Blu-ray Discs
What are Blu-ray discs? How did they get their name? To know about Blu-ray discs, you must read on...
Blu-ray Discs Explained
With the advent of high-definition television, a digital television broadcasting system, in 1998, there arose a need to record and play high-definition content. During those times, the use of shorter-wavelength lasers was known to facilitate optical storage of higher densities. Soon, Shuji Nakamura, a professor at the Material Department of the College of Engineering, University of California, invented blue laser diodes, which hit the markets much later. The development of Blu-ray disc is attributed to the Blu-ray Disc Association (BDA) that also licenses and establishes format standards for Blu-ray discs.
In the Blu-ray discs of initial years, the data-recording layer is placed close to the surface of the disc, thus making them vulnerable to scratches and contamination. For this reason, the blu-ray discs of those times had to be protected by means of plastic cartridges. The physical specifications of the Blu-ray disc were completed in 2004. In the beginning of 2005, TDK declared of having developed a hard coating polymer for Blu-ray discs, thus eliminating the need of cartridges. Sony and Panasonic followed suit by developing hard-coat technologies.
Blu-ray discs use a blue-colored or rather violet-colored laser that operates at a wavelength of 405 nanometers to read and write data. Owing to the shorter wavelengths of the laser, it is possible to store more data onto these discs. A laser beam is focused on the disc through the numerical aperture of a lens. If the wavelength is reduced and the numerical aperture increased, the laser beam can be focused onto a smaller spot, thus enabling more information to be stored on a smaller area. Hence, despite having similar physical dimensions as those of CDs and DVDs, blu-ray discs facilitate greater data storage. A single layer blue-ray disc can store 25 GB while a dual layer stores as much as 50 GB of data. Isn't that amazing?
How are Blu-ray disks different from the existing storage media? Current optical storage devices available such as DVDs, DVD-R, DVD-RW and DVD-RAM make use of a red-colored laser to read and write data whereas the Blu-ray discs use a violet-colored laser beam. Blue-ray discs offer higher storage capacities as compared to CDs and DVDs and offer backward compatibility with them.
Even today, the Blu-ray technology is getting updated as per the latest advancements. Engineers have come up with quad-layer discs, which can store as much as 100 GB of data. In 2006, TDK announced to have designed a Blu-ray disc that can store 200 GB of data. Ritek Corporation, a Taiwanese consumer electronics group declared to have devised an optical disc storage process that increases the disk capacity to 10 layers, thus raising the Blu-ray disc capacity to 250 GB. In 2007, Hitachi brought out a 100-GB Blu-ray disc consisting of four layers of 25 GB each. Later that year, Pioneer Corporation came up with a 400 GB Blu-ray disc consisting of 16 data layers, of 25 GB each.
Mini Blu-ray disks, BD9/BD5 Blu-ray discs and AVREC are some of the variants of Blu-ray discs. Mini Blu-ray discs can store around 7.5 GB data, on lines similar to MiniDVDs. BD9 and BD5 contain video and audio streams that are compatible with the Blu-ray format. They are suitable for home users and can be used on conventional DVD players. AVREC is used to store Blu-ray disc compatible content onto standard DVDs. Similar to recordable and writable CDs and DVDs, BD-R and BD-RE discs are also available. BD-R discs can be written just once while BD-RE discs can be erased and recorded many times.
As of December 2008, over 1200 Blu-ray titles have been released in the United States and more than 640 in Japan. Many more Blu-ray titles are expected to be released by 2009. Blu-ray discs have revolutionized the field of data storage. They are here to stay!
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