Abstract: A Soller slit 16 in an X-ray spectrometer can parallelize fluorescent radiation which emanates from a specimen 4 and is to be analyzed according to wavelength by an analyzer crystal 18. Because the aim is to irradiate an as large as possible surface of the specimen 4 by means of primary X-rays 10, inevitably disturbing fluorescent radiation is also generated by the environment of the specimen, for example the specimen holder 6. In order to intercept this disturbing radiation so that it cannot reach the X-ray detector, a collimator mask 12 is arranged in a fixed location in the beam path. In the case of varying specimen dimensions it is not always possible to choose such dimensions for this mask that the disturbing radiation is intercepted. Therefore, a second collimator mask 28 is provided (behind the Soller slit 16) in order to intercept the disturbing radiation in cooperation with the first mask 12.

Abstract: An X-ray collimator in an X-ray analysis apparatus, consisting of plates of X-ray absorbing material, for example tungsten, which are arranged transversely of the X-ray beam. The plates are identical and provided with a pattern of rows and columns of rectangular openings 40, 42 which have a vertical period p.sub.1 and a horizontal period p.sub.2. The openings take up an opening fraction t.sub.1 and t.sub.2 of the periods p.sub.1 and p.sub.2, respectively. The plates are arranged in the collimator in a series in which the ratio between two successive distances (d.sub.i, d.sub.i+1) between the plates of the series is equal to the given opening fractions t.sub.1 and t.sub.2 of the periods p.sub.1 and p.sub.2, respectively. It has been found that all directions in the X-ray beam are then intercepted except for the direction to be collimated. Moreover, this configuration also enables transverse collimation.