Abstract: An atomic force microscope comprises a vibrating device for producing transverse vibrations between a sample and a probe and a vertical load-adjusting device for adjusting the vertical load between the sample and the probe. The sample is vibrated transversely, thus inducing a deflecting vibration on a cantilever. The phase and the amplitude of this deflecting vibration are simultaneously measured. The dependence of the measured value on the vertical load between the sample and the probe is measured. Thus, the friction between the sample and the probe is analyzed.