Temperature-dependent transmittance of luminous and solar radiation for quartz fibers immersed in carbon tetrachloride.

We study thermochromism in fiber composites with a view to their possible use for controlling the transmission of luminous and solar radiation. Spectrophotometric measurements of collimated and total transmittance were carried out for quartz fibers in carbon tetrachloride. The collimated transmittance showed a peak structure consistent with index matching. The total transmittance was almost featureless; the integrated luminous and solar transmittance decreased by ~20% as the temperature went from 0 to 35 degrees C if the fiber fraction was ?5 vol %. The optical properties could be reconciled with a four-flux model with parameters obtainable from the Mie theory. Specifically, we treated scattering off cylindrical objects in the Rayleigh- Gans limit.