A laminar X-ray beam, collimated to 110 mm width by 4 mm height by a slit system, is reflected two times by a double monochromator crystal. Energy is selected by changing the agle between beam and crystal surface (Bragg reflection).

Downstream of the monochromator crystal, and after further collimation (not shown), the photon flux impinging on the sample is measured by means of an ionization chamber. The sample itself is mounted on an holder which can be vertically scanned through the beam using a remotely controlled movement stage.

  Finally, the silicon detector, which is fixed and aligned with respect to the beam, faces the incoming photons with a grid of pixels (typical pixel dimensions are 200 micron x 300 micron) covering the beam cross-section: each pixel has its own electronic chain capable of counting the number of photons hitting the pixel in a given time interval.