HDSS ppt

Holographic Data Storage System

Presented ByAnoop Nair

B.Tech, 8th SemComputer Science

Seminar on

Holographic datastorage

₪ It is a memory that can store information in form of holographic image.

₪ As computer systems continue to become faster, they will need a way to access larger amounts of data in shorter periods of time.

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

₪ Hence holographic storage system has the potential to became the next storage generation over conventional storage system.

INTRODUCTION TO HOLOGRAPHIC MEMORY

₪ Storage Density media stores data in whole volume

₪ Speed parses many bits at once

₪ Reliability Good shelf life High number of write cycles

FEATURES

A BRIEF HISTORY

₪ More than 30 years of research and development. scientist Pieter J. van Heerden first proposed the idea of holographic (three-dimensional) storage in the early 1960s.

₪ Early HDSS (Holographic Data Storage System) had capacity of 125 GB and transfer rate of about 40 MB/sec.

₪ When HDSS was first proposed the components for constructing was very expensive and large.

₪ The researchers are quite confident that this technology would be widely used in some years.

TYPES OF HOLOGRAMS

₪ Transmission HologramCan be used to store dataUses coherent light

₪ Reflection HologramThe kind you find on credit cardsUses white light

HOLOGRAPHY VS PHOTOGRAPHY

₪ Black and white photograph Intensity

₪ Color photograph Intensity and wavelength

₪ Hologram Intensity, phase, and sometimes wavelength

BASIC COMPONENTS

₪ Blue-green argon laser

₪ Beam-splitters

₪ Mirrors to direct the laser beams

₪ LCD panel (Spatial Light Modulator)

₪ Lenses to focus the laser beams

₪ Lithium-Niobate crystals or photopolymer

₪ Charge –coupled device (CCD) camera

WORKING PRINCIPLE

₪ Blue-green argon laser is fired.

₪ Beam-splitter creates two beams.

₪ One beam ,signal beam will go straight bounce off one mirror

and travel through SLM.

₪ SLM is a LCD that show pages of raw binary data.

₪ The information from binary code is carried by signal beam

around the light sensitive lithium–niobate crystal.

₪ 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 signal beam.

₪ This is a hologram.

WORKING PRINCIPLE (cntd….)

Beam Splitte

r

Object

Beam

Mirror

Mirror

Lens

Object

Plate

Hol

der

Mirror

Lens

Inte

rfere

nc

e Patte

rn

Reference Beam

CREATING HOLOGRAM

LASER

PATTERN LEFT ON MEDIA

RECONSTRUCTING THE IMAGE

Hologram3- Dimensional

image seen as suspended in space behind the hologram

Coherent light of laser is required to see this kind of hologram sharply. It can be viewed with a filtered spectral source but will not be as resolved

ACTUAL DESIGN

OPTICAL DISC TECHNOLOGY

0.7 GB 9 GB 30~50 GB

What is next ?

Holographic VersatileDisc

₪ Holographic Versatile Disc (HVD) is an optical disc technology still in the research stage which would hold up to 3.9 terabyte (TB) of information.

₪ It employs a technique known as collinear holography, whereby two lasers, one red and one blue-green, are collimated in a single beam.

₪ The blue-green laser reads data encoded as laser interference fringes from a holographic layer near the top of the disc while the red laser is used as the reference beam and to read servo information from a regular CD-style aluminum layer near the bottom.

HOLOGRAPHIC VERSATILE DISC

HOLOGRAPHIC 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.

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

TECHNOLOGY COMPARISON

1. Green writing/reading laser (532nm)

2. Reference laser (650nm)

3. Hologram (data)

4. Polycarbon layer

5. Photo polymeric layer (data containing layer)

6. Distance layers

7. Dichronic layers (reflecting green light)

8. Aluminium reflective layer (reflecting red light)

9. Transparent base

HOLOGRAPHIC VERSATILE DISC STRUCTURE

1 2

3

4

5

6

7

8

9

WORKING PRINCIPLE OF HVD

₪ HVD uses a technology called 'collinear holography,' in which two laser rays, one blue-green and one red, are collimated into a single beam..

₪ The blue-green laser reads data encoded as laser interference fringes from a holographic layer near the top of the disc while the red laser is used as the reference beam and to read servo information from a regular CD-style aluminium layer near the bottom.

₪ Servo information is used to monitor the position of the read head over the disc, similar to the head, track, and sector information on a conventional hard disk drive.

Recording Process

Media

Lens

SLM

Reference Pattern

Information Pattern

COLLINEAR HOLOGRAPHY

Reconstructing Process

Media

Reconstructed

SLM

Beam Splitter

Lens

Reference Pattern

Reflective Layer

COLLINEAR HOLOGRAPHY

ADVANTAGES OF HVD

₪ 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.

₪ 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 48 times the capacity of standard computer hard drives.

₪ 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.

LIMITATIONS OF HVD

₪ Angle at which the second ,reference beam is focused on the crystal to a page of data must match the original reference beam exactly without deviation

₪ Too many pages stored in one crystal, diminishes the strength of hologram

₪ 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 back ground from the other holograms stored around it

₪ It requires lens system for imaging the signal from the SLM to the detector array or for steering the angle of the reference beam

₪ The laser must have sufficient power at the required wavelength

CONCLUSION

₪ HVD will soon replace previous DVDs.

₪ It is currently supported by more than 170 of the world's leading consumer electronics, personal computer, recording media, video game and music companies.

₪ The format also has broad support from the major movie studios as a successor to today's DVD format.

Thank You