How do infrared cameras actually measure temperature?
The principles of infrared technology are rooted in Plank’s Law, which describes the way that objects emit electromagnetic energy as a function of temperature and wavelength. However, in practice, radiometric (i.e., quantitative) IR temperature measurements are made by comparing the output (for example, a change in voltage or resistance) of a detector with a calibration table. Since the response from the detector is a function of many things (detector material, the electronics of the signal processing system, materials & coatings of the optics in the light path, etc.), the calibration table is unique to each system.
