ABSTRACT

Modern ultrasonic imaging is, in most peoples’ minds, almost invariably and nearly automatically associated with its numerous uses in medicine. Although nondestructive testing provides one of the larger and better known industrial markets for ultrasonic equipment, it is only one of many areas in which low-intensity ultrasonic energy is applied. This chapter discusses several additional areas of applications. Imaging using schlieren visualization started with the work of Robert Hooke who used it to visualize thermals in air caused by a candle. Electron acoustic image converters are modified from the original Sokolov disclosures. Sokolov envisioned a television-camera tube in which the light-sensitive element is replaced by a pressure-sensitive element—a piezoelectric plate. Schlieren imaging has been used for many years to visualize sound fields, and it has been a useful tool for studying the propagation of ultrasonic waves. The optical system also may be adjusted for bright-field operation, in which the ultrasonic disturbance appears as dark shadows.