marcush. wrote:so it´s more likely it´s a minature Thermographic camera we might see here -sort of mikrobolometer sensor array with an optical lens in front giving real time surface temperature pictures
Quite.
You can't really use a photodetector for the temperature range involved, because you need a long enough wavelength to be usable and then you'd need to cool the detector to ridiculous levels. A midwave (3-5um) photodetector will be running 70-90 Kelvin and the camera will be around the size of a small shoe-box; it's not going to fit on a wing. The longer the wavelength, the lower the energy of the photons, and the more the signal will be overwhelmed by the thermal vibrations of the atoms in the detector material. Hence, you try to lower the thermal noise by cooling the detector. It does make for some pretty fancy cameras though. For example: a shortwave (0.9-1.7um) detector, cooled with liquid nitrogen, integrating 30 minutes for a single image to detect fabrication faults in integrated circuits.
Luckily, you can go to 8-13um and run an uncooled microbolometer in that range. It doesn't count incoming photons, but allows the incoming radiation to heat the pixels. The change in temperature changes the resistance of the pixel, which is then measured. The thermal calibration becomes a little trickier, because you need to compensate for the current temperature of the detector (and, ideally, the lens and any filters too). Running a current through the pixel to measure the resistance will also cause it to self-heat, so your detector will see the scene -and- itself. Both the dynamic range and the level of the readout will vary, but it's not rocket science to handle.
In addition, you'll be somewhat limited in framerate (say 50 to 100fps) because of the thermal time constant of the pixels. The pixels need some time to react to a change in incoming radiation. You could read them out faster, but you won't be getting any extra information, just using more power.
This is, of course, assuming it's a thermal camera at all :).