PDF [4833KB] - Sony

Blue-violet laser achieves high
recording density
Data on an optical disc is recorded and read by
passing a beam from the laser through the lens
and onto a spot on the disc called the beam
spot. Since blue-violet light has a shorter wavelength
than red, it can produce a smaller beam
spot. The result is higher recording density.
Blue-violet lasers with a wavelength of 405
nanometer enable Blu-ray Disc to increase
recording density about 2.6 times, and combined
with high-powered lenses, the recording
capacity of Blu-ray Disc is six times that of the
standard DVD.
1.2
mm
DVD
Comparison of beam spot size
100% 19%
Blu-ray Disc
1.2
mm
High-speed data rate of 36Mbps to accommodate
digital content
Blu-ray Disc has a data rate of 36Mbps, much
greater than the maximum speed of 24Mbps
in digital HDTV from a broadcasting satellite
(BS). This speed enables Blu-ray Disc to easily
record digital HDTV programs from the BS and
play them with remarkably high-quality picture.
Blu-ray Disc recorder
In April 2003, Sony unveiled the world’s first
Blu-ray Disc recorder. By using the same MPEG-
2TS video recording method used in BS digital
TV broadcasts, this unit can record more than
two hours of BS digital TV programming with
no degradation in picture quality.
The development of three-wavelength
recording/playback optical pickups
that are compatible with Blu-ray Disc,
DVDs and CDs
Sony has developed a three-wavelength recording/playback
optical pickup that is compatible
with the Blu-ray Disc, DVD and CD. In addition
to reducing the number of components required
and decreasing its size, Sony is striving to
increase the optical pickup’s reliability and
productivity, in order to rapidly commercialize
this product. As the key component for the
Blu-ray Disc system, this new optical pickup is
positioned to contribute to the expansion of
this market.
Lens numerical aperture
(approx. doubles density)
0.6 0.85
Laser wavelength
(raises density approx. 2.6 times)
650nm 405nm
(simplified diagram)
Prototype of the newly developed three-wavelength
optical pickup for recording and playback
0.1mm optical cover layer improves
reliability
On a Blu-ray Disc, data is stored at more than
2.5 times the density of a DVD, while the width
of the recording tracks is less than half that of a
DVD. Furthermore, the tracks where the data is
stored are only 0.1mm below the disc surface.
Placing the recording tracks closer to the surface
means that Blu-ray Discs are less prone to
problems caused by disc warping and other
factors compared to CDs and DVDs.
Optical cover layer
For 0.6mm thickness
(same as in a DVD)
Blu-ray Disc
0.6mm
Substrate
NA 0.85
Optical cover layer
For 0.1mm thickness
0.1mm
Blu-ray Disc recorder
Success in developing a 25GB optical
disc made of paper
Sony and Toppan Printing Co., Ltd., have succeeded
in developing a 25GB paper optical disc
with a paper content of more than 51%. Part of
the disc uses paper because Blu-ray Discs can be
played and recorded on the 0.1mm surface
layer. The use of paper reduces the need for
plastic, making the discs more environmentfriendly
and decreasing manufacturing costs.
A paper disc
Optical pickup for conventional DVDs/CDs
(top) and Blu-ray Disc (bottom)
Cross-licensing agreement for optical
disc-related blue-violet laser diode
patents
Sony and Nichia Corporation from Japan have
agreed to cross-license patents involving the
Blu-ray Disc format’s blue-violet laser diode. This
agreement is expected to open the door to
Sony’s mass-production of blue-violet laser
diodes, a big step that will position it to respond
to expansion in the market for Blu-ray Discformat
products.
Scanning electron
microscope view
DVD-RW
Scanning electron
microscope view
Recording
layer
Optical
cover layer
Shortest
recording mark of
0.4m
Track pitch of
0.74m
Shortest
recording mark
(0.16m for 23GB;
0.149m for 25GB;
0.138m for 27GB)
Track pitch of
0.32m
Substrate
Recording layer
Optical cover layer
(simplified diagram)
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