The invention provides an assembled conductor, which is formed by rolling a conductor bundle including a central conductor and a peripheral conductor arranged around the central conductor. The apparatus includes an area absorbing X-rays and an aperture opening. Control loop internal preset value calculating sections correct the preset values of the second to n-th control loops according to the progress 1 of the step response so that the controlled variables of the second to n-th control loops vary synchronously with the controlled variable of the first control loop and give the corrected preset values to the controllers. The coupling of light into the optical waveguide plate takes place through the side walls. Attaching and detaching the ball support from the rod requires inversion of the parts relative to one another.