Calibration of the electrical response of piezoelectric elements at low voltage using laser interferometry

A laser interferometric method is described by which the length-to-voltage sensitivity of piezoelectric elements, as used e.g., in scanning tunneling microscopes, can be calibrated. The method is based on measuring the optical frequency of a laser locked to a piezoelectrically tuned interferometer, relative to a stable reference. The high sensitivity of this technique allows the calibration to be carried out in the low-voltage regime.