holographic data storage full report
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Seminar Report On Holographic data storage system (HDSS)

ABSTRACT:
Holographic memory is a technique that can store information at high density inside crystals Holographic memory is developing technology that has promised to revolutionalise the storage systems. It can store data up to 1Tb in a sugar cube sized crystal. Data from more than 1000 CDs can fit into a holographic memory System. . Holographic storage has the potential to become the next generation of storage media Conventional memories use only the surface to store the data. But holographic data storage systems use the volume to store data. It has more advantages than conventional storage systems. It is based on the principle of holography This paper provides a description of Holographic data storage system (HDSS), a three dimensional data storage system which has a fundamental advantage over conventional read/write memory systems. A brief overview of properties of holograms will be presented first. Applications to computer systems are then covered, with the future of holographic memory presented as a conclusion.


Presented by BY
A.Arjun Reddy
AND
A.Santosh


ADVANTAGES OF HDDS
1 Personal computer with a holographic technology platform (HoloPCs) will be able to access data more rapidly and in a qualitatively different manner than conventional PCs.
2 Two-dimensional data saving systems such as CDs and DVDs record and retrieve files in a serial fashion -- one bit at a time. Holographic data systems retain and retrieve data in parallel, a total (million- bit) page of files at a time.
3 The interface of holography and robotics may make "holobots" that learn through creative identification of useful patterns in big quantities of files. 4 Eventually, optical neural networks may be possible using holographic research

INTRODUCTION
Each time you watch a fast-paced DVD movie or pull down a piece of information from the Internet or even access the ATM at the corner of your street, you are actually tapping into large repositories of digital information. The hard disk, the mainstay of personal and corporate storage, has faithfully obeyed the exponential law. This has happened largely due to increases in aerial density, that is, how many bits are crammed into a square inch. This paper provides a description of Holographic data storage system (HDSS), a three dimensional data storage system which has a fundamental advantage over conventional read/write .
The first step in understanding holographic memory is to understand what "holographic" means. Holography is a method of recording patterns of light to produce a three-dimensional object. The recorded patterns of light are called hologram memory systems. Holographic memory is a technique that can store information at high density inside crystals or photopolymers. As current storage techniques such as DVD reach the upper limit 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. The advantage of this type of data storage is that the volume of the recording media is used instead of just the surface.

WORKING OF HDSS
RECORDING DATA ON MEDIUM
Creating holograms is achieved by means of two coherent beams of light split from one laser source, one being the reference beam and the other the signal beam. When both these beams interfere with one another, a resulting interference pattern is formed which encompasses the pattern both in amplitude and phase information of the two beams. When an appropriate photorefractive material is placed at the point of interference, the interference patterns are recorded inside the material.
The beam's angle is crucial, and it can't vary by more than a fraction of a degree. This apparent flaw in the recording process is actually an asset. It's how holographic storage achieves its high data densities. By changing either the angle of the reference beam or its frequency, you can write additional data pages in to the same volume of crystal. The dynamic range of the medium determines how many pages it can hold reliably.

When the reference beam illuminates the material in the absence of the signal beam, the hologram causes the light to be diffracted in the same direction of the initial signal beam and all the information of the original signal beam is reconstructed

MULTIPLEXING
Once one can store a page of bits in a hologram, an interface to a
computer can be made. The problem arises, however, that storing only
one page of bits is not beneficial. Fortunately, the properties of
holograms provide a unique solution to this dilemma. Unlike magnetic
storage mechanisms which store data on their surfaces, holographic
memories store information throughout their whole volume. After a
page of data is recorded in the hologram, a small modification to the
source beam before it reenters the hologram will record another page
of data in the same volume. This method of storing multiple pages of
data in the hologram is called multiplexing. The thicker the volume
becomes smaller the modifications to the source beam can be.
. IMPLEMENTATION
A holographic data storage system consists of a recording medium, an
optical recording system, a photo detector array. A beam of coherent
light is split into a reference beam and a signal beam which are used
to record a hologram into the recording medium. The recording medium
is usually a photo refractive crystal
A Ëœhologramâ„¢ is simply the three-dimensional
interference pattern of the intersection of the reference and signal
beams are perpendicular to each other. This interference pattern is
imprinted into the crystal as regions of positive and negative
charges. To retrieve the stored hologram, a beam of light that has
the same wavelength and angle of incidence as the reference beam is
sent into the crystal and the resulting diffraction pattern is used
to reconstruct the pattern of the signal beam. Many different
holograms may be stored in the same crystal volume by changing the
angle of incidence of reference beam

