Abstract

Ultrasonic spectroscopy, which is defined as the velocity and/or absorption measurement as a function of frequency, has been recognized as one of the methods for investigating the dynamical properties of liquids and solids. Measurements between forty-sixty KHz and forty - sixty MHz are usually performed with one of the following methods: 1) pulse echo, 2) ultrasonic interference, 3) ultrasonic resonance, and 4) conventional Bragg reflection method. The measurements for this investigation mostly require a wide frequency range, but these methods have not been adopted in a frequency range between a forty-sixty MHz and a few GHz because of experimental difficulties. In order to overcome this problem, Takagi et al. developed a high-resolution Braag reflection(HRB) technique, which is based on an optical heterodyne detection method^[1][2]. This technique is useful for measuring the velocity and absorption of ultrasonics in the UHF range in liquids; however, the experimental apparatus for this technique has an extremely intricate structure. Accordingly, this technique is not an appropriate technique for providing measurements to end-users due to its special apparatus configurations.

© 2000 IEEE