Reflective coating is applied to a wide variety of substrates where the application requires high reflectivity. Thin films of dielectric or metal materials are precisely deposited in order to create the coatings specific to application wavelength and reflectivity requirements. Small improvements in a mirror’s reflectivity can have dramatic impact upon the general performance of a system with reflective coating. Compared to polished metals, mirrors and other similar optics are, in general, able to meet the higher standards of reflectivity requirements when using some form of reflective coating.