| 摘要 |
An optical system is provided to reduce a lens mold cost by arranging a second lens and a third lens to symmetrize the same lenses around an axis. An optical system includes a first lens(110), a second lens(120), a third lens(130), and a fourth lens(140) which are successively arranged from an object. The second lens and the third lens are arranged to symmetrize the same lenses around the axis between the second lens and the third lens. The first lens has both convex surfaces. The first lens has a positive refractive index. The second lens is comprised of a meniscus lens with a convex surface in an object side. The second lens has a negative refractive index. The third lens is comprised of the meniscus lens with an upper convex surface. The fourth lens has the convex surface. The iris diaphragm is positioned between the second lens and the third lens.
|
