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首页> 外文期刊>IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control >Probing acoustic fields of clinically relevant transducers: the effect of hydrophone probes' finite apertures and bandwidths
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Probing acoustic fields of clinically relevant transducers: the effect of hydrophone probes' finite apertures and bandwidths

机译：探索临床相关换能器的声场：水听器探头的有限孔径和带宽的影响

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摘要

The influence of finite aperture and frequency response of piezoelectric ultrasonic hydrophone probes on the free-field pulse intensity integral (PII) and mechanical index (MI) was investigated using a comprehensive acoustic wave propagation model. The model developed was capable of predicting the true pressure-time waveforms at virtually any point in the field. The input to the model used pressure amplitude data measured in the immediate vicinity of the acoustic source or transducer considered. The experimental verification of the model was obtained using a commercially available, 8 MHz, dynamically focused linear array and a single element, 5 MHz, focused rectangular source. The verification was performed at low and high excitation levels, corresponding to linear and nonlinear acoustic wave propagation, respectively. The pressure-time waveforms were recorded using piezoelectric polymer hydrophone probes that had different sensitivities, frequency responses, bandwidths, and active element diameters. The nominal diameters of the probes ranged from 50 to 500 Μm, and their useable bandwidths varied between 55 and 100 MHz. The PII, used to calculate the thermal index (TI), was found to increase with increasing bandwidth and decreasing effective aperture of the probes. The MI, another safety indicator, also was affected, but to a lesser extent. The corrections predicted using the model were used to reduce discrepancies as large as 30% in the determination of PII. The results of this work indicate that, by accounting for hydrophones' finite aperture and correcting the value of PII, all intensities derived from the PII can be corrected for spatial averaging error. The results also point out that caution should be exercised when comparing acoustic output data. In particular, hydrophone's frequency characteristics of the effective diameter and sensitivity are needed to correctly determine the MI, TI, and the total acoustic output power produced by an imaging transducer.
机译：利用综合声波传播模型研究了压电超声水听器探头的有限孔径和频率响应对自由场脉冲强度积分（PII）和机械指数（MI）的影响。所开发的模型能够预测现场几乎任何点的真实压力时间波形。该模型的输入使用在所考虑的声源或换能器附近测量的压力幅度数据。使用可商购的8 MHz动态聚焦线性阵列和单个元素5 MHz聚焦矩形源对模型进行实验验证。验证是在低激励水平和高激励水平下进行的，分别对应于线性和非线性声波传播。使用具有不同灵敏度，频率响应，带宽和有源元件直径的压电聚合物水听器探头记录压力-时间波形。探头的标称直径范围为50至500微米，其可用带宽在55至100 MHz之间变化。发现用于计算热指数（TI）的PII随着带宽的增加和探头有效孔径的减小而增加。 MI，另一个安全指标，也受到了影响，但程度较小。使用该模型预测的修正值可将PII的确定差异减少多达30％。这项工作的结果表明，通过考虑水听器的有限孔径并校正PII的值，可以校正源自PII的所有强度的空间平均误差。结果还指出，比较声学输出数据时应格外小心。特别地，需要水听器的有效直径和灵敏度的频率特性，才能正确确定MI，TI和成像换能器产生的总声输出功率。

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