  The outstanding design feature of an XPS microprobe Quantum 2000 is the
double focussing ellipsoidally shaped quartz monochromator of the X-ray source.
This device monochromatizes the Alk{\alpha} radiation and refocuses the X-rays
from the Al anode to the sample surface. This way, on one hand a variation of
the diameter of the X-ray generating electron beam allows to vary the X-ray
beam diameter on the sample surface. On the other hand a scanning of the
electron beam across the Al anode scans the X-ray beam across the sample
surface. The X-ray source was characterized in detail. The lateral dependency
of the primary X-ray intensity and the peaks FWHM were measured as function of
the position within the electrostatically rasterable scan area. Additionally,
the focussing quality of the monochromator was determined. Therefore the
lateral intensity distribution within the primary X-ray beam was estimated far
below the 1% intensity level.
