White-light spectral interferometry with the uncompensated Michelson interferometer and the group refractive index dispersion in fused silica

Spectral interference fringes resolved at the output of the uncompensated (dispersive) Michelson interferometer by a low-resolution miniature fibre-optic spectrometer are used to measure the equalization wavelength as a function of the displacement in the interferometer. In the spectral range approximately from 500 to 900 nm, it is confirmed that the group refractive index dispersion in the interferometer beam splitter made of fused silica agrees well with that resulting from the Sellmeier dispersion equation. Moreover, the beam splitter effective thickness is determined either by using the slope of a linear fit function for the displacement dependence on the group refractive index or by means of a least-squares fitting of the experimental data to the theoretical differential group refractive indices. (C) 2001 Elsevier Science B.V. All rights reserved.