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Physics, Astronomy & Cosmology
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11/05/2007 02:24:18 »
I have night vision (not infra red) on my camera's, and have used night vision binoculars, but how do they work?
Reply #1 on:
11/05/2007 04:14:06 »
Real nigh vision (the electronic ones) amplify the incoming light.
Not sure what they use these days - it could be just very sensitive CMOS light sensitive arrays - certainly that is all they could be using using for the camera. On the other hand, the camera is easier because you are only looking to capture a still image, and if you need to take a 3 minute exposure for a single frame, that is no problem. The binoculars are looking for a real time image, so you need to have the frame refresh about 60 times a second, so each image can only contain no more light than you were able to receive on the light sensitive detector within
of a second.
In the past, they tended to use a phosphor that emitted an electron upon receiving incoming light (like an old fashioned TV camera - opposite of the old CRT screens), but then either accelerated the electrons emitted from the surface with a high voltage, or passed them through thin tubes that would have that one electron knock more electrons off the side of the tube to create a cascade of electrons.