Night vision goggles
soldiers pictured during the 2003 Iraq War
Night vison goggles are a type of eye-wear that allows one to see in the dark. They are most often used by the military. Night vision goggles are one of two types. One type of night vision goggles pick up any light in the given area and amplify it several thousand times. This type is commonly used for war reporting, tinting the picture green. The color green is chosen because the human eye is most sensitive and able to discern the most shades in that color. The other common type of night vision goggles are heat-sensing/infrared goggles. These show anything that emits normal heat radiation in the given area. There are currently goggles that combine both of these technologies to create images that are almost as clear as day. In addition to goggles, night vision technology is also used in rifle scopes, security cameras, binoculars, etc.
Night vision goggles work by the photo-electric effect. As a photon collides with a detector plate, multiple electrons are ejected from the metal that are then amplified by a series of electron ejections onto a phosphorus screen. The colour green is selected as it is the optimum luminosity for the human eye during night time.
See also
Night vision
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