| 摘要 |
PROBLEM TO BE SOLVED: To surely prevent influence of flare light generated in an optical system, wherein a rotating polygon mirror is subjected to deflection scanning by beams in symmetrical directions. SOLUTION: In a scanning optical device, first image-forming lenses 2a, 2b for forming the images of laser beams that are deflected and scanned by the polygon mirror 1 are arranged symmetrically with respect to the polygon mirror 1. A rib 6, for forming the abutting reference surface of the first image-forming lens 2a, covers the side of the polygon mirror 1 in the first image-forming lens 2a, and is in a shape having an opening 6a at a height equal to the thickness of the polygon mirror 1. COPYRIGHT: (C)2005,JPO&NCIPI
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