Patent ID: 7425698
Filing Date: 2008-09-16
Classification: B82Y,G01Q

Abstract:
1. A scanning probe microscope apparatus for increased-quality-factor intermittent contact imaging of a sample surface comprising: A. a device including 1) a base, 2) a member which is displaceable relative to the base, 3) a tip mounted on the member to intermittently contact the sample surface to be imaged, and 4) a characteristic of a quality factor; B. means for actuating the member; C. means for measuring displacements of the member relative to the base and generating a displacement signal indicative thereof; D. an oscillator generating a driving signal which includes characteristics of 1) a driving frequency and 2) a driving amplitude, the driving signal causing oscillations in the means for actuating which in turn causes the member to oscillate which in turn causes the displacement signal to oscillate; E. a feedback loop including a feedback controller, the feedback controller receiving 1) the displacement signal and 2) the driving signal and applying an oscillatory actuation signal to the means for actuating, the oscillatory actuation signal being mathematically dependent on 1) the displacement signal, 2) the driving signal, and 3) a gain function of the feedback controller, the feedback loop further including a characteristic of a quality factor, the gain function being such that the quality factor of the feedback loop is higher than the quality factor of the device when the tip is remote from the sample surface; F. a scanner for altering a separation distance between the sample surface and the device in a direction predominantly perpendicular to the sample surface and for imparting relative motions between the sample surface and the device in a plane predominantly parallel to the sample surface; G. an amplitude detector measuring a displacement amplitude from the displacement signal and generating a displacement amplitude signal indicative thereof, the displacement amplitude being smaller while the tip intermittently contacts the sample surface in comparison to when the tip is remote from the sample surface; H. a phase detector measuring a phase of the displacement signal with respect to a reference signal and generating a phase signal indicative thereof; I. means for controlling the scanner including means for 1) receiving the displacement amplitude signal, 2) setting a demanded displacement amplitude, 3) controlling the separation distance to bring the tip into intermittent contact with the sample surface and to maintain the displacement amplitude in general agreement with the demanded displacement amplitude while the tip intermittently contacts the sample surface, and 4) driving the relative motions to raster scan the sample surface; and J. an imager operatlively coupled to 1) the means for controlling the scanner, 2) the amplitude detector, and 3) the phase detector, the imager forming spatially-correlated images derived from 1) the separation distance, 2) a discrepancy between the displacement amplitude and the demanded displacement amplitude, and 3) the phase.