How infrared thermometers work and how they are classified
1, infrared principle: any object as long as its temperature is higher than absolute zero (-273 ° C), there is thermal radiation emitted to the outside, the object temperature difference, the energy radiated is also different, and the wavelength of the radiation wave is also different, but always including infrared radiation, thousands of degrees Celsius of the following objects, the heat radiation hit the strongest electromagnetic waves are infrared waves, so the object's own infrared radiation measurements, can be determined correctly Its external temperature, this is the infrared thermometer temperature measurement based on the objective base and the root source of the underlying rationale.
Blackbody is a kind of ambitious radiation body, it absorbs all wavelengths of radiant energy, no energy reflection and transmission, its external emissivity is 1. However, the existence of real objects in the natural world, almost all are not a blackbody, in order to clarify and get the infrared radiation diffusion discipline, in the theoretical study must be selected to meet the model, which is the quantization of Planck put forward by the body cavity radiation oscillator modulus, which leads to the derivation of the Planck's law of blackbody radiation, that is, the wavelength of the blackbody spectral radiance, which is the starting point of the theory of infrared radiation, it is called the law of blackbody radiation.
All the radiation of the real object in addition to the wavelength of the radiation and the temperature of the object, but also with the composition of the object of the material type, preparation method, thermal process, as well as the appearance of the state and the situation conditions and other factors. Therefore, in order to make the law of blackbody radiation practical for all real objects, it is necessary to introduce a proportionality coefficient, i.e., the emissivity, which is related to the nature of the material and the state of the external surface. This coefficient expresses the level of proximity of the thermal radiation of a real object to the blackbody radiation, and its value is between 0 and 1. According to the law of radiation, as long as we know the emissivity of the material, we know the infrared radiation characteristics of any object. Influence the emissivity of the important reason yarn in: material type, surface roughness, physical and chemical layout and thickness of the material.
2, infrared thermometer principle and layout: in the natural world, the temperature is higher than the relative zero degree objects are in the absolute infrared radiation energy to the surrounding space. The size of the object's infrared radiation energy and its diffusion by wavelength, and its external temperature has a very intimate relationship. Therefore, through the measurement of infrared energy radiated by the object itself, it will be able to correctly determine its external temperature, which is the objective basis for infrared radiation temperature measurement.
Infrared thermometer temperature measurement principle is the object (such as steel) emitted infrared radiation has the radiation energy changes into electrical signals, infrared radiation energy and the size of the object (such as steel) their own temperature corresponds to the size of the electrical signals change into the size of the object (such as steel) can determine the temperature. Infrared thermometer by the optical system, photoelectric detector, signal amplifier and signal processing punishment, performance output and other components. Optical system convergence of its field of view of the purpose of infrared radiation energy, the field of view of the size of the optical parts of the pyrometer and its location to determine. Infrared energy focused on the photodetector and change into the corresponding electrical signal. The signal is reversed amplifier and signal processing punishment circuit, and according to the instrument within the treatment algorithm and the purpose of the emissivity corrected for the purpose of the measured temperature value.
When using infrared radiation thermometer to measure the temperature of the purpose of the first measurement of the purpose of the infrared radiation in the scope of its band, and then calculated by the thermometer to be measured by the purpose of the temperature. Infrared thermometer according to the principle can be divided into monochrome pyrometer and dual-color pyrometer (radiation than the colour pyrometer), monochrome pyrometer and the amount of radiation within the band is proportional to; dual-color pyrometer and the ratio of the amount of radiation of the two bands is proportional.
