The team that managed to demonstrate the first practical “invisibility cloak” or “cloaking device” using a sheet of superheated carbon nanotubes one molecule thick submerged in water is at it again, only this time, they’re aiming to get it to work in the air, a considerably harder task, given the different properties of the material, but one that promises to make the technology much more practical.
“In water you get large light bending angles,” said Ray Baughman, a researcher at the Alan G. MacDiarmid NanoTech Institute at the University of Texas at Dallas and one of the trio of scientists who authored a paper on the water-based mirage effect.
“In air, you get very small bending angles,” he explained to TPM in a phone interview. “You would need to be viewing the object from afar for the effect to work.”
In their original demonstration, the team managed to achieve the effect by sending an electrical current to rapidly increase the temperature of a highly conductive sheet of carbon nanotubes in a petri dish filled with water.
The heat was then transferred from the carbon nanotubes to the water around it, raising the nearby water molecules’ temperature compared to the rest of the body of water and causing light hitting them to bend light around the sheet itself. Whatever is behind the sheet is rendered effectively “invisible,” in the sense that all the viewer can see is a refracted image of water. In the case of the research team’s demonstration, the obscured objected was wood panel.
Technically, this is “mirage concealment,” rather than cloaking, since it doesn’t render the object itself invisible, only the space in front of it.
But now the team wants to recreate a real “mirage effect” essentially as it occurs in nature, when a surface heats rapidly and warms the air immediately above it, distorting light in the same way as water.
“What we want do is demonstrate it in air, on video” Baughman told TPM, “We’ll know better the answer to how successfully we can cloak in air when we actually test it out on some other objects, which we’re about to do.”
In fact, Baughmann told TPM that the first objects he bought were children’s toys, including a model of a stealth fighter jet. If actually applied to a working stealth jet in real life, the carbon nanotube mirage-effect would actually render the stealth bomber visible on infrared radar, since the carbon nanontube sheets must be heated up to produce the effect, and infrared detects heat signatures.
Still, Baughmann told TPM he has grandiose plans for what his experiment could eventually be used for and surprisingly, they are not necessarily military applications.
Instead, he envisions the cloaking effect to be used to make offshore wind farms invisible to those on shore, allowing them to be put in controversial places like Cape Cod, Massachusetts, without spoiling the view.
“Our intention is to think about the implications of our work,” Baughmann wrote.
Although the mirage concealment has gone viral online, Baughmann noted that his team’s work with carbon nanotubes extends far beyond just that one application. They are also working on thermal acoustic loudspeakers that could be used by U.S. Naval warships to hail incoming ships even in choppy waters and determine whether or not they are friendly or foe, ideally preventing acts of terrorism such as the U.S.S. Cole and friendly fire incidents.