hdss seminar report

8/3/2019 Hdss Seminar Report

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CERTIFICATE

This is to certify that the Seminar Report entitled HOLOGRAPHIC

DATA STORAGE being submitted by RAJARSHI RAJ bearing

Registration No: 0801289320, in partial fulfillment of the requirement for

the award of the 6th semester ofBachelor of Technology in Information

Technology is a bonafide work carried out at Trident Academy of

Technology, Bhubaneswar under my/our supervision. The matter

embodied in this seminar report is original and has not been submitted for

the award of any other degree.

ALKA NANDA TRIPATHY ADITYA NARAYAN DAS NANI GOPAL DAS

SEMINAR CO-ORDINATOR GUIDE HOD IT

2HOLOGRAPHIC DATA STORAGE

Seminar Report By RAJARSHI RAJ ( Regd No:- 0801289320 )


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ACKNOWLEDGEMENTFirst of all Iwould like to thank the Almighty, who has always guided

me to work on the right path of the life. My greatest thanks are to my parents

who bestowed ability and strength in me to complete this work.

This work would not have been possible without the encouragement

and able guidance of my Guide Mr. ADITYA NARAYAN DAS . His

enthusiasm and optimism made this experience both rewarding and enjoyable.

Most of the novel ideas and solutions found in this thesis are the result of our

numerous stimulating discussions. I am equally grateful to Ms. ALKA

NANDA TRIPATHY, B.Tech. Seminar Coordinator, Information

Technology , a nice person, who always encouraged me to keep going with

work and always advised me with his invaluable suggestions.

I would like to express my sincere gratitude towards Mr. NANI

GOPAL DAS, H.O.D, Information Technology, and the entire faculty and

staff members of Information Technology Department for their directindirect

help, cooperation, love and affection, which made my stay at Trident Academy

of Technology memorable.

RAJARSHI RAJ

Registation No: 0801289320

6th Semester

B.Tech (IT-F)

2008-2012




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Contents

1. HOLOGRAPHIC DATA STORAGE 5

2. CHAPTER 1 INTRODUCTION 63. CHAPTER 2 A LITTLE BACKGROUND 7 - 8

4. CHAPTER 3 HDSS THE NEXT BIG THING 9

5. CHAPTER 4 BASIC PRINCIPLES OF HDSS 10 11

6. CHAPTER 5 BASIC COMPONENTS OF HDSS 12

7. CHAPTER 6 RECORDING OF DATA 13

8. CHAPTER 7 READING OF DATA 14

9. CHAPTER 8 MULTIPLEXING 15 - 17

10. CHAPTER 9 ADVANTAGES 18

11. CHAPTER 10 DISADVANTAGES 19

12. CHAPTER 11 APPLICATIONS 20 -21

13. CHAPTER 12 CONCLUSION 22

14. REFERENCES 23




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Holographic Data Storage System

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 (1terabyte = 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.

Guided By :Aditya Narayan Das

Submitted By:

Rajarshi RajRegd. No:-0801289320




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Branch:- IT

Introduction

Every enterprise needs archival storage to meet compliancerequirements and address litigation issues, but "deep" archivingremains a challenge. Nobody wants to keep discs powered, spinningand serviced for up to 50 years or more. Tape is removable andsecurable, but tape carries its own long-term readability and reliabilityconcerns. Optical storage is emerging as an attempt to fill this gap,

and holographic storage may emerge as the next vehicle for long-term offline archival storage, bringing a mix of large capacity anddecades of media stability.

However, holographic storage technology is far from being thenext big thing. It has been on the drawing boards for years, and eventhough most of its technological components are well-founded incurrent CD/DVD devices, practical holographic storage systems arestill in development. In fact, there are really only two principalsuppliers. This article examines holographic storage technology,

highlights its anticipated deployment and considers the potentiallyrocky road ahead for this high-capacity optical storage scheme.



