Slit scan illumination for dynamic focusing

This mode describes a modification of the spot scan mode1 in which areas on a photographic plate are exposed one after the other using small illuminating spots. The spot scan mode in transmission electron microscopes (TEM) reduces specimen damage and specimen drift. In addition to this it allows dynamic focussing at high tilt angles of the specimen. High-resolution, 3-D specimen reconstruction and reflection electron imaging using specimen tilt angles of up to 90° require dynamic focussing rectangular to the tilt axis of the goniometer for imaging of off-axis specimen areas. A slit-type illumination of the specimen parallel to the goniometer tilt axis may provide a better solution for such types of problems.