Optical scanner and image forming apparatus

An image forming apparatus that forms an image on transfer paper by executing respective charging, exposure, development, and transfer processes, comprising:

• an exposing unit that executes the exposure process, including
• 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 a plurality of scanning lenses that guide the beams from the deflector to a surface to be scanned, wherein a scanning lens closest to the deflector has a meniscus shape with a concave facing the deflector side in the horizontal scanning direction, a surface close to the deflector, of the scanning lens closest to the deflector, 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 decreases from an optical axis of the lens surface toward a periphery of the horizontal scanning direction and increases bordering on an extreme value, the surface close to the deflector, of a scanning lens farthest from the deflector, has a convex shape toward the deflector side in the horizontal scanning direction, and the scanning lens farthest from the deflector has a negative power in the horizontal scanning direction.