Patent ID: 8069493

Claim:
An atomic force microscope apparatus imaging a surface topography of a sample in a contact mode, the apparatus comprising: a cantilever having a probe interacting with the sample surface via an atomic force and being subjected to a deflection by the atomic force; laser light provision means for allowing first laser light to enter the cantilever; light detection means for detecting second laser light corresponding to the first laser light reflected by the cantilever; a piezo element on which the sample is placed; a controller inputting an input voltage to the piezo element to control the distance between the sample surface and the probe, detecting the deflection of the cantilever as an output voltage based on a relative change in light intensity in a vertical direction to which a photodiode is subjected owing to the second laser light, then during a forward scan, measuring and storing the surface topography, then during a backward scan of the same line as that for the forward scan, using the stored surface topography to generate a tracking error for the backward scan, and measuring the surface topography of the sample surface based on the tracking error; and data storage means for recording the measured tracking error, wherein the controller uses a means for perfect tracking control in which a sampling period and a control period for a target trajectory generated from the tracking error are different from each other and which uses multirate control, to reduce the tracking error to measure the surface topography of the sample surface.