The principle of infrared thermometer is to convert the radiation energy of infrared rays emitted by an object (such as steel) into an electrical signal. The radiant energy of infrared rays corresponds to the temperature of the object (e.g., steel), and the temperature of the object (e.g., steel) can be determined from the converted electrical signal. Infrared temperature measurement technology has evolved to the point where it is possible to scan a surface with thermal changes, determine its temperature distribution image, and quickly detect hidden temperature differences, called infrared thermography.

　　Infrared thermometry uses a point-by-point analysis, where the thermal radiation from a local area of an object is focused on a single detector, and the radiated power is converted to temperature by knowing the emissivity of the object. The external design and internal structure of infrared thermometers differ due to different objects, measurement ranges and applications, but the basic structure is similar and mainly includes optical system, photoelectric detector, signal amplifier, signal processing, display and output. The infrared radiation is emitted from the radiator. After entering the optical system, the infrared radiation is modulated by the modulator into transmissive radiation, and the transmissive radiation is converted into a corresponding electrical signal by the detector. The signal is converted into the temperature value of the measured target after passing through an amplifier and a signal processing circuit, corrected according to the algorithm in the instrument and the emissivity of the target.

　　Pyrometers are used in the steel industry because the products are in motion and have high temperatures. A common application in the steel industry is where the temperature is a constant state and the steel starts to turn into a lump. Reheating the steel at the same temperature is the key to prevent its deformation, and infrared pyrometers are used to measure the internal temperature of the heat storage chamber. In high temperature rotary mills, infrared thermometers are used to confirm that the product temperature is within the rotational limit. In cooling machines, infrared thermometers monitor the temperature of the steel during cooling.

　　In the plastics industry, infrared thermometers are used to prevent product contamination, to measure dynamic objects and to measure high temperature plastics. In the blown film process, temperature measurements are used to regulate heating and cooling, helping to maintain the tension and thickness of the plastic. During the coating of cast film, the sensor helps control temperature to ensure product thickness and uniformity. As the sheet is pressed out, the sensor allows the operator to adjust the extinguished heater and cold coils to ensure product quality.

　　The environmental conditions of the pyrometer have a great impact on the measurement results and should be considered and properly addressed, otherwise it will affect the measurement accuracy and even cause damage to the pyrometer. When the ambient temperature is too high, there is dust, smoke and steam, you can use the protective cover, water cooling, air cooling system, blower and other accessories provided by the manufacturer. These accessories can effectively solve the environmental impact, protect the pyrometer and achieve accurate temperature measurement. When determining accessories, standardized service should be required whenever possible to reduce installation costs. Two-color pyrometers are a good choice when smoke, dust or other particles reduce the measurement energy signal. Fiber optic two-color pyrometers are a good choice in environments with noise, electromagnetic fields, vibration or difficult access, or other harsh conditions.