The heart of the instrument is the "SPM Head" which is built around a small cantilever beam. At the end of this beam is a minute needle-like tip. The point of the tip can be as small as a few atoms across. It is this tip that will ride across (or just above) the sample being measured "feeling" the shape of its surface.
These cantilever / tip assemblies come in many different styles. Further, because they wear out quickly, they are not built into the SPM. Instead, they are clipped into a removable holder so that they can be replaced or different style tips can be easily swapped in and out of the SPM.
