Magnified hard X-ray microtomography

Summary form only given. In the field of hard X-ray microtomography one goal is the enhancement of resolution. Several ways can be followed to obtain this objective. One possibility is the use of high-resolution X-ray films or detector screens coupled with a microscope optical system. The limitation of resolution is either given by the grain size of the X-ray film or the point spread function of the scintillator screen and the diffraction limit of the microscope. Tomography resolution can also be improved by magnified imaging of the object on the detector system. The appearance of X-ray lenses, such as Fresnel zone-plates, Bragg-Fresnel lenses and recently compound refractive lenses opened a large field for magnified imaging, similar to glass lenses for visible light. These new optical elements are already employed for X-ray imaging and can also be used for magnified microtomography. They have the potential of improving the resolution to a few hundred nanometers, which would overcome the resolution limits of current detectors. First tomography experiments with compound refractive lenses using a monochromatic beam as well as a so-called "pink" beam with a large energy bandwidth (DE/E=10-2 compared to DE/E=10-4 for a monochromatic beam) give promising results.