Optimum choice of acoustic properties of filling materials using optical measurement

In this work the effect of the cross-coupling due to the filling material on the vibration maps of linear array ultrasound probes was investigated. Eight different filling materials (including air) were tested on eight probes. The tests were carried out not on prototypal transducers but on completely manufactured probes which include the matching layers and the acoustic lens. In this way, the actual influence of the filling materials was pointed out. Only the central element of the group was energized at its central frequency: the vibration amplitude and the cross-coupling level clearly emerged. Measurements were carried out by means of a laser interferometer (LDV). The obtained data clearly outlined typical interelement crosstalk of roughly -10dB, well above the electrically induced crosstalk. Moreover, conventional tensile tests were performed on the filling materials and the values were reported together with the respective hardness expressed in the Shore scale.