‘X-ray vision’ laser camera shoots ‘invisible objects’ around corners

Friday, November 19, 2010

LONDON - US scientists have developed a laser camera that can take photos around corners.

The prototype uses an ultra-short high-intensity burst of laser light to construct a basic image of its surroundings - including objects hidden around the corner - by collecting the tiny amounts of light that bounce around the scene.

It could find applications in search and rescue operations, say its creators.

“It’s like having x-ray vision without the x-rays,” the BBC quoted Professor Ramesh Raskar, head of the Camera Culture group at the MIT Media Lab, as saying.

“You could generate a map before you go into a dangerous place like a building fire, or a robotic car could use the system to compute the path it should take around a corner before it takes it,” he added.

But the scope of the device is unclear as of now.

“What is not entirely clear is what complexities of invisible scenes are computable at this point. They have not yet shown recovery of an entire [real-world] scene, for instance,” said Professor Shree Nayar of Columbia University, an expert in light scattering and computer vision.

If there is a corner, some of the light will be reflected around it. It will then continue to bounce around the scene, reflecting off objects - or people - hidden around the bend.

In this method known as “time-gating”, the experimental camera shutter opens once the first reflected light has passed, allowing it to mop up the ever-decreasing amounts of reflected light - or “echoes” as Raskar calls them - from the scene.

It also measures the arrival time of the particles at each pixel.

This is the central idea used in so-called “time-of-flight cameras” or Lidar (Light Detection And Ranging) that can map objects in the “line of sight” of the camera.

To build a picture of a scene, the experimental set up must repeat the process of firing the laser and collecting the reflections several times.

Then, complex algorithms construct a probable 3D model of the surrounding area - including objects that may be hidden around the corner.

“In the same way that a CAT scan can reveal what is inside the body by taking multiple photographs using an x-ray source in different positions, we can recover what is beyond the line of sight by shining the laser at different points on a reflective surface,” he said.

Although still in experimental stages for now, Raskar’s team hopes to build something large scale based on the idea. (ANI)

Filed under: Science and Technology

will not be displayed