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Effects of Extraneous Radiation on the Performance of Lightpipe Radiation Thermometers



Christopher W. Meyer


Experiments were performed to study the influence of irradiation and heating of light pipe radiation thermometers (LPRTs). LPRTs are currently the sensor of choice for temperature measurement in rapid thermal processing. Eight sheathed sapphire light pipes from two separate manufacturers were used. The experiments demonstrated that the temperature of a light pipe and the radiation surroundings can significantly affect the temperature displayed by an LPRT. The influence on the display temperature is much higher when the environment of the light pipe is at a higher temperature than that of the surface being observed. Measurement uncertainty due to environmental influence can be minimized by calibrating the LPRT in an environment similar to that in which it will be used. The experimentsshowed that some light pipes are less affected by their environment than others, suggesting that careful selection of light pipes can also minimize the measurement uncertainty.


light pipe radiation thermometers, optical fiber thermometry, radiation thermometry, temperature measurement


Meyer, C. (2001), Effects of Extraneous Radiation on the Performance of Lightpipe Radiation Thermometers, TEMPMEKO, [online], (Accessed May 21, 2024)


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Created January 1, 2001, Updated February 17, 2017