Editing Optical cavity (section)

=== Alignment ===
[[File:Metrology-system-paper-4.jpg|thumb|Alignment of a folded cavity using an autocollimator<ref>{{cite web |last=Aharon |url=http://www.plxinc.com/white-papers/metrology-system-for-inter-alignment-of-lasers-telescopes-and-mechanical-datum |title=Metrology System for Inter-Alignment of Lasers, Telescopes, and Mechanical Datum}}</ref>]]
Precise alignment is important when assembling an optical cavity. For best output power and beam quality, optical elements must be aligned such that the path followed by the beam is centered through each element.

Simple cavities are often aligned with an alignment laser—a well-collimated visible laser that can be directed along the axis of the cavity. Observation of the path of the beam and its reflections from various optical elements allows the elements' positions and tilts to be adjusted.

More complex cavities may be aligned using devices such as electronic [[autocollimator]]s and [[laser beam profiler]]s.