Patent attributes
An object of the present invention is to provide a scanning optical system capable of reducing the number of its components and its size with a simple construction, and an image forming apparatus using the scanning optical system. In a specific scanning optical system, a plurality of light beams emitted from a plurality of light source units are deflected and scanned by a plurality of different deflecting facets of a common optical deflecting unit, and a plurality of scanned surfaces are scanned with the light beams deflected and scanned by the different deflecting facets, respectively. In the scanning optical system, the number of the light source units is 4 n, the number of the light beams is 4 nm (n and m are positive integers, respectively), incidence optical paths of the light beams incident on the optical deflecting unit are symmetrically disposed with respect to a first cross section and a second cross section which are perpendicular to each other, the first cross section is parallel to a rotational axis of the optical deflecting unit, and the second cross section is perpendicular to the rotational axis of the optical deflecting unit.
