Editing Halogen lamp (section)

{{short description|Incandescent lamp variety}}
[[File:Halogen lamp operating.jpg|thumb|right|A halogen lamp operating in its fitting with the protecting glass removed]]
[[File:Halogen.jpg|thumb|right|A halogen lamp behind a round UV filter. A separate filter is included with some halogen light fixtures to remove UV light.]]
[[File:Wolfram-Halogenglühlampe.png|thumb|upright|Halogen lamp (105 W) for replacement purposes with an [[E27 screw base]]]]
[[File:Halogen-bulb-3.jpg|thumb|upright|A close-up of a halogen lamp capsule]]

A '''halogen lamp''' (also called '''tungsten halogen''', '''quartz-halogen''', and '''quartz iodine''' lamp) is an [[Incandescent light bulb|incandescent lamp]] consisting of a [[tungsten filament]] sealed in a compact transparent envelope that is filled with a mixture of an [[inert gas]] and a small amount of a [[halogen]], such as [[iodine]] or [[bromine]]. The combination of the halogen gas and the [[tungsten]] filament produces a [[#Halogen cycle|halogen-cycle]] chemical reaction, which redeposits evaporated tungsten on the filament, increasing its life and maintaining the clarity of the envelope. This allows the filament to operate at a higher temperature than a standard incandescent lamp of similar power and operating life; this also produces light with higher [[luminous efficacy]] and [[color temperature]]. The small size of halogen lamps permits their use in compact optical systems for [[projector]]s and illumination. The small glass envelope may be enclosed in a much larger outer glass bulb, which has a lower temperature, protects the inner bulb from contamination, and makes the bulb mechanically more similar to a conventional lamp.<ref name=double>{{cite web |url= http://www.lamptech.co.uk/TH%20DJ.htm |title=Tungsten Halogen - Double Jacket |website=Lamptech.co.uk |date=14 September 2014 |access-date= 23 January 2019}} Source has illustrations of various double-envelope halogen bulbs.</ref>

Standard and halogen incandescent bulbs are much less efficient than [[LED lamp|LED]] and [[compact fluorescent lamp]]s, and therefore have been or are being [[Phase-out of incandescent light bulbs|phased out in many places]].