HOLOGRAPHIC VERSATILE DISC
A SEMINAR REPORT
Submitted by
NIKESH BHARTI
impartial fulfillment of requirement of the Degree
of
Bachelor of Technology (B.Tech)
IN
COMPUTER SCIENCE AND ENGINEERING
SCHOOL OF ENGINEERING
COCHIN UNIVERSITY OF SCIENCE AND TECHNOLOGY
KOCHI- 682022
AUGUST 2008Page 2

Certificate
DIVISION OF COMPUTER SCIENCE AND ENGINEERING
SCHOOL OF ENGINEERING
COCHIN UNIVERSITY OF SCIENCE AND TECHNOLOGY
KOCHI-682022
Certificate
Certified that this is a bonafide record of the seminar entitled
" HOLOGRAPHIC VERSATILE DISC "
presented by the following student
Nikesh Bharti
of the VII semester, Computer Science and Engineering in the year 2008 in partial
fulfillment of the requirements in the award of Degree of Bachelor of Technology in
Computer Science and Engineering of Cochin University of Science and Technology.
Ms. Remyamol K M Dr. David Peter S.
Seminar Guide Head of Division
DatePage 3

Acknowledgement
Many people have contributed to the success of this. Although a single sentence hardly
suffices, I would like to thank Almighty God for blessing us with His grace. I extend my
sincere and heart felt thanks to Dr. David Peter, Head of Department, Computer
Science and Engineering, for providing us the right ambience for carrying out this work. I
am profoundly indebted to my seminar guide, Ms. Remyamol K M for innumerable acts
of timely advice, encouragement and I sincerely express my gratitude to her.
I express my immense pleasure and thankfulness to all the teachers and staff of the
Department of Computer Science and Engineering, CUSAT for their cooperation and
support.
Last but not the least, I thank all others, and especially my classmates who in one way or
another helped me in the successful completion of this work.
NIKESH BHARTIPage 4

ABSTRACT
The Information Age has led to an explosion of information available to
users.While current storage needs are being met, storage technologies must
continue to improve in order to keep pace with the rapidly increasing
demand. However, conventional data storage technologies ,where
individual bits are stored as distinct magnetic or optical changes on the
surface of a recording medium, are approaching physical limits. Storing
information throughout the volume of a medium ” not just on its surface
”offers an intriguing high-capacity alternative. Holographic data storage
is a volumetric approach which , although conceived decades ago, has
made recent progress toward practicality with the appearance of lower-
cost enabling technologies , significant results from longstanding
research efforts, and progress in holographic recording materials.
Holographic versatile disc (HVD) is a holographic storage format capable of
storing far more data than DVD. Prototype HVD devices have been created
with a capacity of 3.9 terabytes (TB) and a transfer rate of 1 gigabit per
second (1 Gbps). At that capacity, an HVD could store as much
information as 830 DVDs or 160 Blu-ray discs.
This paper presents an introduction to holographic versatile disc, its
challenges , and opportunities.Page 5

TABLE OF CONTENTS
Chapter No. Title Page
LIST OF TABLES iii
LIST OF FIGURES iii
1 INTRODUCTION 1
1.1 Breif history 2
1.2 Longevity 3
1.3 Features 3
2 UNDERLYING TECHNOLOGY 4
2.1 Holography 4
2.2 Collinear Holography 6
3 STRUCTURE 7
3.1 HVD Structure 7
3.2 HVD Reader Prototype 8
4 DATA STORAGE 9
4.1 Recording Data 9
4.2 Reading Data 11
5 HARDWARE 13
5.1 Spatial Light Modulator 13Page 6

6 TYPES 15
6.1 Read Only 15
6.2 Read-Write 15
7 MORE ONHVD 17
7.1 Competing Technologies 17
7.2 HVD Adoption 17
7.3 HSD Forum 17
7.4 Standards 18
7.5 Storage Capacity 18
7.6 HVD at a Glance 19
8 COMPARISON 20
9 DEVELOPMENT ISSUES 21
10 CONCLUSION 22
11 REFERENCES 23Page 7

LIST OF TABLES
NO:
NAME
PAGE
Features Comparison
LIST OF FIGURES
NO:
NAME
PAGE
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
Interference
Holography
Collinear Holography
Fringes Pattern
Disc Structure
HVD Reader Prototype
Recording Data
Reading Data
SLM
Data Storage
Electron cloud
HVD
4
5
6
6
7
8
10
12
13
14
16
19
inPage 8

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1. INTRODUCTION
An HVD (Holographic Versatile Disc), a holographic storage media, is an advanced
optical disk that's presently in the development stage. Polaroid scientist J. van Heerden
was the first to come up with the idea for holographic three-dimensional storage in
1960. An HVD would be a successor to today's Blu-ray and HD-DVD technologies. It
can transfer data at the rate of 1 Gigabit per second. The technology permits over 10
kilobits of data tobe written and read in parallel with a single flash. The disk will store
upto 3.9 terabyte (TB) of data on a single optical disk.
