The dispersion and thermo-optic behaviour of vitreous silica

Abstract

The refractivity and the dispersion of vitreous silica are shown to be calculable from those of quartz by considering the diminished density. The temperature variation of its refractive indices over the entire range of wavelengths is in quantitative accord with the hypothesis that the characteristic absorption frequencies in the ultra-violet fall with rise of temperature. The rate of change of these frequencies has been traced from -160° to 1000°C, and shows remarkable variations in the vicinity of the temperature at which the α-βtransformation in crystalline quartz occurs.