When the object is above absolute zero, because of the movement of the charged particles inside, it radiates energy in the form of electromagnetic waves of different wavelengths. The wavelength involves the ultraviolet, visible, and infrared light regions, but it is mainly in the near infrared of 0.76~3μm, 3~6μm. Mid-infrared, 6~15μm far infrared region. The size of the infrared radiation energy of an object and its distribution by wavelength have a very close relationship with its surface temperature. Therefore, by measuring the infrared energy radiated by the object itself, it can accurately determine its surface temperature, which is the objective of infrared radiation temperature measurement.