Wednesday, February 19, 2014

The World’s Most Powerful 3-D Laser Imager

Airborne laser scanning has produced stunning maps and insights in the last few years. Among others, it revealed the faint outlines of a vanished medieval city street grid obscured by the jungle surrounding Cambodia’s Angkor Wat (see “Laser Scanning Reveals New Parts of an Ancient Cambodian City”), a feat that required 20 hours of helicopter flight time to map 370 square kilometers to a resolution of one meter.

But in a secure hangar at Hanscom Air Force Base in Bedford, Massachusetts, the belly of a Bombardier turboprop has been outfitted with technology that could pull off the Cambodian job in about half an hour. The fuselage holds a new LIDAR (light detection and ranging) 3-D imaging system that works with unprecedented speed and high resolution, says Dale Fried, principal developer of the system at Lincoln Laboratory, a federally funded R&D center run by MIT.

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.

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