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Proceedings Paper

Emissivity independent low-temperature pyrometry
Author(s): Ivan Dolezal; Lubos Hes
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Paper Abstract

Uncertainty of a target emissivity and environment transmittance and possible reflected radiation are major origins of pyrometer inaccuracy. Measurement without knowledge of emissivity requires gaining at least two independent signals relating to the target. The patented method takes advantage of two same infrared detectors but maintained on different temperatures. A simplified approach implies a radiation enclosure that consists of 2 bodies (target vs. detector), thus a formula for temperature obtained from a set of 2 equations appears simple. Infrared detectors that can work at considerable high temperature are unavailable so temperature range of this method is limited. In an experimental facility, the first thermopile detector is heated by a transistor, the second one is cooled by a Peltier cooler. The swivel radiant heater of cube shape exhibits single of 4 surfaces with different emissivity towards the detectors. The radiation is both concentrated and switched to single detector by a pivoted toric mirror. Close mutual arrangement without optics is optional. All sensors and actuators are connected to a Data Acquisition Switch Unit. The experiment including control loops is fully managed by a PC program. Various side effects of realization like probably an influence of housing radiation at ambient temperature and reflection cause that simple formula is not adequate so that multivariable regression had to be involved. Experimental results are shown in graphs.

Paper Details

Date Published: 17 March 2008
PDF: 11 pages
Proc. SPIE 6939, Thermosense XXX, 693904 (17 March 2008); doi: 10.1117/12.778991
Show Author Affiliations
Ivan Dolezal, Technical Univ. of Liberec (Czech Republic)
Lubos Hes, Technical Univ. of Liberec (Czech Republic)

Published in SPIE Proceedings Vol. 6939:
Thermosense XXX
Vladimir P. Vavilov; Douglas D. Burleigh, Editor(s)

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