{{short description|Incandescent lamp variety}} [[File:Halogen lamp operating.jpg|thumb|right|A halogen lamp operating in its fitting with the protective 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 [[Incandescent light bulb ban|being banned in many places]].
==History== A carbon filament lamp using [[chlorine]] to prevent darkening of the envelope was patented<ref>{{Cite patent|country=US|number=254780|title=Electric incandescent lamp|pubdate=1882-03-07|assign=United States Electric Lighting Co. |inventor1-last=Scribner|inventor1-first=Edward A.}}</ref> by Edward Scribner of the [[United States Electric Lighting Company|US Electric Lighting Co.]] in 1882, and chlorine-filled "NoVak" lamps were marketed in 1892.<ref>{{cite journal|last=Furfari |first=F.A. |title=A different kind of chemistry: A history of tungsten halogen lamps |doi=10.1109/2943.959111 |journal=IEEE Industry Applications Magazine |page=11 |volume=7 |issue=6 |date= 2001|bibcode=2001IIAM....7f..10F }}</ref>
The use of iodine was proposed in a 1933 patent <ref name="US Patent 2883571">{{Cite patent|country=US|number=2883571|title=Electric incandescent lamp|pubdate=1959-04-21|assign=[[General Electric Co.]]|inventor1-last=Fridrich |inventor1-first=Elmer G.|inventor2-last=Wiley|inventor2-first= Emmett H.}}</ref> which also described the cyclic redeposition of tungsten back onto the filament. In 1959, [[General Electric]] patented<ref name="US Patent 2883571"/> a practical lamp using iodine.<ref>{{cite book |last1=Kane |first1=Raymond |last2=Sell |first2=Heinz |title=Revolution in lamps : a chronicle of 50 years of progress |date=2001 |publisher=Fairmont Press |location=Lilburn, GA |isbn=9780881733785 |edition=Second}}</ref>
===Bans=== In 2009, the [[European Union|EU]] and other [[European countries]] began to [[Incandescent light bulb ban|ban incandescent light bulbs]]. The production and importation of directional mains-voltage halogen bulbs was banned on 1 September 2016, and non-directional halogen bulbs followed on 1 September 2018.<ref>{{cite web|url=https://www.lyco.co.uk/advice/the-light-bulb-phase-out-schedule/|title=The light bulb phase out schedule / Lighting Advice - Lyco|website=www.lyco.co.uk|access-date=30 April 2018|url-status=dead|archive-url=https://web.archive.org/web/20171027025028/https://www.lyco.co.uk/advice/the-light-bulb-phase-out-schedule/|archive-date=27 October 2017}}</ref> [[Australia]] banned some halogen light bulbs above 10W from September 2021 in favour of eco-halogen bulbs,<ref>{{cite web |url=https://www.lightingcouncil.com.au/wp-content/uploads/2020/03/200210-halogen-phase-out_FINAL1.pdf |title=HALOGEN LAMP (GLOBE) PHASE-OUT IN AUSTRALIA |last=Crossley |first=David |date=February 2020 |website=lightingcouncil.com.au |publisher=Lighting Council Australia |access-date=2023-10-02 |archive-date=29 November 2023 |archive-url=https://web.archive.org/web/20231129152211/https://www.lightingcouncil.com.au/wp-content/uploads/2020/03/200210-halogen-phase-out_FINAL1.pdf |url-status=dead }}</ref> later than the planned date of September 2020<ref>{{cite web|title=Halogen Bulbs to be Banned in the EU Market from September - LEDinside|url= https://www.ledinside.com/news/2018/8/halogen_bulbs_to_be_banned_in_the_eu_market_from_september |access-date=26 August 2018|website=www.ledinside.com}}</ref> to keep the policy in line with the European Union.<ref>{{Cite web|last=Carabott|first=Mike|date=2020-05-26|title=Halogen lamps phase-out in Australia pushed back to late 2021|url= https://www.leadingedgeenergy.com.au/news/halogen-lamps-ban-in-australia-moved-to-late-2021/ |access-date=2021-03-09|website=Leading Edge Energy|language=en-AU}}</ref> In June 2021, the [[United Kingdom|UK]] government also announced plans to end the sale of halogen light bulbs from September, as part of the UK's wider efforts to tackle [[climate change]].<ref>{{Cite web|date=2021-06-09|title=End of halogen light bulbs spells brighter and cleaner future|url= https://www.gov.uk/government/news/end-of-halogen-light-bulbs-spells-brighter-and-cleaner-future |access-date=2021-06-09|website=gov.uk}}</ref>
