X-ray Fresnel diffractometry for ultralow emittance diagnostics of next generation synchrotron light sources

A novel technique using single-slit x-ray Fresnel diffraction has been developed to resolve $\ensuremath{\mu}\mathrm{m}$-order electron beam sizes at the insertion devices (IDs) of photon beam lines. The new technique is promising for diagnostics of next-generation light sources, where a tuning of ultralow emittance at insertion devices is essentially important to ensure the absence of the degradation of brilliance and the transverse coherence of radiation at beam lines due to distortion of lattice functions. The validity of the method was experimentally studied at SPring-8, and the achievable resolution is discussed.