Editing Beam splitter (section)

{{Short description|Optical device which splits a beam of light in two}}
{{Refimprove|date=May 2014}}
[[File:Beam-splitter.svg|255px|thumb|Schematic illustration of a beam splitter cube.<br>
'''1''' - Incident light<br>'''2''' - 50% transmitted light<br>'''3''' - 50% reflected light<br>In practice, the reflective layer absorbs some light.]]
[[File:Beamsplitter-2.jpg|255px|thumb|Beam splitters]]

A '''beam splitter''' or '''beamsplitter''' is an [[optical instrument|optical device]] that splits a beam of [[light]] into a transmitted and a reflected beam. It is a crucial part of many optical experimental and measurement systems, such as [[Interferometry|interferometers]], also finding widespread application in [[fibre optic]] [[telecommunications]].