Refractive index determination of highly absorbing materials by oblique transmittance measurements

We propose a simple technique for determining the refractive indices of highly absorbing materials. This method uses two transmittance measurements at oblique incidence. A theoretical analysis of the proposed method is presented. The refractive index of water was experimentally determined with a relative error ranging from 0.12% to 1.3%. We discuss the extension of this method to spectroscopic measurements.