Patent ID: 6288850
Filing Date: 2001-09-11
Classification: G02B

Abstract:
An image readout lens comprising, successively from an object side, a first lens made of a positive meniscus lens having a convex surface directed onto the object side, a second lens made of a biconcave lens, a third lens made of a biconvex lens, and a fourth lens made of a negative meniscus lens having a convex surface directed onto an imaging surface side, wherein at least one surface in at least one of said first and third lenses is an aspheric surface, wherein a stop is disposed between said second and third lenses and satisfying the following conditional expressions (1), (2), and (3):1.38<f(1/R.sub.9 -1/R.sub.8)<2.38 (1)0.28<R.sub.1 /f<0.58 (2)0.27<D.sub.7 /f<0.46 (3)wheref is the composite focal length of the whole lens system;R.sub.i is the radius of curvature of the i-th surface; andD.sub.i is the distance between the i-th surface and the (i+1)-th surface.