The optical properties of high-porosity lithium fluoride ceramics

The effective absorption coefficient and the radiation diffusion coefficient are determined for high-porosity lithium fluoride ceramics. A laser photometer designed for measuring low transmissions is used for measuring the normal-hemispherical transmissivity of cylindrical samples of different thicknesses. Results are given for wavelengths of $0.63$, $1.15$, $3.39$, $5.25$, and $5.95$ $\mu$m. The thus obtained data are used to calculate the dependence of the bihemispherical reflectivity of a plane layer on the layer thickness.