Unformatted text preview: that more
of them are at higher energy levels (excited state) than are at lower
energy levels. When an excited electron drops back to a lower
energy level, a photon of a particular wavelength is released. This
photon stimulates other electrons to emit photons. All these photons
are in phase. Holograms
As with any type of wave, light waves can interfere with one another.
The interference of two or more waves will carry the whole information
about all the waves. It is on this basis that holograms work.
Holograms make use of lasers and they work in the following fashion:
(Explanation on next slide.)
Beam Splitter Laser Object Beam
Beam Spreader Object Reference Reference Beam Mirror Light wave interference
Film Plate Holograms (cont.)
As the laser hits the beam splitter, it is split in two. The object beam heads
towards the object of interest, while the reference beam heads toward a
mirror. The beams are identical until the object beam shines on the object.
There some of the light is absorbed; some is reflected toward the film. After
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