Patent ID: 7570061

Claim:
In an atomic force microscope that measures a surface shape of a measurement object, a cantilever control device comprising: a cantilever that has a probe at a tip thereof and oscillates; an oscillation source that causes self-excited oscillation in the cantilever; oscillation velocity displacement detection means for detecting oscillation velocity and oscillation displacement of the cantilever; and control means for feedback controlling the oscillation source on the basis of the oscillation velocity and the oscillation displacement of the cantilever, wherein a feedback control signal generated by the control means is represented as S={K−G·|x| m ·( dx/dt ) n−1 }·dx/dt, where S is a feedback control signal, K is a feedback gain of a positive value, G is a feedback gain of a positive value, x is the oscillation displacement of the cantilever, dx/dt is the oscillation velocity of the cantilever, m is an integer equal to or larger than 0, and n is a positive odd number that satisfies m+n≧2.