Elimination of standing wave effects in ultrasound radiation force excitation in air using random carrier frequency packets.
Elimination of standing wave effects in ultrasound radiation force excitation in air using random carrier frequency packets.
复制标题
使用随机载波频率包消除空气中超声辐射力激励的驻波效应。
DOI：
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发表时间：
2011
影响因子：
2.4
通讯作者：
J. Helps
中科院分区：
文献类型：
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作者：
T. M. Huber;N. Beaver;J. Helps
超声波辐射力已用于从微悬臂梁到原声吉他等设备的非接触式激励。对于超声辐射力激励，一项挑战是超声换能器和被测设备之间形成驻波。驻波会产生相长/相消干扰，从而导致超声场强度发生显着变化。驻波引起的辐射力强度变化可能是由换能器位置、载波频率的微小变化或环境温度变化引起的声速变化引起的。目前的研究表明，通过随机改变数据包中的超声载波频率，可以消除驻波形成所造成的负面后果。中心频率为 550 kHz 的会聚超声换能器聚焦在黄铜悬臂上。 267 Hz 共振由超声波辐射力激发，载波频率以 10 个周期为一组，在 525 kHz 至 575 kHz 之间随机变化。由于每个数据包具有不同的载波频率，因此与 550 kHz 的恒定频率激励相比，驻波伪影的幅度减少了 20 倍。
The ultrasound radiation force has been used for noncontact excitation of devices ranging from microcantilevers to acoustic guitars. For ultrasound radiation force excitation, one challenge is formation of standing waves between the ultrasound transducer and the device under test. Standing waves result in constructive/destructive interference causing significant variations in the intensity of the ultrasound field. The standing-wave induced intensity variations in the radiation force can result from minor changes in the transducer position, carrier frequency, or changes in the speed of sound due to changes in ambient temperature. The current study demonstrates that by randomly varying the ultrasound carrier frequency in packets, it is possible to eliminate the negative consequences resulting from the formation of standing waves. A converging ultrasound transducer with a central frequency of 550 kHz was focused onto a brass cantilever. The 267 Hz resonance was excited with the ultrasound radiation force with a carrier frequency that randomly varied between 525 kHz to 575 kHz in packets of 10 cycles. Because each packet had a different carrier frequency, the amplitude of standing wave artifacts was reduced by a factor of 20 compared to a constant frequency excitation of 550 kHz.