Abstract: Various examples include an apparatus to characterize substrate and film thicknesses of the substrate and films formed thereon. The apparatus uses one or more wavelengths of light from a light source (e.g., a swept laser) to interrogate the substrate. The light is directed substantially orthogonally to an upper surface of the substrate. A polarizer and an analyzer element are coupled between the light source and the substrate. Therefore, the polarizer and the analyzer are both located in the beam propagation path from the light source to the substrate. An optical detector is arranged substantially orthogonally to the upper surface of the substrate. The optical detector receives light returned back from the substrate. The apparatus is capable of determining the thickness of the substrate and one or more films contained thereon, regardless of substrates having optical anisotropies, such as chiral characteristics or stress-induced films. Other apparatuses and methods are also disclosed.