Broad-Band Transducers: Radiation Field and Selected Applications

Abstract

In many applications, broad-band ultrasonic transducers capable of producing short video pulses are required. Previously, plane-wave analysis with equivalent circuits has proven successful in predicting pulse shape in the time and frequency domains. The present approach is to recognize that piston sources radiate nonplanar waves, and that the frequency spectrum of a broad-band piston source can be measured experimentally. With the spectrum as a weighing function for the field profiles of a monofrequency piston source, a superposition is performed to find the pressure and phase profiles in the radiation field of a broad-band transducer. Experimental measurements are presented that take advantage of the broad-band pulse technique combined with spectrum analysis. These include thickness gauging of thin materials and interface layers, and relative viscosity measurements.