| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical system enabling simultaneous observation of an object in front and an object nearly on the side, and close enlarging observation of the object in front. SOLUTION: The optical system is constituted by arranging a front group including a catadioptric element and having negative refractive power, an aperture stop, and a rear group including a moving lens group moving in a direction along an optical axis and having positive refractive power in order from the side of the object in front. The catadioptric element has a first surface having a first transmission surface formed with an optical axis as center and a first reflection surface formed annularly around the first transmission surface and facing an image side, and formed on the side of the object in front, a second surface having a second transmission surface formed with the optical axis as center and a second reflection surface formed annularly around the second transmission surface and facing the side of the object in front, and formed on the image side, and a third surface formed as a transmission surface between the first surface and the second surface. By moving the moving lens group, the refractive power of the front group and the refractive power of the rear group are relatively changed to enlarge or reduce an area where an image of the object in front is formed in an observation area. COPYRIGHT: (C)2011,JPO&INPIT |
