Patent Number: 6,295,169

Title: Image readout lens and image readout apparatus using the same

Abstract: In an image readout lens comprising four lens elements having positive, negative, negative, and positive refracting powers, respectively, the glass material for at least one of the second and third lenses is defined in terms of relative partial dispersion and Abbe number, so as to yield an image readout lens which favorably corrects chromatic aberration and is suitable as a color-image readout lens. Disposed successively from the object side are a first lens L.sub.1 made of a positive meniscus lens which is convex toward the object, a second lens L.sub.2 and a third lens L.sub.3 each having a surface on an image side concave toward the image and a negative refracting power, and a fourth lens L.sub.4 made of a biconvex lens, wherein a lens glass material of at least one of the second lens L.sub.2 and third lens L.sub.3 satisfies the following conditional expression (1): where .theta..sub.g.multidot.F is the relative partial dispersion of the lens glass material, and .upsilon..sub.d is the Abbe number of the lens glass material.

Inventors: Yamakawa; Hiromitsu (Omiya, JP)

Assignee: Fuji Photo Optical Co., Ltd.

International Classification: G02B 9/56 (20060101); G02B 9/00 (20060101); G02B 009/36 (); G02B 009/14 ()

Expiration Date: 09/25/2018