| 摘要 |
PROBLEM TO BE SOLVED: To provide a lens for image reading and an image reader which realize a compact and inexpensive lens system with a smaller number of lenses and are capable of obtaining a wide angle of view and a high quality of a read image and are capable of satisfactorily correcting, especially, axial chromatic aberration and chromatic difference of magnification simultaneously. SOLUTION: A first lens L1 comprising a positive meniscus lens having a convex directed to the object side, a second lens L2 comprising a negative meniscus lens having a concave directed to the object side, and a third lens L3 comprising a positive lens having a convex directed to the image side are arranged in order from the object side. The object-side surface of the second lens L2 is formed into a diffraction lens surface. A stop St is disposed between the first lens L1 and the second lens L2. It is preferable that the first lens L1 and the second lens L2 are aspheric resin lenses and the third lens L3 is a glass lens. COPYRIGHT: (C)2007,JPO&INPIT
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