Lorentz Stem: A Digital Approach to an old

Abstract

The study of magnetic materials using electron column instruments has been a fruitful area of research for microscopists/microanalysts for nearly 4 decades. A number of techniques have been developed for both the SEM and TEM which enable visualization of magnetic fields ranging from Fresnel imaging (Fuller and Hale, Silcox), Differential Phase Contrast (Chapman), through to Electron Holography (Tonomura). The latter are generally qualitative, while the former quantitative, albeit at the price of significant complexity. The advent of microprocessor control of modern instruments, CCD detectors, and experimental diligence allows us to revisit and in fact revitalize this area of measurement.The experimental work reported here is being carried out in the ANL AAEM HB603Z 300 kV FEG instrument. in this instrument, the electron optical column was operated in a zero field mode (figure 1), where the objective lens is turned off and the probe forming lens functions were reallocated to the C1, C2, and C3 lenses.