  Non-destructive cross-sectional characterization of materials systems with a
resolution in the nanometer range and the ability to allow for time-resolved
in-situ studies is of great importance in material science. Here, we present
such a measurements method, extreme ultraviolet coherence tomography (XCT). The
method is non-destructive during sample preparation as well as during the
measurement, which is distinguished by a negligible thermal load as compared to
electron microscopy methods. Laser-generated radiation in the extreme
ultraviolet (XUV) and soft x-ray range is used for characterization. The
measurement principle is interferometric and the signal evaluation is performed
via an iterative Fourier analysis. The method is demonstrated on the metallic
material system Al-Al$_2$Cu and compared to electron and atomic force
microscopy measurements. We also present advanced reconstruction methods for
XCT which even allow for the determination of the roughness of outer and inner
interfaces.

Materials Science;Applied Physics;Optics