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Science Technology

Laser Camera Can See Around Corners 97

Hugh Pickens writes "Researchers at MIT have developed a laser camera that can 'see' around corners and take pictures of a scene not in its direct line of sight. The camera system fires extremely short bursts of light that can reflect off one object, such as the open door of a room, and then off a second object inside the room before reflecting back to the first object and being captured by the camera, after which algorithms can use the information to reconstruct the hidden scene exploiting 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 camera creates a '3D time-image' of the scene it can't directly see. 'It's like having X-ray vision without the X-rays,' says Professor Ramesh Raskar. 'We're going around the problem rather than going through it.'"
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Laser Camera Can See Around Corners

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  • by ciaran_o_riordan ( 662132 ) on Friday November 19, 2010 @07:42AM (#34280090) Homepage

    Great, so instead of x-raying or groping travellers, maybe TSA can subtly take a few snaps up the leg of people's trousers and down the top of your t-shirt :-) [] []

  • by Anonymous Coward on Friday November 19, 2010 @07:44AM (#34280102)

    It's like having X-ray vision without the X-rays...

    So it's like having vision?

  • by Anonymous Coward on Friday November 19, 2010 @07:46AM (#34280106) []

    Enough of Slashdot's SEO link farming spammy shit. Here's what you want to read, unless you like your science news dumbed down to a third grade level.

    • by icebraining ( 1313345 ) on Friday November 19, 2010 @08:06AM (#34280192) Homepage

      [quote]Light travels 1 foot/nanosecond(...)[/quote]
      How much is that in Libraries of Congress?

      Really, foots per nanosecond? I thought it was a scientific experiment.

      C is exactly 299792458 ms.

      • You were modded funny but you should have been modded pedantic. If you really want to be pedantic you should have pointed out that in an atmosphere or other non-vacuum medium it is slower than theoretical C. Second, one foot is a very good approximation of the speed of light and perfectly suitable to use in a non-journal science article. Seriously, if you're going to nitpick like that you really need to get a life and move out of your mother's basement.

      • There's nothing wrong with writing for your audience. If you see ft/ns in "Nature", feel free to flame.

      • Damn /. eating my superscript. It's m/s.

      • by argStyopa ( 232550 ) on Friday November 19, 2010 @10:32AM (#34281234) Journal

        "C is exactly 299792458 ms" ...which is precisely as arbitrary, if more widely accepted, than cubits per moon phase.

        I swear, metric evangelism is becoming more rabid every week. Oh wait, I'm sorry, it's becoming more rabid every 2/100ths of a year.

        • It's not, because the meter is defined by c, so in this particular case, it offers a precise value.

          In 1983 the metre was defined as "the length of the path traveled by light in vacuum during a time interval of 1299,792,458 of a second", fixing the value of the speed of light at 299,792,458 m/s by definition

          • sure would have been nice if they fixed it at 300,000,000 m/s as it would be pretty damn close to where it is now anyway and the number would be much easier to remember.

          • Find a better source. The metre still hasn't been tied to anything tangible.

          • "Distance traversed in vacuum by light in 1/299792458 of a second"

            Wow, you sure proved me wrong. That's not arbitrary at ALL.
            Of course, that was the definition in 1983.

            Of course, in 1960 it was "Hyperfine atomic transition; 1650763.73 wavelengths
            of light from a specified transition in Krypton 86 (11th CGPM)" ...Which isn't arbitrary.

            "Platinum-iridium bar at melting point of ice, atmospheric pressure, supported by two rollers (7th CGPM)" (1927)

            Nope, not arbitrary either.

            I'm so embarrassed at my obvious igno

      • C is exactly 299792458 ms.

        The speed of light is 3.46982012 days?

        Can you do the Kessel run in less than twelve parsecs?

    • by mcgrew ( 92797 ) *

      Yes, that's been annoying me at work. Most of the links are firewalled off, but I can usually find a better FA with Google. With dozens or hundreds of stories written by professionals and posted on sites that can handle a slashdotting, why do these stories link to some blog that merely quotes a mainstream news source, is firewalled off in many places, and is frequently slashdotted to oblivion?

      Firehosers, I'm calling on you all to turn these down. I'll bet there were half a dozen submissions of this same sto

  • Pics (Score:1, Funny)

    by Anonymous Coward

    or it didn't happen!

  • It would make a helluva lot more sense to just use high-intensity microwaves. Think of how Dolphins and bats see their environment. the device to see around corners would have to take various additional factors into account of course, like distance from the reflecting surface and angle of beam contact to said surface. After that, it's just a matter of painting a 3d version of the room. :|

  • Hmmmm... (Score:3, Interesting)

    by tygerstripes ( 832644 ) on Friday November 19, 2010 @08:07AM (#34280194)

    The process has to be incredibly time-sensitive in order to work, and the imaging process has to subtract ambient light in order to obtain the reflected-laser data. This ambient-light recording has to happen at a different time to when the laser is fired, so variable-light conditions or the lack of an incredibly steady camera, image object and reflective surface will make it basically impossible to render the image.

