Direct imaging monochromatic electron microscope

Claim 1

A direct imaging, monochromatic electron microscope including emitting means for emitting electrons from a plurality of spots across a sample surface, objective means for collecting a substantial portion of the emitted electrons from the sample surface, collimating means for collimating the substantial portion of the emitted electrons into a plurality of groups of electron beams, an energy filter receptive of the groups of beams to transmit monochromatic beams having a selected energy, imaging means receptive of the monochromatic beams for focusing the same to effect an image of the spots, and detector means for detecting the image, the objective means comprising an objective lens formed of a magnetic field generating toroidal coil having a central hole therein with a dish-shaped magnetically permeable member cupped coaxially over the toroidal coil, the permeable member having a neck portion extending substantially through the central hole, and the objective lens being situated to collect the substantial portion of the emitted electrons from a sample surface interposed proximate the neck portion between the objective lens and the collimating means.