was made available only in Japan. The recommended price was US$3800; however, there was no standard for pre-recorded video and no movies were released for this player. The Blu-ray Disc standard was still years away as a newer, more secure DRM system was needed before Hollywood studios would accept it, not wanting to repeat the failure of the Content Scramble System used on standard DVDs. On October 4, 2004, the Blu-ray Disc Founders was officially changed to the Blu-ray Disc Association (BDA) and 20th Century Fox joined the BDA's Board of Directors.