SYMPOSIA PAPER Published: 01 January 1985

Fiber-Optic Thermometry


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.

Author Information

Kreider, KG
National Bureau of Standards, Gaithersburg, MD
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Developed by Committee: E20
Pages: 151–161
DOI: 10.1520/STP38714S
ISBN-EB: 978-0-8031-5558-9
ISBN-13: 978-0-8031-0445-7