The use of polycapillary optics for the concentration of the X-ray beam on a small spot on the sample with a diameter of only 100 µm warrants highest excitation intensity. A low-power microfocus X-ray tube as radiation source is sufficient for this purpose.
The higher magnifying video microscope used for sample viewing has an adjustable focal plane , which permits the use of different working distances and according variation of the beam diameter between 100 µm and approximately 500 µm without significant loss in intensity.