Raptor05121
01-04-2012, 10:27 AM
Here's a little write-up in response to several requests. This should be a one-swing kind of deal to help noobs know the real truths and myths about new automotive lighting. Let's start with some terms you will see throughout this guide, then we will examine the basics of a headlight. A headlight is a pair of light-emitting devices on a motor vehicle. By law, a passenger vehicle needs to have two separate light mounts, and two separate beams, a high and low. All information was compiled by me. This post cannot be distributed in whole without my express consent.
Watt- Measure of electrical power (w)
Volt- Measure of electrical charge (v)
Kelvin- Measure of color temperature (K)
Lumen- Measure of light brightness (lu)
Capsule- technically correct term for a HID "bulb".
Candela- Measure of light intensity (cd)
Ampere- Measure of electrical current
SAE- Society of Automotive Engineers. The Society is a standards development organization for the engineering of powered vehicles of all kinds, including cars, trucks, boats, aircraft, and others.
Cut off- A distinctive line of light produced by the shield in a headlight that blocks light above a certain height in order to prevent blinding of other motorists.
FMVSS- Federal Motor Vehicle Safety Standard. A subsection of the National Highway Traffic Safety Administration. They set the laws on all vehicles intended for use in the USA
ECE- Economic Commission for Europe. they set the safety standards for all things intended to be sold and used in the United Kingdom.
Beam Pattern- The pattern of light that is projected onto the ground which includes angle of lateral dispersion, width and depth of illumination.
Capsule- Another term for an HID bulb. Some refer to HID bulbs as gas discharge capsules.
Optics- The lighting control assembly structured around the bulb, which effects the dispersion of light and it's characteristics to a great degree.
HID (High Intensity Discharge)= Gas Discharge
Overview
Low Beam
Low beam headlights provide a distribution of light designed to provide adequate forward and lateral illumination with limits on light directed towards the eyes of other road users, to control glare. This beam is intended for use whenever other vehicles are present ahead. North American SAE beam standard contained in FMVSS states that the low beam must illuminate objects up to 150 ft in front of the vehicle without causing glare to oncoming headlights.
http://upload.wikimedia.org/wikipedia/commons/thumb/4/48/Low_beam_light_pattern_for_right-hand_traffic.svg/800px-Low_beam_light_pattern_for_right-hand_traffic.svg.pnghttp://i89.photobucket.com/albums/k227/Raptor05121/Lighting/Headlights/DSC_2175.jpg
High Beam
High beam headlamps provide a bright, center-weighted distribution of light with no particular control of light directed towards other road users' eyes. As such, they are only suitable for use when alone on the road, as the glare they produce will dazzle other drivers. FMVSS states high beams must illuminate objects up to 400 feet in front of the vehicle with no regard to glare since they should only be used when no oncoming traffic is present.
http://upload.wikimedia.org/wikipedia/commons/thumb/b/b1/Phare_route.png/800px-Phare_route.pnghttp://i89.photobucket.com/albums/k227/Raptor05121/Lighting/Headlights/DSC_2176.jpg
Fog Lamps
Front fog lamps provide a wide, bar-shaped beam of light with a sharp cutoff at the top, and are generally aimed and mounted low. They may be either white or selective yellow. They are intended for use at low speed to increase the illumination directed towards the road surface and verges in conditions of poor visibility due to rain, fog, dust or snow. As such, they are often most effectively used in place of dipped-beam headlamps, reducing the reflected glare from fog or falling snow, although the legality varies by jurisdiction of using front fog lamps without low beam headlamps. Use of fog lamps and high-beams is illegal and disable on most vehicles since foglights can cause your eyes to focus on the foreground rather than down the road.
Use of the front fog lamps when visibility is not seriously reduced is often prohibited, as they can cause increased glare to other drivers, particularly in wet pavement conditions, as well as harming the driver's own vision due to excessive foreground illumination.
The respective purposes of front fog lamps and driving lamps are often confused, due in part to the misconception that fog lamps are necessarily selective yellow, while any auxiliary lamp that makes white light is a driving lamp. Automakers and aftermarket parts and accessories suppliers frequently refer interchangeably to "fog lamps" and "driving lamps" (or "fog/driving lamps"). In most countries, weather conditions rarely necessitate the use of fog lamps, and there is no legal requirement for them, so their primary purpose is frequently cosmetic. They are often available as optional extras or only on higher trim levels of many cars. Studies have shown that in North America more people inappropriately use their fog lamps in dry weather than use them properly in poor weather.
http://i89.photobucket.com/albums/k227/Raptor05121/Lighting/fog1.jpghttp://i89.photobucket.com/albums/k227/Raptor05121/Lighting/Headlights/Picture070.jpg
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Optics
Today, there are two main ways of providing nighttime illumination. Reflector are the most common and projector are the newest. They both can utilize either a halogen or arc-xenon light source (see below).
