Editing Coherence length (section)

{{Short description|Distance over which a propagating wave maintains a certain degree of coherence}}
{{Use American English|date = March 2019}}
In [[physics]], '''coherence length''' is the propagation distance over which a [[coherence (physics)|coherent]] wave (e.g. an [[electromagnetic wave]]) maintains a specified [[degree of coherence]].  [[Interference (wave propagation)|Wave interference]] is strong when the paths taken by all of the interfering waves differ by less than the coherence length. A wave with a longer coherence length is closer to a perfect sinusoidal wave. Coherence length is important in [[holography]] and [[telecommunications engineering]].

This article focuses on the coherence of [[Classical physics|classical]] electromagnetic fields.  In [[quantum mechanics]], there is a mathematically analogous concept of the [[Coherence (physics)#Quantum coherence|quantum coherence]] length of a [[wave function]].