Deflection Mode
Using the feedback control in the AFM, it is possible to scan a sample with a fixed cantilever deflection. Because the deflection of the cantilever is directly proportional to the force on the surface, a constant force is applied to the surface during a scan. This scanning mode is often called "contact" mode. However, because the forces of the probe on the surface are often less than a nano-newton, the probe is minimally touching the surface.
Figure 7: In contact mode AFM the probe directly follows the topography of the surface as it is scanned. The force of the probe is kept constant while an image is measured.
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