23-06-2012, 02:27 PM
BLU RAY DISC
INTRODUCTION
Blu-ray Disc is an optical disc storage medium designed to supersede the standard DVD format.
Its main uses are for storing High Definition Video, video games, and other Data storage applications.
The name Blu-ray Disc derives from the Blue – violet laser used to read the disc.
Background Information
1998 – Release of High-Definition Televisions
Shuji Nakamura invents blue-laser technology but kept off market due to patent problems
The first DVR Blue prototypes unveiled at the CEATEC exhibition in October 2000
The DVD Forum deeply split over whether to develop blue laser technology because of its higher expense.
Sony includes blu-ray players in PlayStation3 – although HD DVD head starts in the high-definition video market, this changed the game
By February 2008, Toshiba withdrew its support for the HD DVD format, leaving Blu-ray the victor
WORKING OF BLU-RAY DISC
Discs store digitally encoded video and audio
Information in pits , spiral grooves that run from the
center of the disc to its edges .
A laser reads the other side of these pits
to play the movie or program that is
stored on the disc.
The more data that is contained on a disc, the
smaller and more closely packed the pits must be.
Laser and Optics Used in Blu-ray
The blue-violet 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
light and the NA of the lens used to focus it .
By decreasing the wavelength and increasing the numerical
aperture from 0.60 to 0.85, and making the cover layer thinner
to avoid unwanted optical effects, the laser beam can be
focused to a smaller spot.
This allows more information to be stored in the same area.
For Blu-ray Disc, the spot size is 580 nm.
INTRODUCTION
Blu-ray Disc is an optical disc storage medium designed to supersede the standard DVD format.
Its main uses are for storing High Definition Video, video games, and other Data storage applications.
The name Blu-ray Disc derives from the Blue – violet laser used to read the disc.
Background Information
1998 – Release of High-Definition Televisions
Shuji Nakamura invents blue-laser technology but kept off market due to patent problems
The first DVR Blue prototypes unveiled at the CEATEC exhibition in October 2000
The DVD Forum deeply split over whether to develop blue laser technology because of its higher expense.
Sony includes blu-ray players in PlayStation3 – although HD DVD head starts in the high-definition video market, this changed the game
By February 2008, Toshiba withdrew its support for the HD DVD format, leaving Blu-ray the victor
WORKING OF BLU-RAY DISC
Discs store digitally encoded video and audio
Information in pits , spiral grooves that run from the
center of the disc to its edges .
A laser reads the other side of these pits
to play the movie or program that is
stored on the disc.
The more data that is contained on a disc, the
smaller and more closely packed the pits must be.
Laser and Optics Used in Blu-ray
The blue-violet 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
light and the NA of the lens used to focus it .
By decreasing the wavelength and increasing the numerical
aperture from 0.60 to 0.85, and making the cover layer thinner
to avoid unwanted optical effects, the laser beam can be
focused to a smaller spot.
This allows more information to be stored in the same area.
For Blu-ray Disc, the spot size is 580 nm.