Size-of-source effect correction for a thermal imaging radiation thermometer

Peter Saunders; Hamish Edgar

doi:10.1068/htrt166

Size-of-source effect correction for a thermal imaging radiation thermometer

High Temperatures-High Pressures ◽

10.1068/htrt166 ◽

1999 ◽

Vol 31 (3) ◽

pp. 283-292 ◽

Cited By ~ 3

Author(s):

Peter Saunders ◽

Hamish Edgar

Keyword(s):

Thermal Imaging ◽

Radiation Thermometer ◽

Source Effect

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

Metrology and Measurement Systems ◽

10.1515/mms-2016-0050 ◽

2016 ◽

Vol 23 (4) ◽

pp. 661-667

Author(s):

David Cywiak ◽

Daniel Cárdenas-García ◽

Hugo Rodriguez-Arteaga

Keyword(s):

Radiation Thermometer ◽

Electrical Signal ◽

Field Of View ◽

Measured Temperature ◽

Temperature Deviation ◽

Source Effect ◽

Long Wavelength ◽

Proposed Model ◽

Long Wavelength Infrared ◽

Infrared Radiation Thermometer

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.

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Radiation thermometer size-of-source effect testing using aperture

10.1063/1.4819612 ◽

2013 ◽

Cited By ~ 1

Author(s):

F. Liebmann ◽

T. Kolat

Keyword(s):

Radiation Thermometer ◽

Source Effect

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Evaluation of the Size-of-Source Effect in Thermal Imaging Cameras

Sensors ◽

10.3390/s21020607 ◽

2021 ◽

Vol 21 (2) ◽

pp. 607

Author(s):

Igor Pušnik ◽

Gregor Geršak

Keyword(s):

Thermal Imaging ◽

Region Of Interest ◽

Thermal Imager ◽

Direct Evaluation ◽

Source Effect ◽

Quantitative Measurements ◽

Central Pixel ◽

Custom Made ◽

Temperature Levels

In numerous applications, including current body temperature monitoring in viral pandemic management, thermal imaging cameras are used for quantitative measurements. These require determination of the measurement accuracy (error) and its traceability (measurement uncertainty). Within error estimation, the size-of-source effect (SSE) is an important error source. The SSE is the relation between the physical size of a target and the instrument’s nominal target size. This study presents a direct evaluation of the error due to the SSE. A stable and uniform temperature, generated by blackbodies, was measured by a high-quality thermal imager. To limit the generated radiation, custom-made blocking tiles with different apertures were used. Effects of aperture shapes and positions, camera-target distances and temperature levels on the error were investigated. The study findings suggest that due to the SSE the measured temperatures are too low, especially at longer camera-target distances. The SSE error depends on the number of pixels available and included into the region of interest, for which the accurate measurement is about to be performed. For an accurate temperature measurement, an array of at least 10 × 10 pixels should be exposed to the observed target radiation, while 3 × 3 central pixel area should be included in the temperature calculation.

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