Osram's Laser Chip for Lidar Promises Super-Short Pulses in a Smaller Package

osram laser chip
Image: Osram Opto Semiconductors

Those twirling banks of lasers you see atop experimental robocars cost plenty, wear fast, and suck power. The auto industry yearns to solve all those problems with a purely solid-state lidar set that designers can hide behind the grill of a car.

Their wish will come true next year, according to Osram Opto Semiconductors. The company says test samples will be available in 2017, and that commercial models could arrive in 2018. With mass production, the price should drop to around 40 Euros (US $43.50), says Sebastian Bauer, the product manager for Osram, in Regensburg, Germany. 

By comparison, Velodyne’s rooftop lidar towers cost $70,000 and up, and that company’s new, hockey-puck-size model runs around $8000.

Osram’s contribution to the lidar system is a laser chip whose four diodes were all made in one piece, then separated. That means they’re perfectly aligned from the get-go, with no need for after-the-fact fiddling. Each channel fires in sequence, so the returning signal can be matched to its source, thus enabling the system to add each petty piece of angular scope into an ensemble capable of sweeping a large vertical swath.

“You need that for the forward-looking lidar,” Bauer says”Think of a car travelling along a hilly road, where a single beam’s not enough—often, you’ll just see the sky.”

The other key part of the lidar is a tiny array of mirrors to steer the laser beam. That’s being provided by Osram’s partner, Innoluce, which Infineon Technologies acquired last month. The mirrors are part of a microelectromechanical system (MEMS), so they move on a tiny scale. The MEMS chip can operate at up to 2 kilohertz, scanning the environment for the data a car needs to perform 3D mapping. 

Osram’s four lasers each pulse for 5 nanoseconds, just one-quarter as long as the one-channel laser the company now makes for emergency stopping systems and other functions. Because the laser quickly reaches peak power and then winks out, it can support a robust peak power of 85 watts while shining for only 0.01 percent of the time. That makes it safe for the eyes.

The overall lidar system covers 120 degrees in the horizontal plane, with 0.1 degree of resolution, and 20 degrees in the vertical plane, with 0.5 degree of resolution. In the light of day, it should detect cars from at least 200 meters away, and pedestrians at 70 meters out.

How did Osram generate such short, powerful pulses? “We integrated the driver chip from a partner and included a capacitor in the package, keeping the distance between the parts short, so there’s little inductance,” Bauer says. 

It seems straightforward enough. Why, then, didn’t somebody do it earlier?

“Good question,” Bauer laughs. “It’s because the lidar market took off just a few years ago, and before that, it was all about these towers on top of the cars. And there were hard problems to solve—it’s not enough to work just in the lab; it has to pass stress tests. It has to be good enough for automotive use.”

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