Total Absorptance Correlations for Semitransparent Solids.

摘要

Correlations which accurately predict the total absorptance of semitransparent solids were sought. By considering the elemental Lorentz,Gaussian and Exponential-Wide band models it was found that a logarithmic functional form is applicable to solids within limited pathlength and temperature ranges. Calculations were made of the total absorptance of lithium flouride and fused silica using a dispersion model and experimental optical properties,respectively. Least-squares regression analysis gave accurate logarithmic correlations over the pathlength ranges 0.1-1cm for LiF and 0.1-10cm for fused silica. In general,the correlation parameters are functions of the medium's temperature. A single correlation of reduced accuracy is reported for LiF. A similar correlation could not be found for fused silica. In the nearly-transparent and opaque limits,the logarithmic correlation is inaccurate for solids. Additional efforts are required to find a universal correlation.