A powerful new imaging technique has been developed by Scottish researchers that can build a 3-D image of a person or object from thousands of feet away. It can detect a single photon hitting its sensor — but interestingly, it can't see your face.
The imaging device fires a beam of light at a target and waits to see how much of it bounces back, and when, known as the "time of flight" method. The result is a 3-D model of the target that, while it may not be detailed, is fairly accurate, even from a distance.
While this long-range aspect of the device makes it sound useful for surveillance, its shortcomings mean it's more suited to scientific and field work. A depth-sensing camera could monitor a large portion of mountainside for rockfall or snow depth, or a plane-mounted device could spy on the height of trees from two thousand feet up.
Using time of flight of determining the distance of an object is a well-established method, but while lasers and sound have been used in the past, this setup relies on something more versatile: infrared light.
Infrared is well outside the visible spectrum, and can pass through minor obstacles like foliage, unlike an ultrasonic pulse or visible-light laser. Until recently, it wasn't possible to use infrared in this way — sensors just weren't sensitive enough. This device, however, uses a "superconducting nanowire single-photon detector" as its sensor, which is incredibly sensitive to light but also very limited in resolution.
So instead of having the entire image hit the senor at once, as is the case with normal cameras, the new device essentially captures a single pixel at a time, taking anywhere from one to a hundred milliseconds before moving on to the next.
That means the exposure takes a few seconds — preventing it, except under special circumstances, from capturing images of anything but stationary or slow-moving objects. A faster exposure can be made, but at the cost of resolution and accuracy.
Another shortcoming of the system is that the wavelength of light they chose, while useful in many regards, happens to scatter in a very inconvenient way off of human skin. The result is a disconcerting black hole where a person's face should be in pictures of people.
The device (not yet named) was developed by a multi-instititional team of physicists, led by Gerald Buller and Aongus McCarthy at Heriot-Watt University in Edinburgh. The paper was published in the journal Optics Express, at the website of which it can be read in its entirety.
via TG Daily
Devin Coldewey is a contributing writer for NBC News Digital. His personal website is coldewey.cc.