FIG INPLEMENTATION OF HDD
The most common holographic recording system uses laser light, a beam
splitter to divide the laser light into reference beam and signal
beam, various lenses and mirrors to redirect the light, a photo
reactive crystal, and an array of photo detectors around the crystal
to receive the holographic data. To record a hologram, a beam laser
light is split into two beams by a mirror. These two beams then
become the reference and signal beams. The signal beam interacts with
an object and the light that is reflected by the object intersects
the reference beam at right angles. The resulting interference
pattern contains all the information necessary to recreate the image
of the object after suitable processing. The interference pattern is
recorded on to a photo reactive material and may be retrieved at a
latter time by using a beam that is identical to the reference beam.
This is possible because the hologram has the property that if it is
illuminated by either of the beams used to record it, the hologram
causes light to be diffracted in the direction of the second beam
that was used to record it, there by recreating the reflected image
of the object if the reference beam was used to illuminate the
hologram. So, the reflected must be transformed into a real image
with mirrors and lenses that can be sent to the laser detector array.
ADVANTAGES
With three-dimensional recording and parallel data readout,
holographic memories can outperform existing optical storage
techniques. In contrast to the currently available storage
strategies, holographic mass memory simultaneously offers high data
capacity and short data access time (Storage capacity of about 1TB/cc
and data transfer rate of 1 billion bits/second).
Holographic data storage has the unique ability to locate similar
features stored within a crystal instantly. A data pattern projected
into a crystal from the top searches thousands of stored holograms in
parallel. The holograms diffract the incoming light out of the side
of the crystal, with the brightest outgoing beams identifying the
address of the data that most closely resemble the input pattern.
This parallel search capability is an inherent property of
holographic data storage and allows a database to be searched by
content.
Because the interference patterns are spread uniformly throughout the
material, it endows holographic storage with another useful
capability: high reliability. While a defect in the medium for disk
or tape storage might garble critical data, a defect in a holographic
medium doesn't wipe out information. Instead, it only makes the
hologram dimmer.
No rotation of medium is required as in the case of other storage
devices. It can reduce threat of piracy since holograms canâ„¢t be
easily replicated.
DISADVANTAGES OF HDDS
Manufacturing cost HDSS is very high and there is a lack of
availability of resources which are needed to produce HDSS. However,
all the holograms appear dimmer because their patterns must share the
material's finite dynamic range. In other words, the additional
holograms alter a material that can support only a fixed amount of
change. Ultimately, the images become so dim that noise creeps into
the read-out operation, thus limiting the material's storage
capacity.
A difficulty with the HDSS technology had been the destructive
readout. The re-illuminated reference beam used to retrieve the
recorded information, also excites the donor electrons and disturbs
the equilibrium of the space charge field in a manner that produces a
gradual erasure of the recording. In the past, this has limited the
number of reads that can be made before the signal-to -noise ratio
becomes too low. Moreover, writes in the same fashion can degrade
previous writes in the same region of the medium. This restricts the
ability to use the three-dimensional capacity of a photorefractive
for recording angle-multiplexed holograms. You would be unable to
locate the data if thereâ„¢s an error of even a thousandth of an inch.-
POSSIBLE APPLICATIONS
There are many possible applications of holographic memory.
Holographic memory systems can potentially provide the high speed
transfers and large volumes of future computer system. One possible
application is data mining. Data mining is the processes of finding
patterns in large amounts of data. Data mining is used greatly in
large databases which hold possible patterns which canâ„¢t be
distinguished by human eyes due to the vast amount of data. Some
current computer system implement data mining, but the mass amount of
storage required is pushing the limits of current data storage
systems. The many advances in access times and data storage capacity
that holographic memory provides could exceed conventional storage
and speedup data mining considerably. This would result in more
located patterns in a shorter amount of time.
Another possible application of holographic memory is in petaflop
computing. A petaflop is a thousand trillion floating point
operations per second. The fast access extremely large amounts of
data provided by holographic memory could be utilized in petaflop
architecture. Clearly advances are needed to in more than memory
systems, but the theoretical schematics do exist for such a machine.
Optical storage such as holographic memory provides a viable solution
to the extreme amount of data which is required for a petaflop
computing.
CONCLUSION
The future of HOLOGRAPHIC DATA STORAGE SYSYEM is very promising. The
page access of data that HDSS creates will provide a window into next
generation computing by adding another dimension to stored data.
Finding holograms in personal computers might be a bit longer off,
however. The large cost of high-tech optical equipment would make
small-scale systems implemented with HDSS impractical. It will most
likely be used in next generation supercomputers where cost is not as
much of an issue. Current magnetic storage devices remain far more
cost effective than any other medium on the market. As computer
system evolve, it is, not unreasonable to believe that magnetic
storage will continue to do so. As mentioned earlier, however, these
improvements are not made on the conceptual level. The current
storage in a personal computer operates on the same principles used
in the first magnetic data storage devices. The parallel nature of
HDSS has many potential gains on serial storage methods. However,
many advances in optical technology and photosensitive materials need
to be made before we find holograms in our computer systems.
REFERENCE
.......holopc.com
........wikeipedia.com
.........engeeniringseminars.com
..........computer.howstuffworks.com
The Herald - the herald is not one of the steps, but an archetype. He
is usually the one who introduces the next step in the hero's
journey. In Star Wars the Herald is R2D2 a little droid with a
holographic message on his hard disc.
2. The Call to Adventure
In Star Wars, the holographic message by Princess Leia is the Call to
Adventure. 'Help me,' she says, 'you're my only hope.' The Call
usually asks the hero to leave his world and go on a quest to save an
object or person of great value. Lord of the Rings seems to
contradict his, because Frodo's goal is to destroy the ring, but
think about it. If he succeeds then he will essentially save Middle
Earth.
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ABSTRACT
Holographic memory is developing technology that has promised to revolutionalise the storage systems. It can store data upto 1 Tb in a sugar cube sized crystal. Scientist Pieter J. van Heerden first proposed the idea of holographic (three-dimensional) storage in the early 1960s. A decade later, scientists at RCA Laboratories demonstrated the technology by recording 500 holograms in an iron-doped lithium-niobate crystal and 550 holograms of high-resolution images in a light-sensitive polymer material. The lack of cheap parts and the advancement of magnetic and semiconductor memories placed the development of holographic data storage on hold.
INTRODUCTION
Devices that use light to store and read data have been the backbone of data storage for nearly two decades. Compact discs revolutionized data storage in the early 1980s, allowing multi-megabytes of data to be stored on a disc that has a diameter of a mere 12 centimeters and a thickness of about 1.2 millimeters. In 1997, an improved version of the CD, called a digital versatile disc (DVD), was released, which enabled the storage of full-length movies on a single disc.
CDs and DVDs are the primary data storage methods for music, software, personal computing and video. A CD can hold 783 megabytes of data. A double-sided, double-layer DVD can hold 15.9 GB of data, which is about eight hours of movies. These conventional storage mediums meet today's storage needs, but storage technologies have to evolve to keep pace with increasing consumer demand. CDs, DVDs and magnetic storage all store bits of information on the surface of a recording medium. In order to increase storage capabilities, scientists are now working on a new optical storage method called holographic memory that wili go beneath the surface and use the volume of the recording medium for storage, instead of only the surface area. Three-dimensional data storage will be able to store more information in a smaller space and offer faster data transfer times.
Holographic memory is developing technology that has promised to revolutionalise the storage systems. It can store data upto 1 Tb in a sugar cube sized crystal. Data from more than 1000 CDs can fit into a holographic memory System. Most of the computer hard drives available today can hold only 10 to 40 GB of data, a small fraction of what holographic memory system can hold. Conventional memories use only the surface to store the data. But holographic data storage systems use the volume to store data. It has more advantages than conventional storage systems. It is based on the principle of holography.
HOLOGRAPHY
A hologram is a block or sheet of photosensitive material which records the interference of two light sources. To create a hologram, laser light is first split into two beams, a source beam and a reference beam. The source beam is then manipulated and sent into the photosensitive material. Once inside this material, it intersects the reference beam and the resulting interference of laser light is recorded on the photosensitive material, resulting in a hologram. Once a hologram is recorded, it can be viewed with only the reference beam. The reference beam is projected into the hologram at the exact angle it was projected during recording. When this light hits the recorded diffraction pattern, the source beam is regenerated out of the refracted light. An exact copy of the source beam is sent out of the hologram and can be read by optical sensors. For example, a hologram that can be obtained from a toy store illustrates this idea. Precise laser equipment is used at the factory to create the hologram. A recording material which can recreate recorded images out of natural light is used so the consumer does not need high-tech equipment to view the information stored in the hologram. Natural light becomes the reference beam and human eyes become the optical sensors.
Holography was invented in 1947 by the Hungarian-British physicist Dennis Gabor (1900-1979), who won a 1971 Nobel Prize for his invention.
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APPLICATION TO BINARY
In order for holographic technology to be applied to computer systems, it must store data in a form that a computer can recognize. In current computer systems, this form is binary. In the previous section, it was mentioned that the source beam is manipulated. In common holograms, this manipulation ;s the creation of an optical image such as a ball or human face. In computer applications, this manipulation is in the form of bits. The next section explains the soatial light modulator, a device that converts laser light into binary data.
SPATIAL LIGHT MODULATOR (SLM)
A spatial light modulator is used for creating binary information out of laser light. The SLM is a 2D plane, consisting of pixels which can be turned on and off to create binary 1.s and O.s. An illustration of this is a window and a window shade. It is possible to pull the shade down over a window to block incoming sunlight. If sunlight is desired again, the shade can be raised. A spatial light modulator contains a two-dimensional array of windows which are only microns wide. These windows block some parts of the incoming laser light and let other parts go through. The resulting cross section of the laser beam is a two dimensional array of binary data, exactly the same as what was represented in the SLM. After the laser beam is manipulated, it is sent into the hologram to be recorded. This data is written into the hologram as page form. It is called this due to its representation as a two dimensional plane, or page of data. Spatial light modulator is a Liquid Crystal Display panel that consists of clear and dark areas corresponding to the binary information it represent.
Spatial light modulator is actually that device which makes holography applicable to computers. Sort is one of the important components of Holographic Data Storage System.
IMPLEMENTATION
The components of Holographic data storage system is composed of
> Blue-green argon laser
> Beam splitters to spilt the laser beam
> Mirrors to direct the laser beams
> LCD panel (spatial light modulator)
> Lenses to focus the laser beams
> Lithium-niobate crystal or photopolymer
> Charge coupled device camera
SPATIAL LIGHT MODULATOR (SLM)
A spatial light modulator is used for creating binary information out of laser light. The SLM is a 2D plane, consisting of pixels which can be turned on and off to create binary 1.s and O.s. An illustration of this is a window and a window shade. It is possible to pull the shade down over a window to block incoming sunlight. If sunlight is desired again, the shade can be raised. A spatial light modulator contains a two-dimensional array of windows which are only microns wide. These windows block some parts of the incoming laser light and let other parts go through. The resulting cross section of the laser beam is a two dimensional array of binary data, exactly the same as what was represented in the SLM. After the laser beam is manipulated, it is sent into the hologram to be recorded. This data Is written into the hologram as page form. It is called this due to its representation as a two dimensional plane, or page of data. Spatial light modulator is a Liquid Crystal Display panel that consists of clear and dark areas corresponding to the binary information it represent.
Spatial light modulator is actually that device which makes holography applicable to computers. So it is one of the important components of Holographic Data Storage System.
IMPLEMENTATION
The components of Holographic data storage system is composed of
> Blue-green argon laser
> Beam splitters to spilt the laser beam
> Mirrors to direct the laser beams
> LCD panel (spatial light modulator)
> Lenses to focus the laser beams
> Lithium-niobate crystal or photopolymer
> Charge coupled device camera
They can be classified into three sections namely recording medium, optical recording system and photodetector array. The laser is used because it provides monochromatic light. Only the interference pattern produced by the monochromatic beam of light is stable in time. Lithium niobate crystal is used as photosensitive material on which hologram is recorded. It has certain optical characteristics that make it behave as photosensitive material. CCD camera detects the information in the light, converts to digital information and forward it to computer.
RECORDING OF DATA IN HOLOGRAPHIC MEMORY SYSTEM
When the blue-green argon laser is fired, a beam splitter creates two beams. One beam, called the object or signal beam, will go straight, bounce off one mirror and travel through a spatial-light modulator (SLM). An SLM is a Liquid crystal display (LCD) that shows pages of raw binary data as clear and dark boxes. The information from the page of binary code is carried by the signal beam around to the light-sensitive lithium-niobate crystal. Some systems use a photopolymer in place of the crystal. A second beam, called the reference beam, shoots out the side of the beam splitter and takes a separate path to the crystal. When the two beams meet, the interference pattern that is created stores the data carried by the signal beam in a specific area in the crystal - the data is stored as a hologram.
RETRIEVAL OF DATA FROM HOLOGRAPHIC MEMORY SYSTEM
An advantage of a holographic memory system is that an entire page of data can be retrieved quickly and at one time. In order to retrieve and reconstruct the holographic page of data stored in the crystal, the reference beam !s shined into the crystal at exactly the same angle at which it entered to store that oage of data. Each page of data is stored in a different area of the crystal, based on the angle at which the reference beam strikes it. During reconstruction, the beam will be diffracted by the crystal to allow the recreation of the original page that was stored. This reconstructed page is then projected onto the charge-coupled device (CCD) camera, which interprets and forwards the digital "'ormation to a computer.
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CCD is a 2-D array of thousands or millions of tiny solar cells, each of which transforms the light from one small portion of the image into electrons. Next step is to read the value (accumulated charge) of each cell in the image. In a CCD device, the charge is actually transported across the chip and read at one corner of the array. An analog-to-digital converter turns each pixel's value into a digital value. CCDs use a special manufacturing process to create the ability to transport charge across the chip without distortion. This process leads to very high-quality sensors in terms of fidelity and light sensitivity. CCD sensors have been mass produced for a longer period of time, so they are more mature. They tend to have higher quality and more pixels.
The key component of any holographic data storage system is the angle at which the second reference beam is fired at the crystal to retrieve a page of data. It must match the original reference beam angle exactly. A difference of just a thousandth of a millimeter will result in failure to retrieve that page of data.
Reading Data
Detector
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PAGE DATA ACCESS
Because data is stored as page data in a hologram, the retrieval of this data must also be in this form. Page data access is the method of reading stored data in sheets, not serially as in conventional storage systems. It was mentioned in the introduction that conventional storage was reaching its
i
fundamental limits. One such limit is the way data is read in streams.
, Holographic memory reads data in the form of pages instead. For example, if a
i
! stream of 32 bits is sent to a processing unit by a conventional read head,
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a holographic memory system would in turn send 32 x 32 bits, or 1024 bits due to its added dimension. This provides very fast access times in volumes far greater than serial access methods. The volume could be one Megabit per page using a SLM resolution of 1024 x 1024 bits at 15-20 microns per pixel.
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MULTIPLEXING
Once one can store a page of bits in a hologram, an interface to a computer can be made. The problem arises, however, that storing only one page of bits is not beneficial. Fortunately, the properties of holograms provide a unique solution to this dilemma. Unlike magnetic storage mechanisms which store data on their surface, holographic memories store information throughout their whole volume. After a page of data is recorded in the hologram, a small modification to the source beam before it reenters the hologram will record another page of data in the same volume. This method of storing multiple pages of data in the hologram is called multiplexing. The thicker the volume becomes, the smaller the modifications to the source beam can be.
ANGULAR MULTIPLEXING
When a reference beam recreates the source beam, it needs to be at the same angle it was during recording. A very small alteration in this angle will make the regenerated source beam disappear. Harnessing this property,
Angular multiplexing changes the angle of the source beam by very minuscule amounts after each page of data is recorded. Depending on the sensitivity of the recording material, thousands of pages of data can be stored in the same hologram, at the same point of laser beam entry. Staying away from conventional data access systems which move mechanical matter to obtain data, the angle of entry on the source beam can be deflected by high-frequency sound waves in solids. The elimination of mechanical access methods reduces access times from milliseconds to microseconds.
WAVELENGTH MULTIPLEXING
Used mainly in conjunction with other multiplexing methods, wavelength multiplexing alters the wavelength of source and reference beams between recordings. Sending beams to the same point of origin in the recording medium at different wavelengths allows multiple pages of data to be recorded. Due to the small tuning range of lasers, however, this form of multiplexing is limited on its own.
SPATIAL MULTIPLEXING
Spatial multiplexing is the method of changing the point of entry of source and reference beams into the recording medium. This form tends to break away from the non-mechanical paradigm because either the medium or recording beams must be physically moved. Like wavelength multiplexing, this is combined with other forms of multiplexing to maximize the amount of data stored in the holographic volume. Two commonly used forms of spatial multiplexing are peristrophic multiplexing and shift multiplexing.
Shift Multiplexing

