Thermal imaging is the use of cameras constructed with specialty sensors that "see" thermal energy emitted from an object. Thermal, or infrared energy, is light that is not visible to the human eye because its wavelength is too long to be detected. It's the part of the electromagnetic spectrum that we perceive as heat. Infrared allows us to see what our eyes can't.A thermal imaging camera produces images of invisible infrared or "heat" radiation. Based on temperature differences between objects, thermal imaging produces a clear image. It can see in total darkness, through fog, in the far distance or through smoke.