Phase measurement of soft x-ray multilayer mirrors

International audience; We propose a new model enabling the extraction of the phase of a multilayer mirror from photocurrent measure- ments in the soft x rays. In this range, the effects of the mean free path of the electrons inside the stack can no longer be neglected, which prevents the phase reconstruction by conventional photocurrent measurements. The new model takes into account this phenomenon and thus extends up to the x rays the applicability range of the technique. This ap- proach has been validated through a numerical and exper- imental study of chromium/scandium multilayers used near 360 eV. To our knowledge, this work constitutes the first measurement of the phase of a multilayer mirror in the soft x-ray range.