| 摘要 |
PROBLEM TO BE SOLVED: To provide a reflection type scanning optical system capable of diverting an emitted unnecessary light for image drawing resulting from repeated reflection on an incident/emitting face of a cylindrical lens in a direction different from that of a flux of laser beams for image drawing. SOLUTION: The reflection type scanning optical system 10 includes, a laser beam source 1, a collimate lens 2, a cylindrical lens 3, a polygon mirror 4, and fθmirror 5. Further, the axis of the cylindrical lens 3 is deviated from a beam axis Ax of a flux of laser beams made incident onto the polygon mirror 4 in a direction equivalent to the subscanning direction. A stray light G emitted onto the polygon mirror 4 resulting from repeated reflections in a plane 3b of the cylindrical lens 3 and a cylindrical face 3a is deflected in an oblique direction from an optical path of the laser beam flux for image drawing into a direction equivalent to the subscanning direction. Thus, the stray light G never reaches a scanning object face by passing through the surrounding of the polygon mirror 4. Further, a shade member 12 can be placed on the optical path of the stray light G.
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