Duke Researchers Develop Anti-Sonar Shield
CHARLOTTE (CBS Charlotte) – Long a staple of science fiction and fantasy, cloaking devices are coming closer to reality.
Scientists at Duke University have built a structure that can hide anything under from sonar…so long as it’s not underwater, reports Live Science.
The pyramid-shaped sheet, made of perforated plastic, changes the shape and speed of any sound wave that hits it.
The key to this cloaking device are the holes in the plastic, say Lucian Zigoneanu, Bogdan-Ioan Popa and Steven Cummer, who created computer models of sound waves to come up with the right shape and material to make it work.
To test their idea, they put a sphere inside their pyramid and put both in an empty room with a sound generator and a microphone.
The sound generator made a “ping” that would bounce off the pyramid and a single microphone recorded the pings from many, many different angles.
The holes had to be exactly the right size and adjusted according to the wavelength of the sound hitting them. Without the holes the sound waves would just bounce off and reveal the presence of the pyramid. With them, some sound waves were slowed down.
The slower waves followed a longer path back to a detector, just as they would if the pyramid wasn’t there. The shape of the reflected wave looks just as it would if it hit a flat surface, fooling any sonar into thinking the cloak and anything under it doesn’t exist.
The next step is to make the design waterproof so it can be fitted to submarines.
The sound cloak is detailed in the March 9 issue of the journal Nature Materials.
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