An X-ray interferometer with a large and variable path length difference

The first chromatic hard X-ray interferometer with a large and variable path length difference has been built and successfully tested. Interference fringe visibility was measured as a function of the path length difference. Based on the measurements, fringe visibility analysis was performed to give the transmitted beam coherence lengths. The results agree very well with expected coherence values based on the angular and spectral acceptances of the interferometer.