| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an imaging lens having a three lens structure which can be more compact (smaller, thinner), reduce costs, and be applied to a high-resolution imaging element of at least megapixel order mounted in a small mobile product such as a portable telephone. Ž<P>SOLUTION: The imaging lens 6 comprises an aperture diaphragm 4, a first lens 1 which has positive refractive power and is formed with a diffraction optical element in the lens surface on the image surface side, a second lens 2 which has positive refractive power and is composed of a meniscus lens having a convex lens surface on the image surface side, and a third lens 3 which has negative refractive power, these parts being positioned in order from the subject side toward the image surface side. If the focal length of the entire optical system is f, the focal length of the first lens 1 is f1, the focal length of the second lens 2 is f2, the focal length of the third lens 3 is f3, and the refractive power of the diffraction optical element is ϕ<SB>DOE</SB>, then the following conditional expressions (1) to (4) are satisfied: (1) 0.9<f1/f<1.3; (2) 0.7<f2/f<1.1; (3) -0.8<f3/f<-0.6; and (4) -0.3<f×ϕ<SB>DOE</SB><0.5. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
|
