Experimental Techniques for Observing Dislocations by the Berg-Barrett Method

Experimental problems in the application of the Berg-Barrett Method to the observation of dislocations in metal single crystals are discussed. The problem of background noise caused by fluorescence from the specimen and inelastic scattering is considered. A criterion for selecting an appropriate filter to discriminate against the background noise is presented. The problem of multiple images is discussed and a scheme for selecting diffraction geometry to eliminate unwanted images is presented. A detailed description of the relatively simple equipment used in Berg-Barrett work is given.