text: The name "ellipsometry" stems from the fact that elliptical polarization of light is used. The term "spectroscopic" relates to the fact that the information gained is a function of the light's wavelength or energy (spectra). The technique has been known at least since 1888 by the work of Paul Drude and has many applications today.
  The first documented use of the term "ellipsometry" was in 1945.