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Holograms
Name: kolin
Status: N/a
Age: N/A
Location: N/A
Country: N/A
Date: Around 1993
Question:
How do holograms work?
Replies:
Most of the time we can ignore the wave nature of light, since it
basically travels in straight lines and obeys simple laws when passing through
lenses or with mirrors. However, when light is specially prepared (as in a
laser) the wave nature can be readily seen - for example, laser light passed
through a pair of slits will produce an "interference" pattern of alternating
dark and light areas as long as the slits are close enough together, and this
is very different from the straight line images you might expect. A hologram
is made by "interfering" in this sort of fashion, laser light that has been
reflected from a 3-dimensional object with light directly from the laser, or
reflected from a flat mirror. Because of the different distances traveled by
the light striking different parts of the object, the light waves arrive at
different parts of their cycle and combine or cancel out. This produces a
very complicated image, which can be recorded on film as a hologram, and
played back to produce something resembling the original 3-dimensional image
(played back by shining laser light through it in the other direction). The
details are pretty complicated, and I have always been amazed that it actually
works. People can now produce these interference patterns on the computer,
and generate a hologram that can be used to produce three-- dimensional images
that were designed on the computer.
Arthur Smith
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Update: June 2012
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