==Halogen cycle== In ordinary incandescent lamps, evaporated tungsten mostly deposits onto the inner surface of the bulb, causing the bulb to blacken and the filament to grow increasingly weak until it eventually breaks. The presence of the halogen, however, sets up a reversible chemical reaction cycle with this evaporated tungsten. The halogen cycle keeps the bulb clean and causes the light output to remain almost constant throughout the bulb's life. At moderate temperatures, the halogen reacts with the evaporating tungsten, the [[Tungsten(V) bromide|halide]] formed being moved around in the inert gas filling. At some point, however, it will reach higher temperature regions within the bulb where it then [[Dissociation (chemistry)|dissociates]], releasing tungsten back onto the filament and freeing the halogen to repeat the process. However, the overall bulb envelope temperature must be significantly higher than in conventional incandescent lamps for this reaction to succeed: it is only at temperatures of above {{convert|250|C|F}}<ref name=":0">{{cite web |url=https://ntrs.nasa.gov/search.jsp?R=19910010012 |title=NASA Technical Reports Server (NTRS) - Vibration and thermal vacuum qualification test results for a low-voltage tungsten-halogen light |newspaper=Https |date=1 February 1991 |author=Sexton, J. Andrew|access-date= 19 January 2019}}</ref> on the inside of the glass envelope that the halogen vapor can combine with the tungsten and return it to the filament rather than the tungsten becoming deposited on the glass.<ref name="Wolke2009">{{cite book|author=Robert Wolke|title=What Einstein Told His Barber: More Scientific Answers to Everyday Questions|url=https://books.google.com/books?id=AVf4AAAAQBAJ&pg=PA52|date=29 July 2009|publisher=Random House|isbn=978-0-307-56847-2|page=52}}</ref> A 300-watt tubular halogen bulb operated at full power quickly reaches a temperature of about {{convert|540|C|F}}, while a 500-watt regular incandescent bulb operates at only {{convert|180|C|F}} and a 75-watt regular incandescent at only {{convert|130|C|F}}.<ref>{{cite web|title=Torchiere Halogen Lamps and Plastic Shades - Policies and Procedures|url=https://www.colorado.edu/firelifesafety/sites/default/files/attached-files/halogen_lamps.pdf|archive-url=https://web.archive.org/web/20121021153315/http://www.colorado.edu/firelifesafety/sites/default/files/attached-files/halogen_lamps.pdf|url-status=dead|archive-date=21 October 2012|publisher=University of Colorado Boulder|author=Fire and Life-Safety Group}}</ref>
The bulb must be made of [[Quartz glass|fused silica (quartz)]] or a high-melting-point glass (such as [[Aluminosilicate#Aluminosilicate glasses|aluminosilicate glass]]). Since quartz is very strong, the gas pressure can be higher <ref>Some lamps have as much as 15 times atmospheric pressure when cold, and some lamps increase pressure five-fold at [[operating temperature]]. Kane and Sell 2001, page 76–77</ref> which reduces the rate of evaporation of the filament, permitting it to run a higher temperature (and so [[luminous efficacy]]) for the same average life. The tungsten released in hotter regions does not generally redeposit where it came from, so the hotter parts of the filament eventually thin out and fail.
Quartz iodine lamps, using elemental iodine, were the first commercial halogen lamps launched by GE in 1959.<ref>Zubler and Mosby Illuminating Engineering 1959 54.734</ref><ref>{{cite web |url=http://home.frognet.net/~ejcov/newhalogen.html |title=The Tungsten-Halogen Lamp |first=Edward J. |last=Covington |access-date=2016-03-04 |url-status=dead |archive-url=https://web.archive.org/web/20160305025647/http://home.frognet.net/~ejcov/newhalogen.html |archive-date=5 March 2016 |df=dmy-all }}</ref> Quite soon, bromine was found to have advantages, but was not used in elemental form. Certain hydrocarbon bromine compounds gave good results.<ref name="autogenerated1" /><ref>T'Jampens and van der Weijer Philips Technical Review 1966 27.173</ref> Regeneration of the filament is also possible with fluorine, but its chemical reactivity is so great that other parts of the lamp are attacked.<ref name="autogenerated1">Burgin and Edwards Lighting Research and Technology 1970 2.2. 95–108</ref><ref>Schroder Philips Technical Review 1965 26.116</ref> The halogen is normally mixed with a [[noble gas]], often [[krypton]] or [[xenon]].<ref name=ullmann>{{cite book |author1=Häussinger, Peter |author2=Glatthaar, Reinhard |author3=Rhode, Wilhelm |author4=Kick, Helmut |author5=Benkmann, Christian |author6=Weber, Josef |author7=Wunschel, Hans-Jörg |author8=Stenke, Viktor |author9=Leicht, Edith |author10=Stenger, Hermann |chapter=Noble gases |title=Ullmann's Encyclopedia of Industrial Chemistry |publisher=Wiley |year=2002 |doi=10.1002/14356007.a17_485|isbn=3527306730 }}</ref> The first lamps used only tungsten for filament supports, but some designs use [[molybdenum]] – an example being the molybdenum shield in the H4 twin filament [[headlight]] for the European Asymmetric Passing Beam.
