Abstract: A lens assembly is formed by a curved dish or support member with piezo-electric transducers mounted on the concave outer surface. Flat mounting facets are machined on the outer surface to accommodate bonding between the transducer and the support member. A small concave focusing surface or lens for each transducer is machined on the concave inner surface of the support member directly opposite to the transducer and mounting facet. The focusing lenses are only slightly more convex than the inner surface of the support member, and the size of the focusing lenses is only a fraction of the size of the support member. Therefore, the path length of the energy from every point on every transducer to the invivo target region is almost identical. The energy arrives at the target region very closely in phase, forming a short pulse of maximum intensity.