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. A subminiature optical system, comprising:
sequentially from an object side,
a first lens having positive refractive power and having a meniscus shape of which an object-side surface is convex;
a second lens having negative refractive power, both surfaces thereof being concave;
a third lens of which an object-side surface is convex and having positive refractive power;
a fourth lens concave toward the image plane and having negative refractive power; and
a fifth lens having negative or positive refractive power, of which an object-side surface is concave,
wherein the fifth lens has at least one inflection point formed in a location thereof other than a location corresponding to an optical axis, and
wherein the optical system satisfies the following Conditional Equation 1,
0.7< TTL/F< 1.0 (Conditional Equation 1)
where TTL indicates a distance from an object side surface of the first lens to the image plane, and F indicates the focal distance of the optical system.
2. The subminiature optical system of claim 1 , wherein a view angle of the optical system satisfies the following Conditional Equation 2,
20< FOV< 35 (Conditional Equation 2)
where FOV indicates the view angle in degrees of the optical system.
3. The subminiature optical system of claim 1 , wherein the first lens of the optical system satisfies the following Conditional Equation 3,
0.16< rdy s 1/ F< 2 (Conditional Equation 3)
where rdy s1 indicates a radius of curvature of the object side surface of the first lens, and F indicates the focal distance of the optical system.
4. The subminiature optical system of claim 1 , wherein an Abbe number of the fourth lens satisfies the following Conditional Equation 4,
Vd 4>50 (Conditional Equation 4)
where Vd4 indicates the Abbe number of the fourth lens.
5. The subminiature optical system of claim 1 , wherein the fourth lens has both surfaces thereof formed to be concave.
6. The subminiature optical system of claim 1 , further comprising an aperture stop disposed on the object side of the first lens.
7. A portable device, comprising:
a first optical system; and
a second optical system having a view angle narrower than that of the first optical system,
wherein the second optical system comprises:
sequentially from an object side,
a first lens having positive refractive power and having a meniscus shape of which an object-side surface is convex;
a second lens having negative refractive power, both surfaces thereof being concave;
a third lens of which an object-side surface is convex and having positive refractive power;
a fourth lens concave toward the image plane and having negative refractive power; and
a fifth lens having negative or positive refractive power, of which an object-side surface is concave,
wherein the fifth lens has at least one inflection point formed in a location thereof other than a location corresponding to an optical axis, and
wherein the second optical system satisfies the following Conditional Equation 1,
0.7< TTL/F< 1.0 (Conditional Equation 1)
where TTL indicates a distance from an object side surface of the first lens to the image plane, and F indicates the focal distance of the second optical system.
8. The portable device of claim 7 , wherein the second optical system has the view angle of 35 degrees or less.
9. The portable device of claim 8 , wherein the first optical system has the view angle of 60 degrees through 80 degrees.