CHAPTER1
http://searchstorage.techtarget.com/sDefinition/0,,sid5_gci966110,00.htmlhttp://www.computerweekly.com/Articles/2007/08/06/226027/is-holography-the-future-for-storage.htmhttp://www.computerweekly.com/Articles/2007/08/10/226140/firms-plan-for-100-year-data-storage.htmhttp://searchstorage.techtarget.com/sDefinition/0,,sid5_gci966110,00.htmlhttp://www.computerweekly.com/Articles/2007/08/06/226027/is-holography-the-future-for-storage.htmhttp://www.computerweekly.com/Articles/2007/08/10/226140/firms-plan-for-100-year-data-storage.htm


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A LITTLE BACKGROUND

Holographic storage works by storing a sequence of discrete

data snapshots within the thickness of the media. The storageprocess starts when a laser beam is split into two signals. One beamis used as a reference signal. Another beam, called the data-carryingbeam, is passed through a device called a spatial light modulator(SLM) which acts as a fine shutter system, passing and blocking lightat points corresponding to ones and zeroes. The reference beam isthen reflected to impinge on the data-carrying beam within the media.This creates a three-dimensional refraction pattern (the "hologram")that is captured in the media. Holographic storage uses circularmedia similar to a blank CD or DVD that spins to accept data along acontinuous spiral data path. Once the media is written, data is readback using the reference beam to illuminate the refraction.

This three-dimensional aspect of data recording is animportant difference between holographic storage and conventionalCD/DVD recording. Traditional optical media uses a single laserbeam to write data in two dimensions along a continuous spiral datapath. In contrast, prototype holographic storage products save onemillion pixels at a time in discrete snapshots, also called pages, which

form microscopic cones through the thickness of the light-sensitivemedia. Today's holographic media can store over 4.4 millionindividual pages on a disc.



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Today, holographic storage is a Worm technology that relieson light-sensitive media housed in removable protective cartridges.Although rewritable media and drives will appear in the next fewyears, much like the progression from CD-R to CD-RW or from DVD-R to DVD-RW, experts note that the most likely application for Wormmedia is for long-term archiving.




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HDSS THE NEXT BIG THING

Devices that use light to store and read data have been thebackbone of data storage for nearly two decades. Compactdiscs 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. In1997, an improved version of the CD, called a digital versatiledisc (DVD), was released, which enabled the storage of full-lengthmovies on a single disc.

CDs and DVDs are the primary data storage methods formusic, software, personal computing and video. A CD can hold 783megabytes of data, which is equivalent to about one hour and 15minutes of music, but Sony has plans to release a 1.3-gigabyte (GB)

high-capacity CD. A double-sided, double-layer DVD can hold 15.9GB of data, which is about eight hours of movies. These conventionalstorage mediums meet today's storage needs, but storagetechnologies have to evolve to keep pace with increasing consumerdemand. CDs, DVDs and magnetic storage all store bitsof informationon the surface of a recording medium. In order to increase storagecapabilities, scientists are now working on a new optical storagemethod, called holographic memory, that will go beneath thesurface 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 informationin a smaller space and offer faster data transfer times.



CHAPTER3
http://www.howstuffworks.com/light.htmhttp://www.howstuffworks.com/cd.htmhttp://www.howstuffworks.com/cd.htmhttp://www.howstuffworks.com/bytes.htmhttp://www.howstuffworks.com/bytes.htmhttp://www.howstuffworks.com/dvd.htmhttp://www.howstuffworks.com/dvd.htmhttp://www.howstuffworks.com/bytes.htmhttp://www.howstuffworks.com/light.htmhttp://www.howstuffworks.com/cd.htmhttp://www.howstuffworks.com/cd.htmhttp://www.howstuffworks.com/bytes.htmhttp://www.howstuffworks.com/bytes.htmhttp://www.howstuffworks.com/dvd.htmhttp://www.howstuffworks.com/dvd.htmhttp://www.howstuffworks.com/bytes.htm


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BASIC PRINCIPLES OF HDSS

Holography is a technique which enables a light field to be

recorded, and reconstructed later when the original light field is no

longer present. It is analogous to sound recording where the sound

field is encoded in such a way that it can later be reproduced.

