Editing Ellipsometry (section)

===Experimental setup===
[[Image:Ellipsometry setup.svg|thumb|right|400px|Schematic setup of an ellipsometry experiment]]
[[Electromagnetic radiation]] is emitted by a light source and linearly polarized by a [[polarizer]]. It can pass through an optional compensator ([[Wave plate|retarder]], [[wave plate|quarter wave plate]]) and falls onto the sample. After reflection the radiation passes a compensator (optional) and a second polarizer, which is called an analyzer, and falls into the detector. Instead of the compensators, some ellipsometers use a [[Photoelastic modulator|phase-modulator]] in the path of the incident light beam. Ellipsometry is a [[Specular reflection|specular]] optical technique (the [[angle of incidence (optics)|angle of incidence]] equals the angle of reflection). The incident and the reflected beam span the ''plane of incidence''.  Light which is polarized parallel to this plane is named ''p-polarized''. A polarization direction perpendicular is called ''s-polarized'' (''s''-polarised), accordingly. The "''s''" is contributed from the German "{{lang|de|senkrecht}}" (perpendicular).

{{See also|Fresnel equations}}