BY –AVINASH MAURYAIT 6th SEM

Roll No-0829213008

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1. Introduction.2. What is Holographic memory?3. What is HVD?4. Structure of HVD.5. How HVD Works?

I. Writing DataII. Reading Data

6. Advantages of HVD7. Limitations AND Challenges8. How HVD compares with other storage device?9. Conclusion

A hologram is a 3D image reproduced form a pattern of interference.

The Holography technique was invented in 1948 by the Hungarian Dennis Gabor.

It can store up to 1-4 TB of information in a sugar cube sized crystal.

It promises to be the data storing system of the future. Hence holographic storage system has the potential to became the next storage generation over conventional storage system.

Introduction

Holographic memory is a three-dimensional data storage system that can store information at high density inside the crystal or photopolymer.

It is a memory that can store information in the form of holographic image (hologram)

Like other media, holographic media is divided into write once (where the storage medium undergoes some irreversible change), and rewritable media (where the change is reversible).

What is Holographic Memory?

Holographic Versatile DiscHolographic Versatile Disc

These discs have the capacity to hold up to 3.9 terabyte (TB) of information, which is approximately 6,000 times the capacity of a CD-ROM, 830 times the capacity of a DVD, 160 times the capacity of single-layer Blu-ray-Discs, and about 8 times the capacity of standard computer hard drives as of 2007.

The HVD also has a transfer rate of 1gigabyte/s

COMPONENTSMost holographic storage systems contain

some components basic to the setup. These are :- a) Laser Beam b) Beam Splitters to split the Laser Beam c) Mirrors to direct the Laser Beam d) A liquid crystal Display panel(SLM) e) Lenses to focus the Laser Beam f) Recording Material g) CCD cameras

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Holographic Versatile Disc structure1. Green writing/reading laser

(532 nm) 2. Red positioning/addressing

laser (650 nm)3. Hologram (data)4. Polycarbon layer5. Photo polymeric layer (data-

containing layer)6. Distance layers7. Dichroic layer (reflecting

green light)8. Aluminum reflective layer

(reflecting red light)9. Transparent base

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The HVD System: Writing Data

When the blue-argon laser is focused ,a beam splitter splits it into two beams a reference beam and a signal beam .

The signal beam passes through a SLM where digital information, organized in a page like format of ones and zeroes, is modulated onto the signal beam as a two dimensional pattern of brightness and darkness .

When the two beams meet, the interference pattern that is created stores the data that is carried by the signal beam on to the surface of the holographic material as a hologram.

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The HVD System: Reading Data

In order to retrieve and reconstruct the holographic page of data stored in the crystal, the reference beam is shined into the crystal at exactly the same angle at which it entered to store that page of data.

Technology Comparison

Data are recorded on to the surface as bit by bit in CD/DVD System

1 Bit Data

SurfaceRecording Layer

Substrate

Conventional Optical Disc

Page Data

Volumetric RecordingLayer

Page data are recorded into the volumetric recording layer in Holographic recording

HVD

~1μm

TM

HVD Compares With Other HVD Compares With Other Storage DeviceStorage Device

  Blu-ray HD-DVD HVD

Initial cost for recordable disc

Approx. $18 Approx. $10 Approx. $120

Initial cost for recorder/player

Approx. $2,000

Approx. $2,000

Approx. $3,000

Initial storage capacity

54 GB 30 GB 300 GB (max 3.9 TB)

Read/write speed

36.5 Mbps 36.5 Mbps 1 Gbps

Capacity:700 mb Capacity: 30-50GbCapacity:1-4TBCapacity:4.7Gb

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ADVANTAGES Resistance to damage - If some parts of the

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.

Fault and Damage Tolerance.

The HVD also has a transfer rate of 1 gigabit/s.

While reading a page the entire page of data can be retrieved quickly and at one time .

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LIMITATIONS AND CHALLENGESIt is very difficult to arrange all of those

components like CCD camera , SLM arrays and beam steering devices.

Needs good recordings sensitive material to allow high data transfer rate.

If too many pages are stored in one crystal, the strength of each hologram gets diminished.

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APPLICATIONS

A) Petaflop Computing

B) Data Mining

C) Future Computing System

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CONCLUSION  

The future of holographic memory is very promising. The holographic storage provide 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.

 But even then the holographic way of storing data is still at the base 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 Experienences.

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