A `beam-selection' high-resolution X-ray diffractometer

A new diffractometer that can be described as a high-intensity low-background high-resolution diffractometer for analysing perfect, nearly perfect and highly imperfect materials on a routine basis is presented. The instrumentation is very simple and uncomplicated, yet the way in which it works is less obvious. The sample requires minimal sample alignment, the resolution can be adjusted to optimize the experiment and the wavelength dispersion can be controlled. This diffractometer can produce near perfect pro®les from bent and imperfect samples. The illuminated area can easily be varied from greater than 3 mm down to 50 mm diameter, offering great opportunities in microdiffraction with high resolution. The instrument appears similar to a double-crystal diffractometer in reverse, i.e. the sample and collimating crystal of a conventional double-crystal diffractometer are reversed; however, the concept is quite different.