University of Illinois researchers have demonstrated an acoustic cloak, a technology that renders underwater objects invisible to sonar and other ultrasound waves.
The cloak is made of metamaterial, a class of artificial materials that have enhanced properties as a result of their carefully engineered structure. The team, led by mechanical science and engineering professor Nicholas Fang, designed a two-dimensional cylindrical cloak made of 16 concentric rings of acoustic circuits structured to guide sound waves. Each ring has a different index of refraction, meaning that sound waves vary their speed from the outer rings to the inner ones.
Next, the researchers plan to explore how the cloaking technology could influence applications, including military stealth, soundproofing, and health care. The cloaking technology also may affect nonlinear acoustic phenomena.
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