For a fixed power and life, the [[luminous efficacy]] of all incandescent lamps is greatest at a particular design voltage. Halogen lamps made for 12 to 24 volt operation have good light outputs, and the very compact filaments are particularly beneficial for optical control (see picture). The ranges of [[multifaceted reflector]] "MR" lamps of 20–50 watts were originally conceived for the projection of [[8 mm film]], but are now widely used for display lighting and in the home. More recently, wider beam versions have become available, designed for direct use on supply voltages of 120 or {{nowrap|230 V}}.
==Effect of voltage on performance== {{see also|Lamp rerating}} Tungsten halogen lamps behave similarly to other incandescent lamps when run on a different voltage. However, the light output is reported as proportional to<math>V^3</math>, and the [[luminous efficacy]] is proportional to<math>V^{1.3}</math>.<ref>Neumann Lichtechnik 1969 21 6 63A</ref> The normal relationship regarding the lifetime is that it is proportional to<math>V^{-14}</math>. For example, a bulb operated at 5% higher than its design voltage would produce about 15% more light, and the [[luminous efficacy]] would be about 6.5% higher, but would be expected to have only half the rated life.
Halogen lamps are manufactured with enough halogen to match the rate of tungsten evaporation at their design voltage. Increasing the applied voltage increases the rate of evaporation, so at some point, there may be insufficient halogen, and the lamp goes black. Over-voltage operation is not generally recommended. With a reduced voltage, the evaporation is lower, and there may be too much halogen, which can lead to abnormal failure. At much lower voltages, the bulb temperature may be too low to support the halogen cycle, but by this time, the evaporation rate is too low for the bulb to blacken significantly. If the bulbs do blacken, it is recommended to run the lamps at the rated voltage to restart the cycle.<ref name="lutron-low-dim">{{cite web |title=Lutron Guide To Dimming Low Voltage Lighting {{!}} Lighting Services Inc |url=http://www.lightingservicesinc.com/about-us/news-events/news/lutron-guide-to-dimming-low-voltage-lighting |website=Lighting Services Inc |language=en |access-date=12 October 2018 |archive-date=7 October 2018 |archive-url=https://web.archive.org/web/20181007223720/http://www.lightingservicesinc.com/about-us/news-events/news/lutron-guide-to-dimming-low-voltage-lighting |url-status=dead }} (Also available as a [http://www.lutron.com/zh-TW/ResourceLibrary/362219.pdf PDF] from lutron.com)</ref> There are many situations where halogen lamps are dimmed successfully. However, lamp life may not be extended as much as predicted. The life span of dimming depends on lamp construction, the halogen additive used, and whether dimming is normally expected for this type.
==Spectrum== [[File:Halogen spectrum.svg|thumb|Power of a halogen light as a function of wavelength. The colored band indicates the visible light spectrum. Note that this spectrum is distorted by the [[responsivity]] of the [[photodiode|optical detector]] used in the measurement, greatly reducing the apparent power in the infrared.]] Like all [[incandescent light bulb]]s, a halogen lamp produces a continuous spectrum of light, from near ultraviolet to deep into the infrared.<ref>[http://zeiss-campus.magnet.fsu.edu/articles/lightsources/tungstenhalogen.html Tungsten-halogen lamp information] {{webarchive|url=https://web.archive.org/web/20110303211343/http://zeiss-campus.magnet.fsu.edu/articles/lightsources/tungstenhalogen.html |date=2011-03-03 }} at Karl Zeiss Online Campus site (accessed Nov. 2 2010)</ref> Since the lamp filament can operate at a higher temperature than a non-halogen lamp, the spectrum is shifted toward blue, producing light with a higher effective [[color temperature]] and higher power efficiency. <!-- good full range spectrum line drawing needed -->
High-temperature filaments emit some energy in the [[ultraviolet|UV]] region. Small amounts of other elements can be mixed into the quartz, so that the ''doped'' quartz (or selective optical coating) blocks harmful UV radiation. Hard glass blocks UV and has been used extensively for the bulbs of car headlights.<ref>Burgin Lighting Research and Technology 1984 16. 2 71</ref> Alternatively, the halogen lamp can be mounted inside an outer bulb, similar to an ordinary incandescent lamp, which also reduces the risks from the high bulb temperature. Undoped quartz halogen lamps are used in some scientific, medical, and dental instruments as a UV-B source.