Reflectors
Reflector headlights have been around for a long time, and they have a proven track record. They're design is simple: take a small light source and magnify it into a powerful beam with an array of mirrors. The housing is curved and covered with a reflective material. A bulb is mounted right in the center, and when it's on, the light strikes the reflective surface and is bounced back as a stronger, brighter and larger beam. The downside to this type of lamp, though, is that some of the light will inevitably scatter away and be lost. Almost 95% of all headlights on the roads use this design.
http://upload.wikimedia.org/wikipedia/commons/3/3b/Headlight_reflector_optics_schematic.pnghttp://www.octanemotorsports.com/images/ANZ-02-AZ-LN03-B-A.jpg
Projectors
The latest and greatest in automotive lighting technology is projector headlight technology. They work much like the traditional reflector optics, but with an added step. After the light bounces off the reflective surface, it travels through a lens, which focuses the light into an incredibly wide, powerful beam. Hardly any light is scattered away, so you're left with brilliant illumination. Along with this focused beam, projectors also feature a cutoff that prevents blindness from oncoming drivers. They can use halogen bulbs or arc-xenon capsules.
http://upload.wikimedia.org/wikipedia/commons/e/ed/Headlight_projector_schematic.pnghttp://i90.photobucket.com/albums/k247/retrofitsource4/HellaRS6BixenonProjector6.jpg
Projectors also have a low and high function. A projector that does both is called a bi-projector (bi- being the prefix for two). Usually the prefix is used in front of the lamp source. For instance, a dual-beam projector using a H11 bulb would be a "bi-halogen" projector. A dual-beam projector using a D2S arc-xenon capsule would be "bi-xenon". When used as a dual-beam, a magnetic solenoid attached to the cutoff shield is lowered out of the way of the light source, as to reveal the rest of the beam (below, left). Coincidentally, single-beam projectors that do not have a moveable cutoff shield must have a separate high-beam lamp (whether reflector or projector) in which case is very common in some vehicles as to preserve the flash-to-pass function required by law. (below, right).
http://i89.photobucket.com/albums/k227/Raptor05121/Lighting/Headlights/AWESOME.gifhttp://i89.photobucket.com/albums/k227/Raptor05121/Write-Ups/projectorReflector.jpg
Watt- Measure of electrical power (w)
Volt- Measure of electrical charge (v)
Kelvin- Measure of color temperature (K)
Lumen- Measure of light brightness (lu)
Capsule- technically correct term for a HID "bulb".
Candela- Measure of light intensity (cd)
Ampere- Measure of electrical current
SAE- Society of Automotive Engineers. The Society is a standards development organization for the engineering of powered vehicles of all kinds, including cars, trucks, boats, aircraft, and others.
Cut off- A distinctive line of light produced by the shield in a headlight that blocks light above a certain height in order to prevent blinding of other motorists.
FMVSS- Federal Motor Vehicle Safety Standard. A subsection of the National Highway Traffic Safety Administration. They set the laws on all vehicles intended for use in the USA
ECE- Economic Commission for Europe. they set the safety standards for all things intended to be sold and used in the United Kingdom.
Beam Pattern- The pattern of light that is projected onto the ground which includes angle of lateral dispersion, width and depth of illumination.
Capsule- Another term for an HID bulb. Some refer to HID bulbs as gas discharge capsules.
Optics- The lighting control assembly structured around the bulb, which effects the dispersion of light and it's characteristics to a great degree.
HID (High Intensity Discharge)= Gas Discharge
Overview
Low Beam
Low beam headlights provide a distribution of light designed to provide adequate forward and lateral illumination with limits on light directed towards the eyes of other road users, to control glare. This beam is intended for use whenever other vehicles are present ahead. North American SAE beam standard contained in FMVSS states that the low beam must illuminate objects up to 150 ft in front of the vehicle without causing glare to oncoming headlights.
http://upload.wikimedia.org/wikipedia/commons/thumb/4/48/Low_beam_light_pattern_for_right-hand_traffic.svg/800px-Low_beam_light_pattern_for_right-hand_traffic.svg.pnghttp://i89.photobucket.com/albums/k227/Raptor05121/Lighting/Headlights/DSC_2175.jpg
High Beam
High beam headlamps provide a bright, center-weighted distribution of light with no particular control of light directed towards other road users' eyes. As such, they are only suitable for use when alone on the road, as the glare they produce will dazzle other drivers. FMVSS states high beams must illuminate objects up to 400 feet in front of the vehicle with no regard to glare since they should only be used when no oncoming traffic is present.
