Careful experiments from CEOS Corrected Electron Optical Systems GmbH in Heidelberg have shown that stochastic magnetic field noise limits the ultimate resolution of transmission electron microscopes. This magnetic field noise is due to unavoidable thermal currents in the conductors of which the TEM is constructed. Best summarized in the authors’ words, “[E]xperiments have revealed a hitherto unknown fundamental performance limitation for electron microscopy due to the stochastic beam deflection caused by the noise fields.” The authors estimate that observed image blur of 15-25 pm can be explained by this phenomenon.
Reference: Stephan Uhlemann, Heiko Müller, Peter Hartel, Joachim Zach, and Max. Haider, “Thermal Magnetic Field Noise Limits Resolution in Transmission Electron Microscopy”, Phys. Rev. Lett. 111, 046101 (2013)