Abstract: A method for producing at least one capillary in a moldable material. The capillary has a large length in relation to its cross-section. A closed cavity is created within the moldable material and the material is stretched in at least one direction so that the cavity forms a substantially elliptical or parabolic capillary whose length is large in relationship to its cross-section. The material may be heated before stretching so that the cavity is expanded and shaped into an essentially spherical form. Suitable materials for the practice of the invention include glass, plastic, quartz, silicon, or metal.

Abstract: The invention relates to a measuring element for a portable micro-X-ray spectrometer, said element comprising a radiation protected housing, at least an X-ray source, a detector, cooling parts for the detector and means for activating the X-ray source and the detector. In accordance with the invention, in order to advantageously guide the X-rays obtained by the X-ray source away from the radiation protected housing (1), at least one capillary tube (3) has been mounted in the X-ray source (4), said capillary tube (3), at the opposite end of the tube as seen from the X-ray source, being connected to a hole formed in the detector (5) for conducting the X-rays out of the radiation protected housing (1). The inner section of the capillary tube (3) is smaller at the end which, seen from the X-ray source, is opposite than at the end at the X-ray source (4).