The refractive indices of synthetic sapphire (Al<sub>2</sub>O<sub>3</sub>) were measured at selected wavelengths and the values of index range from 1.834 at 0.265 µ in the ultraviolet to 1.586 at 5.58 µ in the infrared. A three-term Sellmeier dispersion equation of the form [Equation] was fitted to the experimental data. Dispersive quantities were computed which estimate the optical performance to be expected from sapphire.
IRVING H. MALITSON, "Refraction and Dispersion of Synthetic Sapphire," J. Opt. Soc. Am. 52, 1377-1379 (1962)