The Phased Array concept concerns multielement transducers (see phased array transducers page for transducers characteristics).

Each element of these transducers is connected to a different electronic channel, either directly or through multiplexors, according to electronic device performances.

Each element can be activated or not for each shot. The size and the location of the active aperture of a phased array transducer depends on the activated elements.

An electronic delay can be aplied to each electronic channel when emitting and receiving the signal to/form the transducer elements. The setup corresponding to all the delays of a given shot is called Delay Law. Each delay law defines a different acoustic beam with particular direction, focussing distance and lateral resolution.

This technique requires probes with very low acoustic and electric cross coupling  between the elements, so that all the elements could be fired independently. Thanks to their 1-3 structure, Imasonic piezocomposite materials are completely adapted to this feature.

Electronic Scanning

The beam is electronically translated by alternatively firing a given number of element of a linear or circular array phased array transducer

This technique is an alternative to mechanical translation of a single element probe

The advantages are No mechanical movement required, or reduction of scanline number Faster inspection Possibility of combining with electronic focusing and beam steering (see below)

Electronic Focusing

The beam is electronically focused by applying symmetrical delay laws to the different elements of a linear or annular phased array transducer.

This technique is an alternative to using several transducers to focus at different depths

The advantages are Only one probe can focus at each depth Faster inspection of complete volume of thick pieces with dynamic focusing Electronic focusing can compensate for focusing aberrations due to cylindrical interfaces

Note : Electronic focusing can be used in addition to a cylindrical, spherical or aspherical mechanical pre-focusing of the transducer

Electronic Steering

The beam is electronically deflected by applying delay laws to different elements of a linear, circular or matrix array. Linear and circular arrays allow for 2D beam steering, while matrix arrays allow for 3D beam steering.

This technique is an alternative to using different angled transducers

The advantages are Only one transducer required for inspection at variable angle Faster inspection of complex geometry pieces The advantage of this technique can be combined with the advantages of electronic focussing

Note : To optimise beam characteristics, electronic deflection can be used in addition to a mechanical pre-deflection with a wedge

Tube inspection example

In line testing of tubes requires high acoustic performances and high inspection speed

• Thanks to the electronic rotation of the beam, circular phased array probes allow very fast inspection
• Thanks to Imasonic's Piezocomposite technology, phased array probes provide high resolution and signal to noise ratio

Combination of electronic scanning, focusing and deflection Circular pre-focusing of the array probe Use of 1, 2 or 4 simultaneous beams, depending on the setup Virtual rotation speed up to 10000 rpm Instantaneous electronic adaptation to tube diameter and thickness No rotating probe holder required

Weld inspection example

Conventional Weld inspection with single angled transducers required 2 perpendicular scanlines

• Thanks to electronic translation of the beam, only one mechanical scanline is necessary
• Thanks to their low cross coupling between elements, Imasonic phased array probes allow beam deflection till the required beam angle while keeping the necessary sensitivity.

Combination of electronic scanning, focusing and deflection Only one mechanical scanline required instead of two Adapted Focussing for each shot and acoustic path Faster inspection