BLU-RAY DISC By :pradeep Reddy
Jul 18, 2015
INTRODUCTIONBlu-ray, also known as Blu-ray Disc (BD) is the
name of a next-generation optical disc format. 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 and can hold up to 25GB on a single-layer disc and 50GB on a dual-layer disc.
FoundationBlu-ray disc (BD) is appropriately named after the
blue laser used to write the dataThe first blue laser was developed in 1996 by Shuji
Nakamura (Nichia Corporation)In 2002, an alliance was formed, called the Blu-ray
Disc Association, including the likes of Sony, Samsung, Sharp, Hewlett-Packard, and Royal Phillips.
It has One layer, Two layer, Three layer, Four layer Five layer, Six layer.
Variations and SizesA single-layer Blu-ray disc (BD) has enough
storage capacity (25GB) for approximately two hours of high-definition video with audio.
A dual-layer (50GB) BD can hold enough data for approximately four hours of HD video.
TDK recently announced that they have created a working Blu-ray disc capable of holding 200GB of data (six 33GB data layers).
Laser and optics
Blu-ray systems use a blue-violet laser operating at a wavelength of 405 nm, similar to the one used for HD DVD, to read and write data. Conventional DVDs and CDs use red and infrared lasers at 650 nm and 780 nm respectively.
Blu-ray has two types BD-R and BD-RE with price $19.99 and $24.99 for 25GB and $47.99 and $59.99
for 50GB respectively.
Why Blue Lasers?High-definition TV provides six times more
picture information than standard-definition TV
More bits per second requiredMore gigabytes per disc required
1920 x 1080 x 30 = 62 million pixels/second
720 x 480 x 30 = 10 million pixels/secondHDTV
SDTV
Disc CharacteristicsSingle layer: 25 GB
Dual layer: 50 GBDiameter: 120 mmThickness: 1.2 mmCenter hole
diameter: 15 mmUses GaN laser of
wavelength 400 nmThe smaller laser,
compared to the DVD and CD, keeps the process more efficient (~5 mW) Courtesy Blu-ray Disc Founders “Blu-ray Disc Format White Paper”
Hard-coating technologyIn January 2004 was
introduced a clear polymer coating that gives Blu-ray Discs unprecedented scratch resistance. The coating was developed by TDK Corporation and is called "Durabis". It allows BDs to be cleaned safely with only a tissue.
CompatibilityThis issue has introduced a competitor, the HD-DVD,
that based its technology around being compatible with the DVD
Recently the BDA has developed recorders that are BD/DVD/CD compatible
JVC has advanced the BD by developing a BD/DVD combo disc that stores both DVD and BD data. It is composed of two DVD layers and a third BD layer storing 33.5 GB total
Blu-ray Advantages Record high-definition television (HDTV) without
any quality loss Instantly skip to any spot on the disc Record one program while watching another on
the discEdit or reorder programs recorded on the disc Automatically search for an empty space on the
disc
FutureExpect the BD to become more prevalent once the
HDTV market establishes its presenceAudio and video will reach higher qualities with
larger storage spaceLook for BD with more than two layers as the
technology is further refined
ConclusionBoth DVD and BD would most likely co-exist for
quiet some time until HDTVs become more widespread.