Analysis of sound field profile formed by conical acoustic probe with pinhole

Abstract

This paper analyzes sound pressure field profiles formed by a conical acoustic probe (CAP) with a pinhole much smaller than the ultrasonic wavelength λ. The analysis is done using the Rayleigh integral and the finite element method (FEM). Both calculated results reveal that lateral -3dB widths near the pinhole are approximately equal to the pinhole diameter and that the shape of the CAP does not affect the lateral width. A lateral resolution of the CAP, which is much smaller than λ, is verified by our analysis.