On the refractive index of rutile

There are several reports on the measurement of the refractive indices of single-crystal rutile. Whereas the ordinary refractive indices estimated are in close agreement over a wide range of wavelengths, there is a significant difference in the corresponding values of the extraordinary refractive indices. Observations on the `prism-coupling technique´ using rutile prisms are reported, to show that for the refractive indices of rutile, the work of W.H. Bond, see J. Appl. Phys., vol.36, p.1674, 1965; represents a better standard