MIT's Laser Camera: Help is just Around the Corner

By Peter Bernstein March 22, 2012

I have admitted previously to an eclectic taste in all things relating to technology. Thus, it was with no small measure of delight that I checked in with a favorite web site,, where I am frequently able to learn about something new. Today was no exception, as Clay Dillow weighed in with a posting about MIT Media Lab’s latest video. In it, the good folks at the MediaLab actually explain how their laser camera, announced back in 2010, can see around corners. 

For those of you who get as excited about this as I do, as good as the Dillow posting is, you really ought to check out the MITnews piece on this, which has some fascinating video and a really great, if somewhat technical, description of how all of this works.  In a paper appearing this week in the journal Nature Communications, the researchers describe using their system to produce recognizable 3-D images of a wooden figurine and of foam cutouts outside their camera’s line of sight.

The explanation as to how they did this goes as follows. The camera is periscope-like, but instead of using mirrors, it  uses common surfaces like walls and doors which are not as reflective to redirect light. As the MIT release says:

The system exploits a device called a femtosecond laser, which emits bursts of light so short that their duration is measured in quadrillionths of a second. To peer into a room that’s outside its line of sight, the system might fire femtosecond bursts of laser light at the wall opposite the doorway. The light would reflect off the wall and into the room, then bounce around and re-emerge, ultimately striking a detector that can take measurements every few picoseconds, or trillionths of a second. Because the light bursts are so short, the system can gauge how far they’ve traveled by measuring the time it takes them to reach the detector. The system performs this procedure several times, bouncing light off several different spots on the wall, so that it enters the room at several different angles. The detector, too, measures the returning light at different angles. By comparing the times at which returning light strikes different parts of the detector, the system can piece together a picture of the room’s geometry.

Got all of that? If not quite sure yet, take a look at the video.  

It seems simple enough; but as Ramesh Raskar, an associate professor at the MIT Media Lab, who led the new research stated, “Four years ago, when I talked to people in ultrafast optics about using femtosecond lasers for room-sized scenes, they said it was totally ridiculous.” In fact, the posting goes on to quote several other scientists as marveling at the audaciousness of even attempting this.

While Raskar and his group are still early in the learning curve on perfecting the technology, even in rudimentary form, the data collected by the ultrafast sensor being used was able to provide recognizable -- if not HD quality -- images when processed by algorithms they developed. 

There is no telling how long it may take for cost-effective, commercial application of this technology. There is a lot of hard work ahead on numerous fronts. However, early applications are easy to see. First responders, especially fire fighters and bomb squad members and those digging through rubble in major catastrophes, are obvious users. It also should go without saying how interesting the military will be and probably already is. Think also about the value in security systems where bad actors would have no idea that their activities were under surveillance.  

Kudos to Raskar and his entire team. I invite you once you have finished looking at the MIT videos to enjoy the music of the superstar rock group Coldplay and their hit, “Help is Round the Corner.”

Edited by Rich Steeves
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