Vibrating probe atomic force microscope

Abstract

An atomic force microscope capable of vibrating a cantilever at a constant amplitude at all times. Variations in the vibration of the cantilever are sensed by detecting the variation in the position of reflected light by a photodetector. The output signal from the photodetector is fed to a band-pass filter to extract those frequency components which are close to the resonance frequency of the cantilever. The output from the filter is fed to a waveform converter to convert the signal into a square-wave signal of a constant amplitude via a phase-adjusting circuit. The output from this waveform converter is supplied as a driving signal to a piezoelectric device via an amplitude-adjusting circuit and also to a frequency-to-voltage converter to convert the signal into a voltage signal V.sub.fv corresponding to the frequency. A reference voltage comparator produces the difference between the voltage signal V.sub.fv and a reference signal. This difference signal is supplied as a feedback signal to a z-scanner drive circuit.

Dependencies are inferred from the claim text.