Performance of the Philips CM200 FEG

Abstract

Since its introduction four years ago the Philips Field Emission 200 kV microscope has undergone a number of changes enhancing its performance. It has also become possible to quantify its performance more accurately.New developments are the introduction of the SuperTWIN-α and UltraTWIN objective lenses and the CompuStage goniometer. The SuperTWIN-α objective lens has a higher maximum tilt angle (±40° instead of ± 15°) while the point resolution remains 0.24 nm. The UltraTWIN lens has a point resolution of 0.19 nm and a maximum tilt of ±24°. Better specimens for determining the information limit have resulted in proven information limits of < 0.15 nm and ≤0.13 nm for the SuperTWIN-α and UltraTWIN lenses, respectively. The CompuStage, a five-axis motorised and computer-controlled goniometer, improves performance with regard to safety (no danger of damage to specimen holder or pole pieces), maximum accessible tilt, accuracy of movement, control and drift. The accessibility of the CompuStage to external computer control makes this goniometer ideal for developments in automation such as tomography or computer-assisted tilting for diffraction.