The Optical Display of Ultrasonic Waves in Liquids

Abstract

The distribution and diffraction patterns of propagating ultrasonic waves have been studied previously, both experimentally and theoretically. The work to be described furthers this study in two main areas. The main bulk of experimental work, and its associated theory, concerns a technique for the optical display of ultrasonic waves in liquids. This is achieved by a system which combines optical anisotropy, produced within a thin layer of suitable material, with stroboscopic illumination. The result is a display, providing information across a complete plane of section, with negligible disturbance to the ultrasonic field. The remaining work concerns a theoretical investigation into the radiated pressure distributions of ultrasonic transducers. The approach involves expressing the solution to the appropriate wave equation as a limited series. This method makes it possible to apply mixed boundary conditions, and allows a study to be made of variations in baffle size. The principle is inherently simple and permits a wide range of application. The results have been correlated with existing surface integral techniques.