二维声学超材料透镜的设计与实验

Design and measurements of a two dimensional metamaterial acoustic lens

基于等效媒质理论提出了一种由新型声学超材料设计的渐变折射率透镜.根据电磁学与声学基本参数存在的类比关系,参照电磁人工材料设计中提取单元结构的等效电导率和等效磁导率的方法,分别提取单元结构的等效弹性模量和等效质量密度,并进一步求得其等效相对阻抗和等效折射率,对设计的透镜进行有限元数值仿真在宽频范围内得到了与实验一致的偏折角度.该透镜由光敏树脂3D打印制成,与传统透镜相比,它具有尺寸小、设计简单、精度高,重量轻等特点.仿真结果和测试结果吻合较好,进一步验证了声电类比设计方法的可行性,为设计宽频带新型声学参数人工材料提供了一种新途径.

We describe the design,fabrication,and measurement of a two-dimensional acoustic lens with gradient refractive index.According to the correspondence between material parameters in electromagnetis mand acoustics, the retrieval of the effective material parameters like in electromagnetism is used in design,and the effective relative impedance and refractive index are received.Designed lens is simulated by COMSOL within certain bandwidth,and is consistent with measurement result.This lens is made of photopolymer through rapid prototyping stereo lithography.Compared with traditional acoustic lens,it has a number of advantages including smaller size,higher ac-curacy,lighter weight and easier design methodology.Both the simulated and the measurement results agree very well,furthermore it verifies the feasibility of this design method borrowing from electromagnetism,and provides a new idea for design of broadband acoustic metamaterial.