Characterization of Sound Fields Generated by Ultrasonic Transducers

Abstract

The metrological characterization of sound fields represents an important step in the design and optimization of ultrasonic transducers. In this chapter, we will concentrate on the so-called light refractive tomography (LRT), which is an optical-based measurement principle. It allows noninvasive, spatially as well as temporally resolved acquisition of both, sound fields in fluids and mechanical waves in optical transparent solids. Before the history and fundamentals (e.g., tomographic reconstruction) of LRT are studied in Sects. 8.2 and 8.3, we will discuss conventional measurement principles (e.g., hydrophones) for such measuring tasks. Section 8.4 addresses the application of LRT for investigating sound fields in water. For instance, the disturbed sound field due to a capsule hydrophone will be quantified. In Sect. 8.5, LRT results for airborne ultrasound are shown and verified through microphone measurements. Finally, LRT will be exploited to quantitatively acquire the propagation of mechanical waves in optically transparent solids, which is currently impossible by means of conventional measurement principles.