| 摘要 |
A projection optical system has at least eight reflecting mirrors and is relatively compact in the radial direction. The eight reflecting mirrors (M 1 ~M 8 ) form a reduced image of a first surface on a second surface. A first reflecting image forming optical system (G 1 ) forms a first intermediate image (IMI 1 ) of the first surface based on light from the first surface, a second reflecting image forming optical system (G 2 ) forms a second intermediate image (IMI 2 ) of the first surface based on light from the first intermediate image, and a third reflecting image forming optical system (G 3 ) forms a reduced image on the second surface based on light from the second intermediate image. The number of reflecting mirrors (M 6 ~M 8 ) comprising the third reflecting image forming optical system is greater than the number of reflecting mirrors (M 1 , M 2 ) comprising the first reflecting image forming optical system.
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