A new military LIDAR chip shows promise for faster and more precise aerial mapping—doing in minutes what used to take day. In 2012, 20 hours of helicopter flight time were needed to map 370 square kilometers to a resolution of one meter. A new LIDAR (light detection and ranging) 3-D imaging system could perform the same job in 30 minutes and with higher resolution.
LIDAR systems fire lasers and detect returning photons, using the timing of those return trips to measure distance and thus make 3-D images. At the heart of the new imaging system is a microchip bearing the largest-ever array of pixels that detect just one photon apiece—more than 16,384 pixels in all. The array of pixels, when paired with optical lenses, allows imaging of wider areas. “Arrays of these single-photon detectors are able to map wide areas very quickly,” Fried says.
In today’s airborne LIDAR systems, individual detectors are much less sensitive; and they are mechanically moved along with the laser that emits the light to capture a wider field of view.
Part of the Angkor Wat LIDAR scan
As the chip-making process improves and prices come down, the technology could find far more applications in fields including glaciology, agriculture, and archaeology—and perhaps even find its way into autonomous mass-market cars, says Mark Itzler, CEO of Princeton Lightwave. Right now, commercial versions of automotive LIDAR that can see farther than a few meters cost upwards of $30,000, and usually require a bulky mechanical apparatus.
While a number of different kinds of LIDAR are being considered for cars, the indium gallium arsenide approach has a long-term advantage; it can safely be ramped up to extremely high power levels. Current systems use silicon, which operates within visible light frequencies. As a result, powering them up to levels high enough to be able to tackle important jobs—like detecting an animal 200 meters ahead even on foggy highway—raises the risk of eye injury. “Enough of the [auto suppliers] see eye safety as a long-term issue that they are very interested in single-photon sensitivity at wavelengths where you have this enormously eye-safer operation,” Itzler says.