| 摘要 |
A compact lens system includes, in succession from an object side to an image side, an aspheric first lens element ( 1 ) having a positive power, an aperture stop ( 4 ), an aspheric second lens element ( 2 ) having a negative power, and a third lens element ( 3 ) having a positive power. Both the first and second lens elements are meniscus lenses made of plastic, and the third lens element is a biconvex lens or a plano-convex lens made of glass. The first lens element has a convex surface ( 10 ) facing the object side and an opposite concave surface ( 11 ) facing the aperture stop. The second lens element has a concave surface ( 21 ) facing the aperture stop and an opposite convex surface ( 20 ) curved toward the image side. The surface ( 30 ) of the third lens element facing toward the image side has a radius of curvature larger than that of the other surface ( 31 ) facing the second lens element.
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