To record the change in altitude by the sample a voltage is impressed between the tip and the sample. If the distance is short enough there will be a current. A topographical change in the sample therefore causes a change in the current. The microscope then adjusts its distance through adjusting the voltage in the z piezo. Thus the current and accordingly the distance between the tip and the sample is held constant to not risk a crash of the tip into the sample.
The whole process is recorded so there results a set of horizontal and vertical data of the sample. These can be visualized by a computer. To get a taste of what it could look like we link to our image gallery.
The film shows how the tip reacts to changes in the topography. A laser beam is reflected by a mirror on the cantilever to a light detector which records the changes.
|
 |
Ideally one atom lies on the top of the tip out of which the current flows.
|
|