Experimental determination of the optical properties of fibrous quartz thermal insulation

The absorption and diffusion coefficients of fibrous quartz thermal insulation of $0.144$ g/cm$^3$ density are determined from experimental, values of the transmittance of disk specimens of different thicknesses for the wavelengths $0.63$, $1.15$, and $3.39\,\mu$m. A formula which accounts for the temperature dependence of the absortion coefficient is proposed.