An optical lever measurement of the piezoelectric charge coefficient

Abstract

We present a technique to measure the piezoelectric strain (charge) coefficient using an optical lever technique. The optical lever consists of a laser source, a levered mirror connected to the sample and a linear CCD array detector (pixel size = 13 μm). A field on the sample creates a displacement due to the piezoelectric effect. The displacement levers the mirror and diverts the laser beam through an angle which is twice the angular displacement of the levered mirror. The peak intensity of the laser beam on the CCD array is monitored as the field on the sample is ramped. The functional relationship between the piezoelectric coefficient and the displacement, as measured by the CCD array, is linear. Therefore, the technique is inherently ideal for studying non-linear effects. The resolution of the optical lever is less than one nanometer. The system can also be used to make highly localized measurements of the absolute displacements of piezoelectric or electrostrictive materials.