Homogeneity Of Fluoride Glasses

Convection in molten heavy metal fluoride glass can lead to striae which are normally noticable by eye. The convective mechanisms operate up to the very final stages of melt casting. The scale of inhomogeneity can, however, be such that it eludes assessment by shadowgraph techniques or measurement of the refractive index profile of optical fibres. The Christiansen-Shelybuskii method was used to quantify the homogeneity of glasses melted under various conditions.