LED headlamps are only just trickling onto the market — mostly on high-end cars — but now it seems a certain German automaker has plans for laser headlamps. “Laser light is the next logical step in car light development … for series production within a few years in the BMW i8 plug-in hybrid,” says BMW. Lasers have the potential to be simultaneously more powerful, more efficient, and smaller than other headlamp types. Before you get too excited, though: the output of laser headlights will be modulated for safety so you can’t, for better or worse, come up close and bubble the paint of the car in front that won’t get out of the left-hand lane on the interstate.
The benefits of a laser headlamp are compelling: a near parallel beam of light 1,000 times more intense than conventional LEDs but with less than half the energy consumption; 170 lumens of output per watt for laser headlamps, compared to 100 lumens per watt for LEDs. Both are phenomenally efficient compared to a standard household light bulb; a 100-watt bulb produces about 1,000 lumens of illumination.
A laser diode used in a headlamp array is just 10 microns long while the LEDs (light emitting diodes) have a side length of 1 millimeter, 100 times larger. So it’s theoretically possible to have a tiny headlamp that shouts “new technology,” though BMW says any new laser headlamps it uses would “retain their conventional surface area dimensions and so continue to play an important role in the styling of a BMW.” BMW was one of first automakers with stylized headlamps, in this case the corona rings or angel eyes around its headlamps (photo above). Regardless, the headlamp assemblies would be shallower front-to-back, allowing for greater flexibility in placement and less intrusion into the engine compartment, as long as the automaker uses only laser headlamps on a model.
Laser headlamps would be safe, BMW says, because the illumination leaving the headlamp is indirect. The blue laser beam is also converted by a fluorescent phosphor material into a pure white light — “pleasant to the eye,” BMW says — and the headlamp will also be able to implement several of BMW’s optional features including automatic pedestrian illumination (Dynamic Light Spot in BMW parlance), auto-dimming (Anti-Dazzle High Beam Assistant), and steerable headlamps (Adaptive Headlights).
The history of headlamps of the past generation has been from the yellowish tungsten headlamps dating to the first half of the 20th century to quartz headlamps (longer-lived, brighter) to xenon or high-intensity discharge headlamps with the seeming blue cast (actually closer to white) and LED headlamps. Along the way, automakers first in Europe and then in the US cut lenses into the headlamps to more precisely steer the lighting.
One uncertainty of laser headlamps will be cost. Premium headlamps such as Xenon and LED have had upcharges of as much as £1,000 on premium cars.