Though holography is often referred to as 3D photography, this

is a misconception. A photograph represents a single fixed image of a

scene, whereas a hologram, when illuminated appropriately, re-

creates the light which came from the original scene; this can be

viewed from different distances and at different orientations just as if

the original scene were present. The hologram itself consists of a

very fine random pattern, which appears to bear no relationship to the

scene which it has recorded.

To record a hologram, some of the light scattered from an

object or a set of objects falls on the recording medium. A second

light beam, known as the reference beam, also illuminates the

recording medium, so that interference occurs between the two

beams. The resulting light field generates a seemingly random

pattern of varying intensity, which is recorded in the hologram. The

figure on the right is a photograph of part of a hologram - the objectwas a toy van. The photograph was taken by backlighting the

hologram with diffuse light, and focusing on the surface of the plate.



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http://en.wikipedia.org/wiki/Sound_recordinghttp://en.wikipedia.org/wiki/Imagehttp://en.wikipedia.org/wiki/Interference_(wave_propagation)http://en.wikipedia.org/wiki/Sound_recordinghttp://en.wikipedia.org/wiki/Imagehttp://en.wikipedia.org/wiki/Interference_(wave_propagation)


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It is important to note that the holographic recording iscontained in the random intensity structure (which is a specklepattern), and not in the more regular structure, which is due tointerference arising from multiple reflections in the glass plate onwhich the photographic emulsion is mounted. It is no more possible todiscern the subject of the hologram from this random pattern than it isto identify what music has been recorded by looking at the hills andvalleys on a gramophone record surface or the pits on a CD.

When the original reference beam illuminates the hologram, itis diffracted by the recorded hologram to produce a light field which isidentical to the light field which was originally scattered by the objector objects onto the hologram. When the object is removed, anobserver who looks into the hologram "sees" the same image on hisretina as he would have seen when looking at the original scene. This

image is often called a virtual image, as it can be seen even thoughthe object is no longer present. The figure shown at the top of thisarticle is an image produced by a camera which is located in front ofthe developed hologram which is being illuminated with the originalreference beam. The camera is focused on the original scene, not onthehologram itself.


http://en.wikipedia.org/wiki/Speckle_patternhttp://en.wikipedia.org/wiki/Speckle_patternhttp://en.wikipedia.org/wiki/Diffractionhttp://en.wikipedia.org/wiki/Speckle_patternhttp://en.wikipedia.org/wiki/Speckle_patternhttp://en.wikipedia.org/wiki/Diffraction


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BASIC COMPONENTS OF HDSS

The components of Holographic data storage system iscomposed of

Blue-green argon laserBeam splitters to spilt the laser beamMirrors to direct the laser beamsLCD panel (spatial light modulator)Lenses to focus the laser beamsLithium-niobate crystal or photopolymerCharge coupled device camera

They can be classified into three sections namely recordingmedium, optical recording system and photodetector array. The laseris used because it provides monochromatic light. Only theinterference pattern produced by the monochromatic beam of light isstable in time. Lithium niobate crystal is used as photosensitivematerial on which hologram is recorded. It has certain opticalcharacteristics that make it behave as photosensitive material. CCDcamera detects the information in the light, converts to digital

information..



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RECORDING OF DATA ON

MEDIUM

When the blue-green argon laser is fired, a beam splittercreates two beams. One beam, called the object or signal beam, willgo straight, bounce off one mirror and travel through a spatial-lightmodulator (SLM). An SLM is a Liquid crystal display (LCD) thatshows pages of raw binary data as clear and dark boxes. Theinformation from the page of binary code is carried by the signalbeam around to the light-sensitive lithium-niobate crystal. Somesystems 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 thesignal beam in a specific area in the crystal -- the data is stored as ahologram.



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READING DATA FROMHOLOGRAM

When reading out the data, the reference beam has to hit the

crystal at the same angle thats used in recording the page. To read out

the data, the reference beam again illuminates the crystal. The stored

interference pattern diffracts the reference beams light so that it

reconstructs the checkerboard image of the light or dark pixels.

The image is directed upon a charge-coupled device (CCD) sensor

array that reads the data in parallel, and it instantly captures the entire

digital page. The binary information can now be read from this CCD

and the data is retrieved. This parallel read out of data provides

holography with its fastdata transfer rates.



