An infrared thermometer is a thermometer whichinfers temperature from a portion of the thermalradiation sometimes called black-body radiationemitted by the obiect being measured3. Principle. An infrared thermometer is a device thatmeasures the infrared radiation-a type ofelectromagnetic radiation below the visiblespectrum of light-emitted by an object. The most basic design of infrared thermometers consists of a ens to focus the infrared thermaradiation onto a detector. which converts theradiant energy into an electric signal. This configuration facilitates temperature measurement from a distance. without the needfor contact with the object to be measured.