The document discusses Blu-ray discs, a digital optical storage format designed to replace DVDs, capable of holding high-definition video and large data capacities (up to 128 GB). It highlights the technology behind Blu-ray, including the blue laser's shorter wavelength that allows for greater data storage and access, as well as its applications in high-definition video recording. Key points include the advantages of higher data transfer rates, durable disc cartridges, and the use of phase change technology for data writing and reading.

1. By – Manash Pratim Deka
Roll no. - 1273920014

2. Points to be discussed
Introduction
Need for Blu Ray disc
Key Characteristics
Blue Laser
Some features of Blue Laser
Accessing the disc
Applications
Difference between Blu Ray disc and DVD

3. Introduction
 Blu Ray Disc (BD) is a new optical disc standard or a digital optical
disc data storage format designed to supersede the Digital Versatile
Disc (DVD) format.
 The name Blu-ray Disc refers to the blue laser used to read the disc.
 It is capable of storing high-definition video resolution (1080p).
 The plastic disc is 120 mm in diameter and 1.2 mm thick, the same
size as DVDs and Compact Discs (CDs).
 Conventional Blu-ray Discs contain 25 GB per layer, with dual layer
discs (50 GB).
 Triple layer discs (100 GB) and quadruple layers (128 GB) are available
for BD-XL re-writer drives.

4. contd...
The blue laser has a 405 nm wavelength that can focus
more tightly than the red lasers used for writable DVD
and as a consequence, write much more data in the
same space.
Blu-ray uses phase change technology to enable
repeated writing to the disc.

5. Need for Blu Ray Disc
With the advent of High Definition videos, it is
evident that larger capacity discs are needed.
Data archiving requirements are also driving demand
for increase in capacity.
For High recording speed as well as reading speed.

6. Blu Ray Disc Key Characteristics
Large recording capacity up to 25GB - 27GB.
By adopting a 405nm blue-violet semiconductor laser,
with a 0.85NA field lens and a 0.1 mm. optical
transmittance protection disc layer structure, it can record
up to 27GB video data on a single sided 12cm phase
change disc. It can record over 2 hours of digital high
definition video and more than 13 hours of standard TV
broadcasting (VHS/standard definition picture quality,
3.8Mbps).

7. Contd…
High-speed data transfer rate 36Mbps.
It is possible for the Blu-ray Disc to record digital
high definition broadcasts or high definition images
from a digital video camera while maintaining the
original picture quality.
Easy to use disc cartridge.
An easy to use optical disc cartridge protects the
optical disc’s recording and playback phase from dust
and fingerprints.

8. Blue Laser
A laser is a coherent and focused beam of photons or
particles of light.
The photons are produced as the result of a chemical
reaction between special materials and this special
material in the blue laser technology is Gallium nitride.
A blue laser is a laser with a shorter wavelength than the
red laser used in today’s compact disc and laser printer
technologies and the ability to store and read two to four
times the amount of data.
Even a small shortening of wavelength of light can have a
dramatic effect in the ability to store and access data.

9. contd…
Red lasers used in today’s technologies have wavelengths of
over 630 nanometers. The blue laser has a wavelength of
405 nanometers.
SANYO (Electronics company in Japan)has developed the
world’s first blue laser diode with a new low-noise (stable)
beam structure produced using ion implantation.

10. contd…
The stable beam structure boasts lower noise, and lower
current consumption achieving higher performance
compared to the blue laser diodes used before that.
This structure makes SANYO’s blue laser diode an
optimum light source for large-capacity optical disc
systems like Blu ray discs.
The laser diode is easily mass produced because the stable
beam structure reduces the number of fabrication steps
while the top and bottom electrodes structure reduces chip
size.

11. Blue Laser Diodes

12. Contd…
In recent years, the field of optical disc systems has seen
the development of next- generation large-capacity optical
disc systems like advanced BDs that can record more than
two hours of digital high definition images.
The blue laser diode made of InGaN (indium gallium-
nitride) that is used as a light source for reading signals
recorded on the optical discs was the key to developing
these systems.

13. Some other features of Blue Laser
Fundamental traverse mode
The fundamental traverse mode generates a single
stable beam which means the beam can be focused
into a tiny spot using a simple optical system.
Built-in photodiode for monitoring optical output
A photodiode is installed to monitor optical output
Applications
The new laser diode is suitable for the next-
generation large-capacity optical disc systems like and
many types of measuring instruments.

14. Accessing the Disc
The technology behind writing in the disc and reading
from the disc is “Phase Change Technology”.
Phase change technology do not rely on magnetic
influence as do hard disks and magneto-optic (MO) discs.
In rewritable phase change media, the heat from a short,
high-intensity laser pulse turns a bit in the recording layer
into an unstructured "amorphous" state, and a medium-
intensity pulse sets it to a highly structured "crystalline"
state.

17. contd…
Writing a bit is accomplished by pulsing different
intensities of a laser into the phase change layer, which
changes the bit between crystalline and amorphous states.
The bit is read by sensing the reflected light from a low-
intensity laser pulse.
The crystalline bit reflects the laser beam, while the
amorphous bit absorbs the light.

18. Applications
Ultra Density Optical (UDO)
It utilizes violet laser and phase change media
recording technology to provide a huge leap in data
storage densities.
First generation UDO products were of 30GB capacity
and were launched in August, 2003.
The Future generations increased the capacity to 60GB
and 120GB and provides full backward read compatibility.

19. contd…
Digital Video Recording
The Blu-ray Disc using blue laser achieves over
2-hour digital high definition video recording on a
12cm diameter CD/DVD size phase change optical
disc.
The Blu-ray Disc enables the recording, rewriting and
play back of up to 27 gigabytes (GB) of data on a single
sided single layer disc using a 405nm blue laser.

25. References
World Wide Web
www.whatis.com
www.bluraytalk.com
www.computerworld.com
www.dvdeurope2002.com
www.bluray.org

26. Thank You