Science Of Your World

What is Blu-ray?

Blu-ray Disc (also known as BD or Blu-ray) is an optical disc storage medium designed to supersede the standard DVD format. Its main uses are for storing high-definition video, PlayStation 3 video games, and other data, with up to 25 GB per single layered, and 50 GB per dual layered disc. Although these numbers represent the standard storage for Blu-Ray drives, the specification is open-ended, with the upper theoretical storage limit left unclear. 200 GB discs are available, and 100 GB discs are readable without extra equipment or modified firmware. The disc has the same physical dimensions as standard DVDs and CDs.

The name Blu-ray Disc derives from the blue-violet laser used to read the disc. While a standard DVD uses a 650 nanometer red laser, Blu-ray uses a shorter wavelength, a 405 nm blue-violet laser, and allows for almost ten times more data storage than a DVD.

During the format war over high-devinition optical discs, Blu-ray competed with theHD DVD format. Toshiba, the main company supporting HD DVD, conceded in February 2008, and the format war ended. In late 2009, Toshiba released its own Blu-ray Disc player.

Blu-ray Disc was developed by the Blu-ray Disc Association, a group representing makers of consumer electronics, computer hardware, and motion pictures. As of June 2009, more than 1,500 Blu-ray disc titles are available in Australia and the United Kingdom, with 2,500 in Japan, the United States and Canada.

The Blu-ray Disc physical specifications were completed in 2004. In January 2005, Sony announced that they had developed a hard coating polymer for Blu-ray Discs. Cartridges, originally used for scratch protection, were no longer necessary and were scrapped. The BD-ROM specifications were finalized in early 2006. AACS LA, a consortium founded in 2004, had been developing the DRM platform that could be used to securely distribute movies to consumers. However, the final AACS standard was delayed, and then delayed again when an important member of the Blu-ray Disc group voiced concerns. At the request of the initial hardware manufacturers, including Toshiba, Pioneer, and Samsung, an interim standard was published that did not include some features, such as managed copy.

Here is the process of making Sony's Blu-ray

Rounds to flats ... each Blu-ray disc begins its life as a collection of small polycarbonate granules delivered to the factory by truck and stored in a silo.


Clean room ... to reduce contamination, technicians must enter the production room through a chamber that blasts loose dust off their bodies with air jets.


Go with the flow ... the polycarbonate granules are piped around the factory until they arrive in this hopper above the moulding machine that measures them out evenly.


Under pressure ... the mould compresses the melted plastic into a disc and creates the first layer of data. Then the disc is removed by a robotic arm for the next step.


Shiny ... the disc is then coated in a vaporised layer of silver 90 angstroms thick, in a process called sputtering. An angstrom is one 100 millionth of a centimetre.

The electromagnetic field around the sputtering machine is so strong that it affects pacemakers.


Toward the light ... the sputtered disc is then coated in a layer of UV resin and cured with light, before moving on to have the second layer of data embedded.


Under observation ... Sony Digital Audio Disc Company (DADC) technicians monitor of the of three Blu-ray machines. In full production, each machine can make up to 16,000 discs a day.


Hard layer ... finally, the disc is given another coating of UV resin and a final protective layer before being checked for any tiny bubbles between layers by this machine.


Runtime ... the final stage of the production process is to check the data integrity of each disc through playback and scanning.


All made up ... the discs, having been checked for errors, are then loaded into the printer that will add the artwork to their surface.


Flip and close ... the assembly packing line places the disc and insert into the box. At full production the machine can package 4500 Blu-ray discs per hour.

source>>
wikipedia.org