| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an infrared imaging lens which can be compatible with a recently developed infrared sensor with a small pixel size and has a sufficiently good imaging capability. <P>SOLUTION: An infrared imaging lens comprises following three lenses arranged in an order from an object side: a first lens L1 which is a single positive meniscus lens with a convex surface thereof facing the object side; a second lens L2 which is a single negative lens with a concave surface thereof facing the object side; and a third lens L3 which is a single positive lens with a convex surface thereof facing the object side. Both faces of each of the first lens L1 and the second lens L2 are aspheric surfaces. The object side aspheric surface of the first lens L1 has a shape where an absolute value of a curvature radius at an effective diameter end is larger than a center. The infrared imaging lens also satisfies a following conditional equation: 1.2<f×(n-1)/(Fno×r)<3.0; where f is a focal distance of an entire system; n is a refraction factor of the first lens L1 to a design reference wavelength; Fno is an F value of the entire system; and r is the curvature radius on an optical axis on the object side surface of the first lens L1. <P>COPYRIGHT: (C)2012,JPO&INPIT |
