Bragg magnifier: High-efficiency, high-resolution X-ray detector

X-ray computer microtomography is a powerful tool for non-destructive examinations in medicine, biology, and material sciences. The resolution of the presently used detector systems is restricted by scintillator properties, optical light transfer, and charge-coupled-device (CCD) granularity, which impose a practical limit of about one micrometer spatial resolution at detector efficiencies of a few percent. A recently developed detector, called Bragg Magnifier, achieves a breakthrough in this respect, satisfying the research requirements of an efficient advance towards the submicron range. The Bragg Magnifier uses the properties of asymmetric Bragg diffraction to increase the cross section of the diffracted X-ray beam. Magnifications up to 100x100 can be achieved even at hard X-rays energies (> 20 keV). In this way the influence of the detector resolution can be reduced accordingly and the efficiency increased. Such a device has been developed and successfully integrated into the Tomography Station of the Materials Science Beamline of the Swiss Light Source (SLS). The device can be operated at energies ranging from 17.5 keV up to 22.75 keV, reaching theoretical pixel sizes of 140 nm.