Camera System Uses Diffusely Reflected Light to See Around Corners
20 June 2014
A novel camera system using diffusely reflected light and able to reconstruct the shape of objects outside of the viewing scope has been developed by researchers from the University of British Columbia and the University of Bonn.
In a demonstration, the scientists pointed the camera (equipped with a laser) at a white wall. The laser dot that shines on the wall serves as a source of scattered light that brings information into the camera as it falls back onto the wall and then into the lens. After being processed by a computer, the outlines of an object that is obscured from view start to appear on the system's screen.
Matthias B. Hullin from the Institute of Computer Science II at the University of Bonn describes the process as recording a "light echo." According to Hullin, part of the light provided by the laser during the experiment comes into contact with the unknown object and carries information about its shape and appearance on its way back. In a way, he explained, the camera uses the wall as a mirror.
After making it back to the camera, the echo is measured by a system of sensors recording not only the direction of the incoming light, but also the time it takes for it to travel to the object and back. The camera measures the sum of numerous reflections, obtaining information from what would conventionally be considered "noise," Hullin said.
Using exactly this noise the camera can reconstruct obscured objects, although its capacity is currently limited to rough outlines.