Editing Headlamp (section)

=== Projector (polyellipsoidal) lamps ===
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|[[File:Headlight projector schematic.png|thumb|right|200px|Projector optics, side view]]
|[[File:MB-C250D-2012-Headlight.JPG|thumb|right|207px|Projector headlamps on a [[Mercedes-Benz C-Class (W204)|Mercedes Benz C-Class]]]]
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In this system a filament is located at one [[focus (optics)|focus]] of an [[ellipse|ellipsoidal]] reflector and has a condenser [[lens (optics)|lens]] at the front of the lamp. A shade is located at the image plane, between the reflector and lens, and the projection of the top edge of this shade provides the low-beam cutoff. The shape of the shade edge and its exact position in the optical system determine the shape and sharpness of the cutoff.<ref name="OpticSystems"/> The shade may be lowered by a [[solenoid]] actuated pivot to provide a low beam, and removed from the light path for the high beam. Such optics are known as ''BiXenon'' or ''BiHalogen'' projectors. If the cutoff shade is fixed in the light path, separate high-beam lamps are required. The condenser lens may have minor [[Fresnel lens]] or other surface treatments to reduce cutoff sharpness. Modern condenser lenses incorporate optical features specifically designed to direct some light upward towards the locations of [[retroreflective]] overhead road signs.

[[Hella (company)|Hella]] introduced ellipsoidal optics for [[acetylene]] headlamps in 1911, but following the electrification of vehicle lighting, this optical technique wasn't used for many decades. The first modern polyellipsoidal (projector) automotive lamp was the ''Super-Lite'', an auxiliary headlamp produced in a joint venture between [[Chrysler Corporation]] and [[Sylvania Electric Products|Sylvania]] and optionally installed in 1969 and 1970 full-size [[Dodge]] automobiles. It used an 85-watt transverse-filament tungsten-halogen bulb and was intended as a mid-beam, to extend the reach of the low beams during turnpike travel when low beams alone were inadequate but high beams would produce excessive glare.<ref>{{cite web |url= http://dastern.torque.net/lampics/1969DodgeSuperLite.pdf |title= Chrysler/Sylvania Super-Lite turnpike beam |url-status= dead |archive-url= https://web.archive.org/web/20240318023023/http://dastern.torque.net/lampics/1969DodgeSuperLite.pdf |archive-date= 18 March 2024}}&nbsp;{{small|(8.60&nbsp;MB)}}</ref>

Projector main headlamps appeared in 1981 on the Audi Quartz, a concept car designed by Pininfarina for Geneva Auto Salon.<ref>{{cite web |title=Guide: Audi Quattro Pininfarina Quartz |url=https://supercarnostalgia.com/blog/audi-quattro-pininfarina-quartz |publisher=Supercar Nostalgia |date=16 July 2019 |access-date=18 February 2021}}</ref> Developed more or less simultaneously in Germany by Hella and Bosch and in France by Cibié, the projector low beam permitted accurate beam focus and a much smaller-diameter optical package, though a much deeper one, for any given beam output.{{Citation needed|date=February 2021}} The 1986 [[BMW 7 Series (E32)]] was the first volume-production car to use polyellipsoidal low beam headlamps.<ref>{{cite web |title=BMW Ellipsoid Scheinwerfertechnik und BMW Servotronic |url= https://bmw-grouparchiv.de/research/detail/index.xhtml?id=3359869 |website=bmw-grouparchiv.de |access-date=11 October 2019}}</ref><ref>{{cite news |title=AUTOMOBILE: Goldene Finger |newspaper= Der Spiegel |url= https://www.spiegel.de/spiegel/print/d-13519694.html |publisher=Spiegel Online |access-date=11 October 2019 |date=8 September 1986}}</ref><ref>{{cite web |title=BMW 7er, Modell E32, Pressestimmen zu den Innovationen (www.7er.com) |url= https://www.7-forum.com/modelle/e32/pressestimmen/innovationen.php |website=7-forum.com |access-date=11 October 2019}}</ref> The main disadvantage of this type of headlamp is the need to accommodate the physical depth of the assembly, which may extend far back into the engine compartment.