Michal Lenc

The Scanning Very-Low-Energy Electron Microscope (SVLEEM)

The idea of the scanning very low energy electron microscope is discussed. The use of the immersion objective lens (the specimen as a cathode immersed in the electrostatic field of the cathode lens and in the magnetic field of the single pole-piece lens) is proposed to achieve a higher resolution and the optical properties of the lens are calculated. Preliminary results with the cathode lens in a classical SEM are presented and the new configuration in an ultra-high- vacuum (UHV) SEM is described.

Computation of multi-lens focusing systems

Abstract A computational method based on the trajectory method is presented for the evaluation of systems of magnetic electron lenses. A consistent set of aberration coefficients is derived for third-order geometrical and first-order chromatic aberrations. The coefficients can be evaluated for an arbitrary aperture position, and also for a defocused image position due to the inclusion of the aberration of the gradient. A computer program called SYSTEM incorporating these new features has been written and the use of the program is illustrated with a suitable example.