Ellipsometer Equipped with Multiple Mirrors for Element-selective Soft X-ray Experiments

Abstract

We developed the ellipsometer unit with a switchable mirror holder that can mount two mirrors and switch them without breaking vacuum. The vacuum unit, combined with a differential pumping rotary flange, rotates smoothly with the help of two roll-stands, keeping the optical path stable during an experiment of ellipsometry. The system allows one to efficiently make the measurement at two different photon energies of soft X-ray. Thus, it is useful, for example, in experiments of the resonant magneto-optical Kerr effect on a multi-element magnetic material with an X-ray free electron laser. Moreover, our set-up provides a simple technical tip to rotate a heavy vacuum unit that is attached to a vacuum chamber from the side.