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PHASE-ENCODED MULTIPLEXING
The form of multiplexing farthest away from using mechanical means to record many pages in the same volume of a holograph is called phase-encoded multiplexing. Rather than manipulate the angle of entry of a laser beam or rotate or translate the recording medium, phase-encoded multiplexing changes the phase of individual parts of a reference beam. The main reference beam is split up into many smaller partial beams which cover the same area as the original reference beam. These smaller beamlets vary byphase which changes the state of the reference beam as a whole. The reference beams intersects the
source beam and records the diffraction relative to the different phases of the beamlets. The phase of the beamlets can be changed by non-mechanical means, therefore speeding up access times.
RECORDING ERRORS
When data is recorded in a holographic medium, certain factors can lead to erroneously recorded data. One major factor is the electronic noise generated by laser beams. When a laser beam is split up ( for example, through a SLM ), the generated light bleeds into places where light was meant to be blocked out. Areas where zero light is desired might have minuscule amounts of laser light present which mutates its bit representation. For example, if too much light gets recorded into this zero area representing a binary 0, an erroneous change to a binary 1 might occur. Changes in both the quality of the laser beam and recording material are being researched, but these improvements must take into consideration the cost-effectiveness of a holographic memory system. These limitations to current laser beam and photosensitive technology are some of the main factors for the delay of practical holographic memory systems.
PAGE-LEVEL PARITY BITS
Once error-free data is recorded into a hologram, methods which read data back out of it need to be error free as well. Data in page format requires a new way to provide error control. Current error control methods concentrate on a stream of bits. Because page data is in the form of a two dimensional array, error correction needs to take into account the extra dimension of bits. When a page of data is written to the holographic media, the page is separated into smaller two dimensional arrays. These sub sections are appended with an additional row and column of bits. The added bits calculate the parity of each row and column of data. An odd number of bits in a row or column create a parity bit of 1 and an even number of bits create a 0. A parity bit where the row and column meet is also created which is called an overall parity bit. The sub sections are rejoined and sent to the holographic medium for recording.
MERITS OF HOLOGRAPHIC MEMORY
Holographic memory offers storage capacity of about 1 TB. Speed of retrieval of data in tens of microseconds compared to data access time of almost 10ms offered by the fastest hard disk today. By the time they are available they can transfer an entire DVD movie in 30 seconds. Information search is also faster in holographic memory. Consider the case of large databases that are stored on hard disk today. To retrieve any piece of information you first provide some reference data. The data is then searched by its address, track, sector and so on after which it is compared with the reference data. In holographic storage entire pages can be retrieved where contents of two or more pages can be compared optically without having to retrieve the information contained in them. Also HDSS has no moving parts. So the limitations of mechanical motion such as friction can be removed.
CHALLENGES
During the retrieval of data the reference beam has to be focused at exactly the same angle at which it was projected during recording. A slight error can cause a wrong data page to be accessed. It is difficult to obtain that much of accuracy. The crystal used as the photographic filament must have exact optical characteristics such as high diffraction efficiency, storage of data safely without any erasure and fast erasure on application of external stimulus light ultra violet rays. With the repeated number of accesses the holograms will tend to decay.
POSSIBLE APPLICATIONS
There are many possible applications of holographic memory. Holographic memory systems can potentially provide the high-speed transfers and large volumes of future computer systems. One possible application is data mining. Data mining is the process of finding patterns in large amounts of data. Data mining is used greatly in large databases which hold possible patterns which can't be distinguished by human eyes due to the vast amount of data. Some current computer systems implement data mining, but the mass amount of storage required is pushing the limits of current data storage systems. The many advances in access times and data storage capacity that holographic memory provides could exceed conventional storage and speed up data mining considerably. This would result in more located patterns in a shorter amount of time.
Another possible application of holographic memory is in petaflop computing. A petaflop is a thousand trillion floating point operations per second. The fast access in extremely large amounts of data provided by holographic memory systems could be utilized in petaflop architecture. Clearly advances are needed in more than memory systems, but the theoretical schematics do exist for such a machine. Optical storage such as holographic memory provide a viable solution to the extreme amount of data
which is required for petaflop computing.
Holographic memory can be used as extended DRAM with 10ns access time, Hard disk drives ,CD ROMs of large storage capacity and rockmounted (combining numerous DASDs) of petabytes storage capacity.
RECENT DEVELOPMENTS
The research on holographic memory is taking place in well guarded and rich companies like IBM, ROCKWELL and InPhase. InPhase claims to have developed a holographic memory of size slightly larger than a DVD. It has a capacity of about 100GB. They are trying to push it upto 1TB.
IBM and ROCKWELL claims to have developed a recording medium less sensitive than lithium niobate crystals.
HOLOGRAPHIC MEMORY VS. CONVENTIONAL STORAGE DEVICES
Storage Medium Access Time Data Transfer Rate Storage Capacity
Holographic Memory 2.4 us lOGB/s 400 Mbits/cm2
Main Memory (RAM) 10-40 ns 5 MB/s 4.0 Mbits/cm2
Magnetic Disk 8.3 ms 5-20 MB/s 100 Mbits/cm2
Comparing the access times holographic memory lies midway between that of main memory and magnetic disk. Data transfer rate is 10GB/s which is higher than that of other storage devices and, and a storage capacity that is higher than both main memory and magnetic disk. Certainly if the issues of hologram decay and interference are resolved, then holographic memory could become a part of the memory hierarchy, or take the place of magnetic disk much as magnetic disk has displaced magnetic tape for most applications.
SUMMARY
STORAGE CAPACITY TERABYTE CLASS
TECHNOLOGY USED OPTICS AND HOLOGRAPHY
DATA TRANSFER SPEED HIGH
TIME FOR IMPLEMENTATION 4
COST OF IMPLEMENTATION HIGH
COMPANIES INVOLVED IBM,ROCKWELL,LUCENT
HOLOGRAPHIC MEMORY LAYOUT
CONCLUSION
The future of holographic memory is very promising. The page access of data that holographic memory creates will provide a window into next generation computing by adding another dimension to stored data. Finding holograms in personal computers might be a bit longer off, however. The large cost of high-tech optical equipment would make small-scale systems implemented with holographic memory impractical.
Holographic memory will most likely be used in next generation super computers where cost is not as much of an issue. Current magnetic storage devices remain far more cost effective than any other medium on the market. As computer systems evolve, it is not unreasonable to believe that magnetic storage will continue to do so. As mentioned earlier, however, these improvements are not made on the conceptual level. The current storage in a personal computer operates on the same principles used in the first magnetic data storage devices. The parallel nature of holographic memory has many potential gains on serial storage methods. However, many advances in optical technology and photosensitive materials need to be made before we find holograms in computer systems.
REFERENCES
http://howstuffworks.com
http://sandj[at]cda.mrs.umn.edu
http :// sta nford.edu/~svngam/
Chip magazine
PC Quest Magazine
CONTENTS
'NTRODUCTION 1
HOLOGRAPHY 2
02. APPLICATION TO BINARY 4
SPATIAL LIGHT MODULATOR 5
:Z. IMPLEMENTATION 5
RECORDING OF DATA IN HOLOGRAPHIC MEMORY 6
RETRIVAL OF DATA FROM HOLOGRAPHIC MEMORY 7
:-. PAGE DATA ACCESS 9
15. MULTIPLEXING 9
ANGULAR MULTIPLEXING 9
WAVELENGTH MULTIPLEXING 10
SPATIAL MULTIPLEXING 11
PHASE ENCODED MULTIPLEXING 11
:5. RECORDING ERRORS 12
PAGE-LEVEL PARITY BITS 13
:7. MERITS OF HOLOGRAPHIC MEMORY 13
08. CHALLENGES 14
39. POSSIBLE APPLICATIONS 14
"0. RECENT DEVELOPMENTS 15
11. HOLOGRAPHIC Vs CONVENTIONAL STORAGE DEVICES 16
12. SUMMARY 16
^3. HOLOGRAPHIC MEMORY LAYOUT 17
CONCLUSION 18
'z. REFERENCES 19
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#4
thanx mate
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#5
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DATA STORAGE USING HOLOGRAPHY HOLOGRAPHY:

