Emissivity independent low-temperature pyrometry

Ivan Dolezal; Lubos Hes

doi:10.1117/12.778991

17 March 2008 Emissivity independent low-temperature pyrometry

Ivan Dolezal, Lubos Hes

Proceedings Volume 6939, Thermosense XXX; 693904 (2008) https://doi.org/10.1117/12.778991
Event: SPIE Defense and Security Symposium, 2008, Orlando, Florida, United States

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.

Citation Download Citation

Ivan Dolezal and Lubos Hes "Emissivity independent low-temperature pyrometry", Proc. SPIE 6939, Thermosense XXX, 693904 (17 March 2008); https://doi.org/10.1117/12.778991

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