| 摘要 |
PROBLEM TO BE SOLVED: To obtain a reflecting reduction image-forming optical system capable of obtaining complete image-forming performance with simple constitution by constituting the system to satisfy a specified condition. SOLUTION: This lens system is constituted by coaxially arranging a reflection mirror M1 having the large radius of curvature, a 1st concave mirror M2, a convex mirror M3 and a 2nd concave mirror M4 in order that a light beam advances from a mask M side to a wafer W side. Then, it is constituted so that the wafer W side may be telecentric and an intermediate image may be formed between the mirrors M2 and M3. Then, it is formed so that high reduction magnification may be applied in a 1st reflection image-forming system from an object to the intermediate image, and the mirror M1 having the large radius of curvature, the mirrors M2 and M4 and the mirror M3 are formed to be aspherical. The optical system is constituted to satisfy 0.8<β1/β<2. In the expression,β1 is the reduction magnification of the 1st reflection image-forming system andβis the reduction magnification of a composite image-forming system constituted of the 1st and the 2nd reflection image-forming systems.
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