The optics of the illuminating system of a TEM/STEM equipped with a high-brightness field emission source has been studied in order to determine the current density distributions of small electron probes used for microanalysis. The experimental distributions were measured from high-magnification TEM images of the small probes, and compared to theoretical distributions calculated using both coherent and incoherent optics. The microscope was shown to be capable of producing an electron probe with a FWHM diameter of 1.7 nm and a current of 1 nA. The size of the probe is limited by electrical and mechanical instabilities.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Atomic and Molecular Physics, and Optics