US Patent 7617720 Surface position measuring method and surface position measuring device

A surface position measuring method capable of measuring a position on a soft surface accurately and rapidly (real time), with low invasiveness. The method comprises the steps of measuring the spectrum of thermal oscillation of a cantilever with the distance between a cantilever tip and a sample surface being changed, extracting a fundamental mode component (spectrum area) from the obtained spectrum of thermal oscillation, and measuring a change in the spectrum area of thermal oscillation (spectrum area) with respect to the distance. A position at which the area of the cantilever thermal oscillation spectrum begins to change is evaluated as a position on the sample surface.