GB907326A - Improvements relating to focusing x-ray cameras for x-ray diffraction studies - Google Patents

Abstract

907,326. X-ray diffraction cameras. SETON CREAGHE ENGINEERING Ltd. March 7, 1961 [Feb. 5, 1960], No. 4210/60. Class 98 (1). An X-ray camera comprises a crystal monochromator mounted for rotation about an axis coincident with the axis of swing of an arm which carries the camera. The whole apparatus is mounted on a base la, which carries a set of cross-slides 2, 3. The slide 3 carries a vertical tubular axle 5 on which is swingably mounted the arm or camera platform 4. Coaxial with the axle 5 is a housing 6 having a table 7 which carries a monochromator crystal 9. Rotation of the table 7 thus adjusts the angle of incidence on the crystal of the beam from the X-ray generator (not shown). A diaphragm with adjustable shutter members 11, 12, 13, 14 forms an adjustable aperture for the X-ray beam reflected from the monochromator. The platform 4 has a guideway 15 along which, moves a slide 16 carrying a swivel mounting 17. The swivel mounting itself is formed as a guideway carrying a slide 22 on which is rotatably mounted the base part 24 of the cassette 25. The cassette can thus be rotated about a central vertical axis, and is provided with means for retaining it in selected indexed positions. The film is held against the inner cylindrical wall of the cassette by spring bands 26. An L-shaped specimen holder 31 is supported in front of the cassette on a disc 27 which can be oscillated by a motoroperated driver shaft 19; thus the specimen holder can be rocked about the vertical axis of the cassette through an appropriate angle, e.g. 8 degrees. The cassette may also include a beam trap, formed as a vertical cylinder having a vertical slot in one wall, to intercept the beam entering the cassette, while the camera is being set up, and movable out of the path of the beam when it is required to make an exposure. In setting up the camera for use, the monochromator is set to approximately the correct orientation, and then the arm 4 swung until the reflected beam from the monochromator is picked up by a suitable screen placed on the mounting 17 adjacent its swivelling axis (the cassette being moved away). The monochromator is then adjusted to produce the correct relationship between the monochromator position and the focus of the incident X-ray beam. The slide 16 is adjusted along the guideway 15 until the focus of the reflected beam is coincident with the rocking axis of the swivel mounting 17. The slide 22 is adjusted along the mounting 17 so that the film in the cassette coincides with the focus of the beam.