Through the use of a set of strictly oriented and densely packed capillaries having a polycapillary structure, it is possible
to obtain a complete image of a spot consisting of the pixels formed by the individual capillaries (Fig. 2). An increase
in the dimensions due to the presence of a gap between the anode and the entry to the capillary system as well as between
the exit from the capillary system and the detector is also easily computed on the basis of the critical angle; specifically, it is
equal to the angular component 2l tanqcr.