| 摘要 |
PROBLEM TO BE SOLVED: To obtain a lens for reading an image which is constituted of the small number of lenses, whose various aberration are sufficiently corrected and which is provided with high optical performance. SOLUTION: This lens is provided with the 1st positive meniscus lens 1 whose convex surface faces a document surface, a diaphragm SP and the 2nd negative meniscus lens 2 whose convex surface faces an image surface, in this order from the document surface. The lens surface of the 1st lens facing the document surface and that of the 2nd lens facing the image surface are constituted of the aspherical surface and a diffraction optical element is added to at least one lens surface of the 1st and the 2nd lenses.
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