Lateral force microscopy calibration using an interferometric atomic force microscope

Abstract: A new method is introduced for calibrating lateral force as measured by an atomic force microscope (AFM), making use of both an interferometric detector and an optical beam detector on the same instrument. The method may be implemented automatically and performed with minimal user input. The microscope has the capability to measure the probe tip height in situ, which allows for a complete lateral force calibration without changing the sample or probe. Two options for lateral force measurements are described wherein the two detectors are alternately used to measure normal and lateral forces, and methods for applying the calibration protocol for both alternatives are provided. The tip height measurement is validated by direct comparison with an electron micrograph and they are generally in agreement to within 1.4 microns. For most cantilevers tested, the complete lateral calibration method is consistent with the wedge calibration method to within the intrinsic uncertainty of the wedge method.