Kumakhov optics consists of different systems of hollow glass tubes, or capillaries [5–7]. The operating principle of
Kumakhov optics is based on the transformation of radiation by means of multiple reflections from the internal walls of the capillaries
at low angles that do not exceed the critical angle. With the use of angular filtration of the polycapillary system by lowangle
reflection, it is possible to obtain an image of the focal spot of the x-ray tube formed by quasi-parallel rays. An analysis
of this image provides a number of required parameters of the focal spot. Thus, based on polycapillary structures of Kumakhov
optics it is possible to create a convenient, precise, and quick technique of determine a number of parameters of the focal spot.