18-10-2010, 10:42 AM
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Blu-ray Disc
ABSTRACT
Optical disks share a major part among the secondary storage devices. Blu-ray Disc is a next-generation optical disc format. The technology utilizes a blue laser diode operating at a wavelength of 405 nm to read and write data. Because it uses a blue laser it can store enormous amounts of data on it than was ever possible.
Data is stored on Blu-Ray discs in the form of tiny ridges on the surface of an opaque 1.1-millimetre-thick substrate. This lies beneath a transparent 0.1mm protective layer. With the help of Blu-ray recording devices it is possible to record up to 4 hours of very high quality audio and video or more than 20 hours of standard-definition TV on a single BD.
Blu-ray also promises some added security, making ways for copyright protections. Blu-ray discs can have a unique ID written on them to have copyright protection inside the recorded streams.
Blu-ray disc takes the DVD technology one step further, just by using a laser with a nice color.
History of Blu-ray Disc
First Generation
When the CD was introduced in the early 80s, it meant an enormous leap from traditional media. Not only did it offer a significant improvement in audio quality, its primary application, but its storage capacity 800 MB also meant a giant leap in data storage and retrieval. For the first time, there was a universal standard for pre-recorded, recordable and rewritable media, offering the best quality and features consumers could wish for themselves, at very low costs.
Second Generation
Although the CD was a very useful medium for the recording and distribution of audio and some modest data-applications, demand for a new medium offering higher storage capacities rose in the 90s. These demands lead to the evolution of the DVD specification and a five to ten fold increase in capacity. This enabled high quality, standard definition video distribution and recording. Furthermore, the increased capacity accommodated more demanding data applications. At the same time, the DVD spec used the same form factor as the CD, allowing for seamless migration to the next generation format and offering full backwards compatibility.
Third Generation
Now High Definition video is demanding a new solution. History proved that a significant five to ten time increase in storage capacity and the ability to play previous generation formats are key elements for a new format to succeed. This new format has arrived with the advent of Blu-ray Disc, the only format that offers a considerable increase in storage capacity with its 25 to 50 GB data capacity. This allows for the next big application of optical media: the distribution and recording of High Definition video in the highest possible quality. In fact, no other proposed format can offer the data capacity of Blu-ray Disc, and no other format will allow for the same high video quality and interactive features to create the ultimate user experience. As with DVD, the Blu-ray Disc format is based on the same, bare disc physical form factor, allowing for compatibility with CD and DVD. The Blu-ray Disc specification was officially announced in February 2002. Blu-ray Disc recorders were first launched in Japan in 2003.