Phased arrays have several advantages over conventional ultrasonic probes that derive from the ability to dynamically control the acoustic beam transmitted into the structure under examination.
Phased arrays can reduce inspection times by eliminating or reducing the need for mechanical scanning and by taking advantage of the ability to perform electronic scanning (see animation below). Electronic scanning is accomplished by firing successive groups of elements in the array. Eliminating or reducing mechanical scanning also increases the reliability of the measurements by eliminating changes in (or loss of) coupling, which is a risk each time the probe is moved.
Whereas a conventional probe has one focal length and one orientation, a single phased-array probe allows the user to change the shape and focal point of the ultrasonic beam to optimize each inspection. The acoustic energy can be focused, and delay laws can be applied to steer the acoustic beam. Dynamic-depth focusing allows measurements to be made at several depths in the same amount of time as it takes to a single depth measurement using a conventional probe.
Phased arrays improve the reliability of the measurements and defect sizing can be improved using tools such as sectorial scanning (see figure below), or focalization after reflection off the back wall, two options available with M2M systems. A distinguishing feature of M2M systems is that the user can tune the beam, for example, to define any focal points in a 2S or 3D CAD drawing.
Because of their flexibility, a phased-array probe can replace an entire toolbox of conventional ultrasonic probes. It can thereby simplify complex inspection procedures by eliminating the need for multiple probes, and the associated calibrations and setups. Phased-arrays provide tremendous functionality including real-time imaging (see image below).