Evaluation of Angular Spectrum Approach for Simulations of Spherically Focused Ultrasound Phased Arrays

Modeling the pressure fields of large ultrasound phased arrays using conventional methods is extremely time-consuming because of the huge number of computational points and transducer elements. The angular spectrum approach (ASA) can simulate the fields accurately with great reduction of computational time. The errors involved with ASA are mostly due to the lack of spectral sampling and this can be compensated by restricting the angular frequency components adaptively with respect to the propagation distance. The performance of the ASA is evaluated by modeling the pressure field generated by a spherical phased array with on-axial, off-axial focus and multiple-foci patterns. With moderate sampling and medium size of source planes, the ASA produces accurate results throughout the three dimensional (3D) computational volume and reduces the simulation time significantly