China infrared pyrometer consists of optical system, photodetector, signal amplifier and signal processing, display output and other parts. The optical system concentrates the infrared radiation energy of the target in its field of view, and the size of the field of view is determined by the optical parts of the thermometer and their positions. The infrared energy is focused on a photodetector and converted into a corresponding electrical signal. The signal is converted into the temperature value of the measured target after passing through the amplifier and signal processing circuit, and corrected according to the internal algorithm of the instrument and the target emissivity.

In nature, all objects with a temperature higher than absolute zero are constantly emitting infrared radiation energy to the surrounding space. The magnitude of an object's infrared radiation energy and its distribution by wavelength -- is closely related to its surface temperature. Therefore, by measuring the infrared energy radiated by the object itself, its surface temperature can be accurately determined, which is the objective basis on which infrared radiation temperature measurement is based.
The principle of China infrared pyrometer A black body is an idealized radiator that absorbs radiant energy of all wavelengths, has no reflection or transmission of energy, and has an emissivity of 1 on its surface. However, almost all actual objects in nature are not black bodies. In order to clarify and obtain the distribution law of infrared radiation, a suitable model must be selected in theoretical research, which is the quantized oscillator model of body cavity radiation proposed by Planck, thus The law of Planck's black-body radiation is derived, that is, the black-body spectral radiance expressed in wavelength, which is the starting point of all infrared radiation theories, so it is called the law of black-body radiation. The amount of radiation of all actual objects depends not only on the wavelength of radiation and the temperature of the object, but also on the type of material that constitutes the object, the preparation method, the thermal process, and the surface state and environmental conditions. Therefore, in order for the law of black body radiation to apply to all practical objects, a proportionality factor related to the properties of the material and the state of the surface must be introduced, namely the emissivity. This coefficient represents how close the thermal radiation of an actual object is to that of a black body, and has a value between zero and a value less than 1. According to the law of radiation, as long as the emissivity of the material is known, the infrared radiation characteristics of any object can be known. The main factors affecting the emissivity are: material type, surface roughness, physical and chemical structure and material thickness.
When measuring the temperature of the target with the China infrared pyrometer, the infrared radiation amount of the target in its wavelength range should be measured first, and then the temperature of the measured target should be calculated by the thermometer. Monochromatic thermometers are proportional to the amount of radiation in the band; bicolor thermometers are proportional to the ratio of the radiation in the two bands.