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Noncontact True temperature measurement

Published online by Cambridge University Press:  26 February 2011

Mark C. Lee
Affiliation:
Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109
James L. Allen
Affiliation:
Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109
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Abstract

A laser pyrometer has been developed for acquiring the true temperature of a levitated sample. The laser beam is first expanded to cover the entire cross-sectional surface of the target. For calibration of such a system, the reflectivity signal of an ideal 0.95cm diameter gold-coated sphere (reflectivity = .99) is used as the reference for any other real targets. The emissivity of the real target can then be calculated. The overall system constant is obtained by passively measuring the radiance of a blackbody furnace (emissivity = 1.0) at a known, arbitrary temperature. Since the photo sensor used is highly linear over the entire operating temperature range, the true temperature of the target can then be computed. Preliminary results indicate that true temperatures thus obtained are in excellent correlation with thermocouple measured temperatures.

Type
Research Article
Copyright
Copyright © Materials Research Society 1987

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References

1. Frish, M.B., Spencer, M.N., Wolk, N.E., Werner, J.S., and Miranda, H.A. Jr., Physical Sciences Inc. Final Report to Jet Propulsion Laboratory / NASA titled “Multi-Color Pyrometer for Materials Processing in Space”, July 15, 1986.Google Scholar
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