The science of producing holograms, an advanced form of photography that allows an image to be recorded in three dimension.
Holographic memory is a technique that can store information at high density inside crystals or photopolymers.
Features:
Data Transfer Rate:1Gbps.
Technology permits over 10 kilobits of data to be written and read in parallel with in a single flash.
CD saves one bit per pulse whereas HVD stores 60,000 bits per pulse in the same place.
1 HVD=5800 CDs=830 DVD=160 Blue Ray
COMPRASION
PROCESS INVOLVED:


In a hologram, both the amplitude and phase of the light are recorded.
When reconstructed, the resulting light field is identical to that which emanated from the original scene, giving a perfect three-dimensional image
Recording Process:
RECONSTRUCTION:

Once the film is processed, if illuminated once again with the reference beam, diffraction from the fringe pattern on the film reconstructs the original object beam in both intensity and phase.
Because of the need for interference between the reference and object beams, holography typically uses a laser in production.
The coherence length of the beam determines the maximum depth the image can have.

Reconstruction medium:

REAL TIME HOLOGRAM:

Here the steps of recording, developing and reconstruction all take place at the same time.
A material with properties which allow continuous updating of the hologram making the hologram dynamic so that the image information which records the hologram can change and the reconstructed output can also track, or change, simultaneously.

Digital Holography:

Makes use of digital devices likes CCD(charge coupled devices) instead of conventional photographic film.
In this, the reconstruction process can be carried out by digital processing of the recorded hologram by a computer.
Image of the object can later be visualized on the computer screen.


Types of errors caused:

The readout conditions change.
The detector array doesnâ„¢t line up with the pixel array in the reconstructed hologram.
The detector is receiving undesired light.
There are brightness variations across the detected image. 



Combating the Errors :
Designer decrease error rate by storing redundant bits with user data.
This forms an ECC(Error Correcting Code).
Advantages:
PC with a holographic technology platform (HoloPCs) will be able to access data more rapidly and in a qualitatively different manner than conventional PCs.
Two-dimensional data saving systems such as CDs and DVDs record and retrieve files in a serial fashion -- one bit at a time. Holographic data systems retain and retrieve data in parallel, a total (million- bit) page of files at a time.
The interface of holography and robotics may make holobots that learn through creative identification of useful patterns in big quantities of files.
Disadvantages:
Manufacturing cost HDSS is very high and there is a lack of availability of resources which are needed to produce HDSS.
Holograms appear dimmer because their patterns must share the material's finite dynamic range.
Writes in the same fashion can degrade previous writes in the same region of the medium.
Future Enhancements:
Erasable Write-once, Read-many drives Confusedupports Terabytes of storage,1 GBit/second read-out and access of data in blocks.
Write-once 3D disk: accessing time is only 10-100msec.
Pre-recorded 3D disks: supports more than 100 Gbytes per 120 mm and readout rates are greater than 200 Mbits/sec.
Conclusion:
The future of HOLOGRAPHIC DATA STORAGE SYSYEM is very promising.
The page access of data that HDSS creates will provide a window into next generation computing by adding another dimension to stored data.
Can achieve higher amount of memory storage.
Can achieve higher data transfer rates so as to reduce the access time.
This technology has revolutionalized the storage media.
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#6
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Holographic Memory for High density data storage & High speed pattern recognition

PRESENTED BY-:

Name: PINKI SINGH, HAPPY BHATT
Roll no: 08BK1A1239, 08BK1A1216
Year & Group: B-TECH IIyr (IT)
College: St Peters Engineering College.

