| 摘要 |
741,854. X-ray apparatus. PHILIPS ELECTRICAL INDUSTRIES, Ltd. Nov. 5, 1953 [Nov. 8, 1952], No. 30616/53. Class 98 (1). Apparatus for X-ray spectrometry of the kind in which material the composition of which is to be estimated is irradiated with primary X-rays, and part of the secondary radiation emitted by the material impinges on a thin plate of crystalline material having a cylindrical surface and rotatable about an axis which coincides with a generatrix of the surface, a convergent beam of secondary radiation reflected by the plate being measured by means of a detector which is located in the neighbourhood of the minimum cross-section of the beam, is characterized in that the shaft 17 which carries the plate 7 of crystalline material is integral with a crank 16, a link 15 the free end of which positions the detector 10, is pivoted on the end of crank 16 remote from shaft 17, and means are provided for rotating the link 15 about its pivot at twice the angular speed of the crystal 7. As shown in Fig. 3, the material 1 is irradiated by means of an X-ray tube 3, and the secondary rays fall, in part, on the curved crystal plate 7, the lattice planes of which are perpendicular to its surface. The shaft 17 is driven by a worm 21 and worm-wheel 22. Arms 15, pivoted to arms 16 fixed to shaft 17, are fast with a gearwheel 19 meshing with a gear-wheel 20 of twice its diameter fast with shaft 17, so that arms 15 move about their pivot with twice the angular speed of arms 16. A shaft 28, journalled in arms 15, carries the radiation detector 10 and beam-limiting diaphragms 23, 24. A slotted strip 27 engaging shaft 17 keeps the detector directed towards the crystal 7. The gears 19, 20 may be replaced by pulleys connected by a belt drive. To increase the accuracy of the positioning of crystal 7, the diameter of gear 19 may be reduced with respect to gear 20; in this case gear 20 is rotated in a direction opposite to the direction of rotation of the crystal. U.S.A. Specification 2,540,821 is referred to. |
