Patent ID: 6624953
Filing Date: 2003-09-23
Classification: G02B

Abstract:
An image readout lens comprising three lens groups of positive, negative and positive refractive power, in successive order from the object side, and a stop located between the second lens group and the third lens group, wherein:the first lens group is formed of a lens having a-convex surface on the object side; the second lens group is formed of a lens made of an optical resin material having a convex surface on the object side; the third lens group is formed of a lens made of an optical resin material having a convex surface on the image side; at least one surface, of among the surfaces of the second lens group and the third lens group, is an aspheric surface; and the following conditions are satisfied: 55290.3f2|/f3<0.6 0.41f2|f<1.1 0.83/f<3.3 where&ngr;3 is the Abbe number, at the d line, of the optical material of a lens element in the third lens group, &ngr;2 is the Abbe number, at the d line, of the optical material of a lens element in the second lens group, f2 is the focal length of the second lens group, f3 is the focal length of the third lens group, and f is the focal length of the image readout lens, wherein the image readout lens further satisfies the following condition:0.8f23|/f<1.2 wheref23 is the resultant focal length of the second lens group and the third lens group.