Patent attributes
In a reflective scanning optical system employing an imaging optical system having a curved mirror with a rotationally symmetrical reflecting surface configuration, the change in magnification of the imaging optical system in the auxiliary scanning direction is reduced and thereby the beam spot diameter on the scan target surface is equalized, as well as equalizing the scan line interval on the scan target surface when the system is applied to a multibeam scanning optical system. The imaging optical system of the reflective scanning optical system includes a curved mirror with a rotationally symmetrical reflecting surface and a lens having an anamorphic lens surface configuration on its one side. In the anamorphic lens surface configuration, slope and curvature of the line of intersection of the lens surface and a plane parallel to the auxiliary scanning cross section change independently of each other as the position in the main scanning direction changes.
