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Wednesday, April 11, 2007

How to Make an Object Invisible

Continued from page 1

By Duncan Graham-Rowe
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The solution was to design a device with tightly spaced needles of nanowires, 10 nanometers in diameter and 60 nanometers long, emanating from a cylindrical central spoke. In the current issue of the journal Nature Photonics, the researchers show how--in theory at least--this would cloak the object from red light of wavelength 632.8 nanometers long.

There are limitations to this approach, however. A very small percentage of light would still be reflected, so the object would not be entirely invisible. Also, while the design can be adapted to work for other frequencies in the visible range, the design will still only work for a very narrow band of light.

"This is a real problem," says Ulf Leonhardt, a professor of theoretical physics at St. Andrews University, in Scotland, and an expert in this field. "It would look completely odd, and you would definitely see something." But he says that this is not an indictment of the Purdue research; rather, it's a general problem with research into cloaking so far.

"It's still an important step to go into the visible range," says Leonhardt. "And it's a definite step forwards." But to make things truly disappear before our eyes, a way will need to be found to make devices work across a broad range of frequencies, he says.

Even so, using nanowires is a very practical way forward, says Pendry. "It's very useful because what we really want now is to see how well people can build them," he says. Indeed, this is what the group is working on now. "The next step is to fabricate and test an actual sample," says Alexander Kildishev, a research scientist at Purdue. This work will be carried out in collaboration with Purdue's Birck Nanotechnology Center.

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Comments

  • Now you see it, now you don´t
    Cesar on 04/11/2007 at 9:55 AM
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    Ver interesting and innovative
    Rate this comment: 12345
    • Re: Now you see it, now you don´t
      louppl72001 on 04/11/2007 at 10:55 AM
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      Can't help but wonder, is our technological advancement determined by the ideas and imagination of scifi writers or were they merely predicting our future.?
      Rate this comment: 12345
      • Re: Now you see it, now you don´t
        martwill38 on 04/11/2007 at 1:14 PM
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        I think a Harry Potter style "invisibility cloak" is far from likely based on this research.  Since it appears to operate over only a narrow range of frequencies, to make it work over a wide range might involve many layers, each operating at different light wavelengths, so as to cover the visible spectrum.  But in stealth applications, you would also want radar invisibility at all microwave frequencies that are now, or could later be, used.  How would you isolate the layers and prevent some from reflecting the light before it reached others?
        Present stealth mechanisms work mainly by absorption and reflection at odd angles not likely to be received by the radar transmitter.
        Rate this comment: 12345
        • Re: Now you see it, now you don´t
          Aiden! on 04/13/2007 at 1:10 AM
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          2
          Probably not Harry Potter style, but something more akin to the cloaking in Ghost in the Shell, where the cloaked object/person is still faintly visible.
          Rate this comment: 12345
      • Re: Now you see it, now you don´t
        montezuma2004 on 04/11/2007 at 5:07 PM
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        Good question, but I wonder if technology is advancing much faster than our ability to adapt to it.
        Rate this comment: 12345
        • Re: Now you see it, now you don´t
          swordfishdata on 04/12/2007 at 6:12 PM
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          I personally think that a person's ability to adapt is limited only by that person's willingness to do so. If one insists upon sticking with what one has always known, one deserves to be left in the dust.  (no offense intended to those who find their employment displaced by technology, but nothing happens overnight. If they don't see something coming, it's partially their fault.)
          Rate this comment: 12345
      • Re: Now you see it, now you don´t
        McMillan968 on 04/11/2007 at 8:25 PM
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        Not trying to steal your thunder but ever since Buck Rogers was patrolling outter space and men were landing on the moon science has ALWAYS strived to catch up.A lot of times working off sci-fi ideas.
        But we are definitely in a period of tech going ahead of what we are ready for,hope it stays that way too!!!
        Rate this comment: 12345
      • Re: Now you see it, now you don´t
        fixerdave on 04/12/2007 at 8:00 PM
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        I've always considered the purpose of art to reflect on our condition or predict new possibilities.  With this knowledge, we can adjust the course of our development.  SciFi, in an age of science and technology, is obviously going to have the greatest effect on our future.  Life imitates art, or avoids it; that's arts job, be it Soylent Green or Blade Runner, Romulan cloaking devices or tri-corders.  Some imagined stuff comes fast - other stuff never seems to get here. 

