The present invention provides a technique for eliminating the effect of
the thermal drift and other variances and to improve the observing or
manipulating accuracy of a scanning probe microscope or atom manipulator
by using the technique to correct the aforementioned change in the
relative position of the probe and the sample due to heat or other
factors during the observation or manipulation. To obtain an image of the
sample surface at the atomic level or perform a certain manipulation on
an atom on the sample surface, the present invention can be applied to a
probe position control method for controlling the relative position of
the probe and the sample while measuring an interaction between the
objective atom on the sample surface and the tip of the probe. In the
present method, the relative position of the probe and the sample are
changed while the probe is oscillated relative to the sample in two
directions parallel to the sample surface at frequencies of f.sub.1 and
f.sub.2 (S1a). Meanwhile, a point (or characteristic point) where the
frequencies f.sub.1 and f.sub.2 disappear from the measured value of the
interaction working in the direction perpendicular to the sample surface
is detected (S1b). Then, the relative movement of the probe and the
sample is controlled so that the measurement value thereby detected is
maintained (i.e. the characteristic point is tracked; S1c), and the speed
of the aforementioned relative movement is determined (S1d).
Subsequently, the relative position control is corrected using the
detected speed (S2).