Determination of the optical functions of transparent glasses by using spectroscopic ellipsometry

Two-channel spectroscopic polarization-modulation ellipsometry measurements have been made on four different glasses (fused SiO(2), finely annealed BK-7, a lead-indium-phosphate glass, and a germanium-arsenic-selenium glass). We show that this technique is sensitive to thin surface layers and that these surface layers can be modeled by using the Bruggeman effective-medium theory with 50% glass and 50% voids. By correcting the experimental spectra for this surface layer, we determined the refractive index of the sample within an error of +/-0.002 in the transparent region. For wavelength regions where the material is normally opaque, the ellipsometric data can be corrected for this overlayer, thereby increasing the accuracy of the determination of both the refractive index and the extinction coefficient.