Optical imaging system
An optical imaging system is described including first to sixth lenses sequentially disposed from an object side to an image side, and an image sensor configured to convert incident light reflected from a subject, having passed through the first to sixth lenses, into an electrical signal. One of the first to sixth lenses includes a spherical object-side surface and another of the first to sixth lenses includes corresponding aspherical object-side surfaces. The first to sixth lenses include corresponding aspherical image-side surfaces, and a lens of the first to sixth lenses that is closer to the object side than the one of the first to sixth lenses including the spherical object-side surface, has a highest refractive index among the first to sixth lenses.
1. An optical imaging system, comprising:
a first lens comprising positive refractive power;
a second lens comprising negative refractive power;
a third lens comprising positive refractive power;
a fourth lens comprising negative refractive power;
a fifth lens comprising refractive power; and
a sixth lens comprising negative refractive power,
wherein the first to sixth lenses are sequentially arranged from an object side to an image side, and
wherein TTL/(2*ImgH)<0.75 is satisfied, where TTL is a distance from an object-side surface of the first lens to an imaging plane of an image sensor and ImgH is half a diagonal length of the imaging plane of the image sensor.
2. The optical imaging system of claim 1 , wherein the lens of the first to sixth lenses that comprises the highest refractive index among the first to sixth lenses is the second lens.
3. The optical imaging system of claim 1 , wherein 2.0<f3/f1<6.0 is satisfied, where f1 is a focal length of the first lens and f3 is a focal length of the third lens.
4. The optical imaging system of claim 1 , wherein f/(CT3+CT4+CT5)<4.0 is satisfied, where f is an overall focal length of the optical imaging system, CT3 is a thickness of the third lens in a paraxial region, CT4 is a thickness of the fourth lens in the paraxial region, and CT5 is a thickness of the fifth lens in the paraxial region.
5. The optical imaging system of claim 1 , wherein |f/f5|+|f/f6|<1.0 is satisfied, where f is an overall focal length of the optical imaging system, f5 is a focal length of the fifth lens, and f6 is a focal length of the sixth lens.
6. The optical imaging system of claim 1 , wherein the first lens comprises a meniscus shape of which the object-side surface is convex, and
the second lens comprises a meniscus shape of which an object-side surface is convex.
7. The optical imaging system of claim 1 , wherein an image-side surface of the fourth lens is concave.
8. The optical imaging system of claim 1 , wherein an image-side surface of the sixth lens is concave.
9. The optical imaging system of claim 1 , further comprising:
a stop disposed between the first lens and the second lens.
10. The optical imaging system of claim 1 , wherein the refractive index of the second lens is greater than 1.66.
11. An optical imaging system, comprising:
a first lens comprising a positive refractive power and a meniscus shape of which an object-side surface is convex;
a second lens comprising a negative refractive power and comprising a refractive index greater than 1.66;
a third lens comprising a positive refractive power;
a fourth lens comprising a negative refractive power;
a fifth lens comprising refractive power; and
a sixth lens comprising a negative refractive power,
wherein TTL/(2*ImgH)<0.75 is satisfied, where TTL is a distance from the object-side surface of the first lens to an imaging plane of an image sensor and ImgH is half a diagonal length of the imaging plane of the image sensor.