Holographic data storage, a potential next generation storage technology, offers both high
storage density and fast readout rate. In this article, I discuss the physical origin of these
attractive technology features, and the components and engineering required to realize
them. The strengths and weaknesses of available write-once and read-writeable storage
media are discussed, including the development issues of achieving non-volatile readout
from read-write media. Systems issues such as the major noise sources and avenues for
defeating or finessing them are detailed, including the potentials and pitfalls of phase-
conjugate readout and holographic storage on spinning media. I conclude by describing
the current state of holographic storage research and development efforts in the context of
ongoing improvements to established storage technologies.
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l.lBRIEF HISTORY
Although holography was conceived in the late 1940s, it was not considered a potential
storage technology until the development of the laser in the 1960s. The resulting rapid
development of holography for displaying 3-D images led researchers to realize that
holograms could also store data at a volumetric density of as much as 1/ A3 where A, is the
wave-length of the light beam used.
Since each data page is retrieved by an array of photo detectors in parallel, rather than
bit-by-bit, the holographic scheme promises fast readout rates as well as high density.
If a thousand holograms, each containing a million pixels, could be retrieved every
second, for instance, then the output data rate would reach 1 Gigabit per second.
Despite this attractive potential and fairly impressive early progress research into
holographic data storage died out in the mid-1970s because suitable devices for the input
and output of large pixelated 2-D data pages were just not available.
In the early 1990s, interest in volume-holographic data storage was rekindled by the
availability of devices that could display and detect 2-D pages, including charge coupled
devices (CCD), complementary metal-oxide semiconductor (CMOS) detector chips and
small liquid-crystal panels. The wide availability of these devices was made possible by
the commercial success of hand-held camcorders, digital cameras, and video projectors.
With these components in hand, holographic-storage researchers have begun to
demonstrate the potential of their technology in the laboratory. By using the volume of
the media, researchers have experimentally demonstrated that data can be stored at
equivalent areal densities of nearly 400 bits/sq. micron. (For comparison, a single-layer
of a DVD disk stores data at ~ 4:7 bits/sq. micron ) A readout rate of 10 Gigabit per
second has also been achieved in the laboratory.
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1.2 LONGEVITY
Holographic data storage can provide companies a method to preserve and archive
information. The write-once, read many (WORM) approach to data storage would ensure
content security, preventing the information from being overwritten or modified.
Manufacturers believe this technology can provide safe storage for content without
degradation for more than 50 years, far exceeding current data storage options.
Counterpoints to this claim point out the evolution of data reader technology changes
every ten years; therefore, being able to store data for 50-100 years would not matter if
you could not read or access it.
1.3 FEATURES
Data transfer rate : lgbps.
The technology permits over 10 kilobits of data to be written and read in
parallel with a single flash.
Most optical storage devices, such as a standard CD saves one bit per pulse.
HVDs manage to store 60,000 bits per pulse in the same place.
1 HVD = 5800 CDs = 830 DVD =160 BLU-RAY Discs.
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2. UNDERLYING TECHNOLOGY
2.1 HOLOGRAPHY
Holographic data storage refers specifically to the use of holography to store and retrieve
digital data. To do this, digital data must be imposed onto an optical wavefront, stored
holographically with high volumetric density, and then extracted from the retrieved
optical wavefront with excellent data fidelity.
