In the field of measurement, "temperature" is one of the most commonly used physical parameters after "time". Based on the principles of Planck's and Boltzmann's laws of radiation, laser thermometers measure the temperature of the measured object by absorbing the infrared radiation emitted by it. So, how is non-contact temperature measurement achieved?

Any object with a temperature above absolute zero (0 K or -273.15°C) emits electromagnetic radiation from the surface, and the radiation is proportional to the object's inherent temperature. In this radiation, infrared radiation used to achieve temperature measurement is included. After the radiation penetrates the atmosphere, it is focused on the detector with the help of special lenses. The detector then generates an electrical signal proportional to this radiation. This signal is amplified and converted into an output signal proportional to the temperature of the object by undergoing continuous digital signal processing. As a result, the measured temperature value is shown on the display or output as a signal.

When using radiation to measure temperature, the emissivity ε (Epsilon) plays a crucial role. It shows the relationship between the radiation value of the actual object and the black body. A black body has an emissivity of 1 (maximum). However, there are not many objects that satisfy the ideal condition of a black body. When calibrating the sensor, the contact surface of the radiator (including the recommended wavelength: 0.99) is generally used.