Double Wien-filter monochromator for JEM-ARM200F is newly developed to realize ultra high energy resolution EELS analysis at atomic-scale.

• Double Wien-filter "Spot-IN and Spot-Out system"

The 1st Wien-filter and the electro-static lens produces a focus with energy dispersion of 12.3 μm/eV at the slit plane. At this plane, the electron beam is monochromated by inserting the slit of several widths ranging from few microns to sub microns. The 2nd Wien-filter cancels the energy-dispersion and produces an achromatic and stigmatic focus at exit plane, resulting in the roundly probe on the specimen plane. Thus, since a spot beam from Schottky source becomes a spot again at the exit after the monochromation, we named this monochromator system "Spot-IN and Spot-OUT system".

• Sophisticated Octopole Wien-filter

The sophisticated Octopole Wien-filter produces homogeneous dipole field with no undesireble hexapole field from inhomogeneity of dipole field.

• Arranged between Schottky source and accelerator

With a preset monochromator setting works universally on every accelerating voltages, since the accelerator is located after the monochromator and axial potential of the monochromator is kept constant.