Infrared thermography: principles and applications

All objects with surface temperatures above absolute zero emit electromagnetic radiation. In this paper we describe the physical principles that allow calculation of the surface temperatures of objects from the wavelength and intensity of electromagnetic radiation emitted in the infrared region of the spectrum (infrared thermography). This technique can be applied to measure the surface temperature of animals without the need for physical contact with them. Infrared thermography allows a direct measure of radiative heat transfer from animals. Convective heat transfer can also be calculated from the detailed information on body surface temperature. We describe some recent applications of infrared thermography to remote measurement of surface temperature which allow identification of the main sites of heat loss from mammals and birds.