Subminiature optical system and portable device including the same
There are provided a subminiature optical system having a miniature size and capable of obtaining a narrow view angle using only five sheets of lenses, and a portable device having the same. The subminiature optical system includes a first lens convex toward the object side and having positive refractive power. a second lens concave toward an image side and having negative refractive power, a third lens convex toward the object side and having positive refractive power, a fourth lens concave toward the image plane and having negative refractive power, and a fifth lens convex toward the image plane and having negative or positive refractive power, sequentially from an object side.
1. An optical system, comprising:
a first lens having positive refractive power and a convex object-side surface;
a second lens having negative refractive power and a concave image-side surface;
a third lens having positive refractive power and a concave image-side surface;
a fourth lens having a concave object-side surface;
a fifth lens having a concave object-side surface in a paraxial region; and
an image sensor,
wherein the first lens to the image sensor are sequentially disposed from an object side,
wherein the optical system satisfies 0.7<TTL/F<1.0, where TTL is a distance from the object-side surface of the first lens to an imaging surface of the image sensor, and F is an overall focal length of the optical system, and
wherein the first to fifth lenses are formed of plastic.
2. The optical system of claim 1 , wherein the optical system satisfies 0.16<rdy s1/f<2, where rdy s1 is a radius of curvature of the object-side surface of the first lens.
3. The optical system of claim 1 , wherein the third lens has a convex object-side surface.
4. The optical system of claim 1 , wherein the fourth lens negative refractive power.
5. The optical system of claim 1 , wherein the fourth lens has a concave image-side surface.
6. The optical system of claim 1 , wherein the fifth lens has positive refractive power.
7. The optical system of claim 1 , wherein the fifth lens has a convex image-side surface.
8. The optical system of claim 1 , wherein the optical system satisfies Vd4>50, where Vd4 is an Abbe number of the fourth lens.
9. The optical system of claim 1 , wherein surfaces of the first lens, the second lens, the third lens, the fourth lens, and the fifth lens are formed as aspherical surfaces.
10. An optical system, comprising:
a first lens having positive refractive power, a convex object-side surface and a concave image-side surface;
a second lens having negative refractive power and a concave image-side surface;
a third lens having a concave image-side surface;
a fourth lens having a concave object-side surface;
a fifth lens having a concave object-side surface in a paraxial region; and
an image sensor,
wherein the first lens to the image sensor are sequentially disposed from an object side,
wherein the optical system satisfies 0.7<TTL/F<1.0, where TTL is a distance from the object-side surface of the first lens to an imaging surface of the image sensor, and F is an overall focal length of the optical system, and
wherein the first to fifth lenses are formed of plastic.
11. The optical system of claim 10 , wherein the fifth lens has negative refractive power.
12. The optical system of claim 10 , wherein the optical system satisfies 20<FOV<35, where FOV is a view angle of the optical system.
13. The optical system of claim 10 , wherein the fifth lens has a convex image-side surface.
14. The optical system of claim 10 , wherein the optical system satisfies 0.16<rdy s1/f<2, where rdy s1 is a radius of curvature of the object-side surface of the first lens.