Patent ID: 7886366

Claim:
A cantilever device used for an atomic force microscope which measures a surface geometry of a measuring object, comprising: a cantilever equipped with a probe at a tip and capable of vibrating; a vibration source which realizes the cantilever to vibrate in a self-excited mode; a detection mechanism which detects a deflection angle of the cantilever; and a control unit which performs a feedback control of the vibration source based on the deflection angle of the cantilever; wherein a feedback control signal V C generated by the control unit is given by the following equation: V c = - K lin ⁢ ∫ ∂ w ∂ s ⁢ ⅆ t ⁢ ❘ s = x s ⁢ + K non ⁢ ∫ ( ∂ w ∂ s ) m + 1 ⁢ ⅆ t ⁢ ❘ s = x s ; ⁢ ⁢ and wherein K lin is a linear feedback gain which is positive; K non is a nonlinear feedback gain which is positive; ∂w/∂s is the deflection angle of the cantilever; X S is a sensing point for the cantilever; and m is an even number equal to or larger than 2.