Toward Reliable Industrial Radiation Thermometry
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Application of radiation thermometry in industrial scenes is rapidly increasing with the widespread use of low-cost infrared thermometers and thermal imagers. However, their performances are not always up to the users’ expectations. This is often due to lack of appropriate information on the limitations of the instrument performance and of radiation thermometry itself. In this article, these limitations are disclosed, namely the targeting capabilities of the thermometers including the size-of-source effect of thermal imagers, reflection errors, and unknown emissivity of the measurement object. Attempts made at the NMIJ are introduced, which aim at alleviating the effect of these difficulties. Two-color radiation thermometers have been neglected from the traceability chain and from standardization efforts due to their technical complexity. Recent activities to incorporate them effectively in the calibration chain and to establish international standards are presented. Calibration of low-cost thermometers with a fixed instrumental emissivity setting has been an issue for calibration laboratories. Simple apparatus that enables calibration of such instruments is described. Methods to compensate for unknown emissivities are presented utilizing auxiliary sources to realize a blackbody condition, which is applied to thermal imagers to overcome the problem of the size-of-source effect and reflection error at the same time. Extensions of the technique to objects with specular and scattering surfaces are described. Such efforts are encouraged in the thermometry community since they are essential in establishing an unbroken chain of traceability to the industrial front.
KeywordsEmissivity compensation Emissivity setting Infrared radiation thermometer Size-of-source effect Thermal imager Two-color ratio thermometer
The authors gratefully acknowledge the assistance of P. Saunders of MSL for providing useful information regarding calibration of low-cost infrared thermometers, and Y. Kaneko and Y. Wang of the NMIJ for performing the measurements. The assistance of T. Iwasaki of Chino Corp. is also acknowledged for conducting measurements on special request.
- 1.T. Iuchi, Y. Yamada, M. Sugiura, A. Torao, Thermometry in steel production, in Radiometric Temperature Measurements. II. Applications, chap. 4, ed. by Z. Zhang, B. Tsai, G. Machin (Elsevier, Amsterdam, 2009)Google Scholar
- 3.S. Takazawa, in Proceedings of the Infrared Array Sensor Forum 2013 (Ritsumeikan University, Kyoto, 2013) [in Japanese]Google Scholar
- 4.IEC/TS 62492-1 Ed 1.0, Industrial Process Control Devices—Radiation Thermometers—Part 1: Technical Data for Radiation Thermometers (International Electrotechnical Commission, Geneva, Switzerland, 2008)Google Scholar
- 5.IEC/TS 62492-2 Ed 1.0, Industrial Process Control Devices—Radiation Thermometers—Part 2: Determination of the Technical Data for Radiation Thermometers (International Electrotechnical Commission, Geneva, Switzerland, 2013)Google Scholar
- 6.Temperature Measurement Subcommittee of Industrial Metrology Committee, 2 Color Ratio Thermometer Working Group Interim Activity Report and Draft Standard (Japan Society for the Promotion of Science, Tokyo, 2015) [partly in Japanese]Google Scholar
- 7.J. Ishii, Y. Yamada, Int. J. Thermophys. 2015. doi: 10.1007/s10765-015-1862-y
- 8.P. Saunders, in Proceedings of Ninth International Temperature Symposium (Los Angeles), Temperature: Its Measurement and Control in Science and Industry, vol. 8, ed. by C.W. Meyer, A.I.P. Conference Proceedings 1552 (AIP, Melville, NY, 2013), pp. 619–624Google Scholar
- 10.T. Iwasaki, Y. Yamada, J. Ishii, T. Shimizu, S. Kadoya, in Proceedings SICE Annual Conference 2013, Nagoya (Society of Instrument and Control Engineers, Tokyo, 2013), pp. 380–384Google Scholar
- 11.Y. Yamada, T. Aoyama, H. Chino, K. Hiraka, J. Ishii, S. Kadoya, S. Kato, H. Kiyama, H. Kondo, T. Kuroiwa, K. Matsuo, T. Owada, T. Shimizu, T. Yokomori, Jpn. J. Appl. Phys. 49, 04DA20 (2010)Google Scholar
- 12.Y. Yamada, J. Ishii, in Proceedings SICE Annual Conference 2014, Sapporo (Society of Instrument and Control Engineers, Tokyo, 2014), pp. 1918–1920Google Scholar