BLU RAY DISC

-P.SAILAJA

WHAT IS BLU RAY DISC???

HIGH DENSITY OPTICAL DISC STORAGE MEDIUM

TO SUPERSEDE DVD FORMAT

STORES HIGH DEFINITION CONTENT

NOMENCLATUREIt utilizes blue-violet laser

BLUE + LASER = BLU RAY (optical ray)

‘e’ dropped---- for trademarking

HISTORY FIRST GENERATION

COMPACT DISC(CD): CAPACITY : 650/ 700 MB WAVELENGTH OF LASER : 780nm COLOUR OF LASER : RED

SECOND GENERATION

DIGITAL VERSATILE DISC(DVD):

CAPACITY : 4.7 GB WAVELENGTH OF LASER : 650nm

COLOUR OF LASER : RED

NEED FOR BLU RAY DISC No particular storage for HD

format

To store HD content big size DVDs were used

Shuji Nakamura invented the violet-blue laser diode which was apt for a Blu-Ray Disc.

THIRD GENERATION

BLU RAY DISC

CAPACITY : 25/50 GB WAVELENGTH OF LASER : 405nm COLOUR OF LASER : BLUE-VIOLET

DVD & BLU RAY DISC- SAME PHYSICAL SIZE

BLU RAY DISC ASSOCIATION Developed blu ray disc format

TYPES OF BLU RAY DISC• SINGLE LAYER 25/27 GB

•DOUBLE LAYER• 50 GB

MULTI LAYER > 50 GB

FORMATS OF BD4 different formats:

BD ROM (read only):- for reading recorded content.

BD – R (recordable):- for PC data storage.

BD – RW (rewritable):- for PC data storage.

BD – RE (rewritable):- for HDTV (High Definition Television) recording.

FEATURES OF BLU RAY DISC:

Record HDTV without any quality loss.

Instantly skip to any spot on disc.

Record on one program while watching other on the disc.

Create play list.

THE TECHNOLOGYDisc stores digitally

encoded data in PITS.

THE TECHNOLOGY

• Pits : spiral grooves that run from the centre of the disc to its edges

Bumps : other sides of these edges.Track pitch : it is the distance between

the two tracks (of pits) on the surface.More pits, less track pitch ----- more

storage capacity

THE TECHNOLOGY

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 (0.74 microns in DVD)

Data transfer rate : 36 Mbps ( where DVD read data at 10Mb/s.)

LASER Closer the pits , more precise laser is

required .

BLUE-VIOLET laser

Gallium Nitride LEDSemiconductor diode which

reads Blu Ray disc

CONSTRUCTION

CONSTRUCTION

WORKINGPlaces data on top of polycarbonate layerPrevents birefringencePrevents disc tiltBirefringence & disc tilt are the drawbacks of

DVD

WHAT ARE BIREFRINGENCE &DISC TILT?

DVD Data is sandwiched between two polycarbonate layers, each 0.6 mm thick.

BIREFRINGENCE Refraction of laser light due to top

polycarbonate layer

DISC TILT Distortion of laser beam due to

uneven surface

ADVANTAGESHard coating technologies make Blu ray Disc

most durable It provides resistance to:- Finger prints Marks Scratches Dust• Faster data seek times– due to high density Much more ROBUST than today’s

polycarbonate – based CD/DVD

Blu Ray UsageRecording mediaVideo games Used by Music companies Watching movies

DISADVANTAGE:EXPENSIVE