Analysis of Main Factors Affecting Emissivity of Infrared Thermometers
A blackbody is an idealized radiator that absorbs radiation energy of all wavelengths without any reflection or transmission of energy, and its surface emissivity is 1.
It should be pointed out that there is no true blackbody in nature, but in order to clarify and obtain the distribution pattern of infrared radiation, appropriate models must be selected in theoretical research;
This is the quantized oscillator model of body cavity radiation proposed by Planck, which derived Planck's law of blackbody radiation;
The blackbody spectral radiance expressed in wavelength is the starting point of all infrared radiation theories, hence it is called the blackbody radiation law.
The influence of object emissivity on radiation temperature measurement: Almost all actual objects in nature are not blackbodies.
The radiation level of all actual objects depends not only on the radiation wavelength and temperature of the object, but also on factors such as the type of material, preparation method, thermal process, surface state, and environmental conditions that make up the object.
Therefore, in order to make the blackbody radiation law applicable to all practical objects, a proportionality coefficient related to material properties and surface states, namely emissivity, must be introduced.
This coefficient represents the degree to which the thermal radiation of an actual object is close to blackbody radiation, with values between zero and values less than 1.
According to the law of radiation, as long as the emissivity of a material is known, the infrared radiation characteristics of any object are known.
The main factors affecting emissivity include material type, surface roughness, physical and chemical structure, and material thickness.
When using an infrared radiation thermometer to measure the temperature of a target, the first step is to measure the infrared radiation of the target within its wavelength range, and then the temperature of the measured target is calculated by the infrared thermometer.
