Collimators

The use of collimators for generating narrow X-Ray beams is straightforward, but can suffer from loss of intensity as the beam diameter decreases.

Passing a relatively large X-Ray beam through a small aperture results in most of the primary X-Rays being blocked by the material around the aperture. X-Rays only pass through the aperture itself, yielding a beam with a diameter approaching that of the aperture.

However, as the aperture is narrowed, the proportion of X-Rays which are blocked increases dramatically. Thus, beams generated in this manner with diameters below 500 µm become low in intensity, and diameters below 100 µm become unworkable because of this problem.

Today collimators are successfully used for high spatial resolution analysis (beam diameters <20 µm) on synchrotron sources, where the extremely high beamline intensities mean that intensity losses are not an issue. For benchtop instruments with less bright X-Ray sources, collimators are not used for ultra-high spatial resolutions.

Collimators