Realization of sinc waves in ultrasound imaging systems

It is known that the transmit pulse waveforms of a limited-diffraction beam in a linear array transducer should be varied according to transducer elem ent location, dictating the use of Sophisticated hardware. In order to over come this disadvantage while achieving the same field response, we propose a method of synthesizing limited-diffraction beams by combined signal proce ssing of pulsed plane waves propagating in distinct directions over several consecutive insonification time intervals. The method is capable of achiev ing both higher transmit power and better lateral resolution over a larger depth of field. Although its field response is not uniform throughout the i maging points, this is not a major problem since the response is quite unif orm within a region of interest. The proposed method requires the use of mu ltiple insonifications for transmit focusing, and, therefore, can be applie d in imaging slowly-moving or still objects. Both simulation and experiment al results corroborate its superiority in terms of the lateral resolution a t all imaging depths.