Infrared thermometer working principle, technical indicators, environmental working conditions
Understand the working principle of infrared thermometer, technical indicators, environmental working conditions and operation and maintenance is to help users to correctly select and use infrared thermometer.
All objects with temperatures above zero are constantly emitting infrared radiation energy to the surrounding space. Objects of infrared radiation characteristics - the size of the radiant energy and its distribution by wavelength - and its surface temperature has a very close relationship. Therefore, through the measurement of the infrared energy radiated by the object itself, it will be able to accurately determine its surface temperature, which is the objective basis for infrared radiation temperature measurement.
Blackbody radiation law: blackbody is an idealised radiation body, it absorbs all wavelengths of radiant energy, no energy reflection and transmission, its surface emissivity is 1. It should be noted that there is no real blackbody in nature, but in order to clarify and obtain the distribution of infrared radiation law, in the theoretical study of must choose the appropriate model, which is the Planck put forward by the body of the radiation of the cavity of the quantum quantization of the vibronic model, thus deriving Planck's blackbody, which is an idealised radiation body. Thus deriving Planck's law of blackbody radiation, that is, expressed in wavelengths of the blackbody spectral radiance, which is the starting point of all infrared radiation theory, so called the law of blackbody radiation.
The effect of object emissivity on radiometric temperature measurement: the existence of real objects in nature, almost all are not black bodies. All the actual object of the radiation in addition to the wavelength of the radiation depends on the temperature of the object, but also with the composition of the object's material type, preparation methods, thermal processes, as well as the surface state and environmental conditions and other factors. Therefore, in order for the blackbody radiation law to apply to all real objects, a proportionality coefficient, i.e., the emissivity, related to the nature of the material and the state of the surface, must be introduced. This coefficient expresses the proximity of the thermal radiation of a real object to the blackbody radiation and has a value between zero and a value less than one. 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.
The main factors affecting emissivity are: material type, surface roughness, physical and chemical structure and material thickness.
When using infrared radiation pyrometer to measure the temperature of the target first of all to measure the target in its band range of infrared radiation, and then by the pyrometer to calculate the temperature of the target to be measured. Single-colour pyrometers are proportional to the amount of radiation in the band; two-colour pyrometers are proportional to the ratio of the amount of radiation in the two bands.