ABSTRACT:

As computers and the internet become faster and faster, more and more information is transmitted, received, and stored everyday. The demand for high density and fast access time data storage is pushing scientists and engineers to explore all possible approaches including magnetic, mechanical, optical, etc. Optical data storage has already demonstrated its potential in the competition against other storage technologies. CD and DVD are showing their advantages in the computer and entertainment market. What motivated the use of optical waves to store and access information is the same as the motivation for optical communication. Light or an optical wave has an enormous capacity (or bandwidth) to carry information because of its short wavelength and parallel nature. In optical storage, there are two types of mechanism, namely localized and holographic memories. What gives the holographic data storage an advantage over localized bit storage is the natural ability to read the stored information in parallel, therefore, meeting the demand for fast access. Another unique feature that makes the holographic data storage attractive is that it is capable of performing associative recall at an incomparable speed. Therefore, volume holographic memory is particularly suitable for high-density data storage and high-speed pattern recognition. In this paper, we review previous works on volume holographic memories and discuss the challenges for this technology to become a reality.



INTRODUCTION

With its omnipresent computer all connected via internet information age has lead an explosion of information available to users. With the decreasing cost of storing data and increasing storage capacity with a same small device footprint have been key enablers of this revolution. While the current storage need is being met, the storage technologies must continue in order to keep pace with a rapidly increasing demand.

However, both magnetic and conventional optical data storage technologies, where individual bits are stored as distinct magnetic or optical changes in the surface of recording medium, are approaching physical limits beyond which individual bits are too small or too difficult to store. Storing information through the volume of the medium not on, its surface offers an intriguing high capacity alternative. Holographic data storage is a volumetric approach, which has made recent progress towards practicality with the appearance of lower cost enabling technologies. Hence, the holographic memory has become a great white whale of technology research.




CONCEPT OF HOLOGRAPHIC MEMORY

Holography is a technique, which allows recording and playback of 3-dimensional images. This is called a hologram unlike other 3-dimenssional picture hologram provide hologram provide what is called parallax. Parallax allows the viewer to move back and forth up and down and see different perspective “ as if the object were actually there.
In Holography, the aim is to record complete wave field (both amplitude and phase) as it is intercepted by recording medium the record in plane may not even be an image plane. The scattered or reflected light by object is intercepted by the recording medium and recorded completely in spite of the fact that the detector is insensitive to the phase difference among the various part of the optical field
In holography, interference between the object wave and reference wave is formed and recorded on a holographic material. The record known as hologram (whole record) captures the complete wave, which can be viewed at the later time by illuminating the hologram with an appropriate light beam.
To this day holography continues to provide the most accurate depiction of 3-D image in the world.



In a holographic memory device, a laser beam is split in two, and the two resulting beams interact in a crystal medium to store a holographic recreation of a page of data.




HISTORICAL ROOTS

Dr.Dennis Gabor is known as the father of holography. In year 1947, Dr.Gabor a Hungarian Physicist gave the idea of holography at the Imperial College of London. In 1971, Dr.Gabor received a noble prize in physics for holography. His theory was originally meant to increase the resolving power of electronic microscope and towards that he used light of beam instead of electronic beam and this resulted in the first hologram ever made.
In 1960s, two engineers from the university of Michigan, Emmit Lerth and Juris Upatlipks, developed a new device that produce a 3-D image of an object Polaroid scientist Peter J.Vann Heerdern proposed the idea of holographic storage in the early 1960s and decade later scientist at RCA laboratories demonstrated the holographic storage technology by recording 500 holograms in an iron doped lithium niobate crystal and 550 holograms of high resolution images in a light sensitive polymer. However, the development of holographic data storage was put on holed for several years because of the absence of cheap parts of the advancement in magnetic and semiconductor memories.
In recent years, IBM and lucent Bell labs are actively involved in creating a successful holographic storage medium because of which it has become possible to store 1000 GB of data in a small cube.



WHAT IS HOLOGRAM?

The word Hologram is derived from Greek word Holosmeaning ËœWholeâ„¢ and GRAM meaning ËœMessageâ„¢. Older English dictionaries define a hologram as a document (such as a last will and testament) hand written by the person whose signature is attached. A hologram is often described as a 3-D picture.

While a photograph has an actual physical image, a hologram contains information about size, shape, brightness and contrast of object being recorded .This information is stored in a very microscopic and complex pattern of interference. The interference pattern is made possible by the properties of light generated by a LASER. In order to record the whole pattern, the light used must be highly directional and must be one of one color. Such light is called coherent. Because the light from a LASER is one color and leaves the LASER with one wave in perfect one-step with all others, it is perfect for making hologram.
When we shine a light on the hologram the information that is stored as an interference pattern takes the incoming light and re-creates the original optical wave front that was reflected off the object hence the eyes and brain now perceives the object as being in front of us once again.

HOLOGRAPHIC MEMORY

Holographic Memory is a simple optical imaging technique that stores digital information throughout the depth of storage medium as opposed to surface storage through conventional means .This enables massive increase in storage capacities over existing technologies and at the same time reduces the cost of storing massive amount of data in a randomly accessible digital format. Most holographic storage systems contain some components basic to the setup.
These are-
i. Laser Beam

ii. Beam Splitters to Split the Laser Beam

iii. Mirrors to direct the Laser Beam

iv. A liquid Crystal Display Panel
Lenses to Focus The Laser Beam

v. Recording Material

vi. CCD Cameras

Technique of storing data on a holographic material

To record on the hologram, a page composer converts the data in the form of electric signals to optical signal the controller generate the address to access the desired page. This results in the exposure of a small area of the recording medium through an aperture. The optical output signal is directed to the exposed area by the deflector.
When the Blue-Argon laser is focused, a beam splitter splits it into two, a reference beam and a signal beam. The signal beam passes through spatial light modulators (SLM) where digital information organized in a page like format of ones and zeros, is modulated onto the signal beam as a two-dimensional pattern of brightness and darkness. This signal beam is then purified using different crystals. When the signal beam and reference beam meets the interference pattern created stores the data that is carried by the Different data pages are recorded over the surface depending on the angle at which the reference beam meet the signal beam a holographic data storage system is fundamentally page oriented with each block of data defined by the no. of data bits that can be spatially impressed onto the object the total storage capacity of the system is then equal to the product of the paper size (in bits) and the no. of pages that can be recorded.



The above diagram shows how data is stored from a holographic data storage system.






Spatial Light Modulator (SLM)

Spatial light modulator is used for creating binary information out of laser light. The SLM is a 2-D plane, consisting of pixels, which can be turned on and off to create 1â„¢s and 0â„¢s. An illustration of this is a window and a window shade. It is possible to pull the shade down over window to block incoming sunlight. If sunlight is desired again, the shade can be raised. A spatial light modulator contains a two dimensional array of windows which are only microns wide. These windows block some parts of the incoming laser light and let other parts go through. The resulting cross section of the laser beam is a two dimensional array of binary data, the same as what was represented in SLM. After the laser beam is manipulated, it is sent into hologram to be recorded. This data is written into the hologram as page form. It is called this due to its representation in

Two“dimensional plane or page of data. Holographic memory reads data in the form of pages instead. For example, if a stream 0f 32 bit is sent to a processing unit by a conventional read head, a holographic memory system would in turn send 32*32 bits, or 1024 bits due to its added dimension this provides very fast access times in volumes for greater than serial access methods. The volume could be one Megabit per page using a SLM resolution of 1024*1024 bits at 15-20 microns per pixel.


Multiplexing


Once one can store a page of bits in a hologram, an interface to a computer can be made. The problem arises, however, that storing only one page of bits is not beneficial. Fortunately, the properties of hologram provide a unique solution to this dilemma. Unlike magnetic storage mechanisms, which store data on their surface, holographic memories store information throughout their whole volume. After a page of data is recorded in a hologram, a small modification to the source beam before it reenters the hologram will record another page of data in the same volume. This method of storing multiple pages of data in the hologram is called multiplexing. The thicker the volume becomes, the smaller the modifications to the source beam can be.

Angular multiplexing

When a reference beam recreates the source beam, it needs to be at the same angle it was during recording. A very small alteration in this angle will make the regenerated source beam disappear. Harnessing this property, angular multiplexing changes the angle of source beam by very minuscule amount after each page of data is recorded. Depending on the sensitivity of recording material, thousands of pages of data can be stored in the same hologram, at the same point of laser beam entry. Staying away from conventional data access system that move mechanical matter to obtain data, the angle of entry of source beam can be deflected by high frequency sound waves in solids. The elimination of mechanical access methods reduces access time from milliseconds to microseconds.

Wavelength multiplexing

Used mainly in conjunction with other multiplexing methods, wavelength multiplexing alters the wavelength of source and reference beams between recordings. Sending beams to the same point of origin in the recording medium at different wavelengths allows multiple pages of data to be recorded. Due to the small tuning range of lasers, however, this form of multiplexing is limited on its own.

