Eli5: how do thermal cameras capture heat without any physical contact
In: 4
Thermal infrared cameras are interesting. A lot of people have replied and said they work just like regular cameras. That is correct only for a small number of infrared cameras. A regular visible light camera directly converts photons into elections which it then counts. It is really hard to make a material which does this for thermal radiation. Instead thermal camera makers have two other tricks up there sleeves. The Pyroelectric effect, and microbolomeeters.
Pyroelectricity is the ability of certain materials to generate a temporary voltage when they are heated or cooled. This combined with a shutter so you can rapidly cycle the sensor between heating and cooling can result in a thermal image.
Microbolomeeters are essentially arrays of tiny resistors held in a vacuum chamber. As the thermal light strikes them they very slightly change resistance which can be used to make an image. These cameras are the most prevalent in the market because they are cheaper to make.
I can answer follow-ups in more detail if you are interested.
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