Night vision
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Night vision is the ability to see in low-light conditions, either naturally with scotopic vision or through a night-vision device. Night vision requires both sufficient spectral range and sufficient
Two American soldiers pictured during the 2003 invasion of Iraq seen through an image intensifier.
The pupil of the eye dilates in the dark to enhance night vision. Shown here is a pupil of an adult naturally dilated to 9 mm in diameter in mesopic light levels. The average human eye is not able to dilate to this extent without the use of mydriatics.
USMC M3 Sniperscope assembled on a M3 Carbine. Introduced during the Korean War, it was an early active infrared night vision equipment powered by a large 12 volt battery that was carried in a rubberized canvas backpack.
An M60 tank with an infrared searchlight mounted on the cannon.
Adaptation (eye)
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In visual physiology, adaptation is the ability of the retina of the eye to adjust to various levels of light. Natural night vision, or scotopic vision, is the ability to see under low-light condition
The pupillary light reflex is a quick but minor mechanism of adaptation
Reflection of camera flash from tapetum lucidum
Extreme red light used on a ship's bridge at night to aid dark adaptation of the crew's eyes
Astronomer preserves night vision