Brown L F
South Dakota State University, Brookings 57007.
Biomed Sci Instrum. 1993;29:385-92.
A characterization technique has been developed to address the problems associated with calibrating very-high frequency (i.e., > 50 MHz) ultrasound transducers. The technique is based on using a pc-controlled network analyzer to acquire the through-transmission voltage transfer function spectrum from a pair of ultrasound transducers which are closely spaced in water. This spectrum, which includes electrical feed-through noise and multiple reflection artifacts, is then corrected for the water's attenuation and the transfer response of the electronics system. An inverse Fourier transform is then performed, to produce the time domain response of the transducers. The portion of the response which corresponds to the first acoustic arrival is then gated out of this response, and a Fourier transform is performed to compute the transducers' true transfer function (insertion loss) spectrum. A pc-controlled automated calibration system based on this technique has been developed and numerous transducer pairs have been tested. Excellent agreement has been shown between this method and the conventional tone-burst technique for accurately characterizing insertion loss spectra. In this paper, a detailed description of the technique, actual transducer test results, and comparisons with the conventional tone-burst method are presented in detail.
已开发出一种表征技术，以解决与校准甚高频（即>50MHz）超声换能器相关的问题。该技术基于使用计算机控制的网络分析仪，从一对在水中紧密间隔的超声换能器获取透射电压传递函数谱。然后，针对水的衰减和电子系统的传递响应，对该谱（包括电直通噪声和多次反射伪像）进行校正。接着进行傅里叶逆变换，以生成换能器的时域响应。然后，从该响应中选通出对应于首次声到达的响应部分，并进行傅里叶变换以计算换能器的真实传递函数（插入损耗）谱。基于该技术的计算机控制自动校准系统已开发出来，并且已对众多换能器对进行了测试。对于准确表征插入损耗谱，该方法与传统的单音突发技术之间已显示出极佳的一致性。本文详细介绍了该技术、实际换能器测试结果以及与传统单音突发方法的比较。
