Patent ID: 7204131
Filing Date: 2007-04-17
Classification: B82Y,G01Q,Y10S

Abstract:
1. A method of analyzing a sample in cyclical mode with a probe-based AFM, the method comprising: providing a cantilever; oscillating the cantilever at an amplitude of oscillation so as to cause a tip of the cantilever to intermittently contact a surface of the sample; scanning the cantilever across the sample; generating a deflection signal in response to said scanning step; demodulating said deflection signal to generate an amplitude signal indicative of the amplitude of oscillation of the cantilever; generating, with a first feedback loop, a first control signal in response to the amplitude signal; using the first control signal as an error signal in a second feedback loop, wherein the first feedback loop is nested within the second feedback loop; and damping the oscillating voltage with an active drive circuit to actively modify the quality factor (Q) of the cantilever resonant frequency during said scanning step.