| 摘要 |
A subminiature optical system using plastic lenses is provided to enhance resolution and shorten the entire length by using only three sheets of plastic lenses having aspheric sides. A subminiature optical system includes a first lens(L1), a second lens(L2), and a third lens(L3). The first lens has a meniscus shape including a convex side directed to an object, includes at least one aspheric side as refractive sides, and is formed of a plastic material. The second lens has a meniscus shape including a concave side directed to the object, includes at least one aspheric side as refractive sides, and is formed of a plastic material. The third lens has a convex side directed to the object, and a minus refractive index. The subminiature optical system satisfies a first conditional expression of 1.5<TL/f<2.0 and a second conditional expression of 1.0 <FNo/f<1.44 where TL is the distance of an image side(IP) from an object side of the first lens, f is an effective focal distance of the entire optical system, and FNo is F number.
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