Surface Temperature Measurement with Unknown Emissivity Using a Two-color Pyrometer Placed with a Reflector

An instrument for measuring surface temperature above 773 K has been developed. A gold-plated reflector is placed ahead of a two-color pyrometer. When the reflector is positioned facing the measured target, the received radiation is increased, and the difference between the effective emissivities of the two received wavelengths is shortened. As a result, the measurement error of the two-color pyrometer is reduced compared with the one without a reflector. The validation experiment has been conducted. The measurement uncertainty is evaluated, and the standard uncertainty is 4.0 K at 973 K.