Index of refraction measurement on sapphire at low temperatures and visible wavelengths.

The ordinary and extraordinary refractive index of two samples of sapphire, which differed in the way each was grown, was measured. The measurements were made over a wavelength range of 477-701 nm and a temperature range of 20-295 K. A three-term Sellmeier dispersion equation was fit to the data to permit refractive-index interpolation within several parts in 10(4).