This Single-Photon Lidar Delivers 10 Times the Resolution, Mile-Scale Ranging
Researchers propose an expansion into a new wavelength, too, which could render smoke and fog no obstacle to 3D sensing.
Researchers from Heriot-Watt University, the California Institute of Technology's Jet Propulsion Laboratory, the Ecole polytechnique fédérale de Lausanne (EPFL), the University of Glasgow, and the Massachusetts Institute of Technology want to shine a light on detailed 3D imaging at a distance — with a single-photon lidar delivering a range of nearly two-thirds of a mile.
"Our system uses a single-photon detector approximately twice as efficient as detectors deployed in similar lidar systems reported by other research groups and has a system timing resolution at least 10 times better," boasts first author Aongus McCarthy of the team's work. "These improvements allow the imaging system to collect more scattered photons from the target and achieve a much higher spatial resolution."
Lidar sensors are based on a similar concept to radar, but rather than using radio for detection and ranging it uses light. Delivering detailed 3D distance measurements, lidar sensors are popular for use in autonomous vehicles — but struggle to work in foggy or smoky conditions and typically operate at a relatively short maximum range.
The team's lidar sensor, by contrast, can operate at a tested range of one kilometer (around 0.6 miles). The trick: a combination of a superconducting nanowire single-photon detector (SNSPD) with a custom single-pixel scanning transceiver and picosecond-resolution timing equipment.
"These factors all provide improved flexibility in the trade-off between standoff distance, laser power levels, data acquisition time, and depth resolution," McCarthy explains. "Also, since SNSPD detectors can operate at wavelengths longer than 1550nm, this design opens the door to developing a mid-infrared single-photon lidar system, which could further enhance imaging through fog and smoke and other obscurants."
In addition to its enhanced range, which the team is hoping to extend to 10km (around 6.2 miles), the sensor also proved dramatically higher resolution than the team's previous creations — resolving features in a 3D-printed target down to 1mm at a distance of 325m (0.04 inches at 1,066 feet), 10 times the team's previous best.
"The excellent depth resolution of the system means that it would be particularly well suited for imaging objects behind clutter, such as foliage or camouflage netting, a scenario that would be difficult for a digital camera," McCarthy opines. "For example, it could distinguish an object located a few centimeters behind a camouflage netting while systems with poorer resolution would not be able to make out the object."
The team's work has been published in the journal Optica under open-access terms.