Spectroscopic Ellipsometer is most commonly used to measure thin film thickness and optical constants. It is sensitive to less than a monolayer of material (sub-nm) on a surface and yet can determine thickness for transparent films up to tens of microns. The spectroscopic Ellipsometer can also measure the optical constants (both n and k) from any type of material, whether dielectric, organic, semiconductor, or metal. In addition to optical constants, there are additional material properties that can be indirectly determined based on how they affect changes to a material’s optical response.