Infrared thermometers have the ability to measure temperature without physical contact. The ability to accomplish this is based on the fact that every object
emits radiant energy, and the intensity of this radiation is a function of its temperature. The infrared ther-mometer simply measures the intensity of radiation and thereby measures the temperature.
The following sections present the fundamentals of radiation physics upon which infrared thermometry is based. Several of the many ways of applying these
fundamentals to the practical methods of temperature measurement will be discussed.