Patent attributes
An optical scanning apparatus which does not require a complex shaped lens and which is capable of eliminating the bow of a beam light even when the shapes of a plurality of correcting lenses are unified by setting a shape of a sub-scanning cross-section of a scanning lens as a spherical surface when an incident angle condition to incident beam light is an angle of 2° or less against a cross-section which is at right angles to a rotational axis of a polygonal mirror. The curvature of an incident surface and an outputting surface of the scanning lens in the sub scanning direction is monotonically changed according to the position in the main scanning direction with respect to the distance from the predetermined center position in the main scanning direction.
