Current Density Distribution in an M-M Vidicon Type Camera Tube

Abstract

The beam current density distribution of 1 inch M-M type vidicon is investigated. A portion of the beam current passing through a fine pinhole in a metallic target with slight beam scanning is detected by an electron-multiplier and three-dimensionally displayed as a current density distribution on an oscilloscope screen. As a result, it becomes clear that the beam spot size of a 1 inch vidicon using a conventional magnetic focus and deflection coil assembly is to 20 to 30μm in diameter, and the current density distribution is very similar to the Gaussian shape. The actual crossover is about 40μm in diameter, but the size of the image at the target is reduced to 20μm due to anode 62 aperture interception.