Scanning Patterns

Electronic linear scanning 

With electronic scanning, a single focal law is multiplexed across  a group of active elements; scanning is performed at a constant angle and along the phased array probe length (aperture. This is equivalent to a conventional ultrasonic transducer performing a raster scan forcorrosion mapping or shear-wave inspection.
If an angled wedge is used, the focal laws compensate for different time delays inside the wedge.

Sectorial scanning

With sectorial scanning (also called azimuthal or angular scanning), the beam is moved through a sweep range for a specific focal depth, using the same elements; other sweep ranges with different focal depths may be added. The angular sectors may have different values.