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
[...] 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 [...]
[...] 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 [...]
this idea have been used in anime and manga stories for a very long time. just a tidbit of trivia there
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.
[...] 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) [...]
[...] 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) [...]
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
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.
I think it may be more like wave cancellation. like quiet comfort headphones
[...] בתקווה, ה-UC-IC של Magestyk יהיה טוב יותר. Cloaking at a Distance. הם מסבירים פה איך להפוך עצמים לבלתי
It’s not the actual space that’s vanishing. It’s the object that occupies that space. The Permeability/Permittivity of the material refers to its’ ability to absorb and emit surrounding light. So if there’s a tree behind you then the material would absorb that light (Permeability) and then emit that light out of the other side (Permittivity). Therefore anyone standing in front of you would see the tree. The space you occupy would then, in effect, “disappear” and only the tree would be seen.
Wacko analogy : your digital camera, one side captures the scene and the other side displays it on the screen. When you look at the the camera back you can see through the device and the insides of the actual camera virtually disappear because the screen in front of your eyes displays what is in front of the lens.
What they’re trying to say is you essentially curve the light waves from behind it and in front of it so that when you are standing a ways away from it, you can see the light waves from the other side after they have been bent to go around it. At least this is my interpretation.
I like cake.
DeeDee: I’m afraid your definitions of permeability and permittivity are misleading – they do not really refer to absorbing/emitting light.
Roughly speaking, permeability refers to how a material affects a magnetic field, and permittivity to how it affects an electric field. Light is a wave of both electric and magnetic fields, and knowing these two properties lets you predict what will happen to the light. By setting these properties in a particular way, you can bend light to achieve this invisibility effect.
Really? Which ones?
my interpitation is that the field properties of the light source are manipulated so that they curve around the solid object,without reflecting in the direction of the source.
details are not understood by myself,but it starts my imagination considering the possibilities.
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