Acoustic Technology

Synhetic aperture radars have progressed radar imaging applications to the point where physically controlled beams are becoming a rarity instead of the norm. Acoustic methods are now following the same path using new materials working as wave guides. Crystal matrices with acoustic refraction properties are being used to focus and direct acoustic fields at specific frequencies. This opens up new application possibilities for a wide range of uses such as targeted medical imaging and non destructive testing of structures like bridges, aircraft fuselage etc.

 Through design of the phase gradient profiles of crystalline surfaces acoustic convex and concave lenses can focus the incoming plane waves and collimate the converging waves, respectively. On the basis of the high converging and diverging capability of these lenses, two kinds of lens combination scheme, including the convex–concave type and convex–convex type are able to tune the incoming beam aperture as needed. The aperture of the acoustic beam can be shrunk or expanded through adjusting these phase gradients that are constructed by the stacking ultrathin labyrinthine structures, which are obtained by the geometry optimization procedure and exhibit high transmission coefficient and a full range of phase shift.