Metamaterial Mirror Reflects Sound Waves in Any Direction

摘要

Researchers have constructed a "meta-mirror" device capable of perfectly reflecting sound waves in any direction. The proof-of-principle demonstration is analogous to looking directly into a mirror and only seeing the person next to you instead of your own face. With a reg-ular mirror, the light follows the Law of Reflection - it must bounce off of it at the same angle at which it entered. The same rules generally apply to sound. To break the law of reflection with sound waves, the researchers engineered a device that could precisely control am-plitude (loudness) and speed throughout the entire wave. To achieve this, metamaterials - artificial materials that manipulate waves like light and sound through their structure rather than their chemistry - were used. While the particular metamaterial that was designed is made out of plastic, it's not the properties of the plastic that are important; it's the shapes of the device's features that allow it to steer sound waves in any direction.