Word: holograms
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Holography produces no familiar photographic negative or print. But when light is directed upon a holographic negative-or hologram-its smudgy and apparently meaningless patterns of concentric circles and parallel lines become a window through which a viewer sees the scene that was photographed. By moving his head from side to side, he can look through that window at different angles and change the perspective of the three-dimensional view; he can look around an object in the foreground to see what is behind it, just as if he were examining the actual scene...
...produce a hologram, light from a laser is split into two beams, one of which is directed by a mirror onto a sheet of photographic film. The other beam is used to illuminate the subject. When the laser light hits the subject, it is scattered by the irregular surface and reflected back toward the film. As a result, many of the reflected light waves are jumbled and out of phase both with each other and with the light from the undisturbed beam reflected by the mirror. When the light waves from subject and mirror are reunited at the surface...