Cloaking objects at a distance

cloaking-at-a-distance

One of the disadvantages of invisibility cloaks is that anything placed inside one is automatically blinded, since no light can get in.

Now Yun Lai and colleagues from The Hong Kong University of Science and Technology have come up with a way round this using the remarkable idea of cloaking at a distance. This involves using a “complementary material” to hide an object outside it.

Here’s the idea: complementary materials are designed to have a permittivity and permeability that are complementary to the values in a nearby region of space. “Complementary” means that the values cancel out the effect that that this region of space has on a plane lightwave passing through. To an observer, that region of space simply vanishes.

Cloaking a region of space is relatively straightforward but cloaking an object in that space is another matter. Lai and co say the trick is to work out the optical properties of the object and then embed the “complementary image” within the cloaking material. So a plane wave would be bent by the object but then bent back into a plane as it passes through the cloaking material.
Et voila: cloaking at a distance. And in a way that doesn’t leave the cloaked object blind.

Of course , creating the complementary materials necessary to do this trick is another matter. And the usual caveats apply: it works only at a single frequency in 2D. But cloaking, in theory at least, is looking more interesting by the day.

Ref: arxiv.org/abs/0811.0458: A Complementary Media Invisibility Cloak that can Cloak Objects at a Distance Outside the Cloaking Shell

10 Responses to “Cloaking objects at a distance”

  1. [...] to date work by hiding an object embedded inside them. Now a group of physicists have worked out how to remotely cloak objects that sit outside a cloaking material. The trick is to make the cloaking material with optical properties that are exactly complementary [...]

  2. [...] to date work by hiding an object embedded inside them. Now a group of physicists have worked out how to remotely cloak objects that sit outside a cloaking material. The trick is to make the cloaking material with optical properties that are exactly complementary [...]

  3. observer says:

    this idea have been used in anime and manga stories for a very long time. just a tidbit of trivia there

  4. It might be the wine I have been into but I am not getting how this works.

    “To an observer, that region of space simply vanishes.”

    As opposed to an unvanished region of space which appear like what?

    Maybe fewer Greek letters in the diagram would make it more laymen friendly. ;-)

  5. [...] the physics arXiv blog » Blog Archive » Cloaking objects at a distance Cloaking a region of space is relatively straightforward but cloaking an object in that space is another matter. Lai and co say the trick is to work out the optical properties of the object and then embed the “complementary image” within the cloaking material. So a plane wave would be bent by the object but then bent back into a plane as it passes through the cloaking material. Et voila: cloaking at a distance. And in a way that doesn’t leave the cloaked object blind. (tags: future weird technology) [...]

  6. [...] All invisibility cloaks to date only work by hiding an object embedded inside them. Now a group of have worked out how to remotely cloak objects that sit outside a cloaking material. The trick is to make the cloaking material with optical properties that are exactly complementary to the space outside them. (Source: http://arxivblog.com/?p=698) [...]

  7. Jim says:

    Like the one note – I don’t understand it either! It seems as though, part of an area of earth could be somehow be rendered devoid of light waves, so it would become invisible and therefore anything with in that space would be rendered invisable as well – am I close??????????
    Jim

  8. jack sprat says:

    It is impossible for a professional to understand what it is that you are talking about. For a layman, it needs an once in a lifetime insert into the brain.

  9. pharmaclees says:

    I think it may be more like wave cancellation. like quiet comfort headphones

  10. [...] בתקווה, ה-UC-IC של Magestyk יהיה טוב יותר. Cloaking at a Distance. הם מסבירים פה איך להפוך עצמים לבלתי