Equipment | Microscopes |Atomic Force Microscopes (AFM)

Atomic Force Microscopes (AFM)

Atomic force microscopes essentially scan the surface of a sample, providing nanometer-scale information. An AFM utilizes a cantilever with a very sharp tip to scan across a sample. As the tip approaches the sample exterior, the attractive force between the sample and the tip causes the cantilever to deflect in the direction of the surface. However, as the cantilever gets even closer so that the tip makes contact with it, a repulsive pressure takes over – deflecting the cantilever away from the sample. A laser beam is used to recognize cantilever deflections towards or away from the exterior. By bouncing an incident beam off the top of the cantilever, any cantilever deflection will cause slight shifts in the direction of the reflected beam. A position-sensitive photodiode (PSPD) is used to follow these tiny variations in the laser beam’s direction.

Other Equipment