Laser Headlights Can Make Roads Brighter—and Cars Smarter

Laser. The very word conjures thoughts of dark magic and planet-pulverizing weaponry. Not the sort of thing you want or need to guide your nighttime driving, especially since today’s LED headlights appear bright enough to convert roadside deer into venison. But Santa Barbara-based SLD Laser says that it has found a way to harness coherent monochromatic light to make it the right tool for lighting the way forward, in more than the literal sense.

The company’s pitch hinges on the work of its cofounder, Shuji Nakamura. The Nobel Prize-winning Japanese physicist invented a way to make laser light, typically invisible to the humans, visible blue light. By running it through a specialized filter called a phosphor, he created a white light that is a hundred times brighter than that emitted by LEDs, yet is safe for human eyes. SLD is now bringing its laser light headlamp to market, starting with BMW in Europe, and expected to land soon in the US, in the M5.

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These laser headlights will add $1,500 to the M5’s price tag, but justify it with a variety of bright spots for use as headlights. Because their beams are less diffuse than those of other light sources, they can be aimed more precisely at their target and less blindingly into the eyes of other motorists. They’re more compact than traditional lighting setups, and can be twisted into threadlike shapes previously unavailable. That helps car designers create new vehicular “faces” or “lighting signatures,” a nice trick in an age where electric propulsion obviates the need for long hoods and big grilles, long focal points in auto aesthetics. Plus, lasers use less electricity than older light forms, saving battery power for moving the wheels.

The fun part, though, is how this tech could go well beyond helping human eyes take in the world around them. Welcome to the world of Li-Fi, a term coined in a 2011 TED Talk by University of Edinburgh mobile communications professor Harald Haas, who’s now a consultant to SLD. “If you think of telecommunications, it is all done with fiber optics, which is laser light vibrating through a glass fiber,” Haas says. Like cellular radio waves, this light is just another chunk of the electromagnetic spectrum, but one that operates at a much higher frequency. As you go up in frequency, the bandwidth available for data transmission increases significantly. “All we’re doing is using the concept of data light, but instead of plumbing it through fiber optics, we’re doing it with safe white light that can also be a light source,” he says.

A big downside for Li-Fi: Light doesn’t go through walls or around corners, so you can only send data to things you can see.

Courtesy of SLD Laser

In other words, your headlamps could someday broadcast data—not that any automakers are working on that at the moment. And not just your headlamps, but anything that emits artificial light. “Could be with a streetlight, could be with stoplights or stop signs,” says Nakamura’s SLD cofounder, Paul Rudy. “Could even be a light bulb inside your house, replacing your Wi-Fi router.” If you want to nix the visible light, these systems work fine in infrared.

That’s exciting on the road because cars are dealing with more data than ever before. The tech could be used for vehicle-to-vehicle, or vehicle-to-infrastructure communication. Broadcasting headlamps could replace some of the functionality of current radar systems used for adaptive cruise control and other in-vehicle safety systems, packaging them within a system that already exists, instead of creating yet another detector suite. This would save engineers and designers the trouble of fighting for valuable real estate on a car’s front fascia, or behind its windshield.

“It is a struggle just to find a few cubic centimeters to package that radar module and cable and all that,” says Tom LeMense. The Detroit-based engineer has worked on radar, lidar, and other automotive communication, safety, and sensing systems for decades, and is a named inventor on more than 20 patents related to these devices. “So a solution that’s integrated elsewhere could be interesting.”

Too bad the challenges facing the widespread implementation of Li-Fi seem nearly as broad as its potential applications. The first revolves around the fact that the tech requires a visible line of sight, since light doesn’t go around corners or through walls. “If you want to just communicate with the vehicles that you can see around you, then yeah, that’s maybe a solution,” Le Mense says. “With Li-Fi, you’ve solved the bandwidth problem, but it’s kind of like a bridge to nowhere.” (This also holds true for in-home uses. Your phone wouldn’t be able to pick up a Li-Fi signal if it was in your pocket. Time to Dad-core up and bring back the belt-borne phone holster?)

Cost is also an issue. Just about all current networked driver assistance technologies operate on the familiar, established, and nearly ubiquitous cellular spectrum. A new setup would mean more spending to build more infrastructure. That would be hard to justify, LeMense says, especially since vehicle-to-vehicle comms mostly entail small amounts of data, like each car’s position, speed, and heading.

That could change as the world moves away from human driving. “Once you’ve got autonomous cars with all their data needs, you need gigabits or tens of gigabits per second, and you’re moving,” Rudy says. “So if you’re going through a stoplight and you want to do a data exchange, you know you need to do it quick.”

Yes, our ephemeral communications may soon require other, invisible spectra to assist their spectral self-driving capabilities. For now, though, the laser fans will have to settle for a better view of the road ahead.

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