The Annular Geometry Electron Gun

The annular geometry gun represents a distinct departure in electron gun design and operation. The modulator section contains an annular cathode, annular control grids and accelerating grids, a beam bending probe and an electron object electrode. Very high modulation sensitivity, inverted modulation characteristics, internal electronic video signal amplification, and automatic "white noise" inversion are among the unique performance features of the annular geometry gun. Beam control is produced by a focus modulation process. The final spot is formed by imaging a geometrical aperture in the object plate. This results in very high resolution capabilities and an optimum focus condition and spot size which are practically independent of beam current.