Emitters of x-radiation with different dimensions and shapes of the focal spot were used. Magnetic lens were
employed to produce additional focusing and variation of the shape of the electron beam.
Examples of images of the focal spot of a micro-focal x-ray tube for different values of the adjusting parameters
obtained on the basis of the technique that has been described here are presented in Fig. 4. The values of the following parameters
were varied: accelerating voltage Uacc; bias voltage Ubias; filament voltage Ufil; and tube current Itube.