Principle : The atomic force microscopy (or afm for atomic force microscopy) is a technique of microscopy, local probe that allows to observe the relief of a surface. for this a very thin tip supported by a microlevier scans the sample. the tip is very close to the surface undergoes the part of it a force attractive or repulsive depending on the distance tip-to-surface measured by the deflection of the lever.
the atomic force microscope can be used in different modes : the touch mode, the touch mode and intermittent mode and non contact.
in the touch mode, the deflection of the micro-lever is maintained constant by a loop dasservissement while the sample is moved in x, y and z. the lever with the edge detector based on the sample analysis. a repulsive force between the surface and the tip is created because there is repulsion of the electrons of the sample and the tip. in this case, the weak interaction between the sample and the tip is kept constant by changing the height of the sample in the device. the variation of the height gives the height of the surface at the location under consideration. a topographic image is three-dimensional can thus be obtained.