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solarguy

01/02/11 12:00 PM

#2771 RE: klangky #2701

Sorry if my post didn't seem to make sense. Let me try again.
There are at least two types of night vision devices. One type works nominally in the visible spectrum and "amplifies" ambient light from sources like moonlight or starlight. These are the type we often see being used by military helicopter pilots and snipers.

Another type of night vision device is commonly referred to as a FLIR (Forward Looking Infared Red) device. These devices work by receiving and detecting infrared radiation emitted by "warm" objects (often called blackbody radiation) and converting the infrared image to a visible display. There is no need for a light source (star or moon) or artificial infrared source. FLIR type devices are used for air-to-ground weapon guidance as well as satellite recon and weather.

I am not sure where this is going but if your point was that the sun emits electromagnetic radiation in the infrared spectrum then that is self evident from the warmth that we all feel when in direct sunlight. The solar spectrum is like that of a blackbody at about 6000 degrees Kelvin. It peaks conveniently in the visible spectrum has a small tail in the UV and a longer one in the infrared. Much of the infrared energy is absorbed in the atmosphere by various absorption bands (H2O, CO2, etc.).

My point is simply that if the Solar Window is transparent then it is simply not absorbing and converting the solar radiation that peaks in the visible spectrum.