Newly Developed Cloak Hides Underwater Objects Form Sonar

Guadalupe Tain

Source of Article: Science Daily

Title: Newly Developed Cloak Hides Underwater objects from Sonar

The experiment demonstrates an acoustic cloak, that is a technology thatrenders underwater objects invisible to sonar and other ultrasound waves. The article I chose explains how by means of controlling sound waves by bending and twisting them in a designer space, you canhide an object from a range of sound waves. I will explain these in depth, but first of all I am going to explain what the cloak is.
The cloak is an advanced stealth technology device that can causeobjects to be partially or wholly invisible to parts of the electromagnetic (EM) spectrum. This was studied by researchers for years, and now scientists already use artificial materials calledmetamaterials to bend light waves. The one used in the experiment was a two-dimensional cylindrical cloak made of 16 concentric rings of acoustic circuits structured to guide sound waves. Each ring has adifferent index of refraction, meaning that sound waves vary their speed from the outer rings to the inner ones.

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Well, coming back now to the experiment itself, what youare basically watching is an array of cavities (a systematic arrangement of objects usually in rows and columns) that are connected by channels. The sound is going to propagate inside those channels,and the cavities are designed to slow the waves down. As you go further inside the rings, sound waves gain faster and faster speed. Since speeding up requires energy, the sound waves instead propagatearound the cloak's outer rings, guided by the channels in the circuits. The specially structured acoustic circuits actually bend the sound waves to wrap them around the outer layers of the cloak.This was tested several times and with different objects and concluded that it does not matter neither the structure of what you are trying to hide nor the densities. However, the article made...