Optical scanning lens, optical scanning device and image forming apparatus

An optical scanning lens which is used in a scanning and image forming optical system which gathers a light flux deflected by a light deflector in the vicinity of a surface to be scanned,

• wherein:
• said lens is formed by plastic molding of polyolefin resin;
• and
• the following condition is satisfied
• 0<|Δn|<8.5×10−5 (B)
• where, when Δn(x) denotes a refractive-index distribution existing inside said lens, in a range between approximately ±1 mm from a center of the light flux, in a range which the light flux passes through, in said lens, Δn denotes a coefficient of second order in second-order least-square approximation of said Δn(x).

An optical scanning lens which is used in a scanning and image forming optical system which gathers a light flux deflected by a light deflector in the vicinity of a surface to be scanned,

• wherein:
• said lens is formed by plastic molding of polyolefin resin;
• and
• the following condition is satisfied
• 0.4×10−5<|Δn(x)−min[Δn(x)]|<16×10−5 (C)
• where Δn(x) denotes a refractive-index distribution existing inside said lens, in a range which the light flux passes through, in said lens, and min[Δn(x)] denotes the minimum value of said Δn(x).

An optical scanning lens which is used in a scanning and image forming optical system which gathers a light flux deflected by a light deflector in the vicinity of a surface to be scanned,

• wherein:
• said lens is formed by plastic molding of polyolefin resin;
• and
• the following condition is satisfied
• 0.1×10−5<|Δn|<4.0×10−5 (D)
• where, when Δn(x) denotes a refractive-index distribution existing inside said lens, in a range between approximately ±1 mm from a center of the light flux, in a range which the light flux passes through, in said lens, Δn denotes a coefficient of second order in second-order least-square approximation of said Δn(x).