The Research Of Focusing And Imaging Based On Tubular Acoustic Super Lens

The phononic crystal can be used to focus the acoustic wave because of its unique negative refraction property,this peculiar physical phenomenon has aroused the concern of the many researchers.In ocean exploration,development and defense,acoustic focusing can realize high resolution imaging sonar.In the medical field,acoustic focusing can provide a more safe and effective therapy for the treatment of cancer.The application of acoustic focusing technique has great advantage and practical value,using acoustic physical lens to realize acoustic focusing is more advanced science and technology.So there is an extremely important research value in theory and design of acoustic lens.Based on the locally resonant phononic crystal,negative refraction theory knowledge,combining the application prospect of acoustic focusing technique,development situation of acoustic lens imaging,we proposed and designed a new type of tubular acoustic lens structure and build a simple model.And explain the formation process of negative refractive index and acoustic wave transmission in phononic crystal.The ideal frequency range of negative refraction formation is obtained by the analysis of phononic crystal cellular vibration characteristics.The band structure of the lens is obtained by layer multiple scattering method.COMSOL Multiphysics software is used for simulate acoustic wave transmission and focusing of near-field point acoustic source through different thickness of tubular super lens,obtained the curves of transmittance and reflectance,which further determines how thick of the acoustic lens will get the best effect of imaging.Under the ideal thickness,the focusing effect of tubular acoustic lens is simulated under different incident frequencies.And the full width at half maxima(FWHM)curve is obtained,which further determines the ideal incident frequencies.In the simulation results,observed the incident wave and emergent wave are close and the dispersion phenomenon is very weak,the simulation results and theory reacheda good agreement,which is a great evidence indicates that this lens is able to achieve good focusing and imaging to near-field point acoustic source.