STP372

    Variable Bias Illumination Control for the Electron Microscope

    Published: Jan 1964


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    Abstract

    Continuously variable control of illumination intensity in the electron microscope can be achieved by use of photoconductive cells for the grid bias resistance in a self-biased electron gun. The simple, highly stable device consists of several photo cells connected in series facing a control lamp, all positioned in a light-tight compartment. Changing the lamp brightness varies the grid resistance from 500,000 ohms to more than 30 megohms, controlling illuminating beam current over a wide range. Microscope stability is unaffected.


    Author Information:

    McPartland, J. O.
    Engineer and senior scientist, Ceramics Research Operation, Richland, Wash.

    Daniel, J. L.
    Engineer and senior scientist, Ceramics Research Operation, Richland, Wash.


    Paper ID: STP48333S

    Committee/Subcommittee: E04.11

    DOI: 10.1520/STP48333S


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