-Color of laser: Blue-violet which was developed by
at NICHIA CORPORATION
The blu-ray name is a combination of “blue”, for the color of the laser that is used and “ray” for optical ray.
The “e” in “blue” was purposefully left off, according to the manufacturers, because an everyday word cannot be a trademark.
TYPES OF BD:
SINGLE LAYER :
Can hold data up to 25/27 GB that means 2 hrs of HD video or about 13 hrs of standard video.
DOUBLE LAYER :
Can hold data up to 50 GB that means 4.5 hrs of HD video or more than 20 hrs of standard video.
SISE OF THE DISC
So, in blu-ray disc:
Pit size – 0.15 microns ( more than twice as small as the pits on DVD )
Track-pitch is : 0.32 microns
Laser needed : blue-violet laser (405 nm)
Data transfer rate : 36 Mbps
• The Blue-laser’s shorter wavelength makes it possible to store more information on a 12 cm CD/DVD size disc. The minimum spot size on which a laser can be focused is limited by diffraction ,and depends on the wavelength of the high and the numerical aperture of the lens used to focus it.
Pits : spiral grooves that run from the centre of the disc to its edges
Track pitch : it is the distance between the two tracks (of pits) on the surface.
BLU RAY ‘S DURABILITY ADVANTAGE
Various hard coating technologies make Blu ray disc most durable and family -friendly”
Hard-coating technology provides resistance to:
- Finger prints
FEATURES OF BD
With BD we can:
Record HDTV without any quality loss
Instantly skip to any spot on disc
Record one program while watching other on the disc
Edit or reorder programs recorded on disc
Automatically search for an empty space on the disc to avoid recording over a program
Access to web to download subtitles and other extra features