Transcript Seminar on Holography

8-Apr-16
www.fakengineer.com
OUT LINES
1.INTRODUCTION
2.CONCEPT OF HOLOGRAM
3.REQUIREMENTS FOR HOLOGRAPHY
4.DIFFERENCE BETWEEN PHOTOGRAPHY & HOLOGRAPHY
5.REDUNDANCY OF HOLOGRAM
6.METHOD OF STORING DATA
7.METHOD OF RETRIVING DATA
8.ADVANTAGES AND CHALLENGES
9.LATEST REASERACH ON HOLOGRAPHIC STORAGE
Holography is the new resolution in the
stroage method of today.It is
an advanced Optical stroage device.
HOLOGRAM CONCEPT
• Holography is a method of lenses
photography in which the wave field of
light scattered by an object is recorded in
a place as an interface pattern.
REQUIREMENTS FOR
HOLOGRAPHY
• There must be specifically two beams
incident on the plate.
•
1-The reference beam
.
2- The object beam
The two beams are required to form the
interface pattern.
The other specially property of light used in
holography is that it must be
Coherent.
The Difference Between Photography And Holography
Photographic
Holographic
Light
Lasers
Point To Point
Redundancy
Surface
Volume
MATERIALS REQUIRED
The practical concern relater to holographic
recording material include:The recording resolution.
• Material sensitive as a function of optical
wave length.
• The processing steps requires developing
of the hologram.
REQUIREMENT:SLM (SPATIAL LIGHT MODULATOR)
CCD CAMERA
BEAM SPLITTER
SLM :It is a device that manipulate the amplitude and
phase of a beam of light at different point of
space. An SLM for a holographic storage need
only be binary.
What is necessary ,however ,is a high contrast
and rapid switching between on and off states to
enable clear distinction between the brightness
and darkness pattern.
CCD CAMERA:The main function of the CCD( Charge
couple device ) device camera is
interpreting the reconstructing data page
and forward the digital information to a
computer.
BEAM SPLITTER
• The beam splitter, which is used to split
the original laser beam of light
Holography: Basic Principle
Mirror
Mirro
r
Laser
Lens
Object Beam
Object
Mirro
r
Lens
Recording Plate
Reference Beam
What Will Be The Next Logical Step In Computer Storage ?
?
Random Access
Serial Access
•Hard Disk
•Floppy Disk
•PCMCIA
Advantages:
Magnetic
- Faster than tape
- Allows direct access to data
Disadvantages: - Performance relies on speed of
mechanical heads
- Neither fault nor damage resistant
•CD-ROM
•Magneto-Optical Disk
Advantages:
Optical
-More data capacity than magnetic disk
-High quality storage of sound and
images
Disadvantages: -Data capacity is small for video
-Limited Data densities
Interference Patterns
Wave A
Two crests coincideConstructive interference
Crest of A concides with
trough of B-Destructive
intererence
White Screen
Wave B
Basic Principle For Data Storage
page mirror
mirror
recording
medium
laser
beam splitter
read/write
shutter
transform
spatial-light lens
modulator
Basic Holographic Storage System
detector
array
imaging lens
Holographic Storage Device
A Holographic Storage Device Is A Page Oriented Device
That Writes And Reads Data, Represented As A Two
Dimensional Array Of Spot Called A Page. Multiple Pages
Are Multiplexed Holographically To Create A Stack Of
Pages, All In The Space Normally Required To Store A
Single Two Dimensional Image.
Stack site: 1 mm2
3000 stacks
( 1 gigabyte)
40 pages per stack
(320 Kbytes)
64K bits per page
Multimedia Floppy Organization
Comparative Table
Holographic
(Tamarack)
CD-ROM
(NEC 3X)
Magnetic
Disk (Sony)
Drive Cost (MB)
$0.70
$0.84
$5.35
Media Cost/MB
$0.01
$0.002
$0.14
Capacity (GB)
1.0
0.14
Average Access
Time (msec)
32
0.6
5
195
Media Size
2.5”
4.7”
300
3.5”/5.25
Storage Capacity Chart
12000
10000
8000
MAGN. DISK
OPTIC. DISK
HOLO. DISK
6000
4000
2000
Year
0
1993
1995
1998
A Holographic Disk can:
•Store information throughout the whole volume
of the medium instead of just the surface as with
other storage technologies.
•Uses fewer or no moving parts at all, thus allowing
greater data processing speeds.
•Hold more information than 100 compact disks of
the same diameter
•Can read 64,000 bits at one time, compared to to just
one or two bits with magnetic storage.
•Provides unique robustness and error insensitivity
Applications
Video-On-Demand
Multimedia
Portable Computing
Consumer Audio/Video
METHOD OF STORING DATA
– When the blue-argon laser is focused ,a beam
splitter splits it into two parts,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 .
– This signal beam is purified using different crystals
(normally , light sensitivity Lithium Niobate crystal,
through some systems use a photopolymer in the
place of the crystal ).
contd.
When the signal beam and the reference beam
meet, the reference pattern created stores the
data that is carried by the signal beam on to the
surface of the holographic material as a
hologram.
Different data pages are recorded over the
surface depending on the angle at which the
reference beam meets the signal beam.
METHOD OF RETRIVING DATA
• To retrieve data, the reference beam is
focused on the hologram at a particular
angle ; this will retrieve the modulated
data stored at the same angle of
interference
• .To read the page ,one need to pass it
thorough detector and then through CCD
camera, which will project the data on to
the display panel.
ADVANTAGES OVER OTHER CONVENTIONAL METHOD
.Large data density
A holography disk can store information
through the whole volume of the medium
Instead of just the surface as with other
storage technologies.
.Better reliability
Uses fewer or no moving part at all, thus
allowing greater data processing speeds.
Cont.
Large capacity
Can hold information more than that of 100 compact
disks of the same diameter.
.High data transfer rate and short access time
Can read 64,000 bits of information at a time,
compared to just one or two bits with magnetic storage.
Fault and damage tolerance
Provides unique robustness and error sensitivity.
MAJOR CHALLENGES
.Integration of the state-of-art-components:Still is very difficult to arrange all of those components like CCD
camera , SLM arrays and beam steering devices.
.Lack of suitable medium:Needs good recordings sensitive material to allow high data transfer
rate.
High optical quality to reading of data without degrading.
Be able to retain data content without loss in the long term.
Versatility to allow update of information as incase of rewritable
systems.
LATEST RESEARCH ON
HOLOGRAPHY STORAGE
• Small farms like Optiteck and Tamarack are the leading
research organization in this field.
• Also large organizations like IBM ,DARPA , LUCENT
etc. have been investing lots of money in the research
field.
• Also great process has been made in other related key
components of a holographic storage device.
• It is expected that the first holographic device will be in
the market within one or two year .
.