| 摘要 |
A fixed focal length optical lens system includes a lens group and a diaphragm which is located in front of the lens group. The lens group includes three lenses, respectively the first, the second and the third lens, which are sequentially arranged as a negative-positive-positive separated focal power system, wherein the first lens is a negative meniscus lens, the second lens is a positive meniscus lens, the third lens is a plano-convex or positive meniscus lens. All the curved surfaces of the first lens and the second lens are bent in the direction towards the diaphragm, and the focal length of the entire optical system is f, the focal lengths of the first, the second and the third lens are respectively f1, f2, and f3, and which satisfies the following requirement: −0.6<f1/f<−0.4; 0.5<f2/f<0.8; 0.9<f3/f<1.2. |
