ASYMPTOTIC ANALYSIS OF GAUSSIAN FOCUSED ULTRASONIC BEAMS OF CIRCULAR SYMMETRY

In this paper, a model of a focused beam with circular symmetry is pre sented. The acoustic field is defined by a Gaussian surface velocity d istribution along the emitter immersed in a fluid. The pressure field is described by a Fourier integral representation, and is evaluated as ymptotically using a generalized steepest descent procedure. Simple an alytical expressions for the acoustic pressure along the axis are obta ined, and the variation of the pressure field as a function of distanc e from the emitter is illustrated.