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What
Are Holograms?
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DEFINITION |
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HISTORY |
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Holography
was first invented and discovered by Hungarian physicist Dennis
Gabor in 1947. He later won the Nobel Prize for his discovery. |
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hologram
- (HOL-o-gram)
definition:
usually a three-dimensional image, produced by capturing a laser light interference
pattern on film. |
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The
word "hologram" is formed from two Greek words, holos (whole)
and gramma (message). |
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TECHNICAL
EXPLANATION |
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Holograms
are the perfect practical example of the "wave" nature of light. |
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While
we often think of light in terms of "photons," light is also a
"wave." The different colors of light that we see are actually
different wavelengths of the light: red is a longer, blue is shorter, and
green is in the middle. |
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Laser
light is used for holograms because it is a very pure source of light (only
one color, or wavelength) with very
orderly waves. When two beams of laser light come together, they
form an interference
pattern. This is the most basic form of a hologram. |
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Imagine
throwing a rock into a quiet lake. The ripple pattern is like the waves
that come from a laser. If you throw two rocks into the water, the two wave
patterns will collide in the middle, creating some areas that have waves
twice as big and some areas where the waves cancel each other out. This
is interference. |
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To
make a hologram, laser light is split into two different beams.
One is reflected off of an object and then scatters to the film, while the
other beam goes directly to the film. The two beams meet at the film causing
an interference pattern of microscopic bright and dark lines. The film captures
this pattern, which is the hologram. |
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A
regular photograph is only two-dimensional (2D) because it only records
the INTENSITY of the light hitting the film, recording shades of brightness
and darkness. A hologram is three-dimensional (3D) because it records both
the INTENSITY and the DIRECTION of the light that hits the film. This additional
information is recorded in the interference pattern, and allows you to "look
around" the recorded object as if it were really there. |
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To
view
the hologram after it is developed (if you are using the Litiholo
"Instant Hologram" Film, there is no developing necessary), it
is placed back in its original position and illuminated with only one beam
coming directly from the laser. The recorded holographic interference pattern
will now diffract the laser light passing through it, creating a 3D image
of the original object as if it was still there. |
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Diffraction
is the bending of light due to a pattern of closely spaced lines. If you
look at the bottom of a CD or DVD disk, you will see a rainbow of colors.
This is because the tracks on the CD create microscopic lines that bend
(or diffract) the light into separate colors, much like a prism. |
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| a
division of Liti Holographics
| info@litiholo.com
| (757)873-6460
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