Thermal sensors operate primarily in the 8 to 14 micrometers wavelength but also in the 3 to 5 micrometers wavelength region of the spectrum. They produce diagnostic data that can aid in identifying materials by their thermal properties.

A thermal sensor detects radiant energy from a surface target, heated through radiation, convection, and conduction. A thermal image can be used to measure variations of temperature on an object or among objects or surfaces contained in an image.