Acoustic Lensing (textbook Level)

Acoustic lensing means controlling the path of sound waves so that they converge toward or diverge from a region, similar in concept to how an optical lens controls light.

Sound changes speed when it travels through materials with different acoustic properties. Carefully designed structures can therefore alter the direction of sound waves and focus them.

An acoustic lens may use: * shaped materials; * layers with different sound speeds; * specially designed structures. Its purpose is to control sound-wave propagation.

A converging acoustic lens directs sound energy toward a smaller region. This can increase sound intensity near the focus.

Possible applications include: * ultrasound imaging; * medical ultrasound treatment; * sonar; underwater acoustics; non-destructive testing; * specialised sound-control systems.

Optical lenses control light. Acoustic lenses control sound. However, the physical waves are different: **light → electromagnetic sound → mechanical**