| 摘要 |
PROBLEM TO BE SOLVED: To provide a high-definition imaging optical system capable of completely correcting chromatic aberration while achieving complete miniaturization by a small number of lenses. SOLUTION: The imaging optical system 10 includes: a first lens 11 having positive optical power; a second lens 12 having positive optical power; and a third lens 13 having negative optical power in order from an object side. In the imaging optical system 10, a diffractive surface is formed on at least one lens surface out of the lens surfaces of the first to the third lenses 11 to 13. Furthermore, the image-side lens surface 13b of the third lens 13 being a lens nearest to an image side is formed so that the vicinity 131 of a center part may be a surface turning its concave surface to the image side and has negative optical power, and a periphery part 132 may be a surface turning its convex surface to the image side and has positive optical power. COPYRIGHT: (C)2007,JPO&INPIT |
