The sharpened probe is positioned close enough to the surface such that it can interact with the force fields associated with the surface. Then the probe is scanned across the surface such that the forces between the probe remain constant. An image of the surface is then reconstructed by monitoring the precise motion of the probe as it is scanned over the surface. Typically the probe is scanned in a raster like pattern.

In an AFM the probe is very sharp, typically less than 50 nanometers in diameter and the areas scanned by the probe are less than 100 um. In practice the heights of surface features scanned with an AFM are less than 20 um. Scan times can range from a fraction of a second to many 10’s of minutes depending on the size of the scan and the height of the topographic features on a surface. Magnifications of the AFM may be between 100 X and 100,000,000 X in the horizontal(x-y) and vertical axis.

Figure 1-2 illustrates the block diagram of an atomic force microscope. In the microscope, the force between a nanoscopic needle and the surface is measured with a force sensor, the output of the force sensor is then sent to a feedback controller that then drives a Z motion generator. The feedback controller uses the force sensor output to maintain a fixed distance between the probe and the sample. X-Y motion generators then move the probe over the surface in the X and Y axis. The motion of the probe is monitored and used to create an image of the surface.