# Hologram

Document Sample

```					3D display

Hologram

Lee. S. R.
Outline

-Introduction
-Theoretical concepts
-Recent application
-Conclusion
-Introduction-

Diverse methods

<3D glasses>       <Non-glasses>       <Hologram>
2D display                                                                                           3D display
Anarchrome          Lenticular          Holography
Polarization        Pulfrich eff

Holography
-Better complete 3D picture
-High redundancy

Astronomy field : galaxy modeling     Entertainment
Medical field : modeling for human’s organs
Ice breaking
How do eyes cognize the depth of virtual image as 3D picture?

Psychological factors help our eyes to sense depth of image (LOST)

A. Linear perspective

B. Overlapping

-Limit
However, all of these is ‘NOT’ real 3D image, but just 2D image which
helps observer to sense depth of image.
Physical factors actually stimulate our eyes to sense 3D effect

Factors are as follows : ABC

A. Accommodation
As the object of location from observer changes, crystalline lens(eye
lens) enables eyes to sense the depth of image by controlling curvature
of eye lens.

B. Binocular disparity
Owing to gap between two eyes, people can get a different image from
same object.

C. Convergence
The angle which two iris make will be different depending on the
distance
-Theoretical concepts-

Hologram means ‘complete picture’

Key point as follows

Light source : Laser , coherence !!

Picture (2D) : Only amplitude
Hologram (3D) : Not only amplitude but also phase

Recording media
Amplitude (Brightness)
Phase (Distance, i.e. perspective)

Main principle as follows
Interference + Diffraction → Complete 3D picture
Schematic diagram of traditional 3D hologram
Approach for holography in terms of wave optics

[1st step: Interference phenomenon] Recording process
coherent reference wave + object wave (wave scattered from object)
→ Interference pattern

A
θ
B

Fig2. Interference pattern on sensitive film
At (b), the relative phase(Φ)
2 x sin                 x                 
 ( x)                                      sin  
                 2 AB    ,
AB
1                1
E  2 E 0 cos  sin( wt  kx   )
2                2
cn 0 2
 I ( x)        E
2
1               1 2               2 1
 c 0 (2 E0 cos  )  2c 0 E0 cos 
2

2               2                   2
[2nd step: Diffraction phenomenon] Reconstruction
process

Object wave
EO  E0O ( x, y ) cos[2 t   ( x, y )]
Amplitude- and phase- modulated carrier wave

2    2
E0 B E0O
I ( x, y )  ( EB  EO )   2
          E0 B E0O cos(  0 )
2    2
The amplitude transmission profile of the processed hologram can be made
proportional to I(x,y).
[Final step: Superposition] Hologram

Reference wave (ER)+ Diffracted wave by fringe I(x,y)
→ Final emerging wave(EF) forms 3D hologram
* ‘Fringe’ serves as if it is slit.

The final emerging wave, EF(x,y) is proportional to the product I(x,y)ER(x,y)

ER ( x, y )  E0 R cos[2 t   ( x, y )]   :reconstructing wave

EF ( x, y )  I ( x, y ) E R ( x , y )
1
 E0 R ( E0 B  E0O ) cos[2 t   ( x, y )] 
2     2

2
1                                       1
E0 R E0 B E0O cos(2 t  2  O )  E0 R E0 B E0O cos(2 t  O )
2                                       2

Note that final emerging wave has both of component
-amplitude and phase- information of object!
Photo plate

How can be information of light encoded in photo plate?

Interference pattern can be fringe pattern.

Photo sensitive film materials

Material                              Properties
Silver halide                         High resolution
Economic
Easy to work

DCG(Dechromated gelatin)              High efficiency of diffration
Long process time
Violet beam
Photopolymer                          Plastic composite
No chemical interaction
Application
-Transparent instrument cluster
-Used in a various field such as car,
airplane, and ship..

Security sensor & system

-ticket, document
-credit card..etc

Holographic Disk
-3 dimensional information –mass storage
-Use polymer as recording media
-Efficiency and portable (Stamp-sized disk can have capacity
as much as 150GB
Conclusion

Holography technology is based on principle of interference and diffraction.

Property
-Complete realization of 3D display without tools-glasses..
-Possible to get higher resolution than any other 3D display methods
(The diffracted wave contains amplitude as well as phase information)

Application field
-Memory : disk
-Screen : HUD
-Security : Holographic sticker and design
Thank you

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 views: 5 posted: 11/19/2012 language: English pages: 14