| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical system for forming an omniazimuth image of 360°having≥90°viewing angle in an up-and-down direction on an image plane, which is compact, whose aberration is satisfactorily corrected and which is excellent in resolving power. SOLUTION: The optical system 50 is equipped with a front group 10 rotationally symmetric around a center axis 1 and including at least one reflection surface 12 or 14, a rear group 20 rotationally symmetric around the center axis 1 and having positive power, and an aperture 21 arranged coaxially with the rear group 20, and is constituted so that beams made incident on the front group 10 from a far place in the progressing order of a light beam pass through the front group 10 and the rear group 20 in order and form an image at a position deviated from the center axis 1 on an image surface 30, and the number of intermediate image forming times is made different between on a cross section including the center axis and a plane orthogonal to the cross section and including the center light beam of the beams. In the optical system 50, the front group 10 and the rear group 20 nearly compensate the aberration each other. COPYRIGHT: (C)2006,JPO&NCIPI
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