Acoustic method for obtaining the pressure reflection coefficient using a half-wave layer

• Published in: Ultrasonics Vol. 51; no. 3; pp. 359 - 368
• Main Authors: Liu, Jia-xin, Wang, Zhi-qiang, Li, Guo-feng, Wang, Ning-hui
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.04.2011; Elsevier
• Subjects: Acoustical measurements and instrumentation; Acoustical properties of liquids; Acoustics; Amplitudes; Attenuation; Condensed matter: structure, mechanical and thermal properties; Exact sciences and technology; Fundamental areas of phenomenology (including applications); Half-wave layer; Liquid; Liquids; Mechanical and acoustical properties of condensed matter; Physics; Receivers; Reflection; Reflection coefficient; Signal to noise ratio; Steady-state; Thin films; Transducers; Ultrasonic; Liquid; Half-wave layer; Reflection coefficient; Steady-state; Ultrasonic; Interfacial layer; Uncertain systems; Uncertainty; Liquids; Density measurement; Pulse echo method; Signal-to-noise ratio; Acoustics; Vibration amplitude; Experimental study; Interface wave; Steady state; Wave reflection; Multiple wave; Thin films; Reflectivity; Half wave plate; Acoustic properties
• ISSN: 0041-624X; 1874-9968
• DOI: 10.1016/j.ultras.2010.11.001

► A measurement of steady-state amplitude of echo signals to obtain the reflection coefficient. ► Reflection and transmission waves generate interference and reach a steady state respectively. ► The uncertainty characteristics of the reflection coefficient. This paper describes a method for obtaining the pressure reflection coefficient by using a half-wave layer. Two transducers were placed in reference liquid and test liquid respectively. The reference and test liquid were separated by the thin half-wave layer. Both transducers could operate in two modes. One acted as a transmitter and worked in pulse-echo mode, and the other operated in receiver mode. By adjusting the frequency of drive signal according to the thickness and material property of the half-wave layer, it was possible to generate the maximum interference signal of multiple waves reflected at the two interfaces of the layer. Therefore, the amplitude of reflection wave in steady-state depended only on the reflection coefficient at the interface between the half-wave layer and the test liquid. The effects of the signal-to-noise-ratio and the half-wave layer attenuation on the uncertainty characteristics of the pressure reflection coefficient were discussed. The experimental results showed high accuracy for measurement of reflection coefficient.