MEASUREMENTS OF REFRACTIVE-INDEXES AND FACTORS AFFECTING DISPERSION IN OXIDE GLASSES

Accurate refractive indexes of oxide glasses--silica, silicate, berate, aluminate, tellurite, antimonate, and heavy metal gallate glasses-are presented in the wavelength range 0.265 to 1.710 mu m. Factors affecting the refractive index dispersion are discussed by using the single-oscillator Drude-Voigt equation. The values of n(d) at 0.5876 mu m are affected mainly by the average resonance wavelength at the ultraviolet region through all of the glass systems, The distinguishing features of berate glasses-relatively high refractive index and low dispersion-are related to the large number of molecules, N, in a unit volume, compared with those of the other glasses, The number N determined by density measurements is related to the fraction of the four-coordinated borons estimated by Greenblatt and Bray.