| 摘要 |
PROBLEM TO BE SOLVED: To remove vignetting due to the pupil of an objective lens and to easily make a device a small unit without irregularity of illumination at the time of rotating an image rotator by arranging the image rotator close to the pupil position of an objective optical system. SOLUTION: An image rotator 50 is arranged in the vicinity of a pupil 52 of an objective lens so that the rotating center is made nearly coincident with the optical axis. Thus, since a distance x between the image rotator 50 and the pupil 52 of time objective lens becomes small, even when a deviated amount 6θ1 is generated between the optical axis and the rotating center of the image rotator 50, the revolving radius (r) of a light spot, is suppressed to be small. This means that the possibility of generation of vignetting due to the pupil 52 of the objective lens by the revolution of spot light is reduced and irregularity of illumination is removed. As for the relation between the image rotator 50 and an image forming lens, since the rotator is arranged near the pupil 52, the size of the image rotator 50 becomes small.
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