How does a Infrared Thermometer(IRT) works?

Working principle of IRT:

Each body above absolute temperature emits electromagnetic radiation, which is related to the actual temperature of the body. A part of this radiation is the infrared radiation, which can be used to measure the intrinsic temperature. This radiation penetrates through the atmosphere and which is focused using a lens to the detector of the IRT instrument.

Construction and operation:

The beam is focused to the infrared detector. The detector generates corresponding electrical signal then it is conditioned and processed to convert it into the digital signal. Digital signal processing transforms the signal into an output value proportional to the object temperature. The result value is either given to the display device or to processing.

In order to compensate influences from the surroundings, a second detector catches the temperature of the measuring device and of his optical channel, respectively. Consequently, the temperature of the measuring object is read and the output is linearised according to it.


  • Temperature measurements of moving or overheated objects and of objects in hazardous surroundings

  • Very fast response and exposure times

  • Measurement without interreaction, no influence on the measuring object

  • Non-destructive measurement

  • Long lasting measurement, no mechanical wear