A quadrupole lens system for use in a parallel recording system for Electron Energy Loss Spectroscopy

Abstract

A design for a quadruplet quadrupole post-spectrometer magnification system for parallel EELS is described. When using 100 keV electrons, it has a magnification range of 5 to 90 in the dispersion direction without image reversal and gives an essentially constant width perpendicular to the dispersion direction. The system does not affect the properties of the sector magnet. The energy range reaching the detector can be controlled using a variable slit in the dispersion plane of the spectrometer, thus reducing the effect of stray scattering from high-intensity spectral regions reaching the detector. The same slit can be used to allow serial scanning for setting up the spectrometer and in those applications where serial detection is advantageous. The system has relatively stationary cross-over points so that additional fixed apertures or slits can be inserted to further alleviate the problem of stray scattering.