hysteresis

"Hysteresis" is a phenomenon where the state of a system depends on its undergoing progress, and a physical effect occurs at a delayed time against a given physical impact. In the case of TEM, the relevant phenomenon occurs in the lens action. The accuracy of the positional reproducibility of the electron probe on a specimen due to the hysteresis of the condenser lens affects the operability of a TEM. The excitation of the intermediate lens is frequently changed in obtaining different magnifications and at switching between the diffraction mode and image mode. The error of magnifications due to the hysteresis of the intermediate lens ranges from 5 to 10% though depending on the operation mode. For the objective and projector lenses, the hysteresis does not become a problem because the excitations of those lenses are almost fixed.