        On the other hand, sometimes, stuff just comes from the lab, stuff that nobody ever thought of before.  I wonder if anyone has done acceptance studies comparing how populations deal with art-imagined verses "straight from the lab" generated technology.  Now, that would be interesting.

        Now, could you imagine some kind of cooling device based on this technology?  Something that could radiate infrared but not absorb it, even on a sunny day.  Art has prepared us for disappearing ships or people, not better air conditioners.
        Rate this comment: 12345
        • Re: Now you see it, now you don´t
          centaur8 on 01/03/2008 at 10:05 AM
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          Whether life imitates art, or art imitates life, or life imitates life, the common strand is people coming up with new ideas, whatever field they are in. New ideas have come out of all kinds of people, even "from the mouths of babes and jokers . . . "
          Rate this comment: 12345
  • What about non-mechanical structures?
    netskip on 04/11/2007 at 12:41 PM
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    I haven't read the report (I wish I could) but I wonder if interference patterns of compression waves (i.e. ultra-short wavelength sound or something like it) could provide a tunable structure to produce the same effect. 
    Rate this comment: 12345
  • making invisible
    beemarao on 04/12/2007 at 6:46 AM
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    1
    it is possible to make things invisible,we have already things that is partialy invisible like glass,water,air. to make object invisible one another method is thier that is

    light ray falling one side of the object should be reproduced on the other side of the object, using a system capable of  light sensing and emitting, maintaining that properties of the ray like wawelength,intensity,diretion by doing this we can see through the object that means the object is invisible.  

    tharas bulpa
    Rate this comment: 12345
    • Re: making invisible
      brunascle on 04/12/2007 at 9:25 AM      		 Technology Review TR Staff
      Web Developer
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      to successfully do that, the object has to be 100% surrounded by a camera lens, in order to capture every angle. and, it also has to be 100% surrounded by some sort of display.

      that's not really possible, as far as i know.
      Rate this comment: 12345
      • Re: making invisible
        zifos on 04/12/2007 at 5:18 PM
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        Even if it was only invisible from one side (could be somewhat useful).  You would still have to carry a bunch of light recievers and emitters and computers to analise the light and reproduce it.  And it would be useless if the cloaked object and the observer object are moving relative to each other.
        Rate this comment: 12345
  • Objects invisible
    sman on 04/16/2007 at 3:02 AM
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    This is a intresting idea and a good innovation. If becomes fully successful it is unknown for what good purposes it will be used.
    www.browsetoknow.blogspot.com
    Rate this comment: 12345
    • Re: Objects invisible
      Dr. Spook on 08/11/2007 at 11:02 PM
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      What would be done with such a technology? Well, I have been working on concepts for invisibility for years. I always knew the "Invisible Man" concept would not work. Nor would anything involving reproduction of images. I see it as being able to control Ultraviolet rays. But one concept I have yet to see explored is to approach the problem using Sound Cancelling technology. Any thoughts on this?

      Also, why does every fictional Invisible Man end up miserable? Hell, there are too opportunities for fun, hunting down bad guys or just being able to walk about, undetected and mess with people. That would never get old.
      Dr. Spook
      Rate this comment: 12345
  • Perfect invisibility device
    cloakingdevice on 04/17/2008 at 3:31 AM
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    That work is excellent and very interesting, however I would also show that a recent work indicates that Perfect Invisibility Devices using isotropic media are possible. Furthermore, the new design allows to get around the Nachman theorem using these isotropic materials.

    you can learn more here...
    http://invisibility.research.googlepages.com/

    http://techon.nikkeibp.co.jp/article/NEWS/20080416/150549/?ST=nano
    Rate this comment: 12345
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