The function and significance of infrared thermometer
In nature, all objects with a temperature above zero are constantly emitting infrared radiation energy into the surrounding space. The purpose of an infrared thermometer is to focus the optical system on the target infrared radiation energy within its field of view. The size of the field of view is determined by the optical parts of the thermometer and its position. And the infrared energy is focused on the photodetector and converted into a corresponding electrical signal. 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 internal treatment algorithm of the instrument and the target emissivity.
The amount of infrared radiation energy of an object and its distribution by wavelength are closely related to its surface temperature. Therefore, by measuring the infrared energy radiated by the object itself, its surface temperature can be accurately measured. This is the objective basis on which infrared radiation temperature measurement is based.
Almost all actual objects that exist in nature are not black bodies. A black body is an idealized radiator that absorbs radiant energy of all wavelengths, has no reflection or transmission of energy, and has an emissivity of 1 on its surface.
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.
When using an infrared radiation thermometer to measure the temperature of a target, the amount of infrared radiation of the target within its band range must first be measured, and then the temperature of the measured target is calculated by the thermometer. A single-color thermometer is proportional to the amount of radiation within the band; a two-color thermometer is proportional to the ratio of the amount of radiation in the two bands.
According to the radiation law, as long as we know the emissivity of the material, we can know the infrared radiation characteristics of any object. The main factors that affect emissivity are: material type, surface roughness, physical and chemical structure, and material thickness.
