Blu-ray Disc

HISTORY

INTRODUCTION Blu-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.

Foundation Blu-ray disc (BD) is appropriately named after the blue laser used to write the data The 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 The “e” is intentionally left out of the name due to trademark restrictions

Blu-ray Disc Association Apple Computer, Inc. Dell Inc. Hewlett Packard Company Hitachi, Ltd. LG Electronics Inc. Matsushita Electric Industrial Co., Ltd. Mitsubishi Electric Corporation Pioneer Corporation Royal Philips Electronics Samsung Electronics Co., Ltd. Sharp Corporation Sony Corporation TDK Corporation Thomson Multimedia Twentieth Century Fox Walt Disney Pictures Warner Bros. Entertainment

Variations and Sizes A 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.

Why Blue Lasers? High-definition TV provides six times more picture information than standard-definition TV –More bits per second required –More gigabytes per disc required 1920 x 1080 x 30 = 62 million pixels/second 720 x 480 x 30 = 10 million pixels/second HDTV SDTV

Disc Characteristics Single layer: 25 GB Dual layer: 50 GB Diameter: 120 mm Thickness: 1.2 mm Center hole diameter: 15 mm Uses GaN laser of wavelength 400 nm The 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 technology In 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.

Parameters Blu-ray DVD Storage capacity 25GB (single- layer) 50GB (dual- layer) 4.7GB (single-layer) 8.5GB (dual-layer) Laser wavelength 405nm (blue laser) 650nm (red laser) Numerical aperture (NA) Disc diameter Disc thickness 120mm 1.2mm Protection layer Hard coating 0.1mm Yes 0.6mm No Track pitch 0.32µm 0.74µm Data transfer rate (data) Data transfer rate (video/audio) 36.0Mbps (1x) 54.0Mbps (1.5x) 11.08Mbps (1x) 10.08Mbps (<1x) Video resolution (max) Video bit rate (max) 1920×1080 (1080p) 40.0Mbps 720×480/720×576 (480i/576i) 9.8Mbps Video codecs MPEG-2 MPEG-4 AVC SMPTE VC- 1 MPEG Blu-ray and DVD

Blu-ray vs DVD capacity

CD vs DVD vs Blu-ray writing

Compatibility This 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 disc Edit or reorder programs recorded on the disc Automatically search for an empty space on the disc

Future Expect the BD to become more prevalent once the HDTV market establishes its presence Audio and video will reach higher qualities with larger storage space Look for BD with more than two layers as the technology is further refined

Conclusion Both DVD and BD would most likely co-exist for quiet some time until HDTVs become more widespread.

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