Piezoelectric dilatometric analysis using homodyne and heterodyne laser interferometry

The electromechanical coupling of piezoelectric materials has been widely studied since such property is found to be a key element of enhanced sensitivity in piezoelectric sensors or actuators. However a unified view of this coupling as function of frequencies verified using multiple measurement techniques has not previously been available. This study examines and compares multiple optical based homodyne and heterodyne interferometry techniques for piezoelectric displacement measurement, over a wide range of frequencies from DC to 20 MHz. A custom configured homodyne optical interferometer and a commercial heterodyne Laser Doppler Vibrometer are used in the study. Because the frequency ranges used by these devices overlap, it is possible to compare the results. Ferroelectric lead titanate PbTiO3 (PT) ceramic sample with high ferroelectric strain is studied in this work. Frequency dependence of the electromechanical displacement is obtained using multiple techniques and the emphasis of the interrogations is given to frequencies near piezoelectric resonances.