Blu-ray Disc
Blu-ray Disc (BD) is an optical disc storage medium designed to supersede the
DVD format. The plastic disc is 120 mm in diameter and 1.2 mm thick, the same
size as DVDs and CDs. Conventional (pre-BD-XL) Blu-ray Discs contain 25 GB per
layer, with dual layer discs (50 GB) being the industry standard for
feature-length video discs. Triple layer discs (100 GB) and quadruple layers
(150 GB) are available for BD-XL re-writer drives.[3] The name Blu-ray Disc
refers to the blue laser used to read the disc, which allows information to be
stored at a greater density than is possible with the longer-wavelength red
laser used for DVDs. The major application of Blu-ray Discs is as a medium for
video material such as feature films. Besides the hardware specifications,
Blu-ray Disc is associated with a set of multimedia formats. Generally, these
formats allow for the video and audio to be stored with greater definition than
on DVD.
Since the Blu-ray Disc data layer is closer to the surface of the disc compared to the DVD standard, it was at first more vulnerable to scratches.[78] The first discs were housed in cartridges for protection, resembling Professional Discs introduced by Sony in 2003.
Using a cartridge would increase the price of an already expensive medium, so hard-coating of the pickup surface was chosen instead. TDK was the first company to develop a working s
ratch-protection coating for
Blu-ray Discs. It was named Durabis. In addition, both Sony and Panasonic's
replication methods include proprietary hard-coat technologies. Sony's
rewritable media are spin-coated, using a scratch-resistant and antistatic
coating. Verbatim's recordable and rewritable Blu-ray Discs use their own
proprietary technology, called Hard Coat.[79]
The Blu-ray Disc specification requires the testing of resistance to scratches by mechanical abrasion.[75] In contrast, DVD media are not required to be scratch-resistant, but since development of the technology, some companies, such as Verbatim, implemented hard-coating for more
The Blu-ray Disc specification requires the testing of resistance to scratches by mechanical abrasion.[75] In contrast, DVD media are not required to be scratch-resistant, but since development of the technology, some companies, such as Verbatim, implemented hard-coating for more
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Some technical info:
  BD drive speeds Drive speed Data rate ~Write time (minutes) Mbit/s MB/s Single-Layer Dual-Layer 1× 36 4.5 90 180 2× 72 9 45 90 4× 144 18 22.5 45 6× 216 27 15 30 8× 288 36 11.25 22.5 10× 360 45 9 18 12× 432 54 7.5 15 14× 504 63 http://en.wikipedia.org/wiki/Blu-ray_Disc |
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Computer
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