| 摘要 |
A search light employs variable polarization angles to enhance target identification. The search light shines a beam of light which may be directed across terrain. The beam of light is alternated in polarization angles at a rate of about five to twelve cycles per second. The alternating contrast in polarization angles produces flashing to an observer viewing certain targets struck by the beam of light. The flashing appears when striking man-made objects which tend to have a differential in polarized light between horizontal and vertical polarization. Natural objects do not appear to provide the flashing to the observer. The rotating polarization angles are accomplished in one instance by using a stationary polarizer and a liquid crystal retarder mounted in front of a light source. In another instance, the change in polarization angles is accomplished by rotating a polarizer in front of a light source. The light source may be infrared, visible or ultraviolet.
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