Calibrating a tuning fork for use as a scanning probe microscope force sensor

Quartz tuning forks mounted with sharp tips provide an alternate method to silicon microcantilevers for probing the tip-substrate interaction in scanning probe microscopy. The high quality factor and stable resonant frequency of the tuning fork allow accurate measurements of small shifts in the resonant frequency as the tip approaches the substrate. To permit an accurate measure of surface interaction forces, the electrical and piezoelectromechanical properties of a tuning fork have been characterized using a fiber optical interferometer.