Demonstration of the Concealment Device
Humans are one step closer to becoming invisible, although you might need to be prepared to get wet first.
US researchers have developed a cloaking device that can hide objects using the same principle that causes mirages, and which works best underwater.
The device is constructed of sheets of carbon nanotubes (CNT)–single-molecule-thick sheets of carbon wrapped up into cylindrical tubes–that are as dense as air and as strong as steel.
Additionally, CNTs are excellent heat conductors, being able to efficiently transfer heat to surrounding areas–a key property in generating the single-beam mirage effect, also known as photothermal deflection.
Mirages are an optical illusion in which heat bends light rays to produce a displaced image of distant objects, and are often observed in hot environments such as deserts.
The most commonly observed instance of a mirage is when the viewer sees what appears to be pools of water on the ground due to warmer air at ground level bending light towards the eyes instead of bouncing back off the surface. This results in an image of the sky appearing on the ground, which the observer perceives as water reflecting the sky.
Based on this phenomenon, the sheet of CNTs submerged in liquid is heated using an electrical current, creating heat distribution similar to that in a mirage. This causes the light waves to bend and any object concealed behind the device to vanish.
"Using these nanotube sheets, concealment can be realized over the entire optical range and rapidly turned on-and-off at will, using either electrical heating or a pulse of electromagnetic radiation," said study lead author Ali Aliev at the University of Texas, Dallas in a media release.
"The research results also provide useful insights into the optimization of nanotube sheets as thermoacoustic projectors for loud speaker and sonar applications, where sound is produced by heating using an alternating electrical current."
This cloaking device could have a wide range of uses, including photo-deflectors and switchable invisibility cloaks.
"It is remarkable to see this cloaking device demonstrated in real life and on a workable scale," said a spokesperson at Institute of Physics (IOP) in the release.
The array of applications that could arise from this device, besides cloaking, is a testament to the excellent work of the authors."
The findings will be published in IOP Publishing’s journal Nanotechnology on Oct. 28.