Chinese researchers have developed a “ghost cape” that can make one object appear to look like another.
The team from Southeast University in Nanjing, China said that their technique is far simpler that other invisibility devices, because instead of making an object disappear entirely, it makes it look like something else, the Daily Mail reported.
The technique scatters incoming light to create two “ghost” images either side of the cloaked object.
“The creation of wave-dynamic illusion functionality is of great interests to various scientific communities,” the researchers led by Tie Jun Cui at Southeast University in Nanjing, China, said.
They said that their research could have unprecedented applications in the advanced-material science, camouflage, cloaking, optical and/or microwave cognition, and defense security, etc.
The team has already built a prototype device to show off their theory.
Depending on the construction of the cloaking device, the shape and other properties of the ghost images can be altered.
“By using the space transformation theory and engineering capability of metamaterials, we propose and realize a functional ‘ghost’ illusion device, which is capable of creating wavedynamic virtual ghost images off the original object’s position under the illumination of electromagnetic waves,” they said
“The scattering signature of the object is thus ghosted and perceived as multiple ghost targets with different geometries and compositions,” the said.
Current invisibility cloaks work using a two stage process.
The first is an invisibility stage which distorts incoming light to remove the scattering effect of the cloaked object, for instance an apple, before a second stage distorts the scattered light to make it look as if it has been scattered off another object, a banana, for example.
The result is that the apple ends up looking like a banana.
The Chinese team have found a way to simplify this process, abandoning the first stage.
Their device takes the light scattered from the apple and distorts it to look like something else such as a banana, according to Technology Review.
The symmetry of the effect means light is scattered on both sides of the apple, producing two ‘ghost’ bananas, one on each side of the apple.
The technique does not remove the apple entirely but distorts it, making it appear much smaller.
So the result is that the apple is changed into a much more complex picture that is significantly different from the original.
The team said that this technique could one day be scaled up to create “ghost” planes, for instance.
The cloak itself is fashioned out of thousands of split-ring resonators, a structure commonly used in metamaterials that affects electromagnetic waves.