A quantitative thermionic projection microscope, employing computer image processing, is described. In this system, thermionic emission from a singlehyphen;crystal hemispherical cathode is projected onto a phosphor screen and the resulting image is digitized by means of a video camera. Singlehyphen;plane effective work functions for the highest emitting planes of the cathode may be measured to within a tenth of an electron volt. copy;1994 American Institute of Physics.
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