Gaussian optics is a technique ingeometrical optics that describes the behaviour of light rays in optical systems by using theparaxial approximation, in which only rays which make small angles with theoptical axis of the system are considered.[1] In this approximation, trigonometric functions can be expressed as linear functions of the angles. Gaussian optics applies to systems in which all the optical surfaces are either flat or are portions of asphere. In this case, simple explicit formulae can be given for parameters of an imaging system such asfocal length,magnification and brightness, in terms of the geometrical shapes and material properties of the constituent elements.
Gaussian optics is named aftermathematician andphysicistCarl Friedrich Gauss, who showed that an optical system can be characterized by a series ofcardinal points, which allow one to calculate itsoptical properties.[2]
