GB1307570A - X-ray diffractometer - Google Patents

Abstract

1307570 Crystallograph YEDA RESEARCH & DEVELOPMENT CO Ltd. 13 May 1970 [20 May 1969] 23235/70 Heading G1A In an X-ray diffractometer a radiation counter 50 is supported within a drum 41 mounted for rotation about its longitudinal axis on a gimbal yoke 26, 27, 28 that is rigidly secured to horizontal gimbal shafts 14, 15. An extended horizontal shaft 18, that is integral with gimbal shaft 14 and is coupled to a ganiometer head 19, supports a crystal 20. Precession motion with respect to X-rays from a collimator is imported to the gimbal by a motor 36 whose output is transmitted via a worm 37 and a gear to a drive shaft 34 (as shown in) Fig. 3. The drum 41 can be rotated by a motor 49 and associated gears 47 & 48. The amount of radiation received by the counter 50 is controlled by means of a sector like aperture 51 in a fixed end face of the drum 41 on which is superimposed a rotatable metal disc with a sector like aperture 52, which a rotation provides variable angular widths ## of the aperture. An additional metal disc 55 provided with a plurality of annular slots of different radii serves to define the height of #r and radial position r n of the aperture with respect to the centre of the drum face. Three modes of operation are described. The first mode involves actuating the drive motors 36, & 49 to set the instrument (i.e. the crystal and the counter) for a particular crystal plane reflection, then maintaining the instrument stationary in this particular setting and measuring the intensity of the reflected rays in terms of the electric pulses from the counter. In the second mode motor 36 and 49 are actuated to displace the instrument to a position in which the respective angular coordinates are somewhat less than the predetermined values corresponding to the particular reflection to be measured, and then discrete stepping pulses are successively fed to drive each motor into and slightly beyond the predetermined value. In the third mode continuous precession of the crystal and counter with respect to particular particles 6 or # values (angular coordinates) is automatically controlled by means of a computer assembly consisting of a desk top calculator, a programmer and an auxiliary storage memory. A further embodiment employing a vicidon tube instead of the counter is disclosed.