OPTICAL SYSTEM

摘要

PROBLEM TO BE SOLVED: To provide an optical system for photographing an image having full 360°-direction (full circumference) angle of view or projecting an image at full 360°-direction (full circumference) angle of view, which is reduced in size and flare light and improved in the resolving power. SOLUTION: The optical system includes a front group 10 that is rotationally symmetric about a center axis 1 and includes two or more reflecting surfaces 12, 13 and 14; and a rear group 20 that is rotationally symmetric about the center axis 1 and has positive power. A light beam coming from far way and made incident on the front group 10 is successively reflected by the reflecting surfaces 12 to 14, all of which are positioned on an entrance side relative to the center axis 1, exits from the front group 10 and forms an image, at a position of an image plane 30 off the center axis via the rear group 20. An optical path incident on the first reflecting surface 12 of the front group 10 and an optical path reflected by the final reflecting surface 14 of the front group 10 cross in a section including the center axis 1, and the number of intermediate image forming times is made to differ between in the section, including the center axis 1 and in a plane that is orthogonal with respect to that section and includes a center beam 2Oof that light beam. COPYRIGHT: (C)2006,JPO&NCIPI