| 摘要 |
PURPOSE: An optical scanning apparatus, a multi-beam optical scanning apparatus and an image-forming apparatus are provided to make the diameter of the spot of the subscanning direction uniformly in the effective scanning zone whole area on the surface to be scanned, which are compact and have high definition, and the image forming device using same. CONSTITUTION: The optical scanner has an incident light optical device(11) to guide the luminous flux emitted from a light source device(1) to a deflection device(5), and has a scanning optical device(6) to make the image of luminous flux reflected and deflected by the deflection device to be formed on a surface to be scanned(7). The scanning optical device has a plurality of axis meridian asymmetrical change surfaces of which the curvature in the axis meridian changes asymmetrically in the direction of a power meridian interposing the optical axis of he scanning optical device. |
