Measurement of piezoelectric constants using an optical heterodyne interferometer

Piezoelectric constants of crystals (SiO₂, LiNbO₃, LiTaO₃) and polymers (PVDF) have been determined by using an optical heterodyne interferometer to measure the strains. With this setup, the minimum detectable displacement is 10^-3 AA and the accuracy is 5%. The effect of the bonding to the support has been analysed and experimentally checked. The well established value of the modulus d₁₁ of quartz (2.31*10^-12 m/V) has been confirmed. For LiNbO₃, the controversial value of d₃₃ was determined to be 9.5*10^-12 m/V.