Spatial multiplexing

Spatial multiplexing is the method of changing the point of entry of source and reference beams into the recording medium. This form tends to break away from the non-mechanical paradigm because either the medium or recording beams must be physically moved. Like wavelength multiplexing, this is combined with other forms of multiplexing to maximize the amount of data stored in the holographic volume. To commonly used forms of spatial multiplexing are peristrophic multiplexing and shift multiplexing.

Technique of retrievin
g data from holographic material

To retrieve the data, the reference beam is focused on hologram at a particular Angle, this will retrieve the modulated data page stored at the same angle of interference to read the page, reference beam is passed through a detector and then through a CCD camera which will project the data on the display panel. The laser (reference beam) is focused on the appropriate page according to the address generated. A photo detector array on the other side of hologram record the image of that sub hologram.

When the stored interference pattern is illuminated with either of the two original beams, it diffracts the light to reconstruct the other beam used to produce the pattern originally. Thus, illuminating the material with the reference beam recreate the object beam, with its imprinted page of data. It is then a relatively simple matter to detect the data pattern with a solid-state camera chips. The data from the chip are interpreted and forwarded to the computer as stream of digital information. The page can be separated either by varying the angle between the object and the reference beam or by changing the laser wavelength.



The above diagram shows how data is retrieved from a holographic data storage system.

Recording material


The recording material over which a holographic pattern is stored can be made of either organic or inorganic material. The most common inorganic material are ones that exhibit photo refractivity such as lithium niobate(LiNBO3). Lithium niobate has been around for many decades can be fabricated in a large crystal of high optical quality.

Holographic recording in organic photo polymer system has been around for a decade and most of the early attention was directed towards fabrication of holographic optical elements and scanners. Such data recorded could not be erased. This was particularly suited for ËœWrite once run many timesâ„¢ applications. The organic materials currently suffer from two major drawbacks as they cannot be fabricated to a thickness greater than 100 microns enhance the no of holograms that can be multiplexed is very much reduced. They also undergo some degree of shrinkage with exposure, which complicates retrieval of multiplexed hologram and leads to a situation of cross talk.

However, research continues because of their inherent advantages over grown and polished inorganic crystals.

TECHNICAL SPECIFICATIONS


i. Latency : 40 m seconds

ii. Potential Transfer Rate : 1 Gigabit per second

iii. Minimum Sector Size : 128 KB

iv. Potential capacity : 1 Terabit( 128 GB in a 1 Cubic centimeter
Crystal)

v. Power : 1 Watt per Square mm of hologram size

ADVANTAGE


1) The very first advantage of holographic memory system is that an entire page of data can be retrieved quickly and at one time.

2) It provides the very high storage density amount in the order of terabytes and be stored in small cubic devices.

3) High data transfer rates can be achieved with a perfect holographic setup with data transfer rate b/w 1-10 GB per second. Since this memory is not serially or sequentially operated like most memory that is why a page of data can be read out in parallel.

LIMITATIONS

1) In any holographic data storage system, the angle at which the second reference beam is focused on the crystal to a page of data is the crucial component. It must match the original reference beam exactly without deviation. A difference of even a thousandth of a millimeter will result in failure to retrieve that page of data.

2) Also, if too many pages are stored in one crystal, the strength of each hologram gets diminished.

3) If there are too many holograms stored on a crystal and a reference crystal used to retrieve a hologram is not focused at the precise angle, it will pick up a lot of background from the other holograms stored around it.

CONCLUSION


The future of holographic memory is very promising. The holographic storage provides high data density. It can easily store 1000GB of data in a small cubic centimeter crystal reducing the cost on the other hand. It may offer high data transfer rate.

Even then, the holographic way of storing data is still at the toddler stage and it may take another couple of years for this technique to hit desktop with a real life data storage solution.

However, this technology itself is dazzling and aims to light up the desktop experience.


Truly the best things in life come small!!!!



REFERENCES

1) CHIP magazine, pp- 26-32, April 2001

2) almaden.com

3) eik.bme.hu

4) vision.caltech.edu

5) Mansi, Mark the hard disk survival guide, BPB publications, 1993

CONTENTS

1) INTRODUCTION

2) A) CONCEPT OF HOLOGRAPHY

B) HISTORICAL ROOT

C) WHAT IS HOLOGRAM

3) HOLOGRAPHIC MEMORY

4) TECHNIQUE FOR STORING DATA ON A HOLOGRAPHIC MATERIAL

5) SPATIAL LIGHT MODULATOR

6) MULTIPLEXING

7) TECHNIQUE FOR RETREIVING DATA FROM A HOLOGRAOHIC
MATERIAL

8) A) ADVANTAGES
B) LIMITATIONS

9) CONCLUSION

10) REFERENCES
please read http://studentbank.in/report-holographic...ull-report
http://studentbank.in/report-holographic-memory--5241
http://studentbank.in/report-holographic...ars-report
http://studentbank.in/report-holographic...ull-report
for getting more information about Holographic memory and related devices
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#7

[attachment=5132]
holographic data storage full report

ABSTRACT:

Holographic memory is a technique that can store information at high
density inside crystals Holographic memory is developing technology
that has promised to revolutionalise the storage systems. It can
store data up to 1Tb in a sugar cube sized crystal. Data from more
than 1000 CDs can fit into a holographic memory System. . Holographic
storage has the potential to become the next generation of storage
media Conventional memories use only the surface to store the data.
But holographic data storage systems use the volume to store data.
It has more advantages than conventional storage systems. It is
based on the principle of holography
This paper provides a description of Holographic data storage system
(HDSS), a three dimensional data storage system which has a
fundamental advantage over conventional read/write memory systems. A
brief overview of properties of holograms will be presented first.
Applications to computer systems are then covered, with the future of
holographic memory presented as a conclusion.


Reference: http://studentbank.in/report-holographic...z11YYSASoz
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#8


Prepared By,
Harshil Dave

[attachment=7704]

INTRODUCTION

>>Devices that use light to store and read data has always become the backbone of our data storage system for nearly two decades. Each time you access towards the large repository of digital information.


>> All the way to the mammoth 320 GB hard disk drives available today, we use also optical devices such as CDs ,DVDs and Blue-Ray Disk .


>> With the promise of tomorrow's operating systems and create new era of storage via laser, the demands of being able to quickly store and retrieve enormous quantities of data are ever increasing.


DEFINITION

>>Holographic memory is a technology that can store information at high density inside crystals or photopolymers.

>>Conventional memories use only the surface to store the data. But holographic data storage systems use the volume to store data.




BASIC PRINCIPLE OF HDSS

>>A hologram is a block or sheet of photosensitive material which records the diffraction of two light sources.

>>To create a hologram, laser light is first split into two beams:
1.Source beam- Data signal
2.Reference beam- Carrier signal


>>And both intersect on hologram.


>> While reading data we hit Reference signal on exact angle which was use during writing process.



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#9


By
Harshil Dave

[attachment=7720]

ABSTRACT
Colossal Storage Inc. has exclusive license patent rights on new ways of non - contact reading and writing with non destructive reading of information to a ferroelectric molecule. These methods will be used to develop the worlds first 2 D / 3D Area / Volume Holographic mass storage device. U.S. Patents, # 6,028,835 2/00 and # 6,046,973 4/00 for an integrated read/write head for ferroelectric optical media.
Keywords: Ferroelectric, holographic, storage, volume, UV, atomic switch.
 For the first time in history, a design concept for fabrication of a laser semiconductor component used for reading/writing data to an optical holographic disk drive storage product will be explained. A unique new approach never tried before by any company, corporation, research facility, university, military, independent private or public research. The FE 3 D Holographic Optical Drive technology plans to push future storage densities of optical mass storage up to 40,000 Terabits/cu.cm. A comparison with 2 D Area magnetic hard drives of today is around at 60 gigabits.Optically assisted 2 D Area drives at 45 gigabits/sq.in. and 2 D Area contact recording AFM, STM, SPM or SFM, i.e. atomic force microscope and their derivatives,at about 300 gigabits/s.
 This presentation attempts an up-to-date review of the status of holographic data storage and highlights the open technical issues. For holographic data storage to be of technical interest it has to compete with established storage techniques on the basis of cost per megabyte and performance. Key performance parameters are data rate, access time and storage density. For a large capacity holographic storage device, high density of the stored data at low media cost would of course translate into low cost per megabyte. All of this has to be provided reliably, i.e. at a bit-error-rate that compares favorably with conventional storage techniques on media with archival quality. Holographic storage demonstrations have shown the potential for the error free read out of a data page of one thousand by one thousand pixels in one millisecond for a data rate of one Gigabit per second.

