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 is an upcoming and a promising optical storage format used for storing high-definition video and data. Wondering where its name came from? Well, it originated from the blue laser, which is used to read from or write in these types of discs. Let us find out more about this brilliant storage device, the Blu-ray disc, abbreviated as BD.
Blu-ray Discs
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 that 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!
| By Manali Oak Published: 12/15/2008 |
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