OPTICAL SYSTEM

摘要

PROBLEM TO BE SOLVED: To provide an optical system for photographing images, having a full 360°-direction (full circumference) angle of view or projecting an image in 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 reflecting surfaces 12 and 13; 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 reflected in a direction where it separates from the rear group 20 by the first reflecting surface 12 positioned on an entrance side relative to the center axis 1; and the light beam, reflected by the first reflecting surface 12, is reflected in a direction where it travels toward the rear group 20 by the second reflecting surface 13, positioned on the same side as the first reflecting surface 12 relative to the center axis 1, exits from the front group 10 and forms an image at the position of an image plane 30, off the center axis via the rear group 20. The number of intermediate image forming times is made to differ between in a section that includes the center axis 1 and in a plane, that is orthogonal to that section and includes a center ray 2Oof that light beam. COPYRIGHT: (C)2006,JPO&NCIPI