A team of physicists from Heriot-Watt University in Edinburgh has developed laser technology that can 3-D image an object up to a kilometer away. The system can accurately (within a millimeter) image even "uncooperative" objects -- meaning those that don't easily reflect laser pulses, like fabric. Though at a kilometer away, it can probably capture an uncooperative human, too.

The imaging technique is called "time-of-flight," or ToF. It runs a low-power infrared laser beam over an object, preferably one that's not moving, like a parked car, then records how long the photons in the laser beam take to bounce off the object and return to their laser-home.

ToF imaging systems are already used in some machine navigation, like autonomous vehicles, but generally they only have a short range and can't image all surfaces. The Heriot-Watt team's system specifically detects longer wavelengths of light that are redder than visible light and can travel more easily. A superconducting nanowire sensor counts individual photons in the laser beam, allowing it to more accurately record depth.

Distance Imaging:  Optics Express