In Atomic Force Microscopy (AFM), positioning units are used to move samples for surface topographies. In doing this, the sensor head of the microscope needs to be cooled down to four degrees Kelvin using liquid helium. Capacitive displacement sensors from the capaNCDT 6300 series are used to monitor these positioning units. The extremely flat design of the sensor enables it to be used in tight or restricted installations. Special materials with very low thermal expansion coefficients enable nanometre precision.