INTRODUCTION
Holographic Memory is a simple optical imaging technique that stores digital information throughout the depth of storage medium as opposed to surface storage through conventional means .This enables massive increase in storage capacities over existing technologies and at the same time reduces the cost of storing massive amount of data in a randomly accessible digital format. Most holographic storage systems contain some components basic to the setup.
These are
->Laser Beam
>Beam Splitters to Split the Laser Beam
>Mirrors to direct the Laser Beam
>A liquid Crystal Display Panel
Lenses to Focus the Laser Beam
>Recording Material
>CCD Cameras


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#10


[attachment=7946]

Submitted by
VIKAS TRIPATHI
B.Tech 4TH Year
UNITED INSTITUTE OF TECHNOLOGY,ALLAHABAD


What is Holographic Technology

Holographic Storage is an optical technology that allows 1 million bits of data to be written and read out in single flashes of light. Thousands of Holograms can be stored in the same location throughout the entire depth of the medium.

Holography breaks through the density limits of conventional storage by going beyond recording only on the surface, to recording through the full depth of the medium. Unlike other technologies that record one data bit at a time, holography allows a million bits of data to be written and read in parallel with a single flash of light. This enables transfer rates significantly higher than current optical storage devices.


Benefits of Holographic Technology

Dynamic Range
Photosensitivity
Dimensional Stability
Optical Flatness
Low Scatter
Non-volatile readout
Long shelf-life of media
Long archival life of stored data
Environmental/thermal stability


APPLICATIONS

1. Holographic Data Storage

Holographic memory is a new optical storage method that can store 1 terabyte (= 1000 GB) of data in a crystal approximately the size of a sugar cube.

Advantages of HDS over conventional storage methods

Data is stored in all three dimensions of the material and not just the surface.

Read/write speeds are also much higher since data is written and read out as 2D digital or analogue images in a 3D volume rather then a bit stream.

The bit rate error is also decreased considerably because error causing factors such as scratches, dust, etc tend to affect the surface only and since a hologram is recorded as a complex interference pattern in the bulk of the material, these affects are limited.

2. HOLOGRAPHIC IMAGES

Holographic images interfaces empower operators to enter commands and data into a wide range of electronic equipment by simply passing a finger through holographic images of what would otherwise be the keys of a keypad or keyboard, appearing to float in the air at a convenient location in front of the equipment.  An infrared sensor scans the plane of those images to detect the intrusion of a finger into the desired portion of those images, identifies which number or symbol has been selected and transmits that selection to the equipment's internal software, much the same way pressing a button on any ordinary keypad would.

Adavantages
Holographic images solve many problems posed by conventional, tactile keypads and keyboards, particularly those regularly subject to contaminants, customer abuse, dirt, moisture, temperature fluctuations and shock.

3. Anti Counterfeit System

Anti-counterfeit security is an attempt to prevent valuable products or
documents from being copied or falsified.

Holography offers certain advantages as a security device.

Producing an original hologram is expensive and time consuming, but mass-produced replicas from the original are relatively inexpensive.

The equipment and skills necessary for mass producing holograms has been fairly difficult to obtain in the past.

Holograms look distinctively different from printed labels.

The tools counterfeiters have traditionally used for counterfeiting (the camera and the printing press) do not work on holograms.




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#11
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INTRODUCTION
Devices that use light to store and read data have been the backbone of data storage for nearly two decades. Compact discs revolutionized data storage in the early 1980s, allowing multi-megabytes of data to be stored on a disc that has a diameter of a mere 12 centimeters and a thickness of about 1.2 millimeters. In 1997, an improved version of the CD, called a digital versatile disc (DVD), was released, which enabled the storage of full-length movies on a single disc.
CDs and DVDs are the primary data storage methods for music, software, personal computing and video. A CD can hold 783 megabytes of data. A double-sided, double-layer DVD can hold 15.9 GB of data, which is about eight hours of movies. These conventional storage mediums meet today's storage needs, but storage technologies have to evolve to keep pace with increasing consumer demand. CDs, DVDs and magnetic storage all store bits of information on the surface of a recording medium. In order to increase storage capabilities, scientists are now working on a new optical storage method called holographic memory that will go beneath the surface and use the volume of the recording medium for storage, instead of only the surface area. Three-dimensional data storage will be able to store more information in a smaller space and offer faster data transfer times.
Holographic memory is developing technology that has promised to revolutionalise the storage systems. It can store data upto 1 Tb in a sugar cube sized crystal. Data from more than 1000 CDs can fit into a holographic memory System. Most of the computer hard drives available today can hold only 10 to 40 GB of data, a small fraction of what holographic memory system can hold. Conventional memories use only the surface to store the data. But holographic data storage systems use the volume to store data. It has more advantages than conventional storage systems. It is based on the principle of holography.
Scientist Pieter J. van Heerden first proposed the idea of holographic (three-dimensional) storage in the early 1960s. A decade later, scientists at RCA Laboratories demonstrated the technology by recording 500 holograms in an iron-doped lithium-niobate crystal and 550 holograms of high-resolution images in a light-sensitive polymer material. The lack of cheap parts and the advancement of magnetic and semiconductor memories placed the development of holographic data storage on hold.
HOLOGRAPHY
A hologram is a block or sheet of photosensitive material which records the interference of two light sources. To create a hologram, laser light is first split into two beams, a source beam and a reference beam. The source beam is then manipulated and sent into the photosensitive material. Once inside this material, it intersects the reference beam and the resulting interference of laser light is recorded on the photosensitive material, resulting in a hologram. Once a hologram is recorded, it can be viewed with only the reference beam. The reference beam is projected into the hologram at the exact angle it was projected during recording. When this light hits the recorded diffraction pattern, the source beam is regenerated out of the refracted light. An exact copy of the source beam is sent out of the hologram and can be read by optical sensors. For example, a hologram that can be obtained from a toy store illustrates this idea. Precise laser equipment is used at the factory to create the hologram. A recording material which can recreate recorded images out of natural light is used so the consumer does not need high-tech equipment to view the information stored in the hologram. Natural light becomes the reference beam and human eyes become the optical sensors.
Holography was invented in 1947 by the Hungarian-British physicist Dennis Gabor (1900-1979), who won a 1971 Nobel Prize for his invention.
APPLICATION TO BINARY
In order for holographic technology to be applied to computer systems, it must store data in a form that a computer can recognize. In current computer systems, this form is binary. In the previous section, it was mentioned that the source beam is manipulated. In common holograms, this manipulation is the creation of an optical image such as a ball or human face. In computer applications, this manipulation is in the form of bits. The next section explains the spatial light modulator, a device that converts laser light into binary data.
SPATIAL LIGHT MODULATOR (SLM)
A spatial light modulator is used for creating binary information out of laser light. The SLM is a 2D plane, consisting of pixels which can be turned on and off to create binary 1.s and 0.s. An illustration of this is a window and a window shade. It is possible to pull the shade down over a window to block incoming sunlight. If sunlight is desired again, the shade can be raised. A spatial light modulator contains a two-dimensional array of windows which are only microns wide. These windows block some parts of the incoming laser light and let other parts go through. The resulting cross section of the laser beam is a two dimensional array of binary data, exactly the same as what was represented in the SLM. After the laser beam is manipulated, it is sent into the hologram to be recorded. This data is written into the hologram as page form. It is called this due to its representation as a two dimensional plane, or page of data. Spatial light modulator is a Liquid Crystal Display panel that consists of clear and dark areas corresponding to the binary information it represent.
Spatial light modulator is actually that device which makes holography applicable to computers. So it is one of the important components of Holographic Data Storage System.
IMPLEMENTATION
The components of Holographic data storage system is composed of
Blue-green argon laser
Beam splitters to spilt the laser beam
Mirrors to direct the laser beams
LCD panel (spatial light modulator)
Lenses to focus the laser beams
Lithium-niobate crystal or photopolymer
Charge coupled device camera
They can be classified into three sections namely recording medium, optical recording system and photodetector array. The laser is used because it provides monochromatic light. Only the interference pattern produced by the monochromatic beam of light is stable in time. Lithium niobate crystal is used as photosensitive material on which hologram is recorded. It has certain optical characteristics that make it behave as photosensitive material. CCD camera detects the information in the light, converts to digital information and forward it to computer.
RECORDING OF DATA IN HOLOGRAPHIC MEMORY SYSTEM
When the blue-green argon laser is fired, a beam splitter creates two beams. One beam, called the object or signal beam, will go straight, bounce off one mirror and travel through a spatial-light modulator (SLM). An SLM is a Liquid crystal display (LCD) that shows pages of raw binary data as clear and dark boxes. The information from the page of binary code is carried by the signal beam around to the light-sensitive lithium-niobate crystal. Some systems use a photopolymer in place of the crystal. A second beam, called the reference beam, shoots out the side of the beam splitter and takes a separate path to the crystal. When the two beams meet, the interference pattern that is created stores the data carried by the signal beam in a specific area in the crystal -- the data is stored as a hologram.
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#12
[attachment=10597]
We Need More Data Storage !
Holographic Data-Storage System

