According to the energy ratio value of multi-band radiating from the measured surface, the 'true' temperature can be
calculated by multi-band pyrometer. Multi-band pyrometer has many advantages: it can hardly be affected by the
emission of measured surface and the environment radiation, and it has higher Signal-to-Noise Ratio and higher
temperature measurement accuracy. This paper introduces the principle of a multi-band pyrometer and the uncertainty of
measurement result is evaluated by using Monte-Carlo Method (MCM). The result shows that the accuracy of effective
wavelength is the largest source of uncertainty and the other main source is reference temperature. When using ordinary
blackbody furnace with continuous temperature, which can provide reference temperature and calibrate effective
wavelength, the uncertainty component is 2.17K and 2.48K respectively. The combined standard uncertainty is 3.30K. A
new calibration method is introduced. The effective wavelength is calibrated by monochromator, and the reference
temperature is provided by fixed point black body furnace. The uncertainty component is decreased to 0.73K and 0.12K
respectively. The measurement uncertainty is decreased to 0.74K. The temperature measurement accuracy is enhanced.
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