Patent ID: 6801374
Filing Date: 2004-10-05
Classification: G02B

Abstract:
A molded lens used in an optical system of an image recorder, wherein:at least a part of a non-effective area through which an image forming flux does not pass, has a concave shape, an outer portion of said lens has a refractive index greater than an inner portion of said lens, said lens is plastic, and when it is assumed that the focal length is f0 in a direction of a line perpendicular to the generating line, calculable from the lens surface curvature, the refractive index of the material, and the optical axis direction thickness of said lens; that the observed focal length in a direction of the line perpendicular to the generating line is f1; and that &Dgr;f is defined by |f1âˆ’f0|=&Dgr;f, then &Dgr;f/f0 of an image forming flux passing through the effective area of said lens is 5% or smaller.