| 摘要 |
PURPOSE:To obtain a large reduction and a large enlargement rate without shifting a mirror in position by arranging >=2 lenses across >=1 mirror of optical system constitution. CONSTITUTION:An auxiliary lens 9 is arranged between the 4th mirror 7 and a photosensitive body 8. Consequently, magnification is obtained from the principle of a composite lens optical system as if there were a lens between the lens 6 and auxiliary lens 9, and the reduction rate when there is one lens at the position of the 4th mirror 7 is obtained by selecting f values of the lens 6 and auxiliary lens 9 optionally, so a larger reduction rate than before is obtained without shifting the mirror in position. Namely, the composite lens system consisting of the 1st and the 2nd lenses 10 and 11 arranged successively satisfies an equation I , which correspond to the case wherein one lens 12 is provided between the 1st and the 2nd lenses 10 and 11 (at distance from the 1st lens 10 as shown by an equation II).
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