A pulse-echo beamformer with high lateral and temporal resolution and depth-independent lateral response

With conventional beamformation techniques, in order to increase the depth of field one must sacrifice either lateral or temporal resolution. An increase in the transmit F-number results in an increase in the depth of field at the expense of lateral resolution. The use of multiple transmit/receive events per line, on the other hand, compromises temporal resolution. In this paper we describe a beamformation technique that is not prone to such tradeoffs. The object is insonified with a field that is cosine-modulated laterally, and the rate of growth of the receive aperture is tuned to this lateral modulation frequency. The resultant round-trip lateral bandwidth is optimal: it equals two times the maximum achievable one-way lateral bandwidth. The advantage of this technique is that this full bandwidth is realized at all depths, and with only a single transmit/receive event. A generalization of this technique allows a full frame of full-bandwidth image to be acquired using only two transmit/receive events.