Diffraction device

摘要

The present invention provides a diffraction device having a high diffraction efficiency with respect to a wide-band radiation beam. A diffraction device comprises a substrate and a diffraction grating formed on the substrate, wherein the diffraction grating is formed so that a full-width of wavelength at half maximum of a diffraction efficiency of a beam diffracted by the diffraction grating is not less than about 8% of a value of a center wavelength of the diffracted beam.