== Safety == [[File:2010-05-30 Destroyed 300W linear halogen bulb.jpg|thumb|A burned-out R7S form factor halogen lamp]] Halogen lamps must run at much higher temperatures than regular incandescent lamps for proper operation. Their small size helps to concentrate the heat on a smaller envelope surface, closer to the filament than a non-halogen incandescent. Because of the very high temperatures, halogen lamps can pose fire and burn hazards. In Australia, numerous house fires each year are attributed to ceiling-mounted halogen downlights.<ref>[http://www.theage.com.au/articles/2007/07/21/1184560109174.html Thousands at risk from halogen-light death traps] {{webarchive|url=https://web.archive.org/web/20121218073303/http://www.theage.com.au/articles/2007/07/21/1184560109174.html |date=2012-12-18 }} at The Sunday Age site (accessed 22 Dec. 2012)</ref><ref>[http://www.fire.nsw.gov.au/page.php?id=709 Halogen down light fire safety] {{webarchive|url=https://web.archive.org/web/20130409220132/http://www.fire.nsw.gov.au/page.php?id=709 |date=2013-04-09 }} at Fire and Rescue NSW site (accessed 22 Dec. 2012)</ref> The Western Australia Department of Fire and Emergency Services recommends that homeowners consider instead using cooler-running [[compact fluorescent lamp]]s or [[LED lamp|light-emitting diode lamps]].<ref>[http://www.dfes.wa.gov.au/safetyinformation/fire/fireinthehome/pages/downlights.aspx Downlights] {{webarchive|url=https://web.archive.org/web/20130208022139/http://www.dfes.wa.gov.au/safetyinformation/fire/fireinthehome/Pages/downlights.aspx |date=2013-02-08 }} at Western Australia Department of Fire and Emergency Services site (accessed 22 Dec. 2012)</ref> Halogen [[Torchère]] floor lamps have been banned in some places, such as [[Dormitory|dormitories]], because of the large number of fires they have caused. They were held responsible by the [[United States Consumer Product Safety Commission]] for 100 fires and 10 deaths between 1992 and 1997.<ref name=pop>{{cite journal | title = The Light Stuff| journal = [[Popular Science]] | date = October 1997 | page = 41| url=https://books.google.com/books?id=3aUMamjxVpMC&dq=%22The+Light+Stuff%22.+Popular+Science%3A+41.+October+1997.&pg=PA41}}</ref> Halogen bulbs operate at high [[temperature]]s, and the tall height of the lamps can bring them near [[Combustibility and flammability|flammable]] materials, such as [[curtain]]s.<ref>{{cite book| author = Nancy Harvey Steorts | title = Safety and You | isbn = 0815628005 | year = 1999| page = 15 | publisher = Syracuse University Press | quote = The halogen lamp industry voluntarily undertook an initiative to repair about 40 million halogen torchère floor lamps. The CPSC is aware of 189 fires and eleven deaths that occurred because of these lamps.}}</ref> Some safety codes require halogen bulbs to be protected by a grid or grille, especially for high-power (1–2 kW) bulbs used in [[Stage lighting|theatre]], or by the glass and metal housing of the fixture, to prevent ignition of draperies or flammable objects in contact with the lamp. To reduce unintentional [[ultraviolet]] (UV) exposure and to contain hot bulb fragments in the event of explosive bulb failure, general-purpose lamps usually have a UV-absorbing glass filter over or around the bulb. Alternatively, lamp bulbs may be doped or coated to [[Optical filter|filter]] out the UV radiation. With adequate filtering, a halogen lamp exposes users to less UV than a standard incandescent lamp producing the same effective level of illumination without filtering.{{citation needed|date=December 2015}}
