What is Blu-ray

Today Blu-ray technology gives the most high quality and high-definition movies, enabled by the higher storage space on disks. For those of you who are curious to know what it's all about, this article has all the answers.

What is Blu-ray Technology?

This technology was designed to create optical storage disks which would be an improvement over the DVD (Digital Versatile Disc) technology. It was developed by the 'Blu-ray Disc Association'. These disks are widely used today as data storage devices, that have a capacity of storing more than 25 GB of data on one disk. Single layered Blu-ray disks have a capacity to store up to 25 GB of data. Whereas, double layered ones have a capacity of storing 50 GB of data. The technology places no upper limit on the amount of data storage capacity that it offers. In fact, in the market, up to 200 GB discs are available today. The high storage capacity enables recording of high-definition video without any losses. With such high storage capacity, one would think that the disks will be thicker but in fact they come in the same standard size as the DVDs.

The name is derived from the 'Blue-Violet Laser' used to read and write data on these disks. This laser operates at a wavelength of 405 nanometers. This use of a shorter wavelength enables almost ten times more data storage as compared to DVDs. The higher data storage capacity guarantees a far better picture quality when it comes to storing movies. Most 'Box Set' movie collections or collector's editions of movies are launched in Blu-ray format nowadays.

The Secret Behind Blu-ray's High Storage Capacity

Data is written on optical disks with the use of lasers. In Blu-ray disks, the data is engraved by a laser on a 1.1 mm thick polycarbonate layer. What decides the storage capacity of the optical disk is the 'Spot Size' of the laser on the disk, which is a measure of the precision achieved by a laser. Smaller the spot size, more is the quantity of data that can be written. The pits engraved by the laser in the disk are therefore comparatively much shorter, that is about 0.15 microns to be precise, compared to 0.4 microns in DVDs. There are two factors which make the high storage capacity of disks possible. First is the fact that it uses a blue-violet laser of a shorter wavelength (405 nm), which is quite shorter than the ones used for DVD technology. The second factor is the size of numerical aperture of the lens, which focuses the laser. That size in case of Blu-ray is 0.85. Both these factors combined with a thinner cover layer and advancement in encoding technology, enables a much smaller spot size and hence greater storage capacity. In the future, Blu-ray disks with a storage capacity of 250 GB will also be available.

The only factor that goes against this technology currently is the price which is a bit higher compared to DVDs, but not too much. Also to play a Blu-ray disc, you need a special player which is expensive compared to DVD players. These disks can also be played in Sony PlayStation 3. Still, the technology is slowly catching up and with high sales volumes, the prices could lower substantially in the future. Blu-ray disks also provide a higher data transfer rate of 36 MB per second, while DVDs offer a transfer rate of only 10 MB per second. They also come with inbuilt encryption that can prevent piracy issues.