| 摘要 |
PROBLEM TO BE SOLVED: To provide a high-performance image-formation optical system which is miniaturized and thinned by folding an optical path by using a reflection surface having a small number of reflecting times. SOLUTION: When it is assumed that this optical system is provided with one prism 10 and three surfaces on the image surface side thereof are surfaces A, B and C in order from the image surface 3 side, at least either surface B or C gives power to luminous flux, has rotationally asymmetric curved surface shape to compensate aberration caused by eccentricity and guides a light beam from an object to the image surface without forming an image in the prism in the optical system. The system has a pupil 2 in the prism, and the surface A has a transmissive surface action to emit the light beam from the inside of the prism, and the surfaces B and C are internal reflection surfaces, then the Z-shaped optical path is formed by arranging the surfaces C and B at opposed positions.
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