Patent ID: 7193759

Claim:
A scanning optical system for emitting at least one beam scanning in a main scanning direction, comprising: a light source that emits the at least one beam; a polygonal mirror that rotates and deflects the at least one beam to scan in the main scanning direction; and an imaging optical system that converges the at least one beam deflected by said polygonal mirror to form at least one beam spot on a surface to be scanned, the at least one beam spot scanning in the main scanning direction on the surface to be scanned, wherein the at least one beam incident on said polygonal mirror is inclined in an auxiliary scanning direction which is perpendicular to the main scanning direction, wherein at least one lens surface of said imaging optical system is configured such that a beam reflected therefrom is not incident on reflective surfaces of said polygonal mirror, wherein said imaging optical system includes a lens having said at least one lens surface, said lens being positioned such that an optical axis of said lens is perpendicular to a rotational axis of said polygonal mirror.