X-ray microbeams based on Kumakhov polycapillary optics and its applications: Analytical consideration 20
As we can see, expression (4) can also be applied for a source with extended spot.
Exit intensity can be determined also by an entrance transparency, which is the ratio
of the area of apertures and walls, and losses on internal reflections. All these factors
as a whole are considered in experimentally received transmission factor Tr. Thus, exit
intensity of radiation will be equal to
Wout = WinTr. (7)