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8/2/2019 Three-Dimensional Data Storage
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Three-Dimensional Data
Storage
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Todays Data Storage Medium
Maximum data storage limits we have reached
today:-
15.9G.B on a double-layer, doubled sided
DVD. 750 GB on SATA hard disk.
Is this enough??
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Holographic Storage Technology
Holographic storage is a breakthrough technology
that stores information within its volume.
It utilizes the space within special types of crystalswith optical characteristics, which are very similar
those used to create 3D holograms.
It has ability to accurately focus the reference laser
on the exact position within the crystal to retrieve
that page of information.
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Holographic storage is an optical technology
that allows 1 million bits of data to be
written or read in a single flash of light. Imagine 2GB of data on a postage stamp,
20GB on a credit card, or 200 GB on a disc.
1 TB on multi-layer discs. Combining high storage densities and fast
transfer rates with durable, reliable, low
cost media, Holographic technology is
poised to become a compelling choice fornext-generation storage and content
distribution needs.
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Holographic storage incorporates the use of
laser, optics, images sensors and specialcrystals that respond to laser light.
For recording, it utilizes intersecting signaland reference laser beams to store data in a
number of 3D hologram images capable ofsaving hundreds of data pages in a singlelocation.
Since it involves no moving parts,
holographic data storage will be far morereliable than existing hard disk
technologies.
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Two Coherent beams, one carrying a page of information, interfere
within a photosensitive material to record a hologram.
SLM:-Spatial Light Modulator.
How To Write Data?
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Ref: http://en.wikipedia.org/wiki/Holography
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Illuminating the hologram with the reference beam reconstructs a copy
of the original information bearing beam for capture with a detector
array.
How To Read Data?
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Illuminating multiple stored holograms with a new page of search
information reconstructs all of the reference beams, computing in
parallel the correlation between data and each of the stored pages.
Parallel Reading
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1. Green writing/reading laser
(532 nm)
2. Red positioning/addressing
laser (650 nm)
3. Hologram (data)
4. Polycarbonate layer
5. Photo polymeric layer (data)6. Distance layers
7. Diachronic layer (reflecting
green light)
8. Reflective layer (reflecting redlight)9. Transparent base
P. PIT
Holographic Versatile Disc structure
This type of disc has transfer rate of 1G bit/s.
Ref: www.holographicversatile.com
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Advantages
In contrast to surface storage techniques such as CD/DVD,where the density is inversely proportional to the square ofthe wavelength, holographic is a volumetric technique,making the density proportional to one over the third powerof the wavelength.
Laser beams can be moved with no mechanical components,allowing access data times of the order of 10 micro seconds,faster than any conventional disk drive will ever able torandomly access data.
Holographic data storage has shown the capability of rapidparallel search through the stored data via associativeretrieval.
By varying the reference beam angle, wavelength or mediaposition many different holograms can be recorded in thesame volume of material.
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Fluorescent MultiLayer StorageTechnology
The concept of multi-layer reflective optical
discs has been proposed by Philips and
IBM. It is a unique breakthrough, solving the
problems of signal degradation associated
with reflective optical disc technologies of
CD/DVD.
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With FMD/C technology, each storage layer
is coated with a transparent fluorescent
material rather than metallic layer of
CD/DVD.
Backward compatibility with existingCD/DVD media.
It allows parallel reading.
A sequence of bits is recorded not along a
track but deep into layers.
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According to FMD-ROM developers, even with a hundred layers a useful
signal will be acceptable.
In case of CD/DVD,
due to multiple
interferences theprocess of reading data
from discs becomes
more complicated as
the number of layers
increases.
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How to write data?
The first principle (thermal) implies usage ofmaterial which possesses fluorescent propertiesfrom the beginning (logical one). And whenrecording those segments which are thermally
acted upon with a laser lose these properties(logical zero). (WORM)
The second principle (chemical) means usage of amaterial that doesn't possess fluorescent propertiesform the beginning. When acting upon with a laser
a photochemical reaction starts, and the materialgets fluorescent properties. There, a low-powerlaser is enough, or even a usual LED.
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Fluorescent Multi-layer Disc
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Fluorescent Multilayer card
The fluorescent multilayer card is a card containing
a square shaped clear part which has multiple layers
each with a different fluorescent material that
reflects light at a different frequency than the otherlayers, so that the number of layers is limited only by
the thickness of the card. A card with the data area
roughly 25 mm or one inch wide, able to hold 10 GB
of data.
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FMD/C Advantages
The multi-layer system is opticallytransparent and homogeneous.
No absorption for the emitted signal
fluorescent light.The emitted fluorescent light from any
given layer is non - coherent,
eliminating the problem of multipleinterference.
FMD technology is compatible withcurrent CD and DVD formats.
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Future Scope
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A holographic format, Tapestry Media,capable of storing up to 1.6TB with a datatransfer rate of 120 MB/s. Hitachi Maxell,
Ltd. plans to enter the market by offering300 GB discs with a data transfer rate of 20MB/s.
A 50 GB prototype disc was demonstratedat the COMDEX industry show in November2000. First generation FMDs were to use650 nm red lasers, yielding roughly 140 GB
per disc. Second and third generation FMDswere to use 405 nm blue lasers, givingcapacities of up to a TB.
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Thank You