A wavefield extrapolation method for simulating B-scan images

We describe an algorithm which improves the efficiency of simulations of B-scan images involving water path acoustical imaging systems. The method is a hybrid approach in which Rayleigh-Sommerfeld diffraction theory is used to extrapolate the propagated part of the acoustic pressure field back to the transducer while the scattered field produced by the tissue is obtained using a time-domain scattering algorithm. Considerable savings in both CPU time and array storage are achieved by elimination of discrete time updates on the computational grid between the source and the tissue.