Glossary of terms

Infrared thermal radiation is electromagnetic radiation emitted by every object above 0 Kelvin (–273 °C). The amount of radiation emitted depends on the temperature and the emissivity of the object.

The emissivity of an object depends on the material and the structure of its surface. This specifies how much infrared thermal radiation the object emits compared with an ideal radiant warmer (black body, emissivity ε = 1) and accordingly has a value between 0 and 1.

The reflected temperature is the thermal radiation that hits an object to be measured and is reflected by it. How much thermal radiation is reflected depends on the structure and material of the object to be measured (i.e. its reflectivity).
The reflected temperature must be taken into consideration when measuring the surface tempreature as otherwise the measuring result may be significantly distorted.