A hologram preserves both the phase and amplitude of an optical wavefront of interest -
called the object beam - by recording the optical interference pattern between it and a
second coherent optical beam - the reference beam. Figure 2.1 shows this process .
Interference
lightwaves
barrier
interference
pattern
Fig 2.1
The reference beam is designed to be simple to reproduce at a later stage. (A common
reference beam is a plane wave: a light beam that propagates without converging or
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diverging.) These interference fringes are recorded if the two beams have been
overlapped within a suitable photosensitive media, such as a photopolymer or inorganic
crystal or photographic film. The bright and dark variations of the interference pattern
create chemical and/or physical changes in the media, preserving a replica of the
interference pattern as a change in absorption, refractive index or thickness.
From Computer Desktop Bicyclopedìa
S 20D6" Trie Computer L^nou^oe Co. Ino.
WRITE
HOLOGRAM
Optic ii I
fvloTei i-il
[K-iT*-i Benin
llllllllllllllllllllllllilllllllllllllll
Â¥% of o re n >c e O o o m
The
i nter-F erer-ioe
pattern,
WTli oh i ^
th"i^ holograi
^ mi 11 i on
II
READ
HOLOGRAM
lllllllllllllllllllllllll
[Kit.! Beïim
Reference Berlin
Fig 2.2
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When the recording is illuminated by a readout beam similar to the original reference
beam, some of the light is diffracted to "reconstruct" a copy of the object beam as shown
in Figure 2.2 . If the object beam originally came from a 3-D object, then the
reconstructed hologram makes the 3-D object reappear.
2.2 COLLINEAR HOLOGRAPHY
HVD uses a technology called 'collinear holography,' in which two laser rays, one blue-
green and one red, are collimated into a single beam. The role of the blue-green laser is to
read the data encoded in the form of laser interference fringes from the holographic layer
on the top, while the red laser serves the purpose of a reference beam and also to read the
servo info from the aluminum layer - like in normal CDs - near the bottom of the disk.
The servo info is meant to monitor the coordinates of the read head above the disk (this is
similar to the track, head and sector information on a normal hard disk drive).
Fig 2.3 shows the two laser collinear holography technique and fig 2.4 shows the
interference fringes pattern stored on the disc.
Fig 2.3
Fig 2.4
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3. STRUCTURE
3.1 HVD STRUCTURE
HVD structure is shown in fig 3.1. The following components are used in HVD.
1.Green writing/reading laser (532 nm)
2. Red positioning/addressing laser (650 nm)
3. Hologram (data)
4. Polycarbon layer
5. Photopolymeric layer (data-containing layer)
6. Distance layers
7. Dichroic layer (reflecting green light)
8. Aluminium reflective layer (reflecting red light)
9. Transparent base
P. PIT
á
Fig 3.1
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3.2 HVD READER PROTOTYPE
To read data from an HVD we need an HVD reader. The following components are used
to make a raeder.
A blue-green argon laser, beam splitters to spilt the laser beams, mirrors to direct the
laser beams, LCD panels (spatial light modulator), lenses to focus the laser beams,
lithium-niobate crystals or photopolymers, and charge-coupled device (CCD) cameras.
Fig 3.2 shows the prototype of a reader.
From Computer Desktop &cyclopedia
Reproduced uurth permission.
S 1996 IBM^maden Research Center
Fig 3.2
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4. DATA STORAGE
4.1 RECORDING DATA
Holographic data storage works on the principle of holography. In holographic data
storage an entire page of information is stored at once as an optical interference pattern
within a thick, photosensitive optical material (Fig 4.1). This is done by intersecting two
coherent laser beams within the storage material. The first, called the object beam,
contains the information to be stored; the second, called the reference beam, is designed
to be simple to reproduce. The resulting optical interference pattern causes chemical
and/or physical changes in the photosensitive medium. A replica of the interference
pattern is stored as a change in the absorption, refractive index, or thickness of the
photosensitive medium. Illuminating the stored grating with the reference wave
reconstructs the object wave.
