Uncertainty Budgets for Calibration of Radiation Thermometers below the Silver Point

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 .

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“…For temperatures below 1000ºC the signal of an RT is well described by the Sakuma-Hattori equation [7]:…”

Section: Temperature Deviations Due To Sse For Direct Temperature Reamentioning

confidence: 99%

“…Sometimes it is more useful to calculate the temperature variation as a function of the measured signal variation, following a procedure similar to that in [7]. In general, this relation is given by:…”

Section: Temperature Deviations Due To Sse For Direct Temperature Reamentioning

confidence: 99%

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

Cywiak¹,

Cárdenas-García²,

Rodríguez-Arteaga³

2016

Metrology and Measurement Systems

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“…The method described in [17,18] was used to derive two different uncertainty budgets for T Au depending on whether the extrapolation or interpolation approach has been used. Uncertainty components used in [11] for the determination of the budget for T Cu also apply for the present exercise.…”

Section: Uncertaintiesmentioning

confidence: 99%

Indirect Determination of the Thermodynamic Temperature of a Gold Fixed-Point Cell

2010

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Since the value T 90 (Au) was fixed on the ITS-90, some determinations of the thermodynamic temperature of the gold point have been performed which form, with other renormalized results of previous measurements by radiation thermometry, the basis for the current best estimates of (T − T 90 ) Au = 39.9 mK as elaborated by the CCT-WG4. Such a value, even if consistent with the behavior of T − T 90 differences at lower temperatures, is quite influenced by the low values of T Au as determined with few radiometric measurements. At INRIM, an independent indirect determination of the thermodynamic temperature of gold was performed by means of a radiation thermometry approach. A fixed-point technique was used to realize approximated thermodynamic scales from the Zn point up to the Cu point. A Si-based standard radiation thermometer working at 900 nm and 950 nm was used. The low uncertainty presently associated to the thermodynamic temperature of fixed points and the accuracy of INRIM realizations, allowed scales with an uncertainty lower than 0.03 K in terms of the thermodynamic temperature to be realized. A fixed-point cell filled with gold, 99.999 % in purity, was measured, and its freezing temperature was determined by both interpolation and extrapolation. An average T Au = 1337.395 K was found with a combined standard uncertainty of 23 mK. Such a value is 25 mK higher than the presently available value as derived by the CCT-WG4 value of (T − T 90 ) Au = 39.9 mK.

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“…It is difficult to measure the non-linearity effect in the infrared region; therefore, the effect is evaluated as follows. Regarding the nonlinearity of the InSb detector, it is reported that the detector should be linear in the modest range of L(800 • C)/L(157 • C) = 176, while for the wider range of L(960 • C)/L(20 • C) = 15500, a nonlinearity of 1 × 10 −3 (normal thermometer) or 1 × 10 −4 (best thermometer) is expected [16,18]. Here, L is the Planck radiance.…”

Section: Detector Noise and Non-linearitymentioning

confidence: 99%

Middle Temperature Scale for Infrared Radiation Thermometer Calibrated Against Multiple Fixed Points

Shimizu

Ishii

2008

Int J Thermophys

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The NMIJ has established a temperature scale for infrared radiation thermometry from 100 to 420 • C consisting of three fixed-point blackbodies at the In, Sn, and Zn points and an InSb detector thermometer at a wavelength of 4.7 µm. The blackbody cavities have large openings of 15 mm diameter. The expanded uncertainties (k = 2) of the In, Sn, and Zn fixed-point radiance temperatures are estimated to be 0.03, 0.03, and 0.05 K, respectively. The expanded uncertainties (k = 2) for the calibration of the infrared radiation thermometer are estimated to be 0.04 K at 157 • C (In point), 0.04 K at 232 • C (Sn point), and 0.07 K at 420 • C (Zn point).

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Uncertainty Budgets for Calibration of Radiation Thermometers below the Silver Point

Cited by 66 publications

References 24 publications

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

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

Indirect Determination of the Thermodynamic Temperature of a Gold Fixed-Point Cell

Middle Temperature Scale for Infrared Radiation Thermometer Calibrated Against Multiple Fixed Points

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