| 摘要 |
According to one embodiment relates to an optical system radially downsized and corrected well for aberration and is applicable, for example, to an aberration measuring apparatus for measuring wavefront aberration of a liquid immersion projection optical system. A catadioptric system of a coaxial type is provided with a first optical system which forms a point optically conjugate with an intersecting point with the optical axis on a first plane intersecting with the optical axis, on a second plane, and a second optical system which guides light from the first optical system to a third plane. The first optical system has a first reflecting surface arranged at or near the first plane, a second reflecting surface having a form of an ellipsoid of revolution the two focuses of which are aligned along the optical axis in a state in which one focus is located at or near a first light transmissive portion, and a medium filling an optical path between the first reflecting surface and the second reflecting surface. The first light transmissive portion is formed in a central region of the first reflecting surface including the optical axis and a second light transmissive portion is formed in a central region of the second reflecting surface including the optical axis. The medium has the refractive index of not less than 1.3. The second optical system has a plurality of lenses.
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