An Assessment of the Angular Spectrum Method for the Propagation of Ultrasound

The purpose of this project is to investigate the limitations of the angular spectrum method when it is applied to the propagation of acoustic waves in the ultrasonic frequency waves. In this experiment, broadband acoustic waves at ultrasonic frequencies were propagated through a water bath. Ten planar scans perpendicular to the direction of the wave propagation were taken at 10 different distances from the transducer. These scans recorded the pressure field data at each plane. The angular spectrum method was applied to this data, and used to predict the pressure field data at the other planes. Comparison between this predicted data and the original data revealed that the angular spectrum method is best used when trying to predict the field at planes further away from the source than the experimental data and it is best applied on experimental data taken near the source, rather than further away.