X-ray waveguide and x-ray waveguide system

An X-ray waveguide system including at least an X-ray source and an X-ray waveguide configured to guide an X-ray emitted from the X-ray source,

• the X-ray waveguide including a cladding and a core to guide the X-ray,
• wherein the core includes a periodic structure, which is made of plural substances each having a different value of a real part of refractive index, in a direction perpendicular to an X-ray guiding direction,
• a Bragg angle determined depending on a wavelength of the X-ray and periodicity of the periodic structure is smaller than a critical angle for total reflection of the X-ray at an interface between the core and the cladding,
• the Bragg angle is larger than a critical angle for total reflection of the X-ray at an interface between the plural substances constituting the periodic structure, and
• the core has two or more regions differing in periodic number of the periodic structure constituting the core with a core width in a direction of period being different between the two or more regions corresponding to change of the periodic number.