A team of scientists at Lawrence Berkeley National Laboratory has tested an ultra-thin cloak which can make things invisible. The cloak consists of a 50nm-thick layer of Magnesium Fluoride covered with different patterns of gold antennas. The antennae are brick-shaped, and tiny in size. The cloak was tested on tiny object, but the team believes that it should work for larger objects too.
The team was led by Xiang Zhang, Director of Material Science at the laboratory. For testing the cloak, they wrapped it around a tiny, irregular object and shone light on it. The cloak reflected the light waves, but in such a way that the object appeared to be invisible. This happened because the gold antennae scattered the incident light, which created an effect of the light striking a perfect mirror. Zhang told LiveScience that the gold antennae can be tuned to modify incident light's reflection angles, thereby applying the principles of total reflection. As a result, the perfect reflection of light will tune the object being covered in synchronisation with the background, and show it in a form factor different from the original one. For instance, an object as large as a tall bookshelf can appear like a stool.
Claiming significant improvement over previous attempts at modifying form factors and invisibility, the new cloak can wrap around edges of objects too, enabling total reflection of the nature of a flat mirror around it. The team had tuned it for incident light wavelength of 730nm, although Zhang said that there should be no reason for the cloak to fail in front of light waves of varying wavelengths. Additionally, it may take up to five to ten years to make the technology suitable for practical usage. Furthermore, it can eventually be used for military applications like making bigger objects appear as vehicles, or aircraft/soldiers appear invisible.
Image Credit: Xiang Zhang group, Berkeley Lab/UC Berkeley