Camera system sees around corners without using a mirror
By Helen Clark
July 25, 2014
Peeking around a corner has long been a staple of spy films and TV, from Get Smart to 007. Researchers at the University of Bonn in Germany and the University of British Columbia in Vancouver, Canada have found a better way than poking a makeup mirror about, however: a camera system that can reconstruct the shape of objects using diffusely scattered laser light.
Essentially, the system works by shining a laser onto a wall and filming this with a camera that records both the direction of the light and the time it takes to reach the camera from the source. As the image is processed and reprocessed the outline of the thing the camera is trying to see becomes apparent. "Part of the light has also come into contact with the unknown object and it thus brings valuable information with it about its shape and appearance," says Professor Matthias B. Hullin of the University of Bonn.
That small laser point is not simply a single point of light but a source of scattered light that bounces off the object and back, eventually transmitting information about it. These are known as "light echoes" and can be recorded by a camera. The challenge is to overcome what is called multipath interference: in other words, the image needs to be pulled from the wider scatter of light, or “noise” generated by the light echo. It is only the direct portion of the signal that is of any use, so the researchers developed a mathematical model that can block the extraneous parts of the signal.
Magical as it sounds this is not tricky technology. The image sensors used by the camera have been around for a long time in video game controllers or depth image cameras, but the method to build the needed images is more complicated. Essentially, one is built from numerous reflections that are layered or superimposed on top of one another on the sensor. It should be noted that the images eventually built are rough outlines rather than photo-real, but the researchers believe that higher resolution results will be achieved as the technical components and mathematical models develop.
In 2012 we reported on a similar project at MIT using direct reflection of lasers with similar results: blurry, but still discernible images of objects from outside the cameras field of view.
While Agent 99 might be better off relying on her powder compact’s mirror when running from Agents of KAOS for the time being, this technology may also have other useful, real world applications in medical imaging, remote sensing and telecommunications.
Source: University of Bonn