The newest cloak (left) is 20" × 4" x< 1" made of 10,000+ individual pieces (6,000 are unique) in parallel rows. Original prototype is on the right.
Back when “Ceramic Tech Weekly” was still just a newsletter (waaay back in mid-2008), I wrote several stories (see here and here) about the emerging technologies related to what is often referred to as “invisibility,” a.k.a., “cloaking” (hello Trekkies). Of course, there is a certain tendency to treat this as something of a novelty. But the fact remains that consistent progress is being made in this area.
First, some clarification: The idea of using advanced materials to “cloak” an object is not so exotic, especially once one is reminded that this ability has been around for decades, i.e., “Stealth” aircraft and ships. Objects that use Stealth technology are simultaneously visible and invisible: They are visible in the wavelengths detected by the human eye, but invisible in the the spectrum used for radar.
So, one way to think about the developments in the last view years is that researchers are applying similar approaches to other parts of the electromagnetic spectrum, moving wavelength by wavelength. Another way to intellectually grasp what is happening in this field is to consider the common mirage drivers often see hovering off in the distance above hot roadways: We take it for granted that the road is there, afar, even though it appears to have disappeared and replaced with the image of a body of water.
The point is that the idea of “invisibility” isn’t so far fetched.
Having noted that, a recent report has come out of Duke University about new advances by a team being led by David Smith. This team has been making progress since at least 2006, when they unveiled their first prototype made of fiberglass that guided electromagnetic waves around an object.
One of the big points in the latest announcement is that whereas the 2006 version of their technology worked with a specific wavelength, the latest iteration works with a broader range of frequencies. Says Smith:
“The difference between the original device and the latest model is like night and day. The new device can cloak a much wider spectrum of waves – nearly limitless – and will scale far more easily to infrared and visible light. The approach we used should help us expand and improve our abilities to cloak different types of waves.”
Besides being applicable to a wider spectrum, the team had made breakthroughs in customizing designs and improving fabrication speed.
The applications for this technology aren’t limited to the obvious. The same approaches could be used to eliminate disruptive effects of obstructions (to improve, for example, wireless communications), develop advanced acoustic shields to block harmful vibrations and build improved light-focusing lenses.
The results of this work is Jan. 16 in the journal Science; first authors of the paper were Liu and Chunlin Li.