Night vision typically utilises two types of technology; thermal imaging (infrared) and image intensification or light enhancement, of which the latter is the most portable and therefore suitable for use in night vision goggles. Light Enhancement devices take the photons present in ambient light (typically moon or starlight) from the front lens, pushing them through a photocathode tube that converts them into electrons, a microchannel plate containing millions of photoelectric channels that multiplies them before bouncing them against a phosphor screen to convert back into the distinctive green-tinged image seen through the eyepiece.
Night vision was first developed for tanks by both sides in WWII before being made portable for sniper scopes in Vietnam and finally for goggles in the Fifties. Now used by military, police and rescue operations worldwide, devices are classified as Generations 0-3, with consumer (Gen 1) devices starting from as little as £200 to far more expensive and sophisticated Gen 3 devices for military and counter-surveillance purposes.
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