Cathode rays and deflecting fields can be used to magnify shadow images in a manner analogous to an optical lens system.
With the help of this supplement, the experiment: Maltese-Cross Tube (item no: UE3070300-115 / 8000659 is modified in such a way that the following electron-optical observations can be made:
By increasing the magnetic field (raising the voltage to the coil) the image is seen to rotate, diminish to a spot and then enlarge again in inverted form.
Anode voltage variations provide a further element of control.