POTENTIAL-MEASURING DEVICE, AND ATOMIC FORCE MICROSCOPE

摘要

A potential measurement device (100) according to the present invention includes: an electrode (104); a displacement measurement unit (212) which outputs a voltage corresponding to an electrostatic force between the electrode and the sample; a first alternating-current power supply (101) which applies a first alternating-current voltage between the electrode and the sample; a second alternating-current power supply (102) which adds, to the first alternating-current voltage, a second alternating-current voltage having a frequency different from a frequency of the first alternating-current voltage, and applies the added voltage; and a signal detection unit (218) which outputs a magnitude of a particular frequency component contained in the output from the displacement measurement unit, in which the signal detection unit extracts, from the output by the displacement measurement unit, and outputs, to a potential calculation unit which calculates potential, (i) a magnitude and a phase of a frequency component of a frequency identical to the frequency of the first alternating-current voltage and (ii) a magnitude of a frequency component of a frequency identical to a frequency equivalent to a difference between the frequency of the first alternating-current voltage and the frequency of the second alternating-current voltage, so that the potential measurement device measures the surface potential of the sample.