25 September 1995 Retarding field optics with field-free sample
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Retarding field immersion lenses are coming into wide-spread use for focusing low energy electron and ion beams. One disadvantage is that any sample non-flatness will distort the focusing field. A more recent variant is a non-immersion retarding field lens, in which the sample is located outside the retarding field. We describe here a simple model and analysis which predicts that the performance of such a lens is competitive with the retarding immersion lens. With this lens design, it should be possible to focus a 1 keV electron beam with an energy spread of 1 eV into a spot of 4 nm diameter using realistic values of maximum voltage and retarding field strength. The effective resolution under these conditions is estimated to be 1.4 nm.
© (1995) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Laurence S. Hordon, Laurence S. Hordon, B. B. Boyer, B. B. Boyer, Roger Fabian W. Pease, Roger Fabian W. Pease, "Retarding field optics with field-free sample", Proc. SPIE 2522, Electron-Beam Sources and Charged-Particle Optics, (25 September 1995); doi: 10.1117/12.221588; https://doi.org/10.1117/12.221588

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