http://upload.wikimedia.org/wikipedia/commons/thumb/b/b1/Phare_route.png/800px-Phare_route.pnghttp://i89.photobucket.com/albums/k227/Raptor05121/Lighting/Headlights/DSC_2176.jpg
Fog Lamps
Front fog lamps provide a wide, bar-shaped beam of light with a sharp cutoff at the top, and are generally aimed and mounted low. They may be either white or selective yellow. They are intended for use at low speed to increase the illumination directed towards the road surface and verges in conditions of poor visibility due to rain, fog, dust or snow. As such, they are often most effectively used in place of dipped-beam headlamps, reducing the reflected glare from fog or falling snow, although the legality varies by jurisdiction of using front fog lamps without low beam headlamps. Use of fog lamps and high-beams is illegal and disable on most vehicles since foglights can cause your eyes to focus on the foreground rather than down the road.
Use of the front fog lamps when visibility is not seriously reduced is often prohibited, as they can cause increased glare to other drivers, particularly in wet pavement conditions, as well as harming the driver's own vision due to excessive foreground illumination.
The respective purposes of front fog lamps and driving lamps are often confused, due in part to the misconception that fog lamps are necessarily selective yellow, while any auxiliary lamp that makes white light is a driving lamp. Automakers and aftermarket parts and accessories suppliers frequently refer interchangeably to "fog lamps" and "driving lamps" (or "fog/driving lamps"). In most countries, weather conditions rarely necessitate the use of fog lamps, and there is no legal requirement for them, so their primary purpose is frequently cosmetic. They are often available as optional extras or only on higher trim levels of many cars. Studies have shown that in North America more people inappropriately use their fog lamps in dry weather than use them properly in poor weather.
http://i89.photobucket.com/albums/k227/Raptor05121/Lighting/fog1.jpghttp://i89.photobucket.com/albums/k227/Raptor05121/Lighting/Headlights/Picture070.jpg
--------------------------------------------------------------------------------------------------------------
Optics
Today, there are two main ways of providing nighttime illumination. Reflector are the most common and projector are the newest. They both can utilize either a halogen or arc-xenon light source (see below).
Reflectors
Reflector headlights have been around for a long time, and they have a proven track record. They're design is simple: take a small light source and magnify it into a powerful beam with an array of mirrors. The housing is curved and covered with a reflective material. A bulb is mounted right in the center, and when it's on, the light strikes the reflective surface and is bounced back as a stronger, brighter and larger beam. The downside to this type of lamp, though, is that some of the light will inevitably scatter away and be lost. Almost 95% of all headlights on the roads use this design.
http://upload.wikimedia.org/wikipedia/commons/3/3b/Headlight_reflector_optics_schematic.pnghttp://www.octanemotorsports.com/images/ANZ-02-AZ-LN03-B-A.jpg
Projectors
The latest and greatest in automotive lighting technology is projector headlight technology. They work much like the traditional reflector optics, but with an added step. After the light bounces off the reflective surface, it travels through a lens, which focuses the light into an incredibly wide, powerful beam. Hardly any light is scattered away, so you're left with brilliant illumination. Along with this focused beam, projectors also feature a cutoff that prevents blindness from oncoming drivers. They can use halogen bulbs or arc-xenon capsules.
http://upload.wikimedia.org/wikipedia/commons/e/ed/Headlight_projector_schematic.pnghttp://i90.photobucket.com/albums/k247/retrofitsource4/HellaRS6BixenonProjector6.jpg
Projectors also have a low and high function. A projector that does both is called a bi-projector (bi- being the prefix for two). Usually the prefix is used in front of the lamp source. For instance, a dual-beam projector using a H11 bulb would be a "bi-halogen" projector. A dual-beam projector using a D2S arc-xenon capsule would be "bi-xenon". When used as a dual-beam, a magnetic solenoid attached to the cutoff shield is lowered out of the way of the light source, as to reveal the rest of the beam (below, left). Coincidentally, single-beam projectors that do not have a moveable cutoff shield must have a separate high-beam lamp (whether reflector or projector) in which case is very common in some vehicles as to preserve the flash-to-pass function required by law. (below, right).
http://i89.photobucket.com/albums/k227/Raptor05121/Lighting/Headlights/AWESOME.gifhttp://i89.photobucket.com/albums/k227/Raptor05121/Write-Ups/projectorReflector.jpg