5093324 holographic memory
TRANSCRIPT
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ContentsContents
1. Introduction.2. What is Holographic memory?3. What is HVD?4. Structure of HVD.5. How HVD Works?
I. Writing DataII. Reading Data
6. Advantages of HVD7. How HVD compares with otherstorage device?
8. Conclusion
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IntroductionIntroduction
As computer systems continue to become faster, they
will need a way to access larger amounts of data in
shorter periods of time.
Holographic memory is a three-dimensional data
storage system that can stored information at high
density inside the crystal or photopolymer.
Hence holographic storage system has the potential tobecame the next storage generation over conventional
storage system.
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What is Holographic Memory ?What is Holographic Memory ?
It is a memory that can store information in form ofholographic image.
It is a technique that can store information at high density
inside crystals or photopolymers.
As current storage techniques such as DVD reach the upperlimit of possible data density (due to the diffraction limited size
of the writing beams), holographic storage has the potential to
become the next generation of storage media.
Like other media, holographic media is divided into write once(where the storage medium undergoes some irreversible
change), and rewritable media (where the change is reversible).
Rewritable holographic storage can be achieved via the photo
refractive effect in crystals.
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Holographic Versatile DiscHolographic Versatile DiscHolographic Versatile DiscHolographic Versatile Disc
Holographic Versatile Disc (HVD) is an optical disc technology still
in the research stage which would hold up to 3.9 terabyte (TB) of
information.
It employs a technique known as collinear holography, whereby two
lasers, one red and one blue-green, are collimated in a single beam.
The blue-green laser reads data encoded as laser interference fringes
from a holographic layer near the top of the disc while the red laser isused as the reference beam and to read servo information from a
regular CD-style aluminum layer near the bottom.
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Holographic Versatile DiscHolographic Versatile Disc
These discs have the capacity to hold up
to 3.9 terabyte (TB) of information,
which is approximately 6,000 times the
capacity of a CD-ROM, 830 times the
capacity of a DVD, 160 times the
capacity of single-layerBlu-ray-Discs,
and about 8 times the capacity of standard
computerhard drives as of 2007.
The HVD also has a transfer rate of1gigabyte/s
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Holographic Versatile DiscHolographic Versatile Discstructurestructure
Holographic Versatile DiscHolographic Versatile Discstructurestructure
1. Green writing/reading laser (532
nm)
2. Red positioning/addressing laser
(650 nm)
3. Hologram (data)4. Polycarbon layer
5. Photo polymeric layer (data-
containing layer)
6. Distance layers
7. Dichroic layer (reflecting green
light)
8. Aluminum reflective layer
(reflecting red light)
9. Transparent base
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The HVD System: Writing Data
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The HVD System: Writing Data
The process of writing information onto an HVD begins
with encoding the information into binary data to be
stored in the SLM. These data are turned into ones and
zeroes represented as opaque or translucent areas on a
"page" -- this page is the image that the information beamis going to pass through.
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The HVD System: Writing Data
1. Once the page of data is created, the next step is to fire a laser beam
into a beam splitter to produce two identical beams. One of the beams
is directed away from the SLM -- this beam becomes thereference
beam. The other beam is directed toward the SLM and becomes the
information beam.
2. When the information beam passes through the SLM, portions of the
light are blocked by the opaque areas of the page, and portions pass
through the translucent areas. In this way, the information beam carries
the image once it passes through the SLM.
3. When the reference beam and the information beam rejoin on the same
axis, they create a pattern of light interference -- theholography data.
This joint beam carries the interference pattern to the photopolymer
disc and stores it there as a hologram.
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The HVD System: Reading Data
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HVDHVD ComparesCompares WithWith OtherOther StorageStorage DeviceDevice
Blu-ray HD-DVD HVD
Initial cost for
recordable
disc
Approx. $18 Approx. $10 Approx. $120
Initial cost for
recorder/playe
r
Approx.
$2,000
Approx.
$2,000Approx. $3,000
Initialstoragecapacity
54 GB 30 GB 300 GB (max 3.9 TB)
Read/write
speed36.5 Mbps 36.5 Mbps 1 Gbps
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Road Map of HVD
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ConclusionConclusion
Capacity increased from 3oo Gbyte to 3.9 TB
No need to turn over the CD,DVD,HD-DVD,etc.
Three-dimensional data storage ,store information
in a smaller space and faster data transfer times .
The HVD playing device would have data rates 25
times faster than today's fastest DVD players.
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