Abstract
The very large (>or=15 cm) out of focus electron microscope techniques used for detecting electric and magnetic fields producing angular deflections of 10-5-10-6 rad are considered. Observations made on weak Lorentz objects, such as the electric field of p-n junctions, (i) by high voltage transmission electron microscopy (TEM) and by high voltage scanning transmission electron microscopy (STEM) performed by means of an attachment to a TEM instrument; (ii) by low and high voltage TEM are compared. The results show that high voltage TEM is very satisfactory-better than conventional TEM and far superior to STEM in imaging very weak Lorentz (phase) objects even in thick specimens, at least with the present state of development of STEM attachments. The operational conditions are given.