PROBLEM TO BE SOLVED: To effectively reduce or prevent the bend of a scanning line in an optical scanner including a plastic lens formed by die forming in a scanning image-formation optical system.;SOLUTION: A lens 404 constituting at least one part of the scanning image- formation optical system for forming a light spot on a surface to be scanned by condensing deflected luminous flux deflected by a light deflector 403 toward the surface to be scanned is molded by the molding work of transparent resin material, formed to be a strip long in a main scanning direction, and its end face 4041 on a lens side in a subscanning direction has a very small cone angle to a lens optical axis AX, and the lens optical axis AX is deviated by a specified distance in the subscanning direction from the symmetric axis (ax) of refractive index distribution in the subscanning direction made inside the lens during the molding.;COPYRIGHT: (C)2001,JPO
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