Light from a single laser beam is divided into two separate beams, a reference beam and
an object or signal beam; a spatial light modulator is used to encode the object beam with
the data for storage. An optical inference pattern results from the crossing of the beams'
paths, creating a chemical and/or physical change in the photosensitive medium; the
resulting data is represented in an optical pattern of dark and light pixels. By adjusting the
reference beam angle, wavelength, or media position, a multitude of holograms
(theoretically, several thousand) can be stored on a single volume. The theoretical limits
for the storage density of this technique are approximately tens of terabits (1 terabyte =
1,000 gigabytes) per cubic centimeter.
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Recording Data m®^
Referente
Beim
Mi] i
. ^ 011101010101001010.
aim light j
Mfliuhtor _^ ¦
\ """"" Data rages
Laser
Fig 4.1
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4.2 READING DATA
A backward-propagating reference wave, illuminating the stored grating from the
"back" side, reconstructs an object wave that also propagates backward toward its
original source where the bit value can be read.
A large number of these interference gratings or patterns can be superimposed in the
same thick piece of media and can be accessed independently, as long as they are
distinguishable by the direction or the spacing of the gratings. Such separation can be
accomplished by changing the angle between the object and reference wave or by
changing the laser wavelength. Any particular data page can then be read out
independently by illuminating the stored gratings with the reference wave that was used
to store that page. Because of the thickness of the hologram, this reference wave is
diffracted by the interference patterns in such a fashion that only the desired object beam
is significantly reconstructed and imaged on an electronic camera.
Another way to retrieve data involves illuminating it with a diverging object beam, which
reconstructs the original plane wave reference beam. This beam can be focused onto a
detector and provides an optical measurement of the correlation between the stored data
and the illuminating object beam. This technique can allow one to search the stored data
according to its content, rather than according to its address (Fig 4.2).
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Reading Data
Recording
Meium\
Reference
Beam
Detector
Optics
DahFagps
011101010101001010.
RmìiiThIhiI
Ml
Fig 4.2
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5. HARDWARE
5.1 SPATIAL LIGHT MODULATOR
To use volume holography as a storage technology, digital data must be imprinted onto
the object beam for recording and then retrieved from the reconstructed object beam
during readout. The device for putting data into the system is called a spatial light
modulator (SLM) - a planar array consisting of thousands of pixels. Each pixel is an
independent microscopic shutter that can either block or pass light using liquid-crystal or
micro-mirror technology. Liquid crystal panels and micro-mirror arrays with 1280 X
1024 pixels are commercially available due to the success of computer-driven projection
displays. The pixels in both types of devices can be refreshed over 1000 times per
second, allowing the holographic storage system to reach an input data rate of 1 Gbit per
second - assuming that laser power and material sensitivities would permit. The data are
read using an array of detector pixels, such as a CCD camera or CMOS sensor array.
optical cylinders
(1mm x 1cm}
From Computer Desktop BicycHopedia
d> 1998 The Computer Language Co. Inc.
spatial light
modulator
Fig 5.1
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To access holographically-stored data, the correct reference beam must first be directed
to the appropriate spot within the storage media. With mechanical access (i.e., a spinning
disk), getting to the right spot is slow (long latency), but reading data out can be quick.
Non - mechanical access leads to possibility for lower latency. A frequently mentioned
goal is an integration time of about 1 millisecond, which implies that 1000 pages of data
can be retrieved per second. If there are 1 million pixels per data page and each pixel
stores one bit then the readout rate is 1 Gigabit per second. This goal requires high laser
power (at least 1 W), a storage material capable of high diffraction efficiencies, and a
detector with a million pixels that can be read out at high frame rates. Frame rates of 1
kHz have been demonstrated in such "megapixel" CCDs , but these are not yet
commercially available. Low-noise megapixel CMOS detector arrays that can support
500 frames per second have also been demonstrated. Even with these requirements, faster
readout and lower latency could be reached by steering the reference beam angle non-
mechanically, by using a pulsed laser, and by electronically reading only the desired
portion of the detector array. Both the capacity and the readout rate are maximized when
each detector pixel is matched to a single pixel on the SLM, but for large pixel arrays this
requires careful optical design and alignment.
