Editing Optics (section)

====Approximations====
Geometric optics is often simplified by making the [[paraxial approximation]], or "small angle approximation". The mathematical behaviour then becomes linear, allowing optical components and systems to be described by simple matrices. This leads to the techniques of [[Gaussian optics]] and ''paraxial [[ray tracing (physics)|ray tracing]]'', which are used to find basic properties of optical systems, such as approximate [[image]] and object positions and [[magnification]]s.<ref>{{cite book|author=J.E. Greivenkamp|year=2004|title=Field Guide to Geometrical Optics. SPIE Field Guides vol. '''FG01'''|publisher=SPIE|isbn=978-0-8194-5294-8|pages=19–20}}</ref>