| 摘要 |
PROBLEM TO BE SOLVED: To obtain a high-performance and inexpensive image-formation optical system constituted of small number of optical devices by arranging a prism member consisting of an eccentric prism and compensating eccentric aberration each other by the object-side part and the image-side part of the prism member. SOLUTION: This image-formation optical system is provided with the prism member 10 formed of medium whose refractive index (n) is larger than 1. As for the member 10; a reflecting optical path is formed of the 1st incident surface 11, the 1st reflection surface 12 and the 2nd reflection surface 13, luminous flux is rotated along a triangular optical path by the 3rd reflection surface 14, the 4th reflection surface 15 and the 1st emitting surface 16, and a crossing optical path is formed by an optical path made incident on the 3rd reflection surface 14 and an optical path leading to the 1st emitting surface 16 from the 4th reflection surface 15. The 1st and the 2nd reflection surfaces 12 and 13 or the 3rd and the 4th reflection surfaces 14 and 15 have curved surface shape by which power is given to the luminous flux and which is constituted of rotationally asymmetric surface shape compensating aberration caused by eccentricity. An intermediate image surface 4 is formed in the optical path between the 1st and the 4th reflection surfaces 12 and 15.
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