| 摘要 |
PROBLEM TO BE SOLVED: To provide a compact, thin and high-performance image forming optical system by folding an optical path by using a reflection surface whose number of reflecting times is small. SOLUTION: This image forming optical system is provided with a first object-side prism 10 and a second image-side prism 20 and constituted so that an intermediate image is not formed. The first surface 11 of the prism 10 is formed so that luminous flux from an object is made incident on the inside of the prism and the luminous flux reflected on the second surface of the prism 10 is reflected in the inside of the prism. The second surface is formed so that the luminous flux made incident from the first surface 11 is reflected in the inside of the prism and the third surface 14 of the prism 10 is formed so that the luminous flux reflected on the first surface is emitted outside the prism. Then, the first surface 11 or the second surface is formed as the rotation asymmetric surface so as to give power to the luminous flux. The prism 20 is shaped in the same way as the prism 10. Then, the third surface 14 of the prism 10 and the first surface 21 of the prism 20 are arranged so as to be opposed.
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