$B/A$ Measurement for Liquid Media Using an LN Transducer with Inverted-Domain Layer

概要

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A system to measure the acoustic nonlinearity parameter $B/A$ for a liquid medium utilizing a high-frequency focusing Gaussian source has been developed. The 19 MHz sound source employing a LiNbO3 (LN) plate with a ferroelectric inversion layer can emit and receive double frequency sound of 38 MHz. An LN plate with a twisted star-shape electrode is attached to a synthetic silica lens whose radius is much larger than the aperture size and thickness to generate a focused Gaussian beam. Linear properties such as the density, sound speed and attenuation coefficient are determined through a comparison of the pressure amplitude reflected from the solid surface located at the focal plane and the reflector distance to maximize the signal amplitude with those for the case in which the medium is replaced by distilled water. Furthermore, the ratio of the second harmonic amplitude in a sound returned from the reflector set at the focal plane and that in the case of distilled water yields the $B/A$ value through a calculation containing the linear property obtained in advance. The measured result for the linear property and the $B/A$ value of various alcohol samples shows a reasonable agreement with the literature values.
Published by the Japan Society of Applied Physics through the Institute of Pure and Applied Physicsの論文
2005-06-15