Luminar made the cost question harder by making its lidar’s receiver (the bit that acts like your eye’s retina) out of indium gallium arsenide (InGaAs) instead of silicon. Why is this important? Well, to make your lidar “see” farther, you have to fire more powerful pulses of light. They have to be powerful so they have the strength to hit faraway objects and make it all the way back. Most lidars use lasers at the 905 nanometer wavelength. That’s invisible to humans. But if it hits an actual eyeball, like yours, with enough power, it can damage the retina. If you want to fire more powerful pulses (and have your lidar “see” farther) without blinding actual people, you can use the 1550 nanometer wavelength, which is further into the infrared part of the spectrum, and thus can’t penetrate a human eyeball.

Which brings us back to silicon. Receivers made of silicon, which is cheap, can’t detect light at the 1550 wavelength. InGaAs can, but it’s far more expensive. So the industry standard is to use silicon, run at 905 nanometers, and accept you just can’t send your lasers all that far.

But Russell insisted on the extra power, which meant 1550 nanometers, which meant using a receiver made of InGaAs. As a result, he can fire pulses 40 times more powerful than what his competitors shoot, so his lidar can see extremely dark objects—the kind that can absorb 95 percent of light—even from 250 meters away. He says no one’s lidar can see so well at such distance.

But seriously, InGaAs, as the French say, coute la peau des fesses*. A receiver array about the size of a big potato chip can cost tens of thousands of dollars, Russell says. So Luminar built its own. The result, now in its seventh iteration, is about the size of a strawberry seed. (The entire unit, including the laser and accompanying electronics, is about half a foot square and three inches deep.) That includes the chip that calculates, down to the second, how long the photon has been out in the world. It costs a piddling $3, obliterating Luminar’s cost concerns while allowing for that extra range and resolution. Russell wouldn’t reveal an exact price for the lidar as a whole, but says his customers are quite pleased. And when they’re finally ready to start offering you rides in their robo-taxis, maybe they won’t have to charge you as much for that trip home from the bar.

Luminar’s R&D team also managed to increase the “dynamic range” of the receiver. Just like how your pupils dilate based on light conditions, lidar receivers are tuned to pick up pulses of a certain strength (the farther a photon goes before bouncing back, the weaker it becomes). If you set it to look for faint signals and it gets hit by a much stronger pulse, you can fry the receiver. “We have countless blown-up detectors,” Russell says. The current unit can handle a much greater range of pulse strengths, without even a wisp of smoke.

Meanwhile, Luminar’s already working on the next generation sensor. That one, Russell says, will be affordable enough to put in consumer cars—making the gift of sight little more than a commodity.

Rolling Toward Ready