Any surface contamination, notably the oil from human fingertips or any uneven coating of dust or other substance, can damage the quartz envelope when it is heated. Because contaminants absorb more light and heat than the glass does, they will create a hot spot on the bulb surface when the lamp is turned on. This extreme, localized heat causes the quartz to change from its [[Glass|vitreous]] form into a weaker, [[crystal]]line form that leaks gas. This weakening may also cause the bulb to form a bubble, weakening it and leading to its explosion and glass shrapnel.<ref>Kremer, Jonathan Z.[http://www.megavolt.co.il/Tips_and_info/types_of_bulbs.html "Types of Light Bulbs and Their Uses"] {{webarchive|url=https://web.archive.org/web/20110629034952/http://www.megavolt.co.il/Tips_and_info/types_of_bulbs.html |date=2011-06-29 }} Megavolt, section "Halogen", Accessed 26 May 2011.</ref>
The small glass envelope may be enclosed in a much larger outer glass bulb, which provides several advantages if a small size is not required:<ref name=double/>
* The outer jacket will be at a much lower, safer temperature, protecting objects or people that might touch it. * The hot-running inner envelope is protected from contamination, and the bulb may be handled without damaging it. * Surroundings are protected from the possible shattering of the inner capsule. * The jacket may filter out UV radiation. * When a halogen bulb is used to replace a normal incandescent bulb in a fitting, the larger jacket makes it mechanically similar to the bulb it replaces * The inner and outer envelopes can be at different pressures, reducing heat dissipation by conduction or convection to optimize the trade-off between luminous efficacy and lifetime.
==Form factors== {{see also|Incandescent light bulb#Bulb shapes}} Halogen lamps are available in a series of different shapes and sizes, and are designated according to a coding system that specifies the diameter of the bulb as well as whether or not the bulb has a built-in infrared-transparent [[Dichroism|dichroic]] reflector. Many such lamps have designations that begin with the letter "T" to indicate that they are "tubular", followed by a number indicating the diameter of the tube in eighths of an inch. Therefore, a T3 bulb is a tubular halogen bulb that is {{Convert abbreviated|3/8|in|mm|order=flip}} in diameter.<ref group=Note>However, a T-3, T ''hyphen'' 3, is a halogen "tube" lamp that is 3/8 of an inch in diameter with a single bi-pin base rather than a T3 ''cylindrical'' tube 3/8 of an inch in diameter with electrodes at ''opposite ends.''</ref> The designation ''MR'' means "[[multifaceted reflector|Multifaceted Reflector]]", with the number following this still corresponding to eighths of an inch in diameter of the overall bulb.<ref group=Note>Thus, an MR11 is a multifaceted reflector bulb that is {{fraction|11|8}} or {{fraction|1|3|8}} inches in diameter.</ref> If a lamp has a "G" code,<ref group=Note>"G" stands for "glass"</ref> this will mean the lamp is a bipin shape and the number following the G will indicate the distance in millimeters between the pins, usually either 4, 6.35 or 10; if the G is followed by a letter "Y", then the lamp's pins are thicker than normal; thus, a G6.35 lamp has pins that are 1 mm in diameter but a GY6.35 has pins that are 1.3 mm in diameter. If there is a "C" code, this represents the number of coils in the filament.<ref name="Protopopov2014">{{cite book|author=Vladimir Protopopov|title=Practical Opto-Electronics: An Illustrated Guide for the Laboratory|url=https://books.google.com/books?id=iT65BQAAQBAJ&pg=PA37|date=17 March 2014|publisher=Springer|isbn=978-3-319-04513-9|page=37}}</ref> The length (sometimes also referred to as "height") of any two-ended cylindrical bulb must be specified separately from its form factor code, usually in millimeters, as must the lamp's voltage and wattage— hence, T3 120 V 150 W 118 mm means a double-ended tube-shaped bulb with a diameter of {{Convert abbreviated|3/8|in|mm|order=flip}} that operates at 120 V and is 150 W and that is also 118 mm long.
An R7S is a double-ended, Recessed Single Contact (RSC) linear halogen lamp, usually measuring a length of either 118 mm or 78 mm. Some less common lengths are 189 mm, 254 mm and 331 mm. These lamps have a T3 shape on an RSC/R7S base. These are also known as J-type and T-type lamps.
