Abstract: There is provided an atomic force microscope (AFM) with increase the speed and sensitivity of detection of the resonant frequency shift in a cantilever. An AFM (1) extracts a reference signal and a phase shift signal from a detection signal from a displacement sensor of the cantilever. The reference signal is restrained from a phase change in accordance with the resonant frequency shift. The phase shift signal has a phase shifted in accordance with the resonant frequency shift. The AFM (1) determines the phase difference of the phase shift signal from the reference signal, as the resonant frequency shift. The AFM (1) may detect the phase difference between a plus-minus inversion point on the reference signal and a corresponding plus-minus inversion point on the phase shift signal. The AFM (1) may adjust phase before phase detection. The phase adjustment may move the detection point for the resonant frequency shift defined on the oscillation waveforms to the plus-minus inversion point.

Abstract: A driving laser unit (11) irradiates a laser beam on a cantilever (5) to cause thermal expansion deformation. A driving-laser control unit (13) performs feedback control for the cantilever (5) by controlling intensity of the laser beam on the basis of displacement of the cantilever (5) detected by a sensor (9). A thermal-response compensating circuit (35) has a constitution equivalent to an inverse transfer function of a heat transfer function of the cantilever (5) and compensates for a delay in a thermal response of the cantilever (5) to the light irradiation. Moreover, the cantilever (5) may be excited by controlling the intensity of the laser beam. By controlling light intensity, a Q value of a lever resonance system is also controlled. It is possible to increase scanning speed of an atomic force microscope.

Abstract: There is provided an atomic force microscope (AFM) with increase the speed and sensitivity of detection of the resonant frequency shift in a cantilever. An AFM (1) extracts a reference signal and a phase shift signal from a detection signal from a displacement sensor of the cantilever. The reference signal is restrained from a phase change in accordance with the resonant frequency shift. The phase shift signal has a phase shifted in accordance with the resonant frequency shift. The AFM (1) determines the phase difference of the phase shift signal from the reference signal, as the resonant frequency shift. The AFM (1) may detect the phase difference between a plus-minus inversion point on the reference signal and a corresponding plus-minus inversion point on the phase shift signal. The AFM (1) may adjust phase before phase detection. The phase adjustment may move the detection point for the resonant frequency shift defined on the oscillation waveforms to the plus-minus inversion point.

Abstract: A driving laser unit (11) irradiates a laser beam on a cantilever (5) to cause thermal expansion deformation. A driving-laser control unit (13) performs feedback control for the cantilever (5) by controlling intensity of the laser beam on the basis of displacement of the cantilever (5) detected by a sensor (9). A thermal-response compensating circuit (35) has a constitution equivalent to an inverse transfer function of a heat transfer function of the cantilever (5) and compensates for a delay in a thermal response of the cantilever (5) to the light irradiation. Moreover, the cantilever (5) may be excited by controlling the intensity of the laser beam. By controlling light intensity, a Q value of a lever resonance system is also controlled. It is possible to increase scanning speed of an atomic force microscope.