- A team of scientists have integrated an ultrasensative sensor called a “superconducting nanowire single-photon detector,” or SNSPD, into a LiDAR system with incredible results.
- Capable of capturing detailed 3D images one full kilometer away, this system could have a huge impact on mapping, military, and space applications.
- One kilometer isn’t the limit of the system, however, and scientists hope to test the distances up to 10 kilometers in the near future.
Light Detection and Ranging (LiDAR)—first developed by the Hughes Aircraft Company in 1961—is a technology you may not think about often, but many scientists and engineers find impossible to live without. By timing laser pulses to measure distance with immense accuracy, the technology has been a game-changer for robotics, autonomous vehicles, ocean seafloor mapping, and much more.
However, like all technologies, there’s always room for improvement. And a new study—led by Heriot-Watt University in Edinburgh and including scientists from NASA’s Jet Propulsion Laboratory (JPL), MIT, and the University of Glasgow—details the creation of a superconducting LiDAR system capable of accurately capturing 3D data up to an astonishing one kilometer away, with resolution at the millimeter-scale.
This breakthrough was only possible due to an ultra-sensitive sensor called the superconducting nanowire single-photon detector (SNSPD). Co-developed by NASA and MIT, this system can track a single photon to an accuracy of just 13 picoseconds (13 trillionths of a second), which is 10 times better than any system timing that currently exists. The results of the study were published in the journal Optica.
“The timing is really phenomenal,” Aongus McCarthy, lead author of the study from Heriot-Watt University, said in a press statement. “It allows us to measure variations in depth very, very accurately—on a millimeter scale—which means we can distinguish between closely separated surfaces at very long distances.”
The team tested the system using three distances: 45 meters, 325 meters, and one kilometer. The above image, which captured the facial contours of research co-author George Taylor, was captured at the 325-meter distance and successfully recorded depths within an accuracy of one millimeter. This kind of super-sight means that the possible applications for this tech—especially in the military—are readily apparent.
“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 said in a press statement. “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 secret superpower of this system is that it can be used during the day with extreme accuracy. Normally, scattering light from the Sun can interfere with measurements, but because SNSPD uses wavelengths at 1550 nanometers, it avoids “clutter and atmospheric obscurants” while also being an ‘eye safe’ wavelength, according to the researchers.
The mid-infrared wavelength also alludes to the initial idea behind the SNSPD’s creation. This is a powerful detector for exploring exoplanets, and mid-infrared wavelengths have a relative lack of high-performing sensors like these, NASA claims. This makes SNSPDs an attractive technological candidate for the proposed MIR Exoplanet CLimate Explorer (MIRECLE) and Large Interferometer For Exoplanets (LIFE) missions.
However, like the dozens of NASA science breakthroughs that eventually impact our everyday lives—including the memory foam in your pillow—SNSPDs can also immensely improve LiDAR systems for more terrestrial purposes. And the team wants to try the system at even further distances.
“Could we recognize a vehicle type at 10 kilometers, whether it’s a car or a van or a tank?” McCarthy said in a press statement. “These kinds of distances would be of real interest.”
One of the big drawbacks of the system is that it isn’t exactly... svelte. The word “superconducting” in SNSPD essentially translates to “ultracold temperatures,” so the system needs to be in a “cryocooler fridge” chilled down to 1 Kelvin, or -272 degrees Celsius. This is vital because the superconducting nanowire contains a continuous current, without any electrical resistance, until a photon lands on the detector. That kind of no-resistance flow needs incredibly low temperatures, or the whole thing stops working properly.
So, while this may not be as ubiquitous a NASA invention as memory foam, it nonetheless demonstrates that that we’re only beginning to understand the true power and utility of LiDAR.
Darren lives in Portland, has a cat, and writes/edits about sci-fi and how our world works. You can find his previous stuff at Gizmodo and Paste if you look hard enough.