==Applications== [[File:Halogenlight.JPG|thumb|A medical halogen penlight to observe [[pupillary light reflex|the pupillary light reflex]]]] Halogen [[headlamp]]s are used in many automobiles. Halogen [[High-intensity discharge lamp|floodlights]] for outdoor lighting systems, as well as for [[watercraft]], are also manufactured for commercial and recreational use. They are now also used in desktop lamps.
Tungsten-halogen lamps are frequently used as a near-infrared light source in [[Infrared spectroscopy]].
===Heating=== Halogen lamps are the heating elements in [[halogen oven]]s, [[infrared heater]]s and ceramic [[cooktop]]s.
Banks of powerful tubular halogen lamps were used to simulate the heat of [[reentry|re-entry]] of [[space vehicle]]s.<ref name="REV01">Raymond Kane, Heinz Sell, ''Revolution in Lamps: A Chronicle of 50 Years of Progress, Second Edition'', 2001 The Fairmount Press, {{ISBN|0-88173-351-2}} pp. 72-74</ref>
===General lighting ===
[[File:PH 2.jpg|thumb|A 150W Halogen floodlight]]
Fixed-mount lamps are used in indoor and outdoor flood lighting, although improvements in LED systems are displacing halogen lamps. Round spotlights with built-in [[multifaceted reflector]] lamps are widely used in residential and commercial lighting. Tubular halogen lamps provide a large quantity of light from a small source and so can be used to produce powerful flood lamps for architectural lighting effects, or for lighting large areas outdoors.
Low-voltage lamps use the GU5.3 and similar [[Bi-pin lamp base|bi-pin bases]], whereas mains voltage lamps use the same caps as normal mains tungsten filament lamps, or a special GU10/GZ10 base. The GU10/GZ10 bases are shaped to prevent [[dichroic]] reflector lamps from being used in [[light fixture|luminaires]] intended for aluminised reflector lamps, which could cause overheating of the fitting. Higher efficiency LED versions of all of these lamps are now available.
Tubular lamps with electrical contacts at both ends are now commonly used in standalone lighting and household fixtures. These come in various lengths and power ratings (50–300 W). More powerful lamps are used as portable work lights, with bulbs rated 250 or 500 watts.
===Stage lighting=== Tungsten halogen lamps are used in the majority of theatrical and studio (film and television) fixtures, including [[Ellipsoidal reflector spotlight]]s, [[Fresnel lantern|Fresnels]], and [[Parabolic aluminized reflector|PAR Cans]].
===Specialized=== [[Projector|Projection]] lamps are used in [[Movie projector|motion-picture]] and [[slide projector]]s for homes and small offices or school use. The compact size of the halogen lamp permits a reasonable size for portable projectors, although heat-absorbing filters must be placed between the lamp and the film to prevent melting. Halogen lamps are sometimes used for inspection lights and microscope stage illuminators. Halogen lamps were used for early flat-screen LCD [[backlight]]ing, but other types of lamps, such as [[Fluorescent lamp|CCFL]] and now [[Light-emitting diode|LED]], are used. Halogen lamps are used as the heating element in the fuser of many types of [[Laser printing|laser printers]]. The long tubular lamp heats the fuser roller from the inside, and the heat melts the toner onto the paper.
==Disposal== Halogen lamps do not contain any mercury. [[General Electric]] says that its quartz halogen lamps would not be classified as hazardous waste.<ref>{{cite web|title=MSDS — Lamp Material Information Sheet - Double-Ended or Pin-Based Quartz Halogen Lamps|url=https://products.currentbyge.com/sites/products.currentbyge.com/files/documents/document_file/msds-quartzline-lamps.pdf|website=Current by GE|date=2017|access-date=22 January 2019|archive-date=23 January 2019|archive-url=https://web.archive.org/web/20190123071659/https://products.currentbyge.com/sites/products.currentbyge.com/files/documents/document_file/msds-quartzline-lamps.pdf|url-status=dead}}</ref>
==See also== * [[Bi-pin connector]] for base designations GY6.35, G8, etc. * [[FEL lamp]] * [[Lightbulb socket]] for other bases * [[List of light sources]]
==Notes== {{reflist|group=Note}}
==References== {{Reflist|30em}}
==External links== *{{commons category-inline}}
{{Artificial light sources}} {{Use dmy dates|date=May 2018}}
{{DEFAULTSORT:Halogen Lamp}} [[Category:Types of lamp]] [[Category:Incandescent light bulbs]]
[[de:Glühlampe#Sonderformen]]