Patent ID: 6958839
Filing Date: 2005-10-25
Classification: H04N

Abstract:
1. A scanning optical system for emitting at least one beam scanning in a main scanning direction, comprising: a light source that emits at least one beam; an anamorphic optical element that converges the at least one beam emitted by said light source in an auxiliary scanning direction which is perpendicular to the main scanning direction; a polygonal mirror that rotates and deflects the at least one beam emerged from said anamorphic optical element to scan in the main scanning direction; 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, said at least one beam spot scanning in the main scanning direction on the surface to be scanned, wherein said imaging optical system has: a scanning lens; and a compensation lens provided on the surface side with respect to said scanning lens, said compensation lens compensating for curvature of field, wherein said scanning lens having at least one convex surface that has a toric surface having a stronger power in the auxiliary scanning direction than in the main scanning direction, wherein one surface of said compensation lens has an anamorphic aspherical surface, said anamorphic aspherical surface being defined as a surface whose radius of curvature in the auxiliary scanning direction at a point spaced from the optical axis thereof in the main scanning direction is determined independently from a cross-sectional shape thereof along the main scanning direction, said anamorphic aspherical surface satisfying a condition:  wherein, r