Improvements to the electrostatic lens optimization method SOEM

Jim Edmond Barth; H. W. G. van der Steen; Jaroslav Chmelik

doi:10.1117/12.221569

25 September 1995 Improvements to the electrostatic lens optimization method SOEM

Jim Edmond Barth, H. W. G. van der Steen, Jaroslav Chmelik

Proceedings Volume 2522, Electron-Beam Sources and Charged-Particle Optics; (1995) https://doi.org/10.1117/12.221569
Event: SPIE's 1995 International Symposium on Optical Science, Engineering, and Instrumentation, 1995, San Diego, CA, United States

Abstract

Lens optimization can be based on the very fast approximate axial potential calculation of the Second Order Electrode Method (SOEM). In this method the free optimization parameters are the physical quantities of an electrostatic lens system. The optimization, to a merit function based on the optical properties of the lens, is within engineering constraints such as the maximum off-axis field between electrodes. Several improvements to the method have been brought into the program SOEM extending the class of electrostatic lenses that can be optimized. The off-axis geometrical aberrations and the chromatic magnification error can now be included in the merit function. The first and last electrodes can intersect the axis, thus allowing non-field-free spaces at the ends of the lens. Electrode parameters (radii/length/gaps/potential) can be required to be equal giving greater control over the lens configuration freedom in the optimization process.

Citation Download Citation

Jim Edmond Barth, H. W. G. van der Steen, and Jaroslav Chmelik "Improvements to the electrostatic lens optimization method SOEM", Proc. SPIE 2522, Electron-Beam Sources and Charged-Particle Optics, (25 September 1995); https://doi.org/10.1117/12.221569

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