| 摘要 |
A hologram is generated from which an image may be reconstructed of a distant object. This image has a brightness which is modulated so that areas or fringes of maximum or minimum brightness represent contours of equal range. This contour pattern is obtained when the beam of light used to record the hologram has a coherence function which is periodic with differences in path length. This periodic coherence function in turn is obtained by periodically modulating a coherent beam of radiant energy. The modulation may be either amplitude or phase modulations, the latter including frequency modulation, or a combination thereof. Since the optical path difference depends directly on the range to different points on the object, the resulting contour pattern directly reflects these differences in length. The hologram may be made by using brief pulses of the light beam, the light being pulsed by pulsing the laser, the hologram, or else the object or the reference beams.
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