阵列形式和界面条件对相位共轭阵列聚焦特性的影响  

Effects of array species and reflecting surfaces on focusing properties of phase conjugation

作　　者：黎胜[1,2] 

机构地区：[1]大连理工大学工业装备结构分析国家重点实验室,辽宁大连116024 [2]大连理工大学船舶工程学院,辽宁大连116024

出　　处：《声学技术》2010年第5期462-466,共5页Technical Acoustics

基　　金：国家自然科学基金资助项目(10972046)

摘　　要：相位共轭阵列可以基于声压测量或质点速度测量使用单极子源或偶极子源在近场或非近场来进行时间反转,海面和海底等反射界面对相位共轭阵列的聚焦特性有影响。采用有限阵元平面阵列使用数值方法研究了5种不同相位共轭阵列的聚焦特性。结果表明:只有在测量距离小于1/5波长,基于声压梯度测量并使用偶极子源的相位共轭阵列才能突破声波衍射极限分辨率。还研究了界面条件对相位共轭阵列聚焦特性的影响,结果表明:界面反射条件对聚焦分辨率影响不大,只是增大了聚焦的强度,界面反射系数的绝对值越大,相位共轭声场的声压幅值越大;当阵列测量距离在声源的近场时,界面对阵列聚焦特性的影响非常小;当阵列测量距离较近时,刚性界面对声压幅值的影响大于自由界面的影响,但自由界面的影响随着阵列与声源距离的增大而增大,当测量距离较远时,自由界面的影响已远大于刚性界面的影响;随着界面与阵列和声源的距离的增大,界面对聚焦特性的影响越来越小。Phase conjugation arrays could be based on pressure or particle velocity measurement and be made of monopoles or dipoles to reverse time in near field or non-near field.The reflecting surfaces such as sea surface and sea bottom influence retrofocus properties.The focusing properties of five species of phase conjugation arrays are studied with the discrete plane arrays numerically.The numerical simulation shows that only the dipole arrays based on the pressure gradient at a distance less than 1/5th of one wavelength from the source lead to subwave length focusing.The numerical results of the effects of a reflecting surface on the focusing properties show that the surface increases the field magnitude produced by the phase conjugation array when the reflection coefficient increases.The reflecting surface does not increase the spatial resolution.The influence of the reflecting surface is insignificant when the measurement is made in the near field or when the reflecting surface is far from the array and the source.The effect of a rigid surface is more significant than a free surface when the measurement is made near the source.With increasing measurement distance from the source,the effect of a free surface becomes more obvious than a rigid surface.

关 键 词：相位共轭阵列 聚焦特性 分辨率 自由界面 刚性界面 

分 类 号：TB53[理学—物理]