How does night vision work?

Night vision works differently depending upon the type of night vision being employed. Low-light imaging, thermal imaging and near infrared imaging are all types of night vision currently in use as of 2014.

Low-light imaging, the type of night vision most commonly used in night vision goggles or scopes, uses light amplification to allow improved sight. The available light is collected through a lens. The electrons from the light are then subjected to an electrical field in order to make them more energetic. The electrons are then projected onto a phosphor screen. A green screen is the most commonly used color, because the human eye can distinguish between more shades of green than any other hue.

Thermal imaging is another type of night vision. Thermal imaging works by collecting the radiation given off by all objects in the form of heat. Instead of improving visibility in low-light situations like low-light imaging, thermal imaging can be used in complete darkness. Most thermal imagers show a black-and-white image. In a black-and-white thermal image, black is typically the cold color, whereas white is hot. Some types of thermal imagers show a false color image, which allows for better distinction between objects.

Infrared imaging uses an infrared illuminator instead of visible light. A camera that has a receptor sensitive to infrared can then be used to view the scene.