Depending on the alloy the surface of an as-polished specimen can be optically
etched by using light microscopy in polarised light mode, darkfield or Differential Interference Contrast according to Nomarski (DIC). Polarised light microscopy is appropriate for the observation of anisotropic metals (Metals which have the ability to reflect light in two different directions). DIC reveals information about intermetallic constituents. DIC makes very small differences in reflectivity and topography visible. Darkfield is an excellent tool for visualisation of scratches of the polished sample surface.