Abstract: A new kind of fiber optic high-temperature sensor for molten metal is presented in this paper. It is composed of a hollow tube and an optic fiber. When the bottom part of the sensor is inserted to the molten metal, the optical fiber receives and transmits the radiation powers emitting from the molten metal surface. Then the temperature of the surface is measured by a double-color pyrometer, based on the assumption that emissivities in used wave band approach each other by using the hollow tube. Regardless of the surface emissivity approaching black body or not, the results of approximating gray body when the sensor is inserted into the molten metal obviated the effect of the uncertain emissivity on temperature measurement. !2
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