Scientists have developed a state-of-the-art detector which that can turn walls and floors into a “virtual mirror“, giving the power to locate and track moving objects out of direct line of sight.
The shiny surface of a mirror works by reflecting scattered light from an object at a well-defined angle towards your eye, but researchers at Heriot-Watt University and the University of Edinburgh found that there is a way to tease out information on the object even from apparently random scattered light.
Their method relies on laser range-finding technology, which measures the distance to an object based on the time it takes a pulse of light to travel to the object, scatter, and travel back to a detector.
Alaser pulse is bounced off the floor and scatters in all directions. A small fraction of the laser light strikes the object, and the back-scattered light is recorded on a patch of floor ¬ the virtual mirror ¬ next to the spot the laser strikes. Because the speed of light is known and constant, by measuring the time interval between the start of the laser pulse and the scattered light reaching the patch of floor, the position of the object can be triangulated.
The prototype system allows the object’s position behind the wall to be localised to within a centimetre or two, and by making measurements every few seconds, the camera can also detect the speed of a moving object.
At present it’s limited to locating objects up to 60 cm away from the virtual mirror on the floor, but this should improve to around ten metres, as well as to more closely detect the shapes of hidden objects as well as their positions.