A multispectral radiometry method for measuring the normal spectral emissivity and temperature

Abstract

A multispectral radiometry method was developed to simultaneously determine normal spectral emissivity of continuum spectra and temperature of materials. Linear dependence assumption would be a constraint to associate the spectral emissivity to the temperature when spectral radiance for various spectrum was measured within small temperature differences. The methodology was evaluated for different parameter constraints, and validated by seven emissivity hypothesis models. To verify the reliability of the experimental device and the multispectral radiometry method, the spectral emissivities of graphite at high temperatures were verified that the deviations between the official experimental data and the results in this work are all less than 5 %. Besides, the spectral emissivity and temperature of the graphite-carbon fiber composite in the spectral range of 0.3–2.5 μm at 1473–1873 K were measured. The temperature uniformity of the sample front surface was evaluated, and the relative error of the temperature distribution is less than 2 %. The uncertainties of the spectral emissivity and temperature in the studied spectrum are less than5.0 % and 6.0 %, respectively. The method is useful for accurately measuring the sample spectral emissivity without direct temperature measurements at high temperatures.