The spring constant of microfabricated cantilevers used in scanning force microscopy (SFM) can be determined by measuring their resonant frequencies before and after adding small end masses. These masses adhere naturally and can be easily removed before using the cantilever for SFM, making the method nondestructive. The observed variability in spring constant-almost an order of magnitude for a single type of cantilever-necessitates calibration of individual cantilevers in work where precise knowledge of forces is required. Measurements also revealed that the spring constant scales with the cube of the unloaded resonant frequency, providing a simple way to estimate the spring constant for less precise work.

The performance of an atomic force microscope using a laser diode interferometer has been improved to the point where its resolution is comparable to that of laser beam deflection systems. We describe the structure of this microscope, present a model that takes into account the main parameters associated with its operation, and demonstrate its sensitivity by showing images of a small area scan with atomic resolution as well as a large area scan in a stand-alone configuration.

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