Research on infrared thermal imaging temperature measurement technology and its application

O Introduction
All objects in nature with a temperature higher than absolute zero radiate energy in the form of electromagnetic waves, including infrared light waves of 0.7 to 1 000 μm. Infrared light has a very high temperature effect, which is the basis of infrared thermal imaging temperature measurement technology.
Infrared thermal imaging temperature measurement technology is one of the rapidly developing high-tech technologies today. It has been widely used in military, paramilitary and civilian fields, and plays an important role that is difficult to replace by other products. Developed countries such as the United States, Germany, the United Kingdom, and France attach great importance to the research and application of infrared thermal imaging temperature measurement technology. Mastering the development process, application fields and development trends of thermal imaging temperature measurement technology is conducive to inspiring scientific and reasonable development ideas and providing directional support for the optimization and development of thermal imagers.

l Principle of infrared thermal imaging temperature measurement and factors affecting temperature measurement
Infrared thermal imager is a precision instrument that can realize thermal imaging temperature measurement and is the core equipment of infrared thermal imaging temperature measurement. It uses real-time scanning thermal imaging technology to perform temperature analysis. Figure 1 shows the mainstream thermal imager currently used in the civilian market. It has a simple structure, powerful functions and fast temperature measurement.

Infrared thermal imaging temperature measurement technology is a technology that receives infrared radiation from the object being measured through an infrared detector and then converts it into a video thermal image of the target through a signal processing system. It converts the thermal distribution of the object into a visible image and displays it in grayscale or pseudo-color on the monitor, thereby obtaining the temperature distribution field information of the object being measured. The principle of infrared thermal imaging temperature measurement is shown in Figure 2.

Since the infrared thermal imager belongs to a narrow-band spectral radiation temperature measurement system, the surface temperature of the object measured by it is not directly measured, but calculated based on the measured radiation energy. Therefore, in actual measurement, the measurement accuracy is affected by factors such as the emissivity and reflectivity of the measured surface, background radiation, atmospheric attenuation, measurement distance, and ambient temperature.
The radiation received by the instrument on the surface of the measured object includes three parts: target radiation, environmental reflection, and atmospheric radiation, namely:
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2.3 Scientific research
In terms of scientific experimental research, infrared thermal imaging technology has shown its advantages in testing the temperature field of objects. Wang Xishi et al. used infrared thermal imagers to measure flame temperature, and Hou Chenggang et al. used them to accurately test the emissivity of objects, and both achieved good results. Xu Yonghua et al. proposed a blast furnace temperature field detection method based on infrared image processing for the distribution of temperature fields in blast furnaces and the distribution of blast furnace materials. The temperature field distribution model was established through infrared image processing, and the temperature was calibrated in combination with cross temperature measurement, realizing the online monitoring of the blast furnace temperature field distribution. The blast furnace infrared thermal imager uses a high-sensitivity infrared detector to measure temperature in real time, with the number of measured temperature points reaching 100,000, and the temperature resolution can reach <0.5℃ (200℃ target). The real-time displayed test data reflects the changes in the temperature of the materials in the blast furnace, which can accurately measure the temperature of the materials on the top of the furnace and intuitively reflect the height of the rising gas flow in the furnace. In this way, subtle changes in the combustion conditions inside the blast furnace (especially the degree of combustion of the materials) can be reflected in a timely manner, as shown in Figure 5.

3 Conclusion
The current thermal imaging system is the product of modern semiconductor technology, precision optical machinery, microelectronics, special infrared technology, new infrared optical materials and system engineering. In recent years, the production of infrared thermal imagers has formed a large industrial group, and its application covers almost all fields. As a new detection and scientific research method, the application prospect of infrared thermal imaging technology is very broad, and we also look forward to finding more uses in practical applications.