REFRACTIVE-INDEXES AND OPTICAL DISPERSION OF 103 SYNTHETIC AND MINERAL OXIDES AND SILICATES MEASURED BY A SMALL-PRISM TECHNIQUE

A technique for measuring the optical dispersion of small single-cryst al specimens has been developed. A ceramic sample holder capable of ho lding eight specimens was used to prepare prisms from samples with thi cknesses of 1-2 mm. By this technique, refractive indices of 50 synthe tic oxide and 53 mineral crystals were measured from 404.7 to 643.8 nm with a Hg-Cd light source with an uncertainty in n estimated to be +/ -0.0002. These refractive indices were used to calculate n at lambda = 589.3 nm (n(D)) and n at lambda = infinity(n(infinity)) with the one- term Sellmeier equation 1/(n(2) - 1) = -A/lambda(2) + B. Dispersion va lues A ranged from similar to 50 X 10(-16) m(2) to similar to 200 X 10 (-16) m(2). Unusually high dispersion was noted for compounds containi ng Cu+, Co2+, Fe3+, As3+, Sb3+, Ti4+, and V5+. Calculated n(D) and the optical axial angle (2V) values agreed well with experimental values listed in the literature. Deviations of dispersion values for cuprite (Cu2O), arsenolite (As2O3), senarmontite (Sb2O3), Yb2O3, ThO2, gahnite (Zn0.92Fe0.10Mg0.01Al1.97O4), and titanite (Ca1.01Ti0.97Fe0.02Al0.02H 0.02SiO5) are discussed. (C) 1997 Optical Society of America [S0740-32 24(97)00407-4].