Double phase-plate setup for chromatic aberration compensation for resonant X-ray diffraction experiments

Inami, Toshiya; Michimura, Shinji*; Matsumura, Takeshi*

Resonant X-ray diffraction is a powerful tool for detecting ordered structures of charge, magnetic and orbital degrees of freedom. The symmetry of an order parameter is determined by changing the relative orientation between the polarization of incident X-rays and the order parameter. A new method suited for extreme conditions is performed by rotating the incident polarization using a diamond phase plate. A disadvantage of this method is significant loss in intensity for low-energy X-rays. In order to obtain both a high degree of linear polarization and strong X-ray intensity, we have constructed optics that compensates chromatic aberration using two diamond phase plates. In a test experiment in beamline BL22XU at SPring-8, two 300 microns diamond phase plates were used. The obtained linear polarization reached more than 96% at 6.15 keV, showing marked improvement compared to the linear polarization 90% obtained by a single 500 microns phase plate.