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FIELD-EMISSION MICROSCOPE
Either one of two kinds of point-projection microscopes, both invented by E. W. Muller: (1) The older device (1936) is a specialised cathode-ray pipe, employing field-emission of electrons from a negatively charged tip of a very sharpneedle in a vacuum, by point-projection of the image onto a positively charged, fluorescent screen. (2) A later device (field-ion-mission microscope, 1950) emits absorbed heliumions from an anode.