| http://www.w3.org/ns/prov#value | - The fourth imaging element 30 of the reflecting optical system 17 is made up of an optical element such as a lens including a predetermined numeric aperture, and with the focal length on the diffraction grating 11T side as F3, and with the focal length on the reflector 29 side as F4, the diffraction grating 11T is disposed on around one of the focal positions of the fourth imaging element 30, and
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