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Multi Reflection of Lamb Wave Emission in an Acoustic Waveguide Sensor
Institute of Sensor and Actuator Technology, Coburg University of Applied Sciences, Am Hofbrauhaus 1, 96450 Coburg, Germany
Measurement Engineering Group, Faculty of Electrical Engineering, Computer Science and Mathematics, University Paderborn, Warburger Str. 100, 33098 Paderborn, Germany
Laboratory for Electrical Instrumentation, Department of Microsystems Engineering-IMTEK, University Freiburg, Georges-Kohler-Allee 106, 79110 Freiburg, Germany
* Author to whom correspondence should be addressed.
Received: 19 December 2012; in revised form: 9 February 2013 / Accepted: 18 February 2013 / Published: 27 February 2013
Abstract: Recently, an acoustic waveguide sensor based on multiple mode conversion of surface acoustic waves at the solid—liquid interfaces has been introduced for the concentration measurement of binary and ternary mixtures, liquid level sensing, investigation of spatial inhomogenities or bubble detection. In this contribution the sound wave propagation within this acoustic waveguide sensor is visualized by Schlieren imaging for continuous and burst operation the first time. In the acoustic waveguide the antisymmetrical zero order Lamb wave mode is excited by a single phase transducer of 1 MHz on thin glass plates of 1 mm thickness. By contact to the investigated liquid Lamb waves propagating on the first plate emit pressure waves into the adjacent liquid, which excites Lamb waves on the second plate, what again causes pressure waves traveling inside the liquid back to the first plate and so on. The Schlieren images prove this multi reflection within the acoustic waveguide, which confirms former considerations and calculations based on the receiver signal. With this knowledge the sensor concepts with the acoustic waveguide sensor can be interpreted in a better manner.
Keywords: multi reflection; lamb wave; emission; acoustic waveguide sensor; surface acoustic waves; leaky lamb waves; schlieren imaging
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Schmitt, M.; Olfert, S.; Rautenberg, J.; Lindner, G.; Henning, B.; Reindl, L.M. Multi Reflection of Lamb Wave Emission in an Acoustic Waveguide Sensor. Sensors 2013, 13, 2777-2785.
Schmitt M, Olfert S, Rautenberg J, Lindner G, Henning B, Reindl LM. Multi Reflection of Lamb Wave Emission in an Acoustic Waveguide Sensor. Sensors. 2013; 13(3):2777-2785.
Schmitt, Martin; Olfert, Sergei; Rautenberg, Jens; Lindner, Gerhard; Henning, Bernd; Reindl, Leonhard M. 2013. "Multi Reflection of Lamb Wave Emission in an Acoustic Waveguide Sensor." Sensors 13, no. 3: 2777-2785.