Measurements of Refractive Indexes and Factors Affecting Dispersion in Oxide Glasses

Abstract

Accurate refractive indexes of oxide glasses—silica, silicate, borate, aluminate, tellurite, antimonate, and heavy metal gallate glasses—are presented in the wavelength range 0.265 to 1.710 μm. Factors affecting the refractive index dispersion are discussed by using the single‐oscillator Drude‐Voigt equation. The values of nd at 0.5876 μm are affected mainly by the average resonance wavelength at the ultraviolet region through all of the glass systems. The distinguishing features of borate 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.