Audi plans to migrate its new advanced laser-based headlamps through its model range, the brand’s technology chief revealed during the 2014 Geneva Motor Show.
Dr. Ulrich Hackenburg, Member of the Board of Management for Technical Development, told Automotive Engineering during a media roundtable that headlamps featuring laser-diode high-beam elements throw a white beam with superior luminosity, optical direction, overall efficiency, and vastly longer life compared to light-emitting diode (LED)-based units now entering the market.
Extensive testing of laser high beams by Audi’s Headlamp Development Project Team has shown an effective illumination range of 600 m (1970 ft), with three times the luminosity of LED-type high beams, Dr. Hackenburg reported, with a brilliant beam quality that provides more nighttime visual acuity and less fatigue for the driver, but doesn’t hit oncoming drivers like a Sci-Fi movie death ray.
Tier 1 lighting suppliers are expecting Audi to offer production laser high-beam elements in the A8 in the 2016 timeframe, one of them told Automotive Engineering. Dr. Hackenburg said initially the powerful laser high beams will be combined with low-beam LED arrays.
Headlamps that feature laser-diode semiconductors typically generate a bluish beam at a wavelength of 450 nm. The beam, generated from the rear of the housing, is directed toward the front through a set of collimating mirrors onto a yellow-phosphorous wafer. Excited by the blue laser, the yellow phosphorous emits a diffused, brilliant white light that is bounced off a reflector, through the headlamp lens, and onto the road ahead. Laser-lighting experts believe automotive headlamps will have electrical-to-optical efficiencies of 50-60%.
Audi broke news of its laser-lighting development last January at the 2014 Consumer Electronics Show, where it displayed the Sport quattro “laser light” concept car (http://articles.sae.org/12729/). That vehicle features a pair of trapezoidal headlamp elements per side, with the laser diodes on the inner ring surrounded by a ring of low-beam LEDs.
The company’s latest R18 e-tron factory-prototype endurance racecar will have laser diodes integrated into matrix-beam LED headlamps at the 24 Hours of LeMans in June to prove the technology’s value in an extreme operating environment.
“Laser light provides a much more homogenous and precise spread in front of the car,” explained Chris Reinke, head of LeMans prototype development at Audi Sport. Systems cooling is a critical issue in designing laser diodes to meet the auto industry’s long-term durability requirements.
Audi used its 2011 R18 to showcase its first full-LED headlamps. It first used LED running lights in 2006, one year before Toyota debuted the first production-car LED headlamps on its Lexus LS 600h.
BMW has claimed it will be first to offer laser-diode headlamps on its $136,000 i8 range-extender EV, setting up an OEM leadership battle on the lighting-technology vanguard.
Audi has been investigating laser-based exterior lighting systems for about five years, and first showed a laser fog lamp on an A2 concept. Dr. Hackenburg indicated that the automaker has been collaborating with two lighting suppliers to develop production-suitable technologies, but did not identify a vendor.
Likely Tier 1 partners might include Hella, which helped develop Audi’s LED-based MatrixBeam system used on European A8 models (http://articles.sae.org/12579/), and Osram Opto Semiconductors, known to have a significant laser-lighting development program.
Audi officials at Geneva told Automotive Engineering that the new laser-diode headlamps will not be available on U.S. models until the technology is approved by federal vehicle safety regulators. The MatrixBeam system also is not yet legal for use in the U.S.