A photocathode internally processed image intensifier inverter tube includes a cathode housing having an outer side wall forming a cylindrical opening for connection to the photocathode of the inverter tube. The side wall forms a cylindrical cavity in which the phototcathode is received. A pair of flat wall surfaces are formed in the side wall. The flat surfaces are spaced radially inwardly such that the distance from the surfaces to the center of the cylindrical opening is less than the radius of the cylindrical opening. A tubular processing side arm is attached from each flat wall surface and is used to introduce antimony and alkali metal vapor, under a vacuum into the cathode housing for the deposit of a photosensitive coating on the photocathode substrate. After forming the photosensitive surface, the side arms are sealingly pinched off at the ends thereof to maintain a vacuum inside the inverter tube. The flat surfaces are positioned relative to the outer side wall and the side arms extend a specified distance from the flat wall surfaces such that the arms do not extend beyond the diameter of the side walls forming the cylindrical opening.