Patent ID: 7551338

Claim:
An optical scanning apparatus comprising: a light-source unit; an incident optical system for directing light beams emitted from the light-source unit to a deflecting unit; and an imaging optical system for guiding the light beams deflected from the deflecting unit to a surface to be scanned, wherein the imaging optical system comprises a toric lens whose power in the main scanning direction is different from that in the sub-scanning direction; in which the curvature centers of the meridians of a first toric surface of the toric lens connected to form a curved line are located in a common plane Ha, and the curvature centers of the meridians of a second toric surface connected to form a curved line are not located in a common plane, and in which the plane Ha is not parallel to principal rays of incoming beams incident on the toric lens traveling toward the central image height of the surface to be scanned in the sub-scanning section.