| 摘要 |
PROBLEM TO BE SOLVED: To obtain a preferable image without the occurence of extreme image deterioration even if object position is changed without using a focus adjusting mechanism in an imaging optical system. SOLUTION: The imaging position in the imaging optical system 1 provided at the top end part of an inserting part of an endoscope is defined to be an imaging position Pi. The spherical abberation amount Zf of a light beam passing through 70% of the pupil diameter at the imaging position Pi with an object disposed at a far point Pf, the curvature of field amount Sf in the sagittal direction at an 80% image height of the maximum image height, the curvature of field amount Tf in the tangential direction at an 80% image height of the maximum image height, the spherical abberation amount Zn of a light beam passing through 70% of the pupil diameter at the imaging position Pi with an object disposed at a near point Pn, the curvature of field amount Sn in the sagittal direction at an 80% image height of the maximum image height, and the curvature of field amount Tn in the tangential direction at an 80% image height of the maximum image height satisfy formula (1). COPYRIGHT: (C)2009,JPO&INPIT
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