| 摘要 |
A reflection/refraction optical system such that the optical adjustment and machine design are easy, the aberrations such as the color aberration are well corrected, and a high resolution of, e.g., 0.1 mu m is achieved. The optical system comprises a first image-forming optical system (G1) for forming a first intermediate image on a first plane (R), a first optical-path folding mirror (1) disposed near the first intermediate image, a second image-forming optical system (G2) having a concave reflecting mirror (CM) and at least one negative lens (3) and adapted for forming a second intermediate image, a second optical-path folding mirror (2) disposed near the second intermediate image, and a third image-forming optical system (G3) for forming a reduced image of the image on the first plane on a second plane (W). The reflecting surface of the first optical-path folding mirror does not overlap spatially with the reflecting surface of the second optical-path reflecting mirror.
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