Transform a ball into a rock -- or make it invisible -- using transformation optics
July 9, 2009 By Miranda Marquit
Image from Phys. Rev. Lett. 102, 253902 (2009). (c)2009 APS. Reprinted with permission.
(PhysOrg.com) -- Science fiction and fantasy tales are full of the ability to "cloak" characters with invisibility. Whether it is a spaceship with a cloaking device, or a young wizard with an invisibility cloak, the interest in rendering someone or something invisible captures our fancy. Scientists have succeeded in creating the illusion of invisibility by bending light around a region for concealment. These types of devices have limitations, however; one of these limitation that the device normally has to be touching the object to be rendered invisible - or in very close proximity.
Instead of bending light, though, what if transformation optics was used to create invisibility - or even give an object the appearance of a completely different object? A team of theorists at the Hong Kong University of Science and Technology propose a technique that might be able to accomplish just that, with a remote device. The group’s proposal appears in Physical Review Letters: “Illusion Optics: The Optical Transformation of an Object into Another Object.”
“Right now, invisibility devices bend light, steering it around an object to make it appear transparent, as if it weren’t there,” Che Ting Chan tells PhysOrg.com. Chan is one of the scientists who proposed the idea of a device that would use illusion optics to transform objects within a confined space. “Our proposed device would have special properties. It would employ a type of illusion that makes an object look exactly like another object.”
Metamaterials, which are manmade with special properties, would be used. A “complementary medium” would be employed to optically cancel a specified area. Then, a “restoring medium” would be used to make the cancelled space “reappear” as something else. For invisibility, the restored area would look like air. “If it looks like air,” Chan explains, “then it is transparent. You can see through it. It is like making something invisible.” This method could also, theoretically, be used to “transform” objects. “You could make a ball look like a rock,” Chan says. “You could hide something in plain sight, as something else.”
In addition to transforming the way an object looks to others, this device would have another advantage over current invisibility devices. “You wouldn’t have to need the device to touch the object being hidden,” Chan insists. “You could remotely control a particular area to entirely exclude a specific wave without having to be as close.”
While the device sounds promising, Chan admits that there are difficulties involved in building such a cloak. “In addition to positive refractive material, which is not a big problem, we would require a negative refractive index.” Positive refractive materials are easily made, but something with a negative refractive index would require special design. “Some sort of structure to create a phase delay would be needed,” Chan says.
Chan and the Hong Kong team are working on interesting experimentalists in the concept. “We are dealing with electromagnetic waves,” Chan explains, “but there are those who are doing similar experiments with acoustic waves. Maybe if our idea was applied to acoustic waves first, it would be easier to see how to extend it to include light.”
More Information: Yun Lai, Jack Ng, HuanYang Chen, DeZhuan Han, JunJun Xiao, Zhao-Qing Zhang, and C.T. Chan, “Illusion Optics: The Optical Transformation of an Object into Another Object,” Physical Review Letters (2009). Available online: http://link.aps.org/doi/10.1103/PhysRevLett.102.253902 .
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Mar 13, 2009 |
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Like they say, it just needs 'meta-materials', which is stuff patterned 'tighter' than the wavelengths involved.
Per Clarke's Law, 'sufficiently advanced technology is indistinguishable from magic'. Go Google...
My point was that "just needs meta-materials" is a bit like saying "in order to fly you 'just' need to be able to suppress gravity" - the clever bit is not describing what you need to do, it's doing it.
There are lots of quaotation marks around the words in the article, which leads me to think it's more speculative than any new discovery.
"speculative" is being generous.
Try - "a load of foolish babble".
when the subject starts to move. Its movement will create different index of refraction for
observer in relation to the subjects that can be seen through the invisible moving subject.
For this reasons those subjects will start to blink. I noticed that effect by observing AFOs (Aliens Flying Object) that using the same technique,
in the night sky at altitude 20 - 40 miles. AFOs are invisible but when they move under the star the latter start to blink and their invisible bodies
surrounded by weak signal lights creating a circle. That is how I know that the reason for the existence of blinking stars is not only
different layers of atmosphere but also the presence of the moving AFOs.
sites.google.com/site/socialcapital1/Home
Either Chan had something, and the PhysOrg editor missed it, or Chan is just waving his hands in the air.
Whatever the case, this article is a waste of PhysOrg's readers' time.