Blu-Ray Disc

 

Blu-Ray Disc 

 

Blu-Ray Disc is a digital video disc that has high storage capacity than ordinary DVDs.
The size of ordinary DVD is 4.7GB that hold up to 2 hours of high definition video.
The Blu-ray Disc has two types. A single layer Blu-ray Disc can hold 27GB of data that has 13 hours of high definition video.
A double layer Blu-ray Disc can hold 50GB of data that has high definition video for more than 20 hours.
The main difference between DVDs and Blu-ray Discs is that it uses blue laser to read and write data.
Normal DVDs uses red laser for reading and writing.
The wavelength of blue laser (405nm) is shorter than red laser (650nm).
Blu-ray discs store video and audio in the form of pits (Pits are grooves that run from Centre of the disc to its edges).
The more data that is on a disc, the smaller and more closely packed the pits will be.
The smaller the pits, the more precise the reading of laser will be.
Blu-ray also has a higher data transfer rate of 36 Mbps.

Data storage on the disc:

The data is place on the top of a 1.1mm thick polycarbonate layer.
A hard coating is done on the outside of the disc to protect it from scratches and fingerprints.
The data is much closer to the lens in the disc; it eliminates the problem of disc tilt.