Patent ID: 7106483

Claim:
An optical scanner comprising: a light source; an optical coupler that couples beams from the light source; an optical line image unit that forms a line image of the beams from the optical coupler, wherein the line image is longer in a horizontal scanning direction than in a vertical scanning direction; a deflector that deflection-scans the beams from the optical line image unit; and an optical scanning unit that includes scanning lenses that guide the beams from the deflector to a surface to be scanned, wherein a surface close to the deflector, of the scanning lens closest to a deflection reflecting surface, has a negative power in the vertical scanning direction, and is a special toric surface in which a radius of curvature in a vertical scanning changes from an optical axis of the lens surface toward a periphery of the horizontal scanning direction, and wherein an F number of the beams toward the surface to be scanned of the scanning lens in the vertical scanning direction is larger in a peripheral part than in a central part in an effective scanning width.