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MULTIPLEXING

Once one can store a page of bits in a hologram, aninterface 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 uniquesolution to this dilemma. Unlike magnetic storagemechanisms that store data on their surface, holographicmemories store information throughout their whole volume.

After a page of data is recorded in the hologram, a smallmodification to the source beam before it reenters thehologram will record another page of data in the samevolume. This method of storing multiple pages of data in thehologram is called multiplexing. The thicker the volumebecomes, the smaller the modifications to the source beamcan be.

1. Angular Multiplexing

When a reference beam recreates the source beam, itneeds to be at the same angle it was during recording. Avery small alteration in this angle will make the regenerated



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source beam disappear. Harnessing this property, angularmultiplexing changes the angle of the source beam by veryminuscule 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 samehologram, at the same point of laser beam entry. Stayingaway from conventional data access systems that movemechanical matter to obtain data, the angle of entry on thesource beam can be deflected by high-frequency soundwaves in solids. The elimination of mechanical accessmethods reduces access times from milliseconds tomicroseconds.

2. Wavelength Multiplexing

Used mainly in conjunction with other multiplexingmethods, wavelength multiplexing alters the wavelength ofsource and reference beams between recordings. Sendingbeams to the same point of origin in the recording mediumat different wavelengths allows multiple pages of data to berecorded. Due to the small tuning range of lasers, however,this form of multiplexing is limited on its own.

3. Spatial Multiplexing

Spatial multiplexing is the method of changing the pointof entry of source and reference beams into the recordingmedium. This form tends to break away from the non-mechanical paradigm because either the medium orrecording beams must be physically moved. Like wavelengthmultiplexing, this is combined with other forms of

multiplexing to maximize the amount of data stored inthe holographic volume. Two commonly used forms ofspatial multiplexing are peristrophic multiplexing and shiftmultiplexing.




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4. Phase-Encoded Multiplexing

The form of multiplexing farthest away from using

mechanical means to record many pages in the samevolume of a holograph is called phase-encoded multiplexing.Rather than manipulate the angle of entry of a laser beam orrotate/translate the recording medium, phase-encodedmultiplexing changes the phase of individual parts of areference beam. The main reference beam is split up intomany smaller partial beams that cover the same area as theoriginal reference beam. These smaller beamlets vary byphase that changes the state of the reference beam as a

whole. The reference beam intersects the source beam andrecords the diffraction relative to the different phases of thebeamlets. The phase of the beamlets can be changed bynon-mechanical means, therefore speeding up accesstimes.

Combining Multiplexing Methods

No single multiplexing method by itself is the best way

to pack a hologram full of information. The true power ofmultiplexing is brought out in the combination of one ormore methods. Hybrid wavelength and angular multiplexingsystems have been tested and the results are promising.Recent tests have also been formed on spatial multiplexingmethods which create a hologram the size of a compactdisc, but which hold 500 times more data.




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ADVANTAGES OF HDSS

HIGH CAPACITY: Holographic storage devices having 125GBcapacity has already been realized. Eventually these devicescould have storage capacities of 1TB or even 1PB.

HIGH TRANFER RATE: Early holographic data storagedevices have transfer rates up to 40MB/sec .It is expectedthat it would have transfer rates up to 1GB/sec

PARALLEL SEARCHING: Holographic data storage enablesrapid parallel searching as data is stored and retrieved inparallel. Hence searching is very fast.

REDUNDANCY: Because a single page of bits may be storedat one time, the information content of the page isintermingled. Thus any defect occurring in the recordingmedium would not destroy the data bits .Rather, only thesignal to noise ratio is affected.

BANDWIDTH: Bandwidth is the amount of information thatcan be contained in Individual channels.



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DISADVANTAGES OF HDSS

The key component of any holographic data storage systemis the angle at which the second reference beam is fired atthe crystal to retrieve a page of data. It must match theoriginal reference beam angle exactly. A difference of just athousandth of a millimeter will result in failure to retrievethat page of data.

