Editing Lighthouse (section)

===Light source===
Many Fresnel lens installations have been replaced by rotating [[aerobeacon]]s, which require less maintenance.

In modern automated lighthouses, the system of rotating lenses is often replaced by a high intensity light that emits brief omnidirectional flashes, concentrating the light in time rather than direction. These lights are similar to obstruction lights used to warn aircraft of tall structures. Later innovations were "Vega Lights", and experiments with [[light-emitting diode]] (LED) panels.<ref name="Crompton"/>

LED lights, which use less energy and are easier to maintain, had come into widespread use by 2020. In the United Kingdom and Ireland about a third of lighthouses had been converted from filament light sources to use LEDs, and conversion continued with about three per year. The light sources are designed to replicate the colour and character of the traditional light as closely as possible. The change is often not noticed by people in the region, but sometimes a proposed change leads to calls to preserve the traditional light, including in some cases a rotating beam. A typical LED system designed to fit into the traditional 19th century Fresnel lens enclosure was developed by Trinity House and two other lighthouse authorities and costs about [[Euro|€]]20,000, depending on configuration, according to a supplier; it has large fins to dissipate heat. Lifetime of the LED light source is 50,000 to 100,000 hours, compared to about 1,000 hours for a filament source.<ref name="baraniuk">{{Cite web|author=Baraniuk|first=Chris|date=15 September 2020|title=When changing a light bulb is a really big deal|url=https://www.bbc.co.uk/news/business-53756582|url-status=live|website=BBC News|archive-url=https://web.archive.org/web/20230619143546/https://www.bbc.com/news/business-53756582|archive-date=Jun 19, 2023}}</ref>

====Laser light====
[[File:Point Danger lighthouse.jpg|thumb|upright 0.6|[[Point Danger Light|Point Danger lighthouse]], [[Queensland]], 1971]]
Experimental installations of [[laser]] lights, either at high power to provide a "line of light" in the sky or, utilising low power, aimed towards mariners have identified problems of increased complexity in installation and maintenance, and high power requirements. The first practical installation, in 1971 at [[Point Danger Light|Point Danger lighthouse]], [[Queensland]], was replaced by a conventional light after four years, because the beam was too narrow to be seen easily.<ref>{{cite web |title=Point Danger Lighthouse |url=https://lighthouses.org.au/qld/point-danger-lighthouse/ |publisher=Lighthouses of Australia Inc. |access-date=11 August 2020 |language=en-AU |date=26 January 2018}}</ref><ref>{{cite journal |title=Lasers |journal=Aids to Navigation Manual |date=March 2010 |page=43 |publisher=[[International Association of Marine Aids to Navigation and Lighthouse Authorities]] |location=St Germain en Laye, France}}</ref>

====Light characteristics====
{{see also|Light characteristic}}
In any of these designs an observer, rather than seeing a continuous weak light, sees a brighter light during short time intervals. These instants of bright light are arranged to create a [[light characteristic]] or pattern specific to a lighthouse.<ref>{{Cite web |title=Aids To Navigation Abbreviations |url=http://www.uscgboating.org/safety/aton/abbreviations.htm |archive-url=https://web.archive.org/web/20080925160404/http://www.uscgboating.org/safety/aton/abbreviations.htm |archive-date=September 25, 2008}}</ref> For example, the [[Scheveningen Lighthouse]] flashes are alternately 2.5 and 7.5&nbsp;seconds. Some lights have sectors of a particular color (usually formed by colored panes in the lantern) to distinguish safe water areas from dangerous shoals. Modern lighthouses often have unique reflectors or [[Radar beacon|racon transponders]] so the radar signature of the light is also unique.