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Laser Headlights Light Up the Highway
Over the past year, automakers Audi and BMW have both announced that they plan to offer vehicles equipped with headlamps featuring diode lasers as a source of light.
Currently it appears as if BMW will cross the finish line first with a production vehicle equipped with the laser technology. It has disclosed that its laser light system will be incorporated into its i8 plug-in hybrid sports car as an option when it goes on sale later this year.
Rival Audi, on the other hand, announced its intention to incorporate lasers into headlamps when it previewed the technology on an Audi Sport Quattro at the CES show in January 2013. The company will also be using laser lighting in its R18 Le Mans prototypes as auxiliary driving lights. However, it remains to be seen when the new lighting system will first make an appearance in headlamps in a production vehicle.
Today, many new vehicles are fitted with LED headlights, including those from Audi, BMW and Mercedes-Benz. So prevalent has LED technology become that, in December last year, Mercedes-Benz disclosed that it will be making a complete switch to LED lighting, and that its new S-Class will become the first vehicle in the world to do without a single light bulb as standard.
But just as LED lighting inexorably gains an increasing foothold in the automotive world, a new kid on the block has arrived that looks to complement it. And that lighting technology employs laser diodes to create a light source. In BMW’s new system, the laser-diode illumination system is used in conjunction with the LED headlamps to provide a boost to the range of the high beam.
According to Dr. John Bullough, a Senior Research Scientist at the Lighting Research Center at Rensselaer Polytechnic Institute in Troy, New York (US), both LED and laser diode headlamps are presently still relatively expensive, because they have not yet achieved the high volumes that will eventually bring about lower pricing.
But he notes that they do have some advantages. Because both LED and laser sources have higher efficiency in terms of "lumens per watt" than halogen lamps, they can produce more light per input power, which can result in greater amounts of light on the road which can create better forward visibility. Alternatively, they can use lower power, which puts less drain on the vehicle's electrical system.
According to Mercedes-Benz, LED low-beam headlamps that require just 34W are more efficient than halogen (120W) and xenon light bulbs (84W) while still able to produce the same equivalent light output. For its part, BMW claims that the new laser technology will increase that energy efficiency by a further 30%.
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Laser light
In the BMW laser lighting system, the rays from three blue laser diodes are focused on to a yellow phosphor conversion module that is cooled to avoid the effects of local heating. The blue light absorbed by the phosphor layer is converted to yellow light, which is combined with blue light that passes through the phosphor layer to produce a broadband white light. The light is then is directed through the optical system of the headlight onto the surface of the road.
Stefan Weber, the Project Manager of BMW’s so-called “Laserlight project†acknowledges that the main advantage of the laser light source is that its luminance is ten times greater than that of an LED. While a typical high-powered LED chip might be 1 mm² in area, the area of a phosphor layer illuminated by blue laser diode might be only 0.3 mm² to produce the same amount of light. This makes it possible to shape a beam pattern with a relatively small optical element very precisely. Because the laser device is small, it also enables designers to build headlights that are more compact than today's models.
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Over the past year, automakers Audi and BMW have both announced that they plan to offer vehicles equipped with headlamps featuring diode lasers as a source of light.
Currently it appears as if BMW will cross the finish line first with a production vehicle equipped with the laser technology. It has disclosed that its laser light system will be incorporated into its i8 plug-in hybrid sports car as an option when it goes on sale later this year.
Rival Audi, on the other hand, announced its intention to incorporate lasers into headlamps when it previewed the technology on an Audi Sport Quattro at the CES show in January 2013. The company will also be using laser lighting in its R18 Le Mans prototypes as auxiliary driving lights. However, it remains to be seen when the new lighting system will first make an appearance in headlamps in a production vehicle.
Today, many new vehicles are fitted with LED headlights, including those from Audi, BMW and Mercedes-Benz. So prevalent has LED technology become that, in December last year, Mercedes-Benz disclosed that it will be making a complete switch to LED lighting, and that its new S-Class will become the first vehicle in the world to do without a single light bulb as standard.
But just as LED lighting inexorably gains an increasing foothold in the automotive world, a new kid on the block has arrived that looks to complement it. And that lighting technology employs laser diodes to create a light source. In BMW’s new system, the laser-diode illumination system is used in conjunction with the LED headlamps to provide a boost to the range of the high beam.
According to Dr. John Bullough, a Senior Research Scientist at the Lighting Research Center at Rensselaer Polytechnic Institute in Troy, New York (US), both LED and laser diode headlamps are presently still relatively expensive, because they have not yet achieved the high volumes that will eventually bring about lower pricing.
But he notes that they do have some advantages. Because both LED and laser sources have higher efficiency in terms of "lumens per watt" than halogen lamps, they can produce more light per input power, which can result in greater amounts of light on the road which can create better forward visibility. Alternatively, they can use lower power, which puts less drain on the vehicle's electrical system.
According to Mercedes-Benz, LED low-beam headlamps that require just 34W are more efficient than halogen (120W) and xenon light bulbs (84W) while still able to produce the same equivalent light output. For its part, BMW claims that the new laser technology will increase that energy efficiency by a further 30%.
>
>
Laser light
In the BMW laser lighting system, the rays from three blue laser diodes are focused on to a yellow phosphor conversion module that is cooled to avoid the effects of local heating. The blue light absorbed by the phosphor layer is converted to yellow light, which is combined with blue light that passes through the phosphor layer to produce a broadband white light. The light is then is directed through the optical system of the headlight onto the surface of the road.
Stefan Weber, the Project Manager of BMW’s so-called “Laserlight project†acknowledges that the main advantage of the laser light source is that its luminance is ten times greater than that of an LED. While a typical high-powered LED chip might be 1 mm² in area, the area of a phosphor layer illuminated by blue laser diode might be only 0.3 mm² to produce the same amount of light. This makes it possible to shape a beam pattern with a relatively small optical element very precisely. Because the laser device is small, it also enables designers to build headlights that are more compact than today's models.
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