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History of Holography
Invented in 1948 by Dennis Gabor for usein electron microscopy, before the
invention of the laser Leith and Upatnieks (1962) applied laser
light to holography and introduced an
important off-axis technique
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Holography:Do you see what I see?
Shawn Kennedy
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Word Origin
Hologram is from the Greek word holos,meaning whole and gramma meaning
message.
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Coherent Light and a Solution
Coherent light is light that ismonochromatic and of a single wavelength
In 1960, the invention of the laserovercame the non-coherent light problem
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History Continued
In 1962 Emmett Leith and Juris Upatnieksrealized that holography could be used as
a 3-D visual medium From their work, they used a laser to
create the first hologram in history, that ofa toy train and bird
This type of hologram required laser lightto be viewed, though.
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White Light and High Speed
Objects In 1962 Dr. Uri Denisyuk of the former
U.S.S.R. developed a white light reflection
hologram, which could be viewed in lightfrom a normal incandescent bulb.
In 1960, with the invention of the pulsed-
ruby laser, holograms of high speedobjects was made possible
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Pulsed-Laser Holography
Laser system emits a very powerful burstof light that lasts only a few nanoseconds,
which effectively freezes movement Enables a hologram to be made of a
human
The first hologram of a person was madein 1967
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How Holograms are Made
Need a laser, lenses, mirror, photographicfilm, and an object
The laser light is separated into twobeams, reference beam and object beam
Reference beam enlarged and aimed at a
piece of holographic film
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Making Holograms
Object beam directed at subject to berecorded and expanded to illuminate
subject Object beam reflects off of object and
meets reference beam at film
Produces interference pattern which isrecorded
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Making Holograms Cont.
Film is developed
Hologram illuminated at same angle as
reference beam during original exposureto reveal holographic image
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Applications of Holography
Design of containersto hold nuclear
materials Credit cards carry
monetary value
Supermarketscanners
Optical Computers
Improve design ofaircraft wings andturbine blades
Used in aircraftheads-up display
Art
Archival Recording offragile museumartifacts
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Holography in the Future
Medical Purposes
Gaming Systems
Personal Defense
Computers
Artwork Amusement Park Rides
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Holography goes Hollywood
Holodeck from Star Trek Holodeck Clip
Star Wars Chess Game
Body Double in Total Recall
The Wizard in Wizard of Oz
http://www.geocities.com/Hollywood/Studio/1164/home288.ramhttp://calvinzone.50megs.com/videos/wookiewin.movhttp://calvinzone.50megs.com/videos/wookiewin.movhttp://www.geocities.com/Hollywood/Studio/1164/home288.ram8/2/2019 Holography Slids
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Conventional vs. Holographic
photography Hologram:
Converts phase information into amplitude
information (in-phase - maximum amplitude, out-of-phase minimum amplitude)
Interfere wavefront of light from a scene with areference wave
The hologram is a complex interference pattern ofmicroscopically spaced fringes
holos Greek for whole message
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Hologram of a point source
Construction of the hologram of a point source
Any object can be represented as a collection of points
Reference wave -plane
Photosensitive plate1. Records
interferencepattern (linearresponse)
2. Emulsion has
small grainstructure ()
Object wave - spherical
Photographic plate
x
z
y
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Point object hologram construction:
Intensity distribution on plate Reference wave
Object wave
Intensity distribution on plate
ROORRROOROyxI
zyxrwhere
oeezyxozyxO
reezyxrzyxR
ikrzyxi
ikzzyxi
****2
222
),,(
),,(
),(
),,(),,(
),,(),,(
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Hologram construction
)cos(2),(
0
)cos(2),,(
22
22
krororyxI
planefilmz
ororzyxI
Maxima for kr=2m or r=m
i.e. if the OPL difference OZ OP is an integral number of wavelengths, thereferencebeam arrives at P in step with the scattered (i.e. object) beam.
Gabor zone plate
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Hologram
When developed the photographic plate will havea transmittance which depends on the intensity
distribution in the recorded plate
tb backgrond transmittance due to |R|2 term
B parameter which is a function of therecording an developing process
)(**2 ORROOBtt b
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Hologram reconstruction
When illuminated by a coherent wave, A(x,y), known asthe reconstruction wave, the optical field emerging fromthe transparency is,
i.e. a superposition of 4 waves
If A(x,y)=R(x,y), i.e. reconstruction and reference wavesare identical,
ORBOBRRBOOttyxR
ABORRABOABOOAttyxA
bp
bp
2*2*
***
)(),(
),(
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Hologram reconstruction
Three terms in the reconstructed wave
ORBOBRRBOOttyxR bp2*2*
)(),(
Direct waveidentical to
reference waveexcept for an
overall change inamplitude
Object waveidentical to object
wave except for achange in intensity
Conjugate wave complexconjugate ofobject wave
displaced by aphase angle 2
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Hologram reconstruction Three terms in the reconstructed wave of
the point hologram
ikrikrkziikz
bp erBeBeeoBttyxR
222
)(),(
Direct waveidentical to
reference wave(propagates
along z) exceptfor an overall
change inamplitude
Object waveSpherical wave
except for achange in intensity
B|r|2i.e. reconstructed wavefront
Conjugate wavespherical wave
collapsing to a pointat a distance z to theright of the hologram
-a real image- displaced by aphase angle 2kz
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Hologram :
Direct, object and conjugate waves Direct wave: corresponds to zeroth order grating
diffraction pattern Object wave: gives virtual image of the object
(reconstructs object wavefront) first orderdiffraction
Conjugate wave: conjugate point, real image(not useful since image is inside-out due to
negative phase angle) first order diffraction In general, we wish to view only the object wave
the other waves just confuse the issue
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Off-axis- Direct, object and conjugate waves
Virtual image
Real image
Direct wave
Objectwave
Conjugate
wave
Reference wave
Use an off-axis system to record the hologram, ensuring separation of the three waves on reconstruction
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Transmission hologram: reference and object wavestraverse the film from the same side
Reflection hologram: reference and object waves
traverse the emulsion from opposite sides
HologramReflection vs. Transmission
View in Transmission View in reflection
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Hologram: Some Applications
Microscopy M = r/s Increase magnification by viewing hologram with longer
wavelength Produce hologram with x-ray laser, when viewed with visible
light M ~ 106 3-d images of microscopic objects DNA, viruses
Interferometry Small changes in OPL can be measured by viewing the direct
image of the object and the holographic image (interference
pattern produce finges l) E.g. stress points, wings of fruit fly in motion, compression wavesaround a speeding bullet, convection currents around a hotfilament
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