| 摘要 |
A lens module of a scanner is provided, including a first lens with a positive diopter, a second lens with a negative diopter, a third lens with a positive diopter, and a fourth lens with a negative diopter. The first, second, third, and fourth lenses are sequentially arranged from an object end to an image end of the lens module, and at least one of the first and fourth lenses is an aspheric lens. The fourth lens has a focal length f4 and an objective side surface with a radius of curvature R7, wherein 0.1<R7/f4<1.
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