Force Microscopy with Actively Stabilized Differential Fiber Detection Mechanism

We present the design and theory of operation of a new fiber-optic detection mechanism for force microscopy. The technique comprises a differential fiber Michelson interferometer, in which most spurious signals due to environmental variations are automatically rejected. Any residual fluctuations are canceled by the action of a feedback mechanism, which also ensures operation at maximum sensitivity. This detection technique is capable of high sensitivity response to both high and low frequency tip variations, and can thus be used in the attractive and repulsive modes. A number of results are presented on the applications of a force microscope utilizing this detection mechanism. Both ac and dc modes of operation are demonstrated. © 1993, American Vacuum Society. All rights reserved.