I have used a commercial optical pyrometer to measure the temperature of
a tungsten strip. I compared the results with temperatures found two
other ways: electrical power input with tables of emissivity versus
temperature (P = sigma*epsilon*area*T^4) and resistivity.
I would make several measurements with the pyrometer, half the time
approaching the temperature from the high end, half the time from the
low end. The readings had about a 100 C scatter. I found that the the
pyrometer and power methods gave temperatures within about 150 C of each
other (when the tungsten was pretty white hot at around 2500 C).
Resistivity always gave a significantly lower temperature estimate
(200-300 C lower). The strips were typically 1 mm wide and 20 cm long.
I did this almost 20 years ago, so some of the details beyond these are
foggy.
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org:Department of Natural Sciences;University of Michigan-Dearborn
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title:Professor of Physics and Chair,
fn:Paul W. Zitzewitz
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