    I absolutely love the concept. I just think that the nay-sayers whom Professor Raskar claims to be defeating were correct. It might not be theoretically impossible, but the practical limitations are so severe that I don't envisage them being "engineered" away - and if they are, such phenomenal engineering accomplishments would make this application appear trivial in comparison with the other things we could do.

    • Indeed, not to mention the limitation that you need a surface off of which you bounce the intitial laser pulse. This "looking round corners" idea/phrase someone has put forward is total crap. Sure, you can look around a corner as long as it's (e.g.) a doorframe and the door opens outwards in the right direction for your camera to use as a reflector. Want to look round the corner of a building? Into a room where the door opens inwards? Over a wall? Then you're shit out of luck.

      Once again the media takes a
    • If it has to be incredibly time sensitive to work why not use sound (ultra-sonic waves, like bats use) instead. This should reduce the time sensitivity requirements by many orders of magnitude. It will also reduce the resolution but considering that bats can catch insects in flight probably will still be good enough to "see" someone hiding behind a door.

      Or perhaps they need a coherent (laser) beam of sound? Perhaps this can be engineered around. Might also be useful underwater.

    • Re: (Score:2, Insightful)

      by Lluc ( 703772 )
      Given that he's using a femtosecond laser and some kind of exotic "streak" camera, I think he has to essentially raster scan the area he's imaging "around the corner". I doubt the ambient lighting or the scene itself will change in a femtosecond, but the raster-scanner better move pretty fast! A fast raster-scanner might be solvable, even. I think the biggest problem he's going to have is dealing with a non-sparse scene. I think this works well for simple geometries, but once he starts dealing with a re
    • by Timmmm ( 636430 )

      This ambient-light recording has to happen at a different time to when the laser is fired, so variable-light conditions or the lack of an incredibly steady camera, image object and reflective surface will make it basically impossible to render the image.

      Yeah but you could record the ambient light 1 ms later. Light is pretty damn fast and ambient light conditions are essentially constant.

      I absolutely love the concept. I just think that the nay-sayers whom Professor Raskar claims to be defeating were correct. It might not be theoretically impossible, but the practical limitations are so severe that I don't envisage them being "engineered" away - and if they are, such phenomenal engineering accomplishments would make this application appear trivial in comparison with the other things we could do.

      I wouldn't be so sceptical. The main limitations are:

      1. Miniaturisation. Obviously this is just an engineering problem. A damn hard one, sure.
      2. Sampling rate of the light signal. This is the one that will really determine the image quality.

      The door requirement is a pretty big limitation though. I think a fibre optic camera poked around the corner might be a bit easier!

    • Engineering a methodology that would permit te reverse compose images of the Big Bang reflected on objects out of its event horizon would be non trivial.
    • I took a look at their supplied graphic and immediatly had a few issues with it. #1 starts with reflection one. Is the door a mirror or is is a surface that will scatter the light into all the room? Same for reflection 2. Think about reflection 2 for a moment. Remember the problem with reflection 1? Which reflection 2? Multiply for reflection 3 and you have no immage, but just a depth sounding ping return from the room with no direction information at all, thus no shape information, only the return ti

    • Assuming your ambient light isn't coming from a laser wouldn't you be able to get rid of the light by filtering out any non-polarized light? If there are lasers (say multiple people in a SWAT team are using this) as part of the ambient light maybe each could be using a slightly different wavelength of light in order to filter out the other devices as well.
    • Actually, it sounds like an alternate way of recording a holographic image. The one thing I don't see mentioned is it becomes increasingly more difficult to make this work, the less smooth and flat your reflecting surface gets. In fact, I'd be surprised if this was even feasible if you are reflecting the laser beams off anything that isn't significantly flat and smooth.

  • And guess what (Score:5, Insightful)

    by Rosco P. Coltrane ( 209368 ) on Friday November 19, 2010 @08:10AM (#34280212)

    The first customer will either be the TSA or some branch of the military.

    High-tech companies would invent anything that would sell to any agency vaguely related to counter-terrorism or warfare these days. If they poured a tenth of the resources they spent developing this kind of devices into finding solutions to the world's real problems, we'd all be cancer-free and solar-powered by now...

  • hearsay (Score:5, Informative)

    by ei4anb ( 625481 ) on Friday November 19, 2010 @08:12AM (#34280222)
    Slashdot says that said that said that Tech Radar said that MIT said that there is an interesting paper at [] and the BBC went to learn more, conduct an interview and take photos []
    • Meh. BBC. Old and proven news organizations. Who needs them? This is the Internet, all we want is hearsay.

