Forward planar projection through layered media.

A planar forward projection algorithm is combined with ray theory to describe longitudinal propagation through an arbitrary number of randomly oriented isotropic layers. This method first measures the space-time pressure field in a plane, then uses wavevector frequency-domain methods to project the field through layered media and to an arbitrary new plane, not necessarily parallel to the initial plane. The approach is valid for longitudinal propagation through liquid layers and in solids, such as soft tissues, that can be approximated as viscous liquids. The algorithm is verified by propagating the field from a 0.5 MHz planar transducer through a combination of rubber, plastic, and water layers. Hydrophone measurements indicate correlation between measured and simulated fields for angles below the longitudinal critical angles of the layered materials.