The recording mechanism for photopolymers also leads tosome disadvantages, including shrinkage of the material witpolymerization and the possibility of nonlinear response.Both of these distort the reconstructed holograms and thuscause errors in decoding digital data.

On the other hand, holographic data storage currentlysuffers from the relatively high component and integrationcosts faced by any emerging technology. In contrast,magnetic hard drives, also known as direct access storagedevices (DASD), are well established, with a broadknowledge base, infrastructure, and market acceptance.

Another important problem that arises is that the wholerecording medium and apparatus should exhibit high degreeof perfection. That is it should be able to even withstand theslightest of jerks.



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POSSIBLE APPLICATION

There are many possible applications of holographicmemory. Holographic memory systems can potentiallyprovide the high-speed transfers and large volumes of futurecomputer systems.

PARALLELISM: In conventional storage, data isrecorded and retrieved serially. Holographic storage, on theother hand, uses the information capacity of an opticalwave-front so that data can be recorded and retrieved inparallel, one page at a time. Due to the page-orientednature of holographic storage, the potential exists forextremely high data rates, subject only to the limitationsimposed by I / O (input/output) devices. Holographicstorage systems can have data rates approaching 1.0Gbytes / sec. In addition, because beam deflection, asopposed to moving parts, is used to access the storedholograms, access times in the 10-ms range could beachieved. Hence searching can be very fast since it usesparallel search.

DATAMINING: One possible application is data mining.Data mining is the process of finding patterns in largeamounts of data. Data mining is used greatly in largedatabases which hold possible patterns which cannot bedistinguished by human eyes due to the vast amount ofdata. Some current computer systems implement data



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mining, but the mass amount of storage required is pushingthe limits of current data storage systems. The manyadvances in access times and data storage capacity thatholographic memory provides could exceed conventional

storage and speed up data mining considerably. This wouldresult in more located patterns in a shorter amount of time.

PETAFLOP COMPUTING: Another possible application ofholographic memory is in petaflop computing. A petaflop is athousand trillion floating point operations per second. Thefast access in extremely large amounts of data provided byholographic memory systems could be utilized in a petafloparchitecture. Clearly advances are needed in more than

memory systems, but the theoretical schematics do exist forsuch a machine. Optical storage such as holographicmemory provide a viable solution to the extreme amount ofdata which is required for petaflop computing.




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CONCLUSION

The future of holographic memory is very promising.The page access of data that holographic memory createswill provide a window into next generation computing byadding 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 makesmall-scale systems implemented with holographic memoryimpractical. Holographic memory will most likely be used innext generation super computers where cost is not as muchof an issue. Current magnetic storage devices remain farmore cost effective than any other medium on the market.The current storage in a personal computer operates on thesame principles used in the first magnetic data storage

devices. The parallel nature of holographic memory hasmany potential gains on serial storage methods. However,many advances in optical technology and photosensitivematerials need to be made before we find holograms incomputer systems.

Holographic techniques may provide a long soughtideal: a mass memory with archival permanence and yetelectronic accessibility. It also promises to provide a long

wished-for mass storage device for data processing that isdevoid of any mechanical motion and which integrates in asingle unit, permanent recording with high speed electronicrandom accessibility.



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REFERENCES

E. Chuang, Methods and architecture for rewritableholographic memories, Ph.D. dissertation, California Inst.Technol., Pasadena, 1998.silicon/liquid crystal devices. Jean-Jacques is currently with Micro Display Corporation, SanPablo, CA.

Holographic Random Access Memory (HRAM):ERNESTCHUANG, WENHAI LIU, JEAN-JACQUES P. DROLET,ASSOCIATE MEMBER, IEEE,AND DEMETRI PSALTIS, SENIOR

MEMBER, IEEE.

IBM Journal of Research and Development ,HOLOGRAPHICMEMORIES by, J. Ashley

PROCEEDINGS OF THE IEEE, VOL. 87, NO. 11, NOVEMBER1999

http://www.optics.arizona.edu/Glenn/holograp1.htm

http://www.research.ibm.com/journal/rd/443/ashley.html

http://optics.caltech.edu/Publications/Papers/Chuang%20HRAM.pdf.



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