二维声子晶体平板成像中的通道特征

利用多重散射理论分析了钢/水声子晶体平板成像过程.发现平板成像中的散射波会聚具有散射通道特征.对于确定的声源位置,不同入射角信号对应不同的通道;耦合进入通道的信号强度也不相同.小角度入射波能较强地耦合进入通道;大角度入射波在入射表面受到强烈散射,较弱地耦合进入通道.非理想成像情况下,不同入射角信号通过平板成像的位置不同,因而形成像差.声源位置改变,对应的通道亦随之改变.散射通道与声子晶体的各向异性能带结构和多重散射密切相关.

Scattering channel in focus imaging of two-dimensional phononic crystal panel

By multiple-scattering theory (MST), disorder effect on the focus image in steel/water phononic crystal panel with negative refraction was investigated. It was found that sonic waves within certain frequency range can propagate along certain directions in periodic crystal and form a focus image with negative refraction characteristics. These directional pathways depend on the periodic scattering in the crystal and are different from the ordinary positional guide. Obstacles in pathways have a deep influence on the focus image. With the increasing of degrec of positional disorder of cylinders, the periodic scattering decreases, pathways are broken, and the focus image becomes blurred or disappears.