Linear Polarization Measurements of Soft X‐ray Emitted from a Figure‐8 Undulator by Using Multilayers

We measured linear polarization state of the synchrotron radiation (SR) from a figure‐8 undulator at 400 eV and 580 eV using rotating‐analyzer ellipsometry with multilayers. The observed spatial distribution of linear polarization agreed with calculations. We could determine the beam axis of radiation which was different from the condition of intensity maximum.