A spectroscopic method to measure the spectral emissivity of semi-transparent materials up to high temperature

A spectroscopic method to measure directional spectral emissivity for homog eneous and heterogeneous semi-transparent materials, giving access to a lar ge spectral 10-12 000 cm(-1) range and to temperatures lying between 600 an d 3000 K is reported. Sample heating is supplied by a carbon dioxide laser and the blackbody flux reference is obtained with a lanthanum chromite furn ace. Experimental results obtained with this setup on several dielectric ox ides such as silica, alumina, and magnesia are in good agreement with the r esults obtained by an indirect method based on the Kirchhoff's laws. A brie f overview of the setup abilities and a detailed discussion of the emissivi ty spectra are also proposed. (C) 1999 American Institute of Physics. [S003 4-6748(99)01810-9].