Patent ID: 6426824
Filing Date: 2002-07-30
Classification: G02B

Abstract:
A scanning optical system for scanning a light beam on an object surface in a main scanning direction, comprising:a light source for emitting the light beam; a polygonal mirror rotating about an rotation axis, said polygonal mirror having a plurality of reflecting surfaces arranged parallel to the rotation axis, said reflecting surfaces deflecting the light beam emitted from said light source toward the object surface to scan the light beam in the main scanning direction; and a scanning lens system for converging the light beam deflected by said reflecting surfaces on the object surface to form a beam spot thereon, a focal length of said scanning lens system in a main scanning direction is the same as a focal length of said scanning lens system in an auxiliary scanning direction, the auxiliary scanning direction being perpendicular to both the main scanning direction and an optical axis of said scanning lens system, wherein a projection of the light beam incident on said reflecting surfaces onto an auxiliary scanning plane, which is perpendicular to the main scanning direction, inclines against the optical axis in a first direction, and wherein a projection of the rotation axis of said polygonal mirror onto the auxiliary scanning plane inclines against the auxiliary scanning direction, in a second direction which is opposite to said first direction.