Pyramid structure defenseless again sensors? (via Duke)
If you’ve ever watched Harry Potter and thought “wow, I want an invisibility cloak,” don’t fret – technology is finally catching up to ancient wizard magic. Engineers at Duke recently unveiled the world’s first sonar cloaking device.
The study was led by Steven Cummer and his team of engineers and was featured in a recent online issue of Nature Materials. While this cloaking device won’t exactly make you invisible, it will make you, or any other object beneath it, undetectable via sound waves.
Cummer and Bogdam Popa, a research scientist who helped design the structure, said the device “tricks” sound waves into behaving as if there is only a flat, uninteresting structure in its path. Anything underneath the structure also remains hidden from the unsuspecting waves. The device itself looks uninteresting, at first glance. It’s composed of multiple layers of flat, perforated plastic sheets that come together to create a pyramid-like structure. Despite its “simple” design, it can actually redirect sound waves to give the impression that it doesn’t exist. Watch out sea creatures. You may be defenseless against Poseidon’s underwater lair.
The team constructed the device based on metamaterials theory – a science which takes common materials and accomplishes supernatural effects by the use of repeated patterns. In this instance, the perforation on the plastic sheets is actually able to redirect sound waves it encounters to mimic a flat surface. It does this by changing the trajectory of incoming sound waves by compensating for the change in speed and distance it experiences when it comes into contact with the device. While its design is simple, Cummer assures us its effects are powerful.
In trials, the team tested its structure by measuring sound waves in various situations. They began by measuring the sound waves across a flat, empty space, and then measured the way those waves changed when encountered by a small sphere, the cloaking device, and the sphere covered by the cloaking device. The team found that the sound waves expressed the same trajectory when it encountered the device and the sphere covered by the device as it did when it encountered a flat, empty surface. This told the researchers that their device successfully completed its magic trick, which we’ll call “now you hear me, now you don’t.”
The device is still in the early stages of development, but the research team believes it will have a number of uses, including underwater sonar avoidance and in the architecture of concert halls, opera houses, auditoriums and any other places that require acoustic control. It can also be used to cloak support beams or other objects inside auditoriums that interfere with sound.
Eventually, of course, the design may also be utilized to hide Lex Luther’s evil lair… but only if Superman doesn’t catch him first.
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