These two diagrams show how information is stored and retrieved in a holographic data storage system.
(Images courtesy of Lucent Technologies)
Capacity, Speed, Cost Comparison
Probable Projects
HDSS Juke box
E-Library
Movie Library
Personal Clan Video
Government Agencies
Educational Tutorials
Magic Sing with Holographic Data Chips
Dream Projects

HVD-RW
Lasers as Transmission Cables
Laser Transformer
Storing Holographic Energy
Sources:
The Economist Technology Quartely, June 2007
How Holographic Memory Will Work
by Kevin Bronsor
How Holographic Versatile Discs Work
by Julia Layton
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#13
presented by:
VISHNU JOSHI

ABSTRACT:
Holographic data storage is a potential replacement technology in the area of high-capacity data storage currently dominated by magnetic and conventional optical data storage. Magnetic and optical data storage devices rely on individual bits being stored as distinct magnetic or optical changes on the surface of the recording medium. Holographic data storage overcomes this limitation by recording information throughout the volume of the medium and is capable of recording multiple images in the same area utilizing light at different angles. Additionally, whereas magnetic and optical data storage records information a bit at a time in a linear fashion, holographic storage is capable of recording and reading millions of bits in parallel, enabling data transfer rates greater than those attained by optical storage.
Holographic data storage captures information using a non optical interference pattern within a thick, photosensitive optical material. Light from a single laser beam is divided into two separate optical patterns 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 is approximately several tens of Terabytes (1 terabyte = 1024 gigabytes) per cubic centimeter. From this we can deduce that a regular disk (with 4 cm radius of writing area) could hold up to a maximum of 3895.6 GB. Holographic data storage can provide companies a method to preserve and archive information. The write-once, read many approach to data storage would ensure content security, preventing the information from being overwritten or modified.

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#14
Presented By:
Manu G.R

[attachment=14504]
HOLOGRAPHIC DATA STORAGE
INTRODUCTION

The storage of information and data has been an important issue since men first drew pictures on the walls of caves. The methods of storing data have changed over the years, especially now that we have CD, DVD, HDD.
Scientist Pieter J. van Heerden first proposed the idea of holographic (three-dimensional) storage in the early 1960s.
Holographic memory is developing technology that has promised to revolutionalise the storage systems.
Holographic data storage is a volumetric approach.
What Is Holographic Storage?  
·     Holographic storage is the computer storage that uses laser beams to store data in 3 dimensions.
·     Holographic Storage is an optical technology that allows 1 million bits of data to be written or read in a single flash of light.
·     Holography records through the full depth of the medium.
·     Holography enables transfer rates significantly higher than current optical storage devices.
Why Holographic Storage?
·    Three dimensional data storage has the potential to store more data in a smaller space and at a quicker speed.
·    Parallel access to data i.e. Multiplex data pages in one location.
·    Fast data transfer rates.
·    Competitive with other optical technology.
·    Thousands of holograms can be stored in the same location throughout the entire depth of the medium.
What Is A Hologram?
A three-dimensional image formed by the interference of light beams from a laser.
The intersection of two beams creates an interference pattern of bright and dark regions.
COMPONENTS OF A HOLOGRAPHIC STORAGE SYSTEM
Blue-green argon laser
Beam splitters
Mirrors
LCD panel (SLM)
Lenses
Lithium-niobate crystal or photopolymer
Charge-coupled device (CCD) camera
How a holographic memory works
ADVANTAGES
Entire page of data can be retrieved quickly and at one time.
Offers storage of 1TB of data in a sugar cube sized crystal.
It offers high density storage.
Low Scatter: Low levels of noise in data recovery
It transfer rate is so high that a person can easily load the required data.
Resistance to damage – If some parts medium are damaged, all information can still be obtained from other parts.
Efficient retrieval – All information can be retrieved from any part of the medium
APPLICATIONS
CONCLUSION

Holographic data storage is a convenient and effective way of data storage.
This storage technique is rapidly gaining attention because of its capacity (GB to TB) and high speed data storage.
Holographic data storage will help to create a new tapeless era in the video production and broadcast industry.
No other storage technology under development can match holography's capacity and speed potential.
Finally, Holography could provide a unique hardware device for searching databases rapidly.
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#15
[attachment=14540]
INTRODUCTION
1.1 History

Digital data are ubiquitous in modern life. The capabilities of current storage
technologies are continually being challenged by applications as far ranging
as the distribution of content, digital video, interactive multimedia, small
personal data storage devices, archiving of valuable digital assets, and downloading
over high-speed networks . Current optical data storage technologies,
such as the compact disk (CD), digital versatile disk (DVD), and Bluray disk
(BD) , have been widely adopted because of the ability to provide random access
to data, the availability of inexpensive removable media, and the ability
to rapidly replicate content (video, for example)[1].
Traditional optical storage technologies, including CD, DVD and BD,
stream data one bit at a time , and record the data on the surface of the
disk-shaped media. In these technologies, the data are read back by detecting
changes in the reflectivity of the small marks made on the surface of the
media during recording. The traditional path for increasing optical recording
density is to record smaller marks, closer together. These improvements in
characteristic mark sizes and track spacing have yielded storage densities
for CD, DVD, and BD of approximately 0.66, 3.2, and 17 Gb in m−2 ,
respectively.
To further increase storage capacities, multi-layer disk recording is possible,
but signal to noise losses, and reduced media manufacturing yields,
make using significantly more than two layers impractical. Considerable
drive technology changes, such as homodyne detection and dynamic spher-
CHAPTER 1. INTRODUCTION 3
ical aberration compensation servo techniques, have been proposed to deal
with the signal to noise losses inherent in multiple layers[2].
1.2 Holographic Data Storage
Holog aphic data storage (HDS) breaks through the density limitations of
conventional storage technologies by going beyond two-dimensional layered
approaches, to write data in three dimensions. Before discussing page-based
HDS, here an alternate approach; bitwise holographic storage .
In bitwise holographic storage, multiple layers of small localized holograms
are recorded at the focus of two counter-propagating beams. Each
of these holograms represents a single bit that is subsequently read out by
monitoring the reflectance of a single focused beam . racking the hologram
locations through the volume in three dimens ions is typically accomplished
using a reference surface or part of the holograms themselves. Bitwise holographic
storage is appealing because the drive technology and components
are similar to traditional optical storage , and because the media is homogenous
and hence easy to manufacture. However, there are several serious
drawbacks. First, it is difficult to achieve fast transfer rates. Also, it requires
the invention of a material that is optically nonlinear. The technique also
requires a complex servo system because the two recording beams must be
dynamically focused into the same volume. Finally, the multiple layers of
micro holograms cause distortion in the optical beams, which significantly
limits the achievable density.
Page-wise HDS has demonstrated the highest storage densities (712 Gb
in m−2 ) of any removable technology, and has a theoretically achievable
density of around 40 Tb in m−2. High storage densities , fast transfer rates
and random access, combined with durable, reliable , low cost media, make
page-wise holography a compelling choice for next-generation storage and
content distribution applications. The flexibility of the technology allows
the development of a wide variety of holographic storage products, ranging
from handheld devices for consumers to storage products for the enterprise
market.
Figure 1.1 shows the highlihts in holographic storage developments over
the last 15years. The right-hand side of the figure shows technical advances
made by Bell Laboratories and InPhase Technologies, while those of other
companies and institutions are shown on the left-hand side of the figure[
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#16
Hi guys, this is aashish.
i want the ppt about the topic mentioned above.
thank you!
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#17

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#18
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#19
can anyone tell in simple wording about holographic data storage
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#20
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