Microwaves can be seen being blocked and scattered with the cloak (New Journal of Physics)
Microwaves can be seen being blocked and scattered with the cloak (New Journal of Physics)

Researchers in the US have "cloaked" a three-dimensional object for the first time, bringing the idea of an invisibility cloak a step closer to reality and releasing the potential to hide fighter jets from radar screens.

Scientists at the University of Texas at Austin were able to make an 18cm (7.2 inches) cylinder technically invisible from all angles after coating it with plasmonic meta-materials.

However, those expecting a Harry Potter-style invisibility cloak will be disappointed as the object was hidden only from the microwave region of the electromagnetic spectrum and was still visible to the naked eye, the scientists said in their research published in the New Journal of Physics.

Most recent breakthroughs in invisibility cloaking have focusssed on transformation-based meta-materials, which are able redirect light around an object but have been used to cloak objects two-dimensional objects.

The plasmonic meta-materials used on the cylinder cancel out the rays of light that bounce off the object and give it its visible status.

"When the scattered fields from the cloak and the object interfere they cancel each other out and the overall effect is transparency and invisibility at all angles of observations," said study co-author study Andrea Alu.

The scientists believe the latest breakthrough could still be used on large objects such as jet fighters, making them invisible to radar microwaves.

"Camouflaging to radar is one important application - a super-stealth device to make objects invisible to radar," Alu said.

"What we are thinking about is not necessarily cloaking the whole warplane but some hot spots, a part such as the tailplane that you would want to cloak because it reflects most of the energy (from microwave radar).

"We have some ideas to make it work. But the human eye is not our priority. Right now, we're focused on improving biomedical imaging."