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Field-emission microscope

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Field-emission microscope

(Science: instrument, microscopy) 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 tube, employing field-emission of electrons from a negatively charged tip of a very sharp needle 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 helium ions from an anode.