If you’ve walked around a major city like San Francisco in the past couple years, you’ve probably noticed cars topped with bulky, spinning discs—the mark of self-driving vehicles in training.
Inside those flying-saucer-like rigs are upwards of tens of thousands of dollars’ worth of lasers used for light radar (lidar). Lidar detects objects like cars, pedestrians, and bicyclists by scanning them with laser light, then measuring the light that gets reflected back. It’s a key enabling technology for self-driving cars. But those cars are going to stay in testing mode forever if lidar costs don’t go down.
Sydney-based startup Baraja, which came out of stealth mode today, plans to provide a less expensive solution by repurposing key technologies from the telecom industry, says CEO and cofounder Federico Collarte. Instead of using moving parts and multiple lasers, the Baraja design uses a single multicolor laser and prismlike optics to split and scan its beam over a field ranging 30 degrees in the vertical and 92 in the horizontal. To get a 360-degree view, the company places four of these sensor sets on the roof of a car.
Baraja’s design places the laser in a small box inside the car, ideally by the onboard computer, well away from the elements. Light from the laser travels to the roof over fiber-optic cables. Each of the rooftop sensor heads contains prismlike optics that split the beam into an infrared rainbow, with hundreds or thousands of different colors each emerging at a slightly different angle. To sweep a particular part of the field, just change the color of the laser to the right band of the spectrum, and the prisms will send beams to the desired place. This takes less than a millisecond—no moving parts required. The sensor heads are resilient, and can be submerged in water or blasted with a hose, says Collarte.
The system can rapidly adapt to the circumstances, changing the visual field or providing more detail in a particular region by changing the color of the laser, says Collarte. The onboard computer might decide to use the lidar to get a more detailed look at who or what is in the crosswalk a couple feet away, or focus farther ahead—up to about 250 meters—when driving at freeway speeds.
Lidar images are made up of matrices of dots, each of which represents a beam of laser light that reflected off a person or thing in range of the system. The resolution depends on how many of these dots are packed into each image, as well as the size of the light beam. Collarte says their images have up to millions of dots and a resolution of about 10 centimeters at 100 meters.
Riding in a van equipped with one of the sensor heads and a display in the back seat, Collarte explains what we’re seeing on a real-time lidar video of the streets of San Francisco.
Baraja’s compact lidar system assembles dots of reflected laser light into an image of its surroundings. Photo: Katherine Bourzac
We’re in the booming Dogpatch neighborhood, so the environment provides plenty of pedestrians, trams, construction cranes, and cars. We start out looking at the world through 64 lines of lidar dots. Each line represents a different color of reflected light. At the touch of a button, Collarte doubles the resolution to 128 lines. The system can distinguish between more or less intense reflected beams, and displays them as yellow or blue dots. That means the bright, close crosswalk shows through bright yellow, while the road ahead looks a more vague, pointillistic blue. Collarte shows how the system can rapidly adjust the field of view to keep on focusing straight ahead when we go up and down a hill, or shift the focus to see a couple hundred meters ahead, which would be important during highway driving.
Collarte and cofounder and CTO Cibby Pulikkaseril met while developing multicolor lasers at optics company Finisar. These lasers are used for wavelength-division multiplexing, which enables telecommunications companies to send or receive multiple colors of light on a single fiber-optic cable—the more bandwidth the better.
The Baraja system has adopted a telecom laser that can emit a spectrum of wavelengths centered around 1,500 nanometers, well into the infrared. Pulikkaseril says these telecom optics have several advantages. This wavelength is invisible to the human eye. And the sun doesn’t emit much of this wavelength either, so that eliminates a potential source of interference. Pulikkaseril says he’s thinking ahead to a future when there might be hundreds of lidar-equipped self-driving cars on the road. “If you have hundreds of cars pulsing all this light out, you will get interference,” he says. Their system eliminates this possibility because the light has to come back at a certain angle, time, and wavelength, or it won’t couple back into the prismlike optics.
Collarte says the company has been in talks with potential buyers while developing its designs but is not currently announcing any customers.
Katherine Bourzac is a freelance journalist based in San Francisco, Calif. She writes about materials science, nanotechnology, energy, computing, and medicine—and about how all these fields overlap. Bourzac is a contributing editor at Technology Review and a contributor at Chemical & Engineering News; her work can also be found in Nature and Scientific American. She serves on the board of the Northern California chapter of the Society of Professional Journalists.