Non-contact temperature field measurement of solids by infrared multispectral thermotransmittance

Abstract

This work aims to achieve contactless absolute-temperature measurements of infrared-semi-transparent solids using an infrared thermal and spectroscopic imaging technique. The multispectral thermo-transmittance coefficient fields in the 3–5 μm wavelength range for Sapphire, KBr, and Silicon are determined to be 6 × 10−4 K−1, 4 × 10−4 K−1, and −3 × 10−3 K−1, respectively. The most interesting result is the high temperature-dependent transmittance coefficient in the middle wave infrared region. With these coefficients, the absolute temperature fields in a range from room temperature to 140 °C are shown.

3D infrared thermospectroscopic imaging

“…The difficulty of such measurements lies in the extreme conditions of temperature and convection. Thus, for a complete quantitative measurement 24 , it is necessary to locally measure the 3D emissivity fields via a spectral approach and to set up iterative methods for estimating the absolute temperature from the emissivity measurement coupled with a transmission calibration procedure. A specific procedure will be developed at a later stage for this type of measurement, but it is currently outside the scope of the present paper, which aims to highlight the ability to perform 3D tomographic imaging of an IR semi-transparent medium.…”

“…Following the methodology described in previous papers 8,24 , the acquired signal S from the contributions of two distinct signals is given by:…”

“…Following the methodology described in previous papers 8 , 24 , the acquired signal from the contributions of two distinct signals is given by: where and are the transmitted IR signal and the proper emission, respectively, (mm) and (mm) are spatial coordinates, (mol m −3 ) is the molar concentration, (μm) is the wavelength, and ( K ) is the temperature. Both signals are hypercubes of thermal and spectral images, as illustrated at the top of the Fig.…”

Capability of THz for Thermo-transmittance/water content measurements of insulating materials: heat and mass transfer

“…For thermal applications, Non-contact methods for temperature measurement have been recently developed [1]. Infrared thermography showed a capability to determine the thermal transmittance of certain solids which allows measuring full-field temperature at steady-state (at given temperature) [1].…”

“…Infrared thermography showed a capability to determine the thermal transmittance of certain solids which allows measuring full-field temperature at steady-state (at given temperature) [1]. The infrared imaging technique showed to be efficient to evaluate the heat transport properties in chemical reaction at micro scale [2].…”