Hologram

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					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


C. Shading and shadow


D. Texture gradient



-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


Resulting irradiance


                                   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
HUD(Head up display)
-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)
-Very prospective (asks high technology)


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

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