Detector
..._ Array
Spatial
Light
Modulator
Fig 5.2
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6. TYPES
6.1 READ ONLY
A material that permanently stores volume holograms must generally support some
irreversible photochemical reaction, triggered by the bright regions of the optical
interference pattern, that can lead to changes in index of refraction or absorption. For
example, a photopolymer material polymerizes in response to optical illumination:
material diffuses from darker to brighter regions so that short monomer chains can bind
together to form long molecular chains. Because this diffusion process can be
phototriggered, sensitivities can be made high enough to support holographic recording
with single short pulses. However, the high sensitivity means that some of the media
volume may be inadvertently affected by partial exposure as nearby spots are recorded. In
contrast to photopolymers, the illuminated molecules in a so-called direct-write or
photochromatic material undergo a local change in their absorption or index of refraction,
driven by photochemistry or photo-induced molecular reconfiguration. Examples include
photoaddressable polymers, and binding of absorbers to polymer hosts. Both types of
materials are inexpensive to make in bulk, but both can have problems reproducing the
object beam faithfully.
6.2 READ-WRITE
In contrast to the organic WORM media, most erasable holographic materials tend to be
inorganic photorefractive crystals doped with transition metals or rare-earth ions. These
materials react to an optical interference pattern by transporting and trapping electrons. In
an ensemble sense, electrons photoexcited at the bright fringes diffuse or drift (are pushed
by an electric field) and are retrapped at a dark fringe. By using noncentro symmetric
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crystals exhibiting a linear electro-optic effect, the resulting spatial modulation of electric
field leads to a corresponding local change in index of refraction. The trapped charge can
be rearranged by later illumination, so it is possible to erase recorded holograms and
replace them with new ones. This would seem to enable a read-write storage device,
where small blocks of data are written, read, and erased with equal facility. However, the
recording rates of photorefractive materials are typically 5-50 times slower than the
achievable readout rate at any given laser power. In addition, erasing individual
holograms from a small storage volume without affecting the other superimposed
holograms is quite complicated.
Fig 6.1 shows spatial re-configuration of elotronic cloud ,thus producing modulation in
electric fields.
Fig 6.1
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7. MORE ON HVD
7.1 COMPETING TECHNOLOGIES
HVD is not the only technology in high-capacity, optical storage media. InPhase
Technologies is developing a rival holographic format called Tapestry Media, which they
claim will eventually store 1.6 TB with a data transfer rate of 120 MB/s, and several
companies are developing TB-level discs based on 3D optical data storage technology.
Such large optical storage capacities compete favorably with the Blu-ray Disc format.
However, holographic drives are projected to initially cost around US$15,000, and a
single disc around US$120-180, although prices are expected to fall steadily. The market
for this format is not initially the common consumer, but enterprises with very large
storage needs.
7.2 HVD ADOPTION
The biggest challenge for HVD will be in establishing itself in the commercial market,
which as of now seems to be a distant dream, given its higher cost margins. It is
anticipated that a single HVD, when commercially available, may cost anywhere between
$100-120 , and the reader will be priced anywhere in the range of $10,000 to $15,000.
However, like anything else associated with technology, the price will soon fall as
R&DD costs are recouped and competitions lowers profit margins.
7.3 THE HSD FORUM
The HSD Forum (formerly the HVD Alliance, & HVD FORUM) is a coalition of
corporations purposed to provide an industry forum for testing and technical discussion
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of all aspects of HVD design and manufacturing. By cooperating, members of the Forum
hope to expedite development and engender a market receptive to HVD technology.
7.4 STANDARDS
On December 9, 2004 at its 88th General Assembly the standards body Ecma
International created Technical Committee 44, dedicated to standardizing HVD formats
based on Optware's technology. On June 11, 2007, TC44 published the first two HVD
standards: ECMA-377, defining a 200 GB HVD "recordable cartridge" and ECMA-378,
defining a 100 GB HVD-ROM disc. Its next stated goals are 30 GB HVD cards and
submission of these standards to the International Organization for Standardization for
ISO approval.
