Dispersing performance of KTP(011) crystal

According to the requirements for the performance of analyzers in soft x-ray regime of synchrotron radiation, the qualities of various crystals often used in soft x-ray range are investigated. We find that crystals KTP (KTiOPO 4 )(011) crystal is an ideal one among large d-spacing crystals. We propose an experimental method to measure diffraction efficiencies of crystals with synchrotron radiation source. In particular, we find that the diffraction efficiency is closely related to the source emittance. The lattice constant and diffraction efficiencies of KTP(011)crystal are also presented in this paper.