Optical lens system
An optical lens system is disclosed. The optical lens system includes a first lens that has negative refractive power, a second lens that has positive refractive power, a third lens that has positive refractive power, a fourth lens that has refractive power, a fifth lens that has positive refractive power, a sixth lens that has negative refractive power, an aperture located between the second lens and the third lens, and conditional expressions of “−1.4<tan θ/f<−1.1” and “4.0<TTL/BFL<6.0” are satisfied when θ is an angle of view of the optical lens system in a diagonal direction, f is a focal length of the optical lens system, TTL is a distance on an optical axis from the object-side surface of the first lens to the sensor, and BFL is a distance on the optical axis from the sensor-side surface of the sixth lens to the sensor.
1. An optical lens system including a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens sequentially arranged from an object side to a sensor side between an object and a sensor on which an image of the object is focused,
wherein
the first lens has a negative refractive power and a sensor-side surface of the first lens is concave in a paraxial region,
the second lens has positive refractive power,
the third lens has positive refractive power and an object-side surface of the third lens is convex in the paraxial region,
the fourth lens has refractive power, an object-side surface of the fourth lens is convex in the paraxial region and concave on the periphery of an effective diameter of the paraxial region, a sensor-side surface of the fourth lens is concave in the paraxial region, both an object-side surface and a sensor-side surface of the fourth lens are aspheric,
the fifth lens has positive refractive power, an object-side surface of the fifth lens is concave in the paraxial region and aspheric,
the sixth lens has negative refractive power, a sensor-side surface of the sixth lens is concave and has at least one inflection point in the effective diameter, both an object-side surface and a sensor-side surface of the sixth lens are aspheric,
an aperture is located between the second lens and the third lens, and
the following conditional expression is satisfied when θ is an angle of view of the optical lens system in a diagonal direction, f is a focal length of the optical lens system, TTL is a distance on an optical axis from the object-side surface of the first lens to the sensor, and BFL is a distance on the optical axis from the sensor-side surface of the sixth lens to the sensor,
−1.4<tan θ/ f<− 1, and
4.0< TTL/BFL< 6. <Conditional Expression>
2. The optical lens system of claim 1 , wherein
the object-side surface of the sixth lens is convex in the paraxial region and concave on the periphery in the effective diameter of the paraxial region.
3. The optical lens system of claim 1 , wherein
an object-side surface of the first lens is convex in the effective diameter.
4. The optical lens system of claim 1 , wherein
an object-side surface of the second lens is concave in the effective diameter.
5. The optical lens system of claim 1 , wherein
a sensor-side surface of the third lens is convex in the paraxial region.
6. The optical lens system of claim 1 , wherein
a sensor-side surface of the fifth lens is convex in the paraxial region.
7. The optical lens system of claim 1 , wherein
the fourth lens is formed of a material having a refractive index of 1.6 or greater.
8. The optical lens system of claim 1 , wherein
the sixth lens is formed of a material having a refractive index of 1.6 or greater.
9. The optical lens system of claim 1 , wherein
the fourth lens and the sixth lens are formed of a material having a refractive index of 1.6 or greater, and the refractive index of the material forming the fourth lens is greater than the refractive index of the material forming the sixth lens.
10. The optical lens system of claim 1 , wherein
the first lens, the second lens, the third lens, and the fifth lens are formed of a material having a refractive index of 1.5 to 1.6.
11. The optical lens system of claim 1 , wherein
at least one of the fourth lens and the sixth lens is formed of plastic.
12. The optical lens system of claim 1 , wherein
the fourth lens has negative refractive power.
13. The optical lens system of claim 1 , wherein the following conditional expression is further satisfied when f1 is a focal length of the first lens,
−1.7< f 1/ f<− 1.4. <Conditional Expression>
14. The optical lens system of claim 1 , wherein the following conditional expression is further satisfied when V1 is the Abbe number of the first lens and V2 is the Abbe number of the second lens,
50<( V 1+ V 2)/2<60. <Conditional Expression>
15. The optical lens system of claim 1 , wherein the following conditional expression is further satisfied when CRA (MAX) is a maximum value of a chief ray angle of the optical lens system,
30.0 deg<CRA(MAX)<35.0 deg. <Conditional Expression>
16. The optical lens system of claim 1 , wherein the following conditional expression is further satisfied when FSL is a distance on the optical axis between the object-side surface of the first lens and the aperture,
0.2< FSL/TTL< 0.3. <Conditional Expression>