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Light enters the NVD (Night Vision Device) through an objective lens and strikes a photo cathode powered by a high-energy charge from the power supply. The energy charge accelerates across a vacuum inside the intensifier and strikes a phosphor screen (like a TV screen) where the image is focused. The eyepiece magnifies the image.
Night Vision Device phosphor screens are purposefully colored green because the human eye can differentiate more shades of green than other phosphor colors. Like cameras, NVDs have various image magnifications. The distance at which a human-sized figure can be clearly recognized under normal conditions (moon and star light, with no haze or fog) depends on both the magnifying power of the objective lens and the strength of the image intensifier. The maximum viewing range is 100 feet to 400 feet. |
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