A collector mirror of an extreme ultraviolet light source is cleaned by removing the collector mirror from a chamber of the extreme ultraviolet light source; mounting the collector mirror to a carrier; inserting the carrier with the collector mirror into a cleaning tank; applying a cleaning agent to a reflective surface of the collector mirror by spraying the cleaning agent through a plurality of nozzles directed toward the collector mirror reflective surface until the collector mirror reflective surface is clean; rinsing the applied cleaning agent from the collector mirror reflective surface; and drying the collector mirror reflective surface.