Abstract
Low energy electron microscopy (LEEM) is a powerful tool for the study of surface structure, and incorporation of an imaging energy filter in a LEEM instrument offers numerous new possibilities that increase the amount of information. We have developed an energy-filtering LEEM instrument, where a Wien filter was adopted for energy selection. One of the advantages of the Wien filter is its straight optic axis, which is exceptional among energy filters. Owing to this nature, tuning of optical conditions for energy-filtering imaging is greatly simplified. However, no successful result for the production of an imaging Wien filter had been reported; this fact may be due to the lack of consideration to aberrations in the process of practical design. This article describes the electron optical work we have done for the realization of an imaging Wien filter.
