Scientists Make 3D Object Invisible
![Microwaves can be seen being blocked and scattered without and "reconstructed" with the cloak, and the upper-band edge of the cloak's performance.](https://d.medicaldaily.com/en/full/222938/microwaves-can-seen-being-blocked-scattered-without-quotreconstructedquot-cloak.jpg?w=670&f=22c1aa3c6f47b7efb2586b0bff62f9d9)
Scientists have managed to cloak a three-dimensional free-standing object to make it appear invisible in from any angle, bringing the mythical invisibility cloak closer to reality.
Researchers from the University of Texas at Austin said they coated an 18-centimeter cylindrical tube with plasmonic metamaterials, a substance capable of redirecting microwave light around an object, according to a study published on Thursday in the New Journal of Physics.
Up until now researchers have only managed to cloak two-dimensional objects with metamaterials, but the 3D advancement was as made with new plasmonic metamaterials that terminate light rays from bouncing off objects.
Objects are made visible when light striking it rebounds and goes towards the eye.
However the cloak of invisibility only works for waves in the microwave region of the electromagnetic spectrum and is still visible to the human eye. Researchers also said that the cloak only works on simple objects and can’t hide complex shapes and materials like a person.
The study directed microwaves towards the cloaked cylinder and measured the resulting scattering both around the object and in the far-field. Researchers said that the cloak demonstrated “optimal functionality” when the microwaves were at a frequency of 3.1 gigahertz and over a moderately broad bandwidth.
Researchers are working on developing an invisibility cloak that works within the visible light region so people would be able to see the cloak work.
"In principle, this technique could be used to cloak light; in fact, some plasmonic materials are naturally available at optical frequencies. However, the size of the objects that can be efficiently cloaked with this method scales with the wavelength of operation, so when applied to optical frequencies we may be able to efficiently stop the scattering of micrometer-sized objects,” said study co-author Professor Andrea Alu in a statement on Wednesday.
Researchers said that the cloak can be applied to the tips of scanning microscopes, which are the most high-resolution microscopes up to date, to produce an improved view of even smaller wavelengths of light.
"Still, cloaking small objects may be exciting for a variety of applications. For instance, we are currently investigating the application of these concepts to cloak a microscope tip at optical frequencies. This may greatly benefit biomedical and optical near-field measurements," Alu said.