Holography physics behind holograms
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Holography – Physics behind holograms. Leow S.T. Aloysius 3O3 (15). Introduction. Ever saw a Star Wars movie and wondered what is that green 3-D image of Yoda? This image is actually a hologram. Background information. Holography was invented in 1947 by Hungarian physicist Dennis Gabor

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Holography – Physics behind holograms

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Holography physics behind holograms

Holography – Physics behind holograms

Leow S.T. Aloysius 3O3 (15)


Introduction

Introduction

Ever saw a Star Wars movie and wondered what is that green 3-D image of Yoda?

This image is actually a hologram.


Background information

Background information

Holography was invented in 1947 by Hungarian physicist Dennis Gabor

Did not really advance until the invention of LASER in 1960

He received the Nobel Prize in physics in 1971


Holography

Holography

It is the process by which three-dimensional pictures can be stored and reproduced by laser light.

A hologram is therefore a record of an image as seen from many viewpoints.


Photography

Photography

What happens when a photo is taken:1) The shutter opens.

2) Light passes through a lens and hits the photographic emulsion on a piece of film.

3) Silver halide reacts with the light and records its amplitude as it reflects off of the scene

4) The shutter closes


Exactly what is a photograph

Exactly what is a photograph?

It is a point-to-point recording of the intensity of light rays that make up an image

Each point on the photograph records just the intensity of the light wave that illuminates that particular point.


Cont d

(cont’d)

When we develop the film and make a print of the picture, our brain interprets the light that reflects from the picture as a representation of the original image.


Light

Light

The wavelength affects the wave’s frequency.

This determines its color and is measured in cycles per second, or Hertz (Hz)


Different types of light

Different types of light

White light:

Contains different wavelengths traveling in different directions and different phase

LASER light:

Monochromatic ( has one wavelength and one color)

Waves are in phase


Why laser

Why LASER?

White light can be used to make or view photographs but a hologram requires the organized light of a LASER

Holograms record differences in both amplitude and the phase

The light has to start out with one wavelength and one phase in order for the film to record these difference.


Holography the transmission hologram

Holography – The Transmission Hologram

1) Light from the LASER is split to form object beam and reference beam.

2) Light from the object beam reflects off the object.

3)  The light from the object and the reference beam form an interference pattern on the film.


Viewing the transmission hologram

Viewing the Transmission Hologram

Shine the light of a LASER on the hologram, in the same orientation as the reference beam

Because both the phase and intensity are reproduced, the image appears three-dimensional

The eye is focused behind the film to see the image suspended in space.


Make your own hologram

Make your own hologram!

Things you need:

1) A LASER: Helium-Neon (HeNe) lasers are common in holography

2) Diverging Lenses

3) A beam splitter: Uses mirrors and prisms to spread a beam into two

4) Mirrors: To direct the beams of light to the correct location

5) Holographic film: To record light at high resolution


Setup

Setup

1) The laser points at the beam splitter, dividing the beam into two.

2) Mirrors are used to direct the beams to intended targets (eg. Make sure the object beam hits the object).

3) The two beams pass through diverging lenses and becomes a wide swath of light.


Cont d1

(cont’d)

4) The object beam reflects off the object, onto the holographic film.

5) The reference beam hits the holographic film without reflecting off anything but the mirror.


Uses of holography

Uses of Holography

A humorous video on the applications of holograms.


Cont d2

(cont’d)

Security

And many more…

Medical

Display

Holography


Holography in security

Holography in Security

The presence of holograms indicates the authenticity of these items

Security holograms are also being used in anti-counterfeiting, identification documents, including credit and phone cards, drivers licenses etc


Holography in entertainment

Holography in Entertainment

Various Hollywood movies, specially the science fiction films, have used holographic special effects. (eg. Star Wars, Star Trek)

Holograms are also used as promotional tools on records and CD covers.


Holography in medicine

Holography in Medicine

Holographic technique is also used in various medical applications. (eg. CAT scans, X-ray, MRI, Ultrasound)


References

References

http://science.howstuffworks.com/hologram.htm

http://www.fact-index.com/h/ho/holography.html

http://hyperphysics.phy-astr.gsu.edu/hbase/optmod/holog2.html

http://www.holo.com/holo//book/book.html#thholo

http://www.holoworld.com/holo/kids.html

http://www.hololight.net/holography.html

http://www.holography.ru/maineng.htm

http://www.holography.co.uk/questions/holuses.htm

http://www.wikipedia.org

http://www.google.com

http://www.hologramsuppliers.com/holograms-applications.html

http://silver.neep.wisc.edu/~lakes/hoAppl.html


Thank you

Thank you! 

Any questions?


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