GB658527A - Improvements in or relating to methods of focusing a diverging polychromatic beam ofx-rays and an apparatus for x-ray analysis - Google Patents

Abstract

658,527. X-ray apparatus. ILLINOIS INSTITUTE OF TECHNOLOGY, ARMOUR RESEARCH FOUNDATION OF. Sept. 10, 1948, No. 23826. Convention date, Sept. 24, 1947. [Class 98 (i)] [Also in Group XL (a)] Apparatus for X-ray analysis comprises a source of diverging polychromatic X-rays, a crystal having a flat face, means for adjusting the crystal to dispose the flat face with respect to the source to produce a diverging diffracted beam of polychromatic X-rays, a polycrystalline sample disposed in the path of the first diffracted beam to produce therefrom a converging diffracted beam, and an X-ray sensitive indicating medium disposed in the path of the second diffracted beam at a predetermined distance from the sample corresponding to the location of the achromatic focus of the second diffracted beam. As shown, a shielding wall 20 encloses a cathode 21 and an anode 22 with a removable target 23, as provided in conventional X-ray tubes. A crystal. 11 with a flat surface is adjustably mounted in the casing in the path of X-rays emitted from a point P on the target, which have wavelengths lying within a finite range. Rays diffracted from the crystal 11 in a plane normal thereto have wavelengths increasing or decreasing with angular displacement from the central ray. The diffracted beam passes through an X-ray transparent window 20a in the wall 20 and impinge on a polycrystalline sample 13 of material to be examined. It is shown that the beam diffracted from the sample is brought to a sharp focus at F. In a modification, the crystal 11 is adjustably mounted outside wall 20 and the incident and diffracted rays pass through a second X-ray transparent window.