Laser-based camera can see around corners

November 17, 2010 by Lisa Zyga, report
The left illustration shows how short light pulses are reflected off a door and scatter in different directions. Some of the light is reflected back to the camera, while some of it is reflected off a hidden object or person in the room. Some of this light is then reflected back to the door, where it can be captured by the camera and used to create an image of the hidden object or person. The right illustration shows the system being used for search and rescue in a burning building. Image credits: Ahmed Kirmani, MIT.

( -- Researchers from MIT have developed a camera that can capture images of a scene that is not in its direct line of sight. The camera is equipped with a femtosecond laser, which fires extremely short bursts of light that can reflect off one object (such as a door or mirror) and then a second object before reflecting back to the first object and being captured by the camera. Algorithms can then use this information to reconstruct the hidden scene.

The laser-based camera system is being designed by MIT Professor Ramesh Raskar and others. They call the system a "femtosecond transient imaging system," and explain that it exploits the fact that it is possible to capture light at extremely short time scales, about one quadrillionth of a second. By continuously gathering light and computing the time and distance that each pixel has traveled, the creates a "3D time-image" of the scene.

"It’s like having x-ray vision without the x-rays," Raskar said. "We’re going around the problem rather than going through it."

The researchers are still in the early stages of development and are working on accurately mapping more complex scenes. They predict that the system could have a variety of applications. For instance, it could be used for search and rescue missions to search for survivors in a collapsed building or a building on fire. It could also be used for avoiding car collisions at blind corners, for machine vision, and for inspecting industrial objects with hidden surfaces. It could have similar biomedical imaging applications by allowing doctors to use endoscopes to view areas inside the body that are normally hidden. The researchers noted that a portable imaging system in the form of an endoscope could be ready in the next two years.

Explore further: Tool to visualize bloodstains created by chemistry researchers

More information: "Femtosecond Transient Imaging" by Ahmed Kirmani

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5 / 5 (1) Nov 17, 2010
Algorithms can then use this information to reconstruct the hidden scene.

Would have been nice to see what these reconstructed images look like.
not rated yet Nov 17, 2010
Military applications insure this area of research will be very well funded. That also bodes ill for commercial uses.
1 / 5 (2) Nov 17, 2010
What they could have admitted is, this is simply a radar that is using visible light.

Now, a regular boat radar is 2D (that is, actually 1D, but since it is rotating, it takes a 1D image in every direction, thus creating a 2D-like image on the round screen.

This is a 2D motion picture system, where the images should resemble those of the "naked aiport scanners", albeit with a lower quality, and live images.

If you reflect the rays off a door, then the result would be what anybody could achieve standing in a dark hallway and looking at a glossy room door, where the reflection of somebody inside the lit room can be seen. Only now we'd be using a flashlight, so we don't need the hallway to be dark or the room to be bright.

The main difference is, however that the image is CGI, like that for side-looking sonar. The computer calculates distances and converts them into an image.
2 / 5 (1) Nov 17, 2010
If you reflect the rays off a door, then the result would be what anybody could achieve standing in a dark hallway and looking at a glossy room door.

Maybe in it's first iteration here, but by using femtosecond lasers the accuracy could be greatly increased with a little computing power. The laser system could take incredibly precise measurements of the door, and use those measurements to correct for the light scatter. All it needs are some good algorithms, a 4g type connection, and a moderate super computer. All things that the military (NASA) has.
3 / 5 (2) Nov 17, 2010
Adaptive optics for telescopes works in much the same way. In fact, i wouldn't be surprised if at least one of these researchers previously worked on telescope adaptive optics.
1.8 / 5 (4) Nov 18, 2010
Now if they can just get those bad guys to leave their doors open at the best possible angle and perhaps a phone call ahead of time so the bad guys can set their doors at the correct angle (perhaps even attach a mirror to the door just to be more helpful) so that the good guys will need less time to set up and calibrate their optical equiptment accordingly.

I percieve that this technology possesses more wishful thinking than any practical applications, military or otherwise.
not rated yet Nov 18, 2010
well i suppose they could send a SMAW through the wall first and then use the corner peek infrared laser and t-rays to see if there are any breathers left
5 / 5 (1) Nov 18, 2010
Smoke and mirrors, only without the smoke.
not rated yet Nov 18, 2010
New way to locate Black Holes!
Just reassemble the reflections of light off all planets in each solar system, rendering a symmetrical 3D image of the scene, and with simple logical deduction of massive gaps left in the image, Black Holes could be spotted in every corner of the galaxy~! Amazing!
not rated yet Nov 22, 2010
man, this is the one that captured my imagination since small, don't you guys have the same dream? I imagined throwing a smooth reflective metal ball into a room and by taking photos of the ball I can reveal the image of the whole room. And this website added it up - it's viable through collection of short burst images at femtosecond scale.

What about axion imaging that can see through walls? You'll need a very cold superconducting magnet with poles gap as small as a pinhole, then capture axions through the pinhole and convert them into light.

You know what? I suppose this page gets filled up with loads of comment. So, the world doesn't seem to resonate with me, MIT though.
not rated yet Dec 14, 2010
new device chemically analyzes fresh stool, determines mood.

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