Figure 6. The trigger count versus the offset between the active element and the mid-plane.

In this experiment the catheter is fixed in a water tank and perpendicular to the image plane. The probe is mounted on a translation stage, which moves perpendicular to the mid-plane. The error bar represents the standard deviation over 10 measurements, each time the translation stage moves from −9 mm to 9 mm, stops at the same sample positions and takes the trigger count reading.