Seeing Around Corners Could Have Inspection Applications
Source: Nature
Good news for those who want to know what lies around the corner: electrical engineers have used an ordinary digital camera to reconstruct rough images of hidden objects just by analysing light that bounces off a wall, as if there were a mirror there. Several teams of researchers have demonstrated devices that could do similar things, but the latest technique is entirely based on an algorithm the team built and requires no special equipment.

"It was thought to be practically impossible to reconstruct an image from only scattered light from a wall without any advanced instruments," says Allard Mosk, an optical physicist at Utrecht University in the Netherlands.

"Itís surprising to see that you can treat a wall as if itís a mirror," says study co-author Vivek Goyal, an electrical engineer at Boston University in Massachusetts. The paper appears on 23 January in Nature1.

Mirrors enable us to see an object even when we do not have a direct line of sight to it. They reflect images faithfully because light bounces off them only at precise angles (at least in the classical, non-quantum explanation, which is accurate for practical purposes).

A mirror sorts the rays of light and redirects them so that our eyes get a faithful image. But when light hits a white wall or another non-shiny surface, it scatters off in random directions. The information is still available, but it is scrambled. Researchers have devised various techniques to unscramble it, which until recently have all required either special lighting (such as scanning by laser), special cameras or both.

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