Analysis of multi-band pyrometry for emissivity and temperature measurements of gray surfaces at ambient temperature

Araújo, António

doi:10.1016/j.infrared.2016.03.014

Cited by 24 publications

(9 citation statements)

References 25 publications

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“…Based on the theoretical analysis in this manuscript, the radiance variation can be discussed as follows. First, the lab (indoor) condition can be regarded as enclosed, and the downwelling radiance in the indoor condition, L dwrin (λ), can be confirmed as the radiance of the blackbody [38,39]. Then, the ambient temperature in the indoor condition is close to the sample temperature; therefore, L dwrin (λ) ≈ L bb (T S ,λ), so Equation (3) can be transformed as:…”

Section: The Potential Significance Of Emissivity Changes In the Fracmentioning

confidence: 99%

“…First, to investigate the emissivity regulation of different types of rocks and minerals, thermal infrared spectrum observation experiments in different lithologies [31][32][33], incline angles [34,35], and roughnesses [36,37] were performed and analyzed. Because of the relatively strong background radiation, emissivity under indoor conditions is easily submerged by the relatively strong background radiation [38,39]. The change in the roughness and observation angle can lead to a change in emissivity by observing the heated rock samples under lab conditions, thereby leading to radiance variation [40].…”

Section: Introductionmentioning

confidence: 99%

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Experimental Study on the Thermal Infrared Spectral Variation of Fractured Rock

Huang

Liu

et al. 2021

Remote Sensing

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Previous studies have shown that thermal infrared radiation (TIR) anomalies occur in the vicinity of fractures that form when a rock is loaded to failure. Different types of fracturing modes correspond to different TIR anomaly trends. However, the spectral features and the mechanisms responsible for the TIR changes in the fracturing stage remain poorly understood. In this paper, experiments involving observations of the thermal infrared spectrum (8.0–13.0 μm) of loaded sandstone during the fracturing stage were conducted under outdoor conditions. The experiment yielded the following results: (1) Different fracturing modes can lead to different trends in the spectral radiance variation; (2) when an extensional fissure appeared on the rock surface, the radiance increased with a local peak in the 8.0–9.7 μm range; 3) when local bulging formed at the surface, the radiance decreased, with a local valley in the 8.0–9.7 μm range. The radiance variation caused by morphologic changes is the combined result of changes in both the temperature and the emissivity. The characteristic waveband corresponding to the reststrahlen features (RF) of quartz was mainly related to the emissivity change. This study provides a preliminary experimental foundation for the detection of crustal surface fractures via satellite-based remote sensing technology.

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Section: The Potential Significance Of Emissivity Changes In the Fracmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Experimental Study on the Thermal Infrared Spectral Variation of Fractured Rock

Huang

Liu

et al. 2021

Remote Sensing

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“…Basically, dualwavelength soot pyrometry is a technique for the measurement of the temperature and/or concentration of soot present in combustion flames. Based on equation (9), assuming that background radiation effects are ignored, and all incoming radiation is absorbed at discrete wavelengths λ i , for spectral channels i = 1 and 2,…”

Section: Soot Pyrometrymentioning

confidence: 99%

“…, n. If Planck's distribution ( 1) is used to model blackbody radiation, since the integrals over finite interval λ i -λ i have no analytical solution [6], the solutions for equations (34) and (35) have to be achieved numerically, e.g. using the secant rootfinding algorithm, along with the adaptive Simpson's method for numerical integration [7][8][9][10].…”

Section: Multi-band Pyrometrymentioning

confidence: 99%

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Multi-spectral pyrometry—a review

Araújo¹

2017

Meas. Sci. Technol.

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In pyrometry measurements, the unknown target emissivity is a critical source of uncertainty, especially when the emissivity is low. Aiming to overcome this problem, various multi-spectral pyrometry systems and processing techniques have been proposed in the literature. Basically, all multi-spectral systems are based on the same principle: the radiation emitted by the target is measured at different channels having different spectral characteristics, and the emissivity is modelled as a function of wavelength with adjustable parameters to be obtained empirically, resulting in a system of equations whose solution is the target temperature and the parameters of the emissivity function. The present work reviews the most important multi-spectral developments. Concerning the spectral width of the measurement channels, multi-spectral systems are divided into multi-wavelength (monochromatic channels) and multi-band (wide-band channels) systems. Regarding the number of unknowns and equations (one equation per channel), pyrometry systems can either be determined (same number of unknowns and equations, having a unique solution) or overdetermined (more equations than unknowns, to be solved by least-squares). Generally, higher-order multi-spectral systems are overdetermined, since the uncertainty of the solutions obtained from determined systems increases as the number of channels increases, so that determined systems normally have less than four channels. In terms of the spectral characteristics of the measurement channels, narrow bands, far apart from each other and shifted towards lower wavelengths, seem to provide more accurate solutions. Many processing techniques have been proposed, but they strongly rely on the relationship between emissivity and wavelength, which is, in turn, strongly dependent on the characteristics of a particular target. Several accurate temperature and/or emissivity results have been reported, but no universally accepted multi-spectral technique has yet been developed.

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Virtual emissivities of infrared thermometers

Ficker

2021

Infrared Physics & Technology

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Analysis of multi-band pyrometry for emissivity and temperature measurements of gray surfaces at ambient temperature

Cited by 24 publications

References 25 publications

Experimental Study on the Thermal Infrared Spectral Variation of Fractured Rock

Experimental Study on the Thermal Infrared Spectral Variation of Fractured Rock

Multi-spectral pyrometry—a review

Virtual emissivities of infrared thermometers

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