| 摘要 |
PROBLEM TO BE SOLVED: To provide an observation optical system capable of observing or obtaining an image that is successfully corrected in aberration in both the front and rear portions of an observation field of view. SOLUTION: The observation optical system includes: a negative lens group 1 which is disposed to be closest to an object side, and constituted of a cemented lens; an annular reflection mirror 2 which is disposed on an image side of the negative lens group 1, and has a reflection surface 2a facing the image side; and an imaging lens group 3 which is disposed on the image side of the negative lens group 1 and the annular reflection mirror 2. The front observation optical system is constituted of the negative lens group 1 and the imaging lens group 3. The rear observation optical system is constituted of the annular reflection mirror 2 and the imaging lens group 3, and the image is formed in position where the image obtained by the rear observation optical system on the imaging surface 10 is different from the image obtained by the front observation optical system. The negative lens 1 and the annular reflection mirror 2 are cemented with each other. COPYRIGHT: (C)2009,JPO&INPIT
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