Abstract

Beryllium oxide has a strong Restsrahlen band in the wavelength interval 9–15µm. This feature makes the material selectively low emitting in the primary atmospheric window 8–13µm, which reduces radiative cooling through a clear skye. It has been suggested to use BeO for condensation and frost prevention in situations when metalic or electrically conducting materials cannot be used, e.g., on ceramic high voltage insulators.¹ In this contribution, spectral emittance data are presented which agree with the previously known bulk reflectance results. Detailed structures observed in the reflectance and emittance spectra are explained as the effect of details in the phonon dispersion relation. The effect of simulated soot contamination upon the surface of BeO has been studied. It is found that even heavy contamination in an industrial atmosphere leaves at least 50% of the emittance reduction intact and consequently there are good prospects that the condensation prevention effect would prevail even after long time exposure to atmospheric contamination.

© 1990 Optical Society of America