Cathode lens microscopy, comprising both Photo Electron Emission Microscopy (PEEM) and Low Energy Electron Microscopy (LEEM), has undergone major developments over the last decade. This includes correction of spherical and chromatic aberration, the increasing use of PEEM for spatially resolved k-space imaging of occupied electron bands, and –most recently- the use of LEEM for spatially resolved k-space imaging of unoccupied electron bands. Correction of spherical and chromatic aberration is now becoming more broadly available, and had distinct advantages for use in synchrotron-based PEEM. However, setup of optimum imaging conditions for a given experiment is still open to discussion. I will show how the electron mirror optics, in combination with the objective lens, can be configured as an adjustable achromat. For example, an achromat centered around a start energy of 2.5 eV, with a bandwidth of 5 eV, yields a spatial resolution of 4-5 nm, while an achromat centered at 30 eV, with a passband from 9 to 62 eV has a resolution of 15 nm. Such a very wide passband (resulting in high transmission) may be extremely useful for imaging samples with weak signals, as often encountered in practice. I will also discuss the prospects for developing an apochromatic system, which would further improve resolution by another factor 2x, and transmission by a factor 10x. Finally, I will show recent results on measuring un-occupied bandstructures by LEEM, yielding information complementary to traditional ARUPS experiments.

　Tromp先生は、低速電子線顕微鏡（LEEM）、光電子顕微鏡（PEEM）研究の第一人者で、最近の収差補正による分解能向上にも大いに貢献されています。今回は、これらの顕微鏡に関する最近の進展についてお話ししていただきます。