CURRENT DENSITY DISTRIBUTION IN AN M-M VIDICON TYPE CAMERA TUBE.

Abstract

The beam current density distribution of a 1 inch M-M type vidicon is investigated. A portion of the beam current passing through a fine pinhole in a metallic target is detected by slight beam scanning with an electron-multiplier and displayed three-dimensionally as the current density distribution on an oscilloscope screen. The results show that the beam spot size of a 1 inch vidicon using a conventional magnetic focus and deflection coil assembly is 20 to 30 mu m in diameter, and the current density distribution is very similar to the Gaussian distribution. The actual crossover is about 40 mu m in diameter, but the size of the image at the target is reduced to 20 mu m due to the anode G//2 aperture interception.