# Optical path

> Mediated Wiki article. Canonical URL: https://mediated.wiki/source/Optical_path
> Markdown URL: https://mediated.wiki/source/Optical_path.md
> Source: https://en.wikipedia.org/wiki/Optical_path
> Source revision: 1246485442
> License: Creative Commons Attribution-ShareAlike 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/)

thumb|The figure shows the optical path of a Mirau-objective respectively a Mirau-interferometer. Reference beam (4 to 6) and object beam (7) have identical optical path length and can thus cause white light interference.

'''Optical path''' ('''OP''') is the [trajectory](/source/trajectory) that a [light ray](/source/ray_(optics)) follows as it propagates through an [optical medium](/source/optical_medium).
The '''geometrical optical-path length''' or simply '''geometrical path length''' ('''GPD''') is the [length](/source/arc_length) of a [segment](/source/curve_segment) in a given OP, i.e., the [Euclidean distance](/source/Euclidean_distance) integrated along a ray between any two points.<ref name="Bass2009">{{cite book | last1=Bass | first1=M. | last2=DeCusatis | first2=C. | last3=Enoch | first3=J.M. | last4=Lakshminarayanan | first4=V. | last5=Li | first5=G. | last6=MacDonald | first6=C. | last7=Mahajan | first7=V.N. | last8=Van Stryland | first8=E. | title=Handbook of Optics, Third Edition Volume I: Geometrical and Physical Optics, Polarized Light, Components and Instruments(set) | publisher=McGraw-Hill Education | year=2009 | isbn=978-0-07-162925-6 | url=https://books.google.com/books?id=acrmuZpdSFEC | access-date=2021-10-11 | page=}}</ref>
The mechanical length of an optical device can be reduced to less than the GPD by using [folded optics](/source/folded_optics). 
The ''[optical path length](/source/optical_path_length)'' in a homogeneous medium is the GPD multiplied by the [refractive index](/source/refractive_index) of the medium.

==Factors affecting optical path==
Path of light in medium, or between two media is affected by the following:
* [Reflection](/source/Reflection_(optics))
** [Total internal reflection](/source/Total_internal_reflection)
* [Refraction](/source/Refraction)
* [Dispersion](/source/Dispersion_(optics)) of light
* [Absorption](/source/Absorption_(optics))

==Simple materials used==
* [Lenses](/source/Lens_(optics))
* [Prisms](/source/Prism_(optics))
* [Mirror](/source/Mirror)s
* [Transparent](/source/Transparency_and_translucency) materials (e.g. [optical filter](/source/optical_filter)s)
* Translucent materials (e.g. [frosted glass](/source/frosted_glass))
* [Opaque](/source/Opacity_(optics)) materials

==References==
{{Reflist}}

{{Authority control}}

{{DEFAULTSORT:Optical path}}
Category:Physical optics
Category:Geometrical optics

{{Optics-stub}}

---
Adapted from the Wikipedia article [Optical path](https://en.wikipedia.org/wiki/Optical_path) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Optical_path?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.