The charactron tube is about a metre in length and yet has quite a small diameter. In consequence, the beam movement even for full deflection is quite small. this results in a high quality image of high accuracy. The addressability is 1023 by 1023 with individual vectors having a maximum X or Y change of 64 pixels. In consequence, several lines needed to be drawn for a full screen line.
The tube is displaying the standard calibration image