Editing Optical aberration (section)

{{Short description|Deviation from perfect paraxial optical behavior}}
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{{technical|date=January 2025}}
{{textbook|date=October 2020}}
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[[File:Lens chromatic aberration.png|thumb|1: Imaging by a lens with [[chromatic aberration]]. 2: A lens with less chromatic aberration]]
In [[optics]], '''aberration''' is a property of optical systems, such as [[Lens (optics)|lens]]es and [[mirror]]s, that causes the ''image'' created by the optical system to not be a faithful reproduction of the ''object'' being observed. Aberrations cause the image formed by a lens to be blurred, distorted in shape or have color fringing or other effects not seen in the object, with the nature of the distortion depending on the type of aberration.

Aberration can be defined as a departure of the performance of an optical system from the predictions of [[paraxial optics]].<ref name="ref1">{{cite book
  | last = Guenther
  | first = Robert
  | title = Modern Optics
  | url = https://archive.org/details/modernoptics00guen
  | url-access = limited
  | publisher = John Wiley & Sons Inc.
  | year = 1990
  | location = Cambridge
  | page = [https://archive.org/details/modernoptics00guen/page/n141 130]
  | isbn = 0-471-60538-7}}</ref> In an imaging system, it occurs when light from one point of an object does not converge into (or does not diverge from) a single point after transmission through the system. Aberrations occur because the simple paraxial theory is not a completely accurate model of the effect of an optical system on light, rather than due to flaws in the optical elements.<ref>{{cite web |url=http://www.edmundoptics.com/technical-support/optics/comparison-of-optical-aberrations/ |archive-url=https://web.archive.org/web/20111206062508/http://www.edmundoptics.com/technical-support/optics/comparison-of-optical-aberrations/ |archive-date=December 6, 2011|title=Comparison of Optical Aberrations |publisher=Edmund Optics |access-date=March 26, 2012}}</ref>

An image-forming optical system with aberration will produce an image which is not sharp. Makers of [[optical instruments]] need to correct optical systems to compensate for aberration.

Aberration can be analyzed with the techniques of [[geometrical optics]].  The articles on [[Reflection (physics)|reflection]], [[refraction]] and [[caustic (optics)|caustics]] discuss the general features of reflected and refracted [[ray (optics)|rays]].