Now technology let you see around corners
The light carries information about the hidden object
(Web Desk) – Vivek Goyal and colleagues at Boston University created invented an technology to see on the other side of wall by using an ordinary digital camera.
The scientists have created their inexpensive non-line-of-sight imaging system using an algorithm to extract information from the shadow cast by an obscuring object.
If the line of sight between a target object and a camera is blocked – by placing the object round a corner, for example — some of the light from the target can reach the camera via diffuse scattering from surrounding objects.
This light carries information about the hidden object, but until now this information had to be captured and unscrambled using advanced detectors and algorithms before an image can be obtained.
One successful technique, for example, uses ultrashort laser pulses to illuminate a hidden object. Advanced optical sensors then pick up light that is scattered diffusely by a relay surface — which is essentially an extremely poor mirror. To reconstruct the image, the sensor measures both the arrival times and the incident angles of the light it receives.
These data are then fed into an algorithm and an image is created. This requires expensive, highly-specialized equipment, which makes it impractical for many applications.
But now, Goyal’s team have achieved non-line-of-sight imaging with an ordinary digital camera and no need for measuring arrival times. Their algorithm analyses information that is contained in shadows cast by an obscuring object that is placed between the target object and the relay surface.
Their technique relies on the fact that shadows are not sharp, but rather have penumbrae at their edges. What is more, subtle variations in the colour and intensity of penumbrae light carry information about what lies behind the obscuring object.
