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Atomic Force Microscopes - Tutorial Page

Resolution in an atomic force microscope

Traditional microscopes have only one measure of resolution; the resolution in the plane of an image. An atomic force microscope has two measures of resolution; the plane of the measurement and in the direction perpendicular to the surface.

In Plane Resolution: The in-plane resolution depends on the geometry of the probe that is used for scanning. In general, the sharper the probe is the higher the resolution of the AFM image. In the figure below is the theoretical line scan of two spheres that are measured with a sharp probe and a dull probe.

Figure 6: The image on the right will have a higher resolution because the probe used for the measurement is much sharper.

Vertical Resolution: The vertical resolution in an AFM is established by relative vibrations of the probe above the surface. Sources for vibrations are acoustic noise, floor vibrations, and thermal vibrations. Getting the maximum vertical resolution requires minimizing the vibrations of the instrument.