Blu-ray,
also known as Blu-ray Disc (BD) is the name of a next-generation optical disc
format jointly developed by the Blu-ray Disc Association (BDA), a group of
leading consumer electronics and PC companies (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 Blu-ray Disc using blue-violet laser achieves over 2-hour digital
high definition video recording on a 12cm diameter CD/DVD size phase change
optical disc. The Blu-ray Disc enables the recording, rewriting and play back
of up to 25 gigabytes (GB) of data on a single sided single layer 12cm CD/DVD
size disc using a 405nm blue-violet laser. By employing a short wavelength blue
violet laser, the Blu-ray Disc successfully minimizes its beam spot size by
making the numerical aperture (NA) on a field lens that converges the laser
0.85. This also allows for disc better readout and an increased recording
density. The Blu-ray Disc's tracking pitch is reduced to 0.32um, almost half of
that of a regular DVD, achieving up to 25 GB high-density recording on a single
sided disc. Because the Blu-ray Disc utilizes global standard "MPEG-2
Transport Stream" compression technology highly compatible with digital
broadcasting for video recording, a wide range of content can be recorded. It
is possible for the Blu-ray Disc to record digital high definition broadcasting
while maintaining high quality and other data simultaneously with video data if
they are received together. In addition, the adoption of a unique ID written on
a Blu-ray Disc realizes high quality copyright protection functions. The
Blu-ray Disc is a technology platform that can store sound and video while
maintaining high quality and also access the stored content in an easy-to-use
way. This will be important in the coming broadband era as content distribution
becomes increasingly diversified.
