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Lidar-on-a-Chip: Scan Quickly, Scan Cheap

Phased-array laser scanner may finally give cars the sharp vision they need

2 min read
Lidar-on-a-Chip: Scan Quickly, Scan Cheap
With a LIDAR chip on every corner you can assemble a panoramic view
Illustration: DARPA

You can hide radar behind the grill of your car or under a plastic body panel, but the laser equivalent, lidar, typically sticks out as a box above the bumper or as a tower on the top. That’s because the laser beam must be steered mechanically.

Besides being big and ugly, today’s lidar is expensive, and for that reason rare on the roads. Only the experimental cars carry it. But that will change, according to DARPA.

The defense research agency has just demonstrated a LIDAR-on-a-chip system that steers its electronic beam much as today’s radars do—using arrays of many small emitters that each put out a signal at a slightly different phase. The new phased array thus forms a synthetic beam that it can sweep from one extreme to another and back again 100,000 times a second. That beats today’s fastest laser roof ornaments by a factor of 10,000.

Like all things military, the device has a long name contrived to produce a suitable acronym:  Short-range Wide-field-of-view Extremely agile Electronically steered Photonic EmitteR. Sweeper—it rhymes with Reaper.

True, the experimental system covers only a 51-degree field, but that’s the best any one-chip deal has ever managed. And it’s more than enough: Just salt a few of these sensors around a car, and the central controller will piece together a perfect panorama.

The main challenge for the chip’s inventors was how to pull off the beam-forming trick not at radio frequencies but at optical ones, whose waves aren’t  even a thousandth as long. “This means that the array elements must be placed within only a few microns of each other and that manufacturing or environmental perturbations as small as 100 nanometers can hurt performance or even sideline the whole array,” DARPA said in a statement.

The project solved those problems with photolithographic wizardry, provided by researchers at the University of California, Berkeley; University of California, Santa Barbara; HRL Laboratories; and MIT (whose work on optical phased array we covered two years ago).

DARPA says there’s every reason to expect the technology to lend itself to mass production. That, of course, would lower the cost per chip—enough to get them into cars, robocopters, and who knows what else.

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We Need More Than Just Electric Vehicles

To decarbonize road transport we need to complement EVs with bikes, rail, city planning, and alternative energy

11 min read
A worker works on the frame of a car on an assembly line.

China has more EVs than any other country—but it also gets most of its electricity from coal.

VCG/Getty Images
Green

EVs have finally come of age. The total cost of purchasing and driving one—the cost of ownership—has fallen nearly to parity with a typical gasoline-fueled car. Scientists and engineers have extended the range of EVs by cramming ever more energy into their batteries, and vehicle-charging networks have expanded in many countries. In the United States, for example, there are more than 49,000 public charging stations, and it is now possible to drive an EV from New York to California using public charging networks.

With all this, consumers and policymakers alike are hopeful that society will soon greatly reduce its carbon emissions by replacing today’s cars with electric vehicles. Indeed, adopting electric vehicles will go a long way in helping to improve environmental outcomes. But EVs come with important weaknesses, and so people shouldn’t count on them alone to do the job, even for the transportation sector.

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