Refractive Index of Strontium Oxide

The refractive index of single crystals of strontium oxide has been measured for 6 wavelengths in the visible spectrum. The crystals were grown from the melt in a graphite resistance furnace by the method of Ohmic heating. They were ground and polished into prisms, and the refractive index was determined by the method of minimum deviation. The absolute refractive index for the best crystal varied from 1.86245±3 ×${10}^{-5\mathrm{}}$ at the wavelength 6562.82 Å to 1.92585±3×${10}^{-5\mathrm{}}$ at the wavelength 4046.56 Å.