OPTICAL SYSTEM, EXPOSING APPARATUS AND EXPOSING METHOD

摘要

An optical system includes a reflecting mirror to which rays are incident across a relatively wide incidence angle range, while well suppressing a change in a polarization state in an optical path of a beam incident substantially as linearly polarized light. The optical system has a first deflecting plane mirror (M11) and a second deflecting plane mirror (M12) and a substantially linearly polarized beam is incident to the optical system. Each of the first deflecting plane mirror and the second deflecting plane mirror is so arranged that a change from a phase difference between p-polarized incident light to a reflecting surface and s-polarized incident light to the reflecting surface, to a phase difference between reflected light of the p-polarized incident light to the reflecting surface and reflected light of the s-polarized incident light to the reflecting surface is within 30° for all rays incident to the reflecting surface.