Gudra Tadeusz, Opieliński Krzysztof J
Institute of Telecommunication and Acoustics, Wroclaw University of Technology, Poland.
Ultrasonics. 2002 May;40(1-8):457-63. doi: 10.1016/s0041-624x(02)00159-2.
In different solutions of ultrasonic transducers radiating acoustic energy into the air there occurs the problem of the proper selection of the acoustic impedance of one or more matching layers. The goal of this work was a computer analysis of the influence of acoustic impedance on the transfer function of piezoceramic transducers equipped with matching layers. Cases of resonance and non-resonance matching impedance in relation to the transfer function and the energy transmission coefficient for solid state-air systems were analysed. With stable thickness of matching layers the required shape of the transfer function can be obtained through proper choice of acoustic impedance were built (e.g. maximal flat function). The proper choice of acoustic impedance requires an elaboration of precise methods of synthesis of matching systems. Using the known matching criteria (Chebyshev's, DeSilets', Souquet's), the transfer function characteristics of transducers equipped with one, two, and three matching layers as well as the optimisation methods of the energy transmission coefficient were presented. The influence of the backside load of the transducer on the shape of transfer function was also analysed. The calculation results of this function for different loads of the transducer backside without and with the different matching layers were presented. The proper load selection allows us to obtain the desired shape of the transfer function, which determines the pulse shape generated by the transducer.
在将声能辐射到空气中的不同超声换能器解决方案中，存在着正确选择一个或多个匹配层声阻抗的问题。这项工作的目标是对配备匹配层的压电陶瓷换能器的声阻抗对传递函数的影响进行计算机分析。分析了固态 - 空气系统中与传递函数和能量传输系数相关的共振和非共振匹配阻抗情况。在匹配层厚度稳定的情况下，通过适当选择声阻抗可以获得所需的传递函数形状（例如最大平坦函数）。正确选择声阻抗需要精心设计匹配系统的精确合成方法。利用已知的匹配标准（切比雪夫、德西莱茨、苏凯），给出了配备一层、两层和三层匹配层的换能器的传递函数特性以及能量传输系数的优化方法。还分析了换能器背面负载对传递函数形状的影响。给出了不同负载下换能器背面有无不同匹配层时该函数的计算结果。正确选择负载可使我们获得所需的传递函数形状，而传递函数形状决定了换能器产生的脉冲形状。