  • Unless I can use it to "see" through the walls of the girls locker-room, then its not X-Ray vision.
    • Unless I can use it to "see" through the walls of the girls locker-room, then its not X-Ray vision

      You didn't specify if the girls in the locker room should remain unaware of your watching them. Cuz if don't, a large lump hammer is enough to see through the wall, no need for X-rays...

  • I can see this being applied to lenses and windshields to give you an idea of who or what is lurking around the corner... []
  • by Digital Vomit ( 891734 ) on Friday November 19, 2010 @08:53AM (#34280442) Homepage Journal
    Now that scene in Blade Runner is making more sense...
    • I thought the exact same thing.
    • by mcgrew ( 92797 ) *

      Funny how impossibilities in science fiction become possible with time. When Star Trek came out in 1966, flat screen monitors, "communicatore", self-opening doors, talking computers, and a lot more stuff that's commonplace now was impossible then.

      However, Blade Runner makes the Doctorow Mistake of setting the fiction too close to the present. It's set just ten years from now. It's doubtful this tech will be mature in ten years, and besides, you can't just feed a print into the scanner and see around corners

  • I love how all the researchers materials are all "Humanitarian" and indicate that this will be used to help people (fires, safety, etc...).

    I give it about 15 minutes before the government gets wind of it and turns it into a tool for mass invasion of privacy and uses it somehow in this ongoing war on our freedoms.

    I would be more optimistic, but their track record isn't encouraging.

  • ... where it doesn't shine:

    However, he said, the team initially aim to use the system to build an advanced endoscope.

    "It's an easy application to target," he said. "It's a nice, dark, damp and warm environment."

    If the team get good results from their trials, he said, they could have a working endoscope prototype within two years.

  • Reminds me of Dual Photography []
  • This sounds like it's fundamentally the same as radar or sonar but using light instead.
    • And the algorithms should be applicable to radar and sonar in cluttered environments.

    • Lidar. Cops use it every day except that they don't have 2D spatial resolution because they only need one dot to do a Doppler measurement and get your speed.

  • by Anonymous Coward

    Oh crap, CSI is real!?!

  • It is ridiculous to call this new technology. It is just another form range sensing that is being researched in universities all over the world. Light is still just electromagnetic radiation. I am sure there are lots of other projects doing the same this as this, but since it is from the MIT Media Lab it gets the "oooo, awww.." factor.

    Using the backscatter from diffuse reflection is seriously limiting.

    Radar systems are brutally prone to clutter, echoes, and interference. The system is limited by range, and

    • Re: (Score:1, Insightful)

      by Anonymous Coward

      Do you know *any* new technology that is not related to an older one ? Me neither.

  • TFP [] mentions that the laser is operated at an average power of 425 mW. So I'd rather not be the guy standing round the corner getting hit in the eye with such a beam.

  • This is great. Its an EDM. Surveyors and engineers have been using this technology for half a century, the only difference is they have been excluding these types of measurements deemed reflective inaccuracy. This is a neat idea.
  • So this is like looking at a mirror. Or pointing a flashlight at a mirror and looking around a corner.

    Different wavelength so the door looks like a mirror So why is this news?
    • by Anonymous Coward

      No, it is not in the least like looking at a mirror.

      You flash the door. It travels at the speed of light. You get the reflection off the door in twice the distance to the door divided by the speed of light. After that, you open the shutter and start watching.

      You then get secondary reflections off the door, as the flash which reflected into the room then reflects off objects in the room, back to the door, and reflects back to you. The intensity of the light reflecting off of the door at any point in time tel

      • by kipb ( 529703 )
        AND they do the same looking at various places on the door, so they see the "distance map" image from various perspectives. This makes it more analogous to the door as a mirror, just as you'd look at various points on a mirror and see a reflected scene from the point of view of that spot on the mirror.
  • I saw this on CSI like eight years ago.

  • That is, when they have the CSI on TV "enhance the photo, show me the reflection in the car side mirror" In real life, we can not, or rather COULD NOT do that. But with these special cameras, apparently we will be able to do it.
  • Hmmm, I seem to remember this technology [] from years ago...

  • That scene with Deckard dissecting the photograph on his weird-ass computer and literally changing the angle and viewpoint arbitrarily always bugged me.

    Now, not so much. It must have had an embedded holographic layer that took several angles.

    Yeah, that's it.

  • Is it really "seeing around corners" if it needs something that the light can bounce off? With a mirror in the right place I can also "see around corners"

    I'm sure it's still a great engineering accomplishment, but I wouldn't call it seeing around corners

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