<p>Actuators employable for oscillating movement of a load. An improved actuator may include at least a first shape memory member that is actuatable to affect at least a portion of the oscillating movement of the load. The actuator may further include a second shape memory member actuatable to affect at least a second portion of the oscillating movement of the load. The utilization of one or more shape memory members facilitates the realization of controllable and reliable oscillating movement of a load in a compact manner. Such actuators may be used in imaging catheters having an ultrasound transducer disposed for oscillating movement to scan across an internal region of interest. Such imaging catheters may be used in generating three dimensional and/or real-time three dimensional (4D) images.</p>
