Digital infrared thermometers are a temperature measuring device designed to measure the temperature of objects without making direct contact with them. That is because in fact, what they measure is the energy being radiated from the object. Every object whose temperature is higher than absolute zero (-273.15°) emits infrared energy. The hotter an object, the more infrared energy it emits.
The basic components of a digital infrared thermometer are a detector, an optical system, and a processing unit. The infrared energy emitted from the object to be measured is gathered by the optical system and then passed through to the detector which transforms the infrared energy into the electric signals. Then in the processing unit, the signals are changed into a temperature measurement.