A laboratory-based Laue X-ray diffraction system for enhanced imaging range and surface grain mapping

Although CCD X-ray detectors can be faster to use, their large-area versions can be much more expensive than similarly sized photographic plate detectors. When indexing X-ray diffraction patterns, large-area detectors can prove very advantageous as they provide more spots, which makes fitting an orientation easier. On the other hand, when looking for single crystals in a polycrystalline sample, the speed of CCD detectors is more useful. A new setup is described here which overcomes some of the limitations of limited-range CCD detectors to make them more useful for indexing, whilst at the same time making it much quicker to find single crystals within a larger polycrystalline structure. This was done by combining a CCD detector with a six-axis goniometer, allowing the compilation of images from different angles into a wide-angled image. Automated scans along the sample were coupled with image processing techniques to produce grain maps, which can then be used to provide a strategy to extract single crystals from a polycrystal.