AFM Theory
In an AFM a constant force is maintained between the probe and sample while the probe is raster scanned across the surface. By monitoring the motion of the probe as it is scanned across the surface, a three dimensional image of the surface is constructed. The constant force is maintained by measuring the force with the "light lever" sensor and using a feedback control electronic circuit to control the position of the Z piezoelectric ceramic. See Figure 4.  Figure 4: This figure illustrates the primary components of the light lever atomic force microscope. The X and Y piezoceramics are used to scan the probe over the surface. The motion of the probe over the surface is generated by piezoelectric ceramics that move the probe and force sensor across the surface in the X and Y directions.
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