7.5 STORAGE CAPACITY IN CONTEXT
The entire US Library of Congress can be stored on six HVDs, assuming that
every book has been scanned in the text format. The Library of Congress is the
largest in the world and contains over 130 million items.
The pictures of every landmass on Earth - like the ones shown in Google Earth -
can be stored on two HVDs.
With MPEG4 ASP encoding, a 3.9 TB HVD can hold anywhere between 4,600-
11,900 hours of video, which is enough for non-stop playing for a year.
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7.6 HVDAT A GLANCE
Fig 7.1
Media type: Ultra-high density optical disc
Encoding : MPEG-2, MPEG-4 AVC (H.264), and VC-1
Capacity : Theoretically up to 3.9 TB
Developed : By HSD Forum
Usage : Data storage, High-definition video, & the possibility of ultra high
definition video.
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8. COMPARISON
Parameters
DVD
BLU-MAY
HVD
capacity
4.7 GB
25 GB
3.9 TB
Laser wave length
650 nm
(red)
405 nm
(blue)
532 nm (green)
Disc diameter
120 mm
120 mm
120 mm
Hard coating
no
yes
yes
Data transfer rate (raw
data)
11.08 mbps
36 mbps
1 gbps
Data transfer rate
(audio/video)
10.08 mbps
54 mbps
1 gbps
Table 8.1
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9. MORE DEVELOPMENT ISSUES
Despite the highly attractive nature of 3D optical data storage, the development of
commercial products has taken a significant length of time. This is the result of the
limited financial backing that 3D optical storage ventures have received, as well as
technical issues including:
¢ Destructive reading. Since both the reading and the writing of data are
carried out with laser beams, there is a potential for the reading process to cause a
small amount of writing. In this case, the repeated reading of data may eventually
serve to erase it (this also happens in phase change materials used in some DVDs).
This issue has been addressed by many approaches, such as the use of different
absorption bands for each process (reading and writing), or the use of a reading
method that does not involve the absorption of energy.
¢ Thermodynamic stability. Many chemical reactions that appear not to take
place in fact happen very slowly. In addition, many reactions that appear to have
happened can slowly reverse themselves. Since most 3D media are based on
chemical reactions, there is therefore a risk that either the unwritten points will
slowly become written or that the written points will slowly revert to being
unwritten. This issue is particularly serious for the spiropyrans, but extensive
research was conducted to find more stable chromophores for 3D memories.
¢ Media sensitivity. As we have noted, 2-photon absorption is a weak
phenomenon, and therefore high power lasers are usually required to produce it.
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10. CONCLUSION
The Information Age has led to an explosion of information available to users. While
current storage needs are being met, storage technologies must continue to improve in
order to keep pace with the rapidly increasing demand. However, conventional data
storage technologies, where individual bits are stored as distinct magnetic or optical
changes on the surface of a recording medium, are approaching physical limits. Storing
information throughout the volume of a medium”not just on its surface”offers an
intriguing high-capacity alternative. Holographic data storage is a volumetric approach
which, although conceived decades ago, has made recent progress toward practicality
with the appearance of lower-cost enabling technologies, significant results from
longstanding research efforts, and progress in holographic recording materials.
HVD gives a practical way to exploit the holography technologies to store data upto 3.9
terabytes on a single disc. It can transfer data at the rate of 1 Gigabit per second. The
technology permits over 10 kilobits of data tobe written and read in parallel with a
single flash. So an HVD would be a successor to today's Blu-ray and HD-DVD
technologies.
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REFERENCES
http:// ibm.com - IBM Research Press Resources Holographic Storage
http:// howstuffworks.com
http:// hvd-forum.org
http:// optware.co.jp/english/what_040823 .htm
http://newsgroups.derkeilerpdf/Archive/A...o.dvd/2005-
09Ansg00487.pdf
http://pdf-search-enginecollinear-holography-pdf.html