from DailyMail.co.uk Science and Tech
Looking through a keyhole could soon reveal far more than you imagine. Scientists have developed a device that could map an entire room simply by shining a laser through a 2cm gap. The system could be used in applications such as firefighting, battlefield surveillance and disaster recovery operations.
The technology is the work of Harbin Institute of Technology in China and is based on a laser that can see around corners, according to a report by Jacob Aron at the New Scientist. The system worked by firing ultrafast laser pulses at walls ‘behind’ an area that can’t be seen, to capture a ghostly 3D reflection. The technique is similar to using a mirror to see round a corner – but instead of a mirror, the ‘reflection’ is reconstructed from laser light that scatters back off a wall. The camera ‘times’ the beams of light as they bounce back to its sensors, and builds an image, which is slightly wobbly, but precise to ranges of just one centimetre.
Peering through a keyhole with lasers.
The group’s latest project has built on this technology to measure the 3D shape and position of three cardboard letters, spelling HIT, through a 2cm hole in a wall.
Last year, British scientists used a similar technique to create a camera that can peer round corners without the aid of a mirror. By taking pictures at the speed of light, the device could reveal hidden objects – from people, to parked cars, to military tanks. The device, created by Jonathan Leach, of Edinburgh’s Heriot-Watt University, is made up of a laser, a super-fast camera which sits beside it and a computer.
To see something that is around a corner, the laser is pointed so that its light ricochets off a wall and onto the hidden object. Some of this light will automatically bounce back off the object and back onto the wall and a tiny fraction will go back towards the camera.
The camera in this device takes 15 billion shots a second, making it fast enough to catch the reflected light. A computer then uses the amount of time the light spent travelling to the camera and the pattern of the reflections to work out the shape of the object and how far away it is.