The temperature measurement principle of the infrared thermometer is to convert the radiant energy of infrared rays emitted by an object into an electrical signal. The size of the infrared radiant energy corresponds to the temperature of the object itself. According to the size of the converted electrical signal, the temperature of the object can be determined. Infrared temperature measurement technology has developed to the point where it can scan and measure the temperature of a surface with thermal changes, determine its temperature distribution image, and quickly detect hidden temperature differences. This is an infrared thermal imaging camera. Infrared thermal imaging cameras were first used in the military. The American TI Company developed the world's first infrared scanning reconnaissance system in 1999. Since then, infrared thermal imaging technology has been used in aircraft, tanks, warships and other weapons in Western countries. , as a thermal sighting system for reconnaissance targets, greatly improves the ability to search and hit targets. The infrared thermal imaging camera produced by the Swedish AGA company is in a leading position in civilian technology.
A black body is an idealized radiator that absorbs radiant energy of all wavelengths without energy reflection or transmission. Its surface emissivity is 1. However, almost all actual objects existing in nature are not black bodies. In order to clarify and obtain the distribution rules of infrared radiation, an appropriate model must be selected in theoretical research. This is the quantized oscillator model of body cavity radiation proposed by Planck. Planck's law of black body radiation was derived, that is, the black body spectral radiance expressed in wavelength. This is the starting point of all infrared radiation theories, so it is called the black body radiation law. The radiation amount of all actual objects depends not only on the radiation wavelength and the temperature of the object, but also on factors such as the type of material, preparation method, thermal process, surface state and environmental conditions of the object.
Infrared temperature measurement adopts point-by-point analysis, that is, the thermal radiation of a local area of the object is focused on a single detector, and the radiation power is converted into temperature through the emissivity of the known object. Due to different objects to be detected, measurement ranges and usage occasions, the appearance design and internal structure of infrared thermometers are different, but the basic structures are generally similar, including optical systems, photodetectors, signal amplifiers and signal processing, and display outputs. composed of other parts. Infrared radiation emitted by a radiator. Entering the optical system, the infrared radiation is modulated into alternating radiation by the modulator, and then converted into corresponding electrical signals by the detector. The signal passes through the amplifier and signal processing circuit, and is converted into the temperature value of the measured target after correction according to the algorithm in the instrument and the target emissivity.
