X-ray imaging using the radiation diffracted by polycrystalline materials

Imaging requires not only an area detector but also optics to relate the elements of the object to those of the detector. For X-rays optical elements based on reflection or refraction allowing the imaging of objects of several mm size are not available. Therefore, image formation like in the human eye cannot be achieved, but an approach realized in the eyes of insects where each facet has its own optics, has to be used. In the X-ray regime such a system can be realized by an arrangement of collimating tubes guiding the radiation from a region of the sample to the corresponding area of the detector and suppressing cross-fire from other regions.

Such an imaging system consisting of a microchannel plate in front of a CCD-detector has been installed on the 2Θ-arm of a 4-circle diffractometer at beamline G3 at HASYLAB, DESY. With this instrument, images as a function of one or more parameters can be collected. The structure of the data obtained in this way is distinct from those obtained by conventional diffraction techniques mostly yielding only one intensity value per scanning step and therefore requires different strategies for processing.