Hilbert, V.V.HilbertBlinne, A.A.BlinneFuchs, S.S.FuchsFeigl, T.T.FeiglKämpfer, T.T.KämpferRödel, C.C.RödelUschmann, I.I.UschmannWünsche, M.M.WünschePaulus, G.G.G.G.PaulusFörster, E.E.FörsterZastrau, U.U.Zastrau2022-03-042022-03-042013https://publica.fraunhofer.de/handle/publica/23478310.1063/1.48211462-s2.0-84885106030We present a Michelson interferometer for 13.5 nm soft x-ray radiation. It is characterized in a proof-of-principle experiment using synchrotron radiation, where the temporal coherence is measured to be 13 fs. The curvature of the thin-film beam splitter membrane is derived from the observed fringe pattern. The applicability of this Michelson interferometer at intense free-electron lasers is investigated, particularly with respect to radiation damage. This study highlights the potential role of such Michelson interferometers in solid density plasma investigations using, for instance, extreme soft x-ray free-electron lasers. A setup using the Michelson interferometer for pseudo-Nomarski-interferometry is proposed.en681journal article