Influence of Size of Source Effect on Accuracy of LWIR Radiation Thermometers

Open access

Abstract

Determining the size of source effect of a radiation thermometer is not an easy task and manufacturers of these thermometers usually do not indicate the deviation to the measured temperature due to this effect. It is one of the main uncertainty components when measuring with a radiation thermometer and it may lead to erroneous estimation of the actual temperature of the measured target. We present an empiric model to estimate the magnitude of deviation of the measured temperature with a long-wavelength infrared radiation thermometer due to the size of source effect. The deviation is calculated as a function of the field of view of the thermometer and the diameter of the radiating source. For thermometers whose field of view size at 90% power is approximately equal to the diameter of the radiating source, it was found that this effect may lead to deviations of the measured temperature of up to 6% at 200ºC and up to 14% at 500ºC. Calculations of the temperature deviation with the proposed model are performed as a function of temperature and as a function of the first order component of electrical signal.

[1] Pušnik, I., Grgić, G., Drnovšek, J. (2004). Calculated uncertainty of temperature due to the size-of-source effect in commercial radiation thermometers. Int. J Thermophys, 29(21), 322-329.

[2] Yoo, Y.S., Kim, B.H., Park, C.W., Lee, D.H., Park, S.N. (2009). Size of source effect of a transfer reference thermometer suitable for international comparisons near to room temperature Fundamental and Applied Metrology, XIX IMEKO World Congress, 1493-1496.

[3] Saunders, P., Edgar, H. (2008). On the characterization and correction of the size-of-source effect in radiation thermometers. Metrologia, 46(1), 62-74.

[4] Pušnik, I., Grgić, G., Drnovšek, J. (2006). System for the determination of the size-of-source effect of radiation thermometers with the direct reading of temperature. Meas. Sci. Technol., 17(6), 1330-1336.

[5] Cárdenas-García, D. (2013). Utilizing size of source effect to determine minimum sample size in radiation measurement with a Fourier transform infrared spectrometer. NCSLI Measure, 8(3), 54-58.

[6] Barber, R., Glass industry applications. Theory and Practice of Radiation Thermometry, ed. by Witt, D.P., Nutter, G.D. (1998), chap. 18, John Wiley and Sons, Inc., 985‒987.

[7] Saunders, P., et al. (2008). Uncertainty Budgets for Calibration of Radiation Thermometers below the Silver Point, Int. J Thermophys, 29(3), 1066−1083.

[8] ASTM E2758-10 (2010). Standard Guide for Selection and Use of Wideband Low temperature Infrared Thermometers, West Conshohocken, PA, 4.

Metrology and Measurement Systems

The Journal of Committee on Metrology and Scientific Instrumentation of Polish Academy of Sciences

Journal Information


IMPACT FACTOR 2016: 1.598

CiteScore 2016: 1.58

SCImago Journal Rank (SJR) 2016: 0.460
Source Normalized Impact per Paper (SNIP) 2016: 1.228

Metrics

All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 143 105 7
PDF Downloads 73 66 6