| 摘要 |
An imaging optical system capable of sufficiently suppressing the occurrence of flare or ghost that degrade the image quality is provided. The imaging optical system is an imaging optical system 7 that includes an aperture stop 5, and first to fourth lenses 1 to 4 as optical members, which are arranged in that order from an object side to an image plane side. The first lens 1 is a biconvex lens having a positive power. The second lens 2 is formed of a meniscus lens that has a negative power and has a concave lens surface on the image plane side. The third lens 3 is formed of a meniscus lens that has a positive power and has a convex lens surface on the image plane side. The fourth lens 4 has a negative power and has a lens surface on the image plane side that is concave in the vicinity of an optical axis. On an effective aperture part of an image-plane-side lens surface e of the second lens 2, a total reflection surface is provided that subjects incident light beams that are incident at angles out of the angle of view to total reflection.
|
