School of Marine Science and Technology, Tokai University, 3-20-1 Orido, Shimizu-ku, Shizuoka 424-8610, Japan.
J Acoust Soc Am. 2010 Jan;127(1):51-61. doi: 10.1121/1.3268602.
On the basis of finite amplitude and comparative methods, the acoustic nonlinearity parameter BA of a liquid sample of as small as 0.1 ml is measured using an 18.6-MHz focused Gaussian beam. The sample fills the space between a polystyrene plate and a tungsten reflector set about 1 mm apart from each other within the focal region. The sound speed c and attenuation coefficient alpha are determined using the time of flight and the insertion loss of the sound passing through the sample, respectively. The density rho is estimated from the reflection coefficient at the interface between the polystyrene plate and the sample, where the transformation from longitudinal to transverse waves is considered. To compensate for the effect of velocity dispersion on the second harmonic generation, the relative phase of the second harmonic sound is also measured using dual-frequency sound. By summarizing all the linear properties and amplitude data of the second harmonic component in the sound transmitted through the sample, the BA value is finally determined. The measurement is validated through the experiments on nondispersive liquids and weakly dispersive biological samples with known BA values.
基于有限振幅和比较方法，使用 18.6MHz 聚焦高斯光束测量了小至 0.1ml 的液体样品的声非线性参数 BA。样品填充在聚碳酸酯板和钨反射器之间的空间内，彼此之间的距离约为 1mm，位于焦区范围内。声速 c 和衰减系数 alpha 分别通过声穿过样品的飞行时间和插入损耗来确定。密度 rho 是根据聚碳酸酯板和样品之间界面的反射系数估计的，其中考虑了纵波到横波的转换。为了补偿速度色散对二次谐波产生的影响，还使用双频声测量了二次谐波声的相对相位。通过总结通过样品传输的声音中二次谐波分量的所有线性特性和幅度数据，最终确定了 BA 值。通过对具有已知 BA 值的非分散性液体和弱分散性生物样品的实验验证了该测量方法。
