Adjusting mechanism

摘要

A mechanism is provided for varying the distance between a detector and a measuring crystal in an X-ray spectrometer. The crystal is arranged on a rotatable shaft and the detector is arranged on an arm which can perform a circular movement about the crystal shaft. The crystal shaft and the detector arm are coupled so that a rotation of the crystal shaft through an angle theta is accompanied by a rotation of the detector arm through an angle 2 theta . A first pulley having a radius r is mounted on the crystal shaft and a second disc having a radius 2r is rotatably mounted on the crystal shaft. A belt or cord is guided over each one of two guide rollers. One end of each of these belts is permanently connected to the first pulley, while its other end is permanently connected to the second pulley.