Primary beam collimation

The radiation emerges from the x-ray tube with some aperture divergence, and the flux intensity varies along the perpendicular to the beam line profile. By placing slit collimators immediately in front of the x-ray tube exit window, one can ensure a high parallelism in the selected line shape beam. If the position and tilt of the collimator can be adjusted (e.g. with some fixing screws) by scanning the beam along the direction perpendicular to the line profile it is possible to select a position corresponding to the maximum flux intensity.

The shape of the collimated beam can be inspected with the help of a ZnS fluorescent screen, and the flux intensity can be assessed if some sample is positioned in the beam line and the radiation scattered at it is measured with the x-ray detector.