Scanning optical system, optical scanner, and image forming apparatus

A scanning optical system that converges, with a single lens, a divergent luminous flux, which is deflected in a main scanning direction by an optical deflector, on a surface of a scan target, the scanning optical system comprising

• a lens configured to have two surfaces in a biconvex shape in both the main scanning direction and a sub-scanning direction, wherein
• the surfaces are anamorphic surfaces.

A scanning optical system that converges, with a single lens, a divergent luminous flux, which is deflected in a main scanning direction by an optical deflector, on a surface of a scan target, the scanning optical system comprising

• a lens configured to have two surfaces in a biconvex shape in both the main scanning direction and a sub-scanning direction, wherein
• one of the surfaces that is closer to the optical deflector is a constant curvature surface in which curvature in the cross section in the sub-scanning direction is constant along the main scanning direction.

A scanning optical system that converges, with a single lens, a divergent luminous flux, which is deflected in a main scanning direction by an optical deflector, on a surface of a scan target, the scanning optical system comprising a single lens, wherein

• the scanning optical system satisfies |R1|>|R2| and |r1|>|r2|, where a radius of curvature of a first surface of the lens in the main scanning direction is R1, a radius of curvature of a second surface of the lens in the main scanning direction is R2, a radius of curvature of the first surface in the sub-scanning direction is r1, and a radius of curvature of the second surface in the sub-scanning direction is r2, and
• one of the surfaces that is closer to the optical deflector is a constant curvature surface in which curvature in the cross section in the sub-scanning direction is constant along the main scanning direction.

A scanning optical system that converges, with a single lens, a divergent luminous flux, which is deflected in a main scanning direction by an optical deflector, on a surface of a scan target, the scanning optical system comprising a single lens, wherein

• the scanning optical system satisfies 4.5<L/d0<7.5, where a distance from a reflection point on a reflective surface of the optical deflector to an incident surface of the lens is d0 and a distance from an emission surface of the lens to the surface of the scan target is L,
• the scanning optical system satisfies |R1|>|R2| and |r1|<|r2|, where a radius of curvature of a first surface of the lens in the main scanning direction is R1, a radius of curvature of a second surface of the lens in the main scanning direction is R2, a radius of curvature of the first surface in the sub-scanning direction is r1, and a radius of curvature of the second surface in the sub-scanning direction is r2, and
• at least one of the surfaces of the lens is an anamorphic surface.