Experimental investigation of focusing properties by sonic crystals with different crystal geometry

Negative refraction studies done for electromagnetic waves have enlarged for acoustic waves for decade and considerable similarities were found between sonic and photonic crystals. Many properties were seen in band structure of sonic crystal and negative refraction properties were investigated to develop applications such as sound isolation, acoustic lens. In the acoustic lens studies, acoustic devices, which focus sound wave to a focal point, were implemented practically. It will particularly contribute development of the medical equipments, based on the linear acoustic properties.The aim of this thesis is to investigate effects of different lattice geometries and effect of various scattering material on focusing properties of sonic crystals. For these proposes, lattice geometries of equilateral triangle, isosceles triangle, square, honeycomb, pressed down honeycomb were used for focusing of sound in convenient frequency. In addition, for every lattice geometry, three different scattering materials, which are aluminum, steel and perspex , were tested.In experimental study, for sonic crystals composed of different lattice geometry and scattering materials, intensity measurements along acoustic axis and intensity measurements on the area, which is specified by acoustic axis and radial axis that is perpendicular to acoustic axis, were presented in the thesis. For numerical analysis, Plane-Wave-Expansion method was used for band structure and equifrequency surface analysis of equilateral triangle, square, honeycomb lattice geometries. Obtained results from experimental study and numerical analysis were discussed. Future works were also outlined briefly.