Reconstruction of cross-sectional temperature distributions of water around a thin heating wire by inverse Abel transform of near-infrared absorption images

摘要

A reconstruction method of temperature distributions of water around a thin heating wire is presented. This method is based on the temperature dependence of the absorption coefficient of water at the wavelength of 1412 nm. In the case that the temperature distribution is assumed to be axisymmetric with respect to the wire, this radial distribution can be determined by applying the inverse Abel transform (IAT) to a one-dimensional profile of the absorbance which is the projection of the absorption coefficient. To perform the IAT robustly, the measured absorbance profiles are approximated by multi-Gaussian functions because the IATs of these functions are obtained analytically. This paper shows a time series of cross-sectional temperature images of water around a heating wire with a diameter of 0.05 mm. They clearly indicate changes in the temperature distribution with a resolution of less than 0.1 K when the heat generation rate varies. These results are verified by comparison with numerically simulated results.