How Blu-Ray DVDs Work

The name blu-ray is derived from the type of technology used to read blu-ray DVDs. Traditional DVD players use red lasers to read and write information onto the DVD, while CD players use lasers that are near infrared. Blu-ray DVDs however, use blue lasers, hence the name.

Blu-ray DVDs first became commercially .available in 2006. Although the discs are the same size as traditional DVDs, blu-ray discs are capable of holding 27 gigabytes of information and up to 13 hours of high quality video. Therefore, their storage capacity by far outstretches that of traditional DVDs. Also, new double layer blu-ray discs are now capable of holding 20 hours of video footage.

Operation:

The basic technology behind blu-ray DVDs follows the same standards s traditional DVDs and CDs. Information is represented on the surface of the disc using a series of pits and troughs laid out in a spiral pattern leading from the centre of the disc to the outer edge.

The blue laser runs along the surface of the disc and decodes the various pits and troughs, interpreting this information which can then be relayed to a TV or monitor screen. The more pits and troughs that a disc is capable of holding, the more information can be stored on the disc.

Pits on the surface of a blu-ray disc are approximately half as small as those on a standard DVD. Therefore, not only can a blu-ray disc store more information than a normal DVD, but they are also capable of storing the latest generation of next generation high quality video, called High Definition.

Traditional DVDs use red lasers operating at 650 nanometre wavelengths, as where blu-ray discs use blue lasers operating at 405 nanometres allowing smaller pits to be written on to the surface of the disc. Incidentally, 650 nanometres (or 0.00000065 of a metre) is less than one hundredth the width of a human hair.

Disc Composition

Traditional DVDs are comprised of two 0.6mm plastic circular discs. Sandwiched between these, there is a thin coating of metal, onto which the disc data can be written.

However, blu-ray discs use only a single layer of polycarbonate, which is 1.1 millimetre thick. In addition, most quality blu-ray discs are usually coated with a harder layer to help protect the surface of the disc from scratches.

Popularity

Within the first year of its release, blu-ray discs were in stiff competition of a rival format know as HD-DVD (High-definition DVD) which was also capable of storing vast amounts of data and high-definition video.

Eventually, by late 2008 Blu-ray had won the battle to become the recognised standard within the market for high-definition video payback. This was due largely to the availability of Blu-ray compatible players and thanks in part to SONY’s decision to incorporate a blu-ray player into its latest Playstation games console.