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    Fiber-Optic Thermometry

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    A sapphire fiber-optic thermometer which was developed at the National Bureau of Standards (NBS) has been evaluated up to 1600 K. The thermometer operates by emitting radiation from a thin-film metal cup on a sapphire light pipe which is immersed in the hot gas to be measured. Characteristic blackbody emission of the thermometer is transmitted through a controlled optical path to a photodiode. Simultaneous measurements at two wavelengths (596 and 702 nm) were made, and their ratio was used to derive two-color radiation measurements. Several tip geometries and platinum thin-film lengths were investigated to verify blackbody conditions. A reference platinum platinum-rhodium thermocouple was used for calibration and comparison, and a discussion of errors in the two-color ratio method is presented.


    fiber optics, hot gas measurements, sapphire thermometer, temperature, temperature measurements

    Author Information:

    Kreider, KG
    Physical scientist, National Bureau of Standards, Gaithersburg, MD

    Committee/Subcommittee: E20.02

    DOI: 10.1520/STP38714S