Improvement of SAXS measurements on Kratky slit systems by Gobel mirrors and imaging-plate detectors

Laboratory X-ray sources emit a highly divergent beam. The Kratky compact camera is constructed to maximize the intensity in the sample using a slit collimation system. The performance of this camera can be further increased if the primary beam is collimated from a divergent into a parallel beam. A recently developed device for this purpose is the so-called 'Gobel mirror'. This mirror is made of parabolically bent multilayers, designed to collimate divergent X-rays from laboratory X-ray sources into a parallel and monochromatic beam of high brilliance. Modification of the block collimation system in combination with a Gobel mirror leads to a different beam geometry, resulting in an intensity increase by a factor of about 10. The gain in intensity implicates the use of imaging-plate detectors, which have a wide linear range in intensity and allow the full use of the increased intensity. Hence the quality of the SAXS data is improved by the higher intensity primary beam, the much lower background due to the exclusive use of Cu K alpha radiation, and a detection unit which is linear in the measured intensity regime. All these advantages, such as intensity gain, lower background, better quality of the data, are demonstrated with some selected experimental results.