Abstract
In case of practising X-ray stress measurement through a diffractometer, the Geiger tube slit must be moved from its normal position to the goniometer center by a displacement r,
r=R{1-cos(φ+η)/cos(φ-η)}
R: The goniometer radius
φ: The angle between the specimen surface and a reflecting plane
η: 90°-θ, θ: Bragg angle,
to complete a focusing condition for any θ and φ.
By means of our automatic focusing apparatus made up of a set of simple link mechanism the Geiger tube slit could follow the newly made focusing circles for a half fixed angle φ and a variable Bragg angle θ, and so all the points on the diffraction profile obtained could satisfy the focusing condition like a normal diffractometer. To test the accuracy of this method the macroscopic stress measurements were performed for various powder patterns, and satisfactory results were obtained.
