Direct Measurement of Refractive-Index Dispersion of Transparent Media by White-Light Interferometry

We report on a technique for measuring the refractive indices of nonabsorbing media over a broad spectral range from 0.5 to 5 (mu)m. White-light interferometry based on a double-interferometer system consisting of a fixed MachZehnder interferometer and a Fourier-transform spectrometer is used for direct measurement of the absolute rotation-dependent phase shift induced by an optical element. Refractive index n ( lambda) over the whole investigated spectral range is thus obtained directly to an accuracy of 10^-4 without the need for any specific assumption about dispersion. Results for synthetic fused silica are presented and discussed.