About BLU-RAY DISC:- :-
Optical
disks share a major part among the secondary storage devices. Blu-ray Disc is a
next-generation optical disc format. The technology utilizes a blue laser diode
operating at a wavelength of 405 nm to read and write data. Because it uses a
blue laser it can store enormous more amounts of data on it than was ever
possible.
Data
is stored on Blu-Ray disks in the form of tiny ridges on the surface of an
opaque 1.1-millimetre-thick substrate. This lies beneath a transparent 0.1mm
protective layer. With the help of Blu-ray recording devices it is possible to
record up to 2.5 hours of very high quality audio and video on a single
BD.
Blu-ray
also promises some added security, making ways for copyright protections. Blu-ray
discs can have a unique ID written on them to have copyright protection inside
the recorded streams.
Parameters for HD Video Storage with Optical Disks
1.Optical
Parameters
2.Disk
Structure Parameters
3.Data
Management Parameters
Optical
parameters include laser wavelength, objective lens numerical aperture,
protective layer thickness and free working distance. Data management
parameters include data rate, video format, HDTV play time and bit-rate scheme.
Disk structure parameters are user data capacity, minimum channel bit length
and track-to-track spacing.
1.Optical Parameters
The
process for exposing data marks on a recordable optical disk is shown in Fig,
where an input stream of digital information is converted with an encoder and
modulator into a drive signal for a laser source. The laser source emits an
intense light beam that is directed and focused onto the surface by the
objective lens. As the surface moves under the scanning spot, energy from the
intense scan spot is absorbed, and a small, localized region heats up. The
surface, under the influence of heat beyond a critical writing threshold,
changes its reflective properties. Modulation of the intense light beam is
synchronous with the drive signal, so a circular track of data marks is formed
as the surface rotates. The scan spot is moved slightly as the surface rotates
to allow another track to be written on new media during the next revolution.
High Definition Camcorder Archiving
As
the market penetration of High Definition TV sets continues to grow, so does
the demand of consumers to create their own HD recordings. With the advent of
the first HD camcorders, consumers can now for the first time record their own
home movies in a quality level unlike any before. As these camcorders are
tape-based, consumers cannot benefit from the convenience and direct access
features they are used to from the DVD players and recorders. Now, the Blu-ray
Disc format, with its unprecedented storage capacity, allows for the HD video recorded
with an HD camcorder to be seamlessly transferred to a Blu-ray Disc. When the
HD content is stored on a Blu-ray Disc, it can be randomly accessed in a way
comparable to DVD. Furthermore, the Blu-ray Disc can be edited, enhanced with
interactive menus for an even increased user experience and the disc can be
safely stored for many years, without the risk of tape wear.
Blu-ray Disc and HD-DVD
The
HD-DVD format, originally called AOD or Advanced Optical Disc, is based on much
of today's DVD principles and as a result, suffers from many of its
limitations. The format does not provide as big of a technological step as
Blu-ray Disc. For example, its pre-recorded capacities are only 15 GB for a
single layer disc, or 30 GB for a double layer disc. Blu-ray Disc provides 67%
more capacity per layer at 25 GB for a single layer and 50GB for a double layer
disc.
Applications
1.High
Definition Television Recording
2.High
Definition Video Distribution
3.High
Definition Camcorder Archiving
Conclusion
The
BD represents a major advancement in capacity as well as data transfer rate. It
would be an ideal choice for the secondary storage purposes. The semiconductor
storage for secondary memory is large, consumes more power and is more
expensive. HDTV video recording and reproducing would essentially require the
large storage capacity and data transfer rates, as offered by the Blu-ray disc.
The Blu-ray disc has a wide variety of applications and is the ultimate storage
device that would lead to digital convergence, ultimately leading to the
convergence of the PC and CE technologies.
2 comments:
more about blu ray disc
more about ac performance of nanoelectronics needed.
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