| US 7,515,358 B2 | ||
| Optical lens system for taking image | ||
| Sayuri Noda, Taichung (Taiwan) | ||
| Assigned to Largan Precision Co., Ltd, Taichung (Taiwan) | ||
| Filed on Mar. 01, 2007, as Appl. No. 11/681,167. | ||
| Prior Publication US 2008/0212205 A1, Sep. 04, 2008 | ||
| Int. Cl. G02B 9/14 (2006.01) | ||
| U.S. Cl. 359—785 [359/784] | 5 Claims |
| 1. An optical lens system for taking image, from object side along the optical axis comprising: an aperture stop, a first
lens element, a second lens element, and a third lens element, wherein:
the first lens element is a positive meniscus plastic lens element with its convex surface facing the object side;
the second lens element is a negative meniscus plastic lens element with its convex surface facing the image side; and
the third lens element is a positive meniscus plastic lens element with its convex surface facing the object side; both surfaces
of each lens elements are aspheric; a focal length of the optical lens system is f; a focal lens of the first lens element
is f1; the focal length of the second lens system is f2; a radius of curvature of object side surface of the first lens element is R1, a radius of curvature of image side surface of the first lens element is R2, a radius of curvature of the object side surface of the second lens element is R3, and a radius of curvature of the image side surface of the second lens element is R4, and they satisfy the relations:
0.7<f1//f<0.9
−3.5<f2/f<−1.2
0.6<R3/R4<0.8
0.20<R1/R2<0.55.
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