An Early American Electron Microscope

Abstract

An interest in the historical aspects of electron microscopy has been shown by several recent publications on the subject. As early as 1936 Dr. Paul Anderson and the late Mr. Kenneth Fitzsimmons were experimenting with an electron microscope in the Physics Department of Washington State University (then Washington State College). The instrument (see illustrations) was constructed somewhat on the designs of Knoll and Ruska. The electron source was a heated filament, and accelerating voltage was 30 KV. The microscope has three electromagnetic lenses; condenser, objective, and projector. External rectangular Helmholz coils (see illustration) corrected for the earth's magnetic field and permitted beam shift. The column is brass. The camera magazine held six lantern slide plates which could be successively exposed without breaking vacuum. Particularly interesting is the attempt to measure beam current at the fluorescent screen in order to determine photographic exposure.