A night vision device (NVD) is an optical instrument that allows images to be produced in levels of light approaching total darkness. They are most often used by the military and law enforcement agencies, but are available to civilian users. The term usually refers to a complete unit, including an image intensifier tube, a protective and generally water-resistant housing, and some type of mounting system. Many NVDs also include sacrificial lenses, IR illuminators, and telescopic lenses.
Night vision devices were first used in World War II, and came into wide use during the Vietnam War. The technology has evolved greatly since their introduction, leading to several "generations" of night vision equipment with performance increasing and price decreasing. Another term is "night optical device" or NOD.
Read more about Night Vision Device: Generations, Figure of Merit, Other Technologies, Legality, US Patents
Famous quotes containing the words night, vision and/or device:
“When I lie down, I say, When shall I arise, and the night be gone? and I am full of tossings to and fro unto the dawning of the day.”
—Bible: Hebrew Job 7:4.
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The workers’ flats in fields of soya beans
Tower up like silver pencils, score on score.”
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—John Donne (1572–1631)