Dual-axis STEM tomography at 200 kV: Setup, performance, limitations.

The interpretation of cell biological processes hinges on the elucidation of the underlying structures. Their three-dimensional analysis using electron tomography has extended our understanding of cellular organelles tremendously. The investigations depend on the availability of appropriate instruments for data recording. So far, such investigations have been done to a great extent on 300 keV transmission electron microscopes. Here we show the implementation of STEM tomography on a 200 kV FEG transmission electron microscope, including the tuning of the condenser for forming a beam with a small illumination aperture, dual-axis data recording, and evaluation of the maximum sample thickness and quality of the data. Our results show that the approach is accomplishable and promising, with high reliability, and reaching excellent data quality from plastic sections with a thickness of at least 900 nm.