Optical system and camera module comprising same
The optical system disclosed in the embodiment includes first to ninth lenses aligned from the object side toward the sensor side, the first lens has a positive refractive power on the optical axis, and the ninth lens has negative refractive power on the optical axis, an object-side surface of the first lens has a convex shape on the optical axis, a sensor-side surface of the ninth lens has a concave shape on the optical axis, and a number of lenses having at least one critical point on object-side surfaces and a sensor-side surfaces among the first to ninth lenses is 40% or more of a total number of lenses, and the following equations are satisfied, Equations: −1.5<f12/f39<1.7 and 0.6<TTL/ImgH<3.2 (f12 is a composite focal length of the first and second lenses, f39 is a composite focal length of the third to ninth lenses, and TTL (Total track length) is a distance from an apex of the object-side surface of the first lens to an upper surface of the image sensor on the optical axis, and ImgH is ½ of the maximum diagonal length of the image sensor).
1 . An optical system comprising:
first to ninth lenses disposed along an optical axis in a direction from an object side to a sensor side,
wherein the first lens has a positive (+) refractive power on the optical axis,
wherein the ninth lens has a negative (−) refractive power on the optical axis,
wherein an object-side surface of the first lens has a convex shape on the optical axis,
wherein a sensor-side surface of the ninth lens has a concave shape on the optical axis,
wherein a number of lenses having at least one critical point on object-side surfaces and sensor-side surfaces among the first to ninth lenses is 40% or more of a total number of lenses, and
wherein the optical system satisfies the following equations,
Equations:
−1.5< f 12/ f 39<1.7
0.6 <TTL /ImgH<3.2
(f12 is a composite focal length of the first and second lenses, f39 is a composite focal length of the third to ninth lenses, and TTL (Total track length) is a distance from an apex of the object-side surface of the first lens to an upper surface of an image sensor on the optical axis, and ImgH is ½ of a maximum diagonal length of the image sensor).
2 . The optical system of claim 1 , wherein the object-side surface of the first lens has a convex shape,
wherein the sensor-side surface of the ninth lens has a concave shape, and
wherein each of object-side surfaces and sensor-side surfaces of the sixth to ninth lenses has at least one critical point.
3 . The optical system of claim 2 , wherein the sensor-side surface of the first lens and an object-side surface of the fourth lens have at least one critical point, and
wherein an object-side surface and a sensor-side surface of the third lens have at least one critical point.
4 . The optical system of claim 1 , wherein a relationship between a distance BFL on the optical axis from the upper surface of the image sensor to a sensor-side surface of a last lens and ImgH satisfies the following equation,
Equation:0.01< BFL /ImgH<0.5.
5 . The optical system of claim 1 , wherein a relationship between effective diameters of the first lens and the ninth lens and a total number of lenses satisfies the following equation,
Equation:1<Σ CA /lens number<10
(ΣCA is a sum of the effective diameters of object-side surfaces and sensor-side surfaces of the first to ninth lenses, and the lens number is the total number of lenses).
6 . The optical system of claim 1 , wherein a relationship between a total focal length and a focal length of each lens satisfies the following equation,
Equation:1.5<Σ| F/fi|< 20
(F is the total focal length, and fi is a sum of focal lengths of the first to ninth lenses).
7 . The optical system of claim 1 , wherein distances on the optical axis between the first to ninth lenses and center thicknesses of each lens satisfy the following equation,
Equation:0.8< Air _ CT _Max/ L _ CT _Min<6.0
(Air_CT_Max is a maximum value among the distances on the optical axis between two adjacent lenses, and L_CT_Min is a minimum value among the thicknesses of each lens on the optical axis).
8 . The optical system of claim 1 , wherein a relationship between a maximum effective diameter and a minimum effective diameter among the first to ninth lenses satisfies the following equation,
Equation:1< CA _Max/ CA _Min<4
(CA_Max is a maximum value among effective diameters of object-side surfaces and sensor-side surfaces of the first to ninth lenses, and CA_Min is a minimum value among the effective diameters of the object-side surfaces and the sensor-side surfaces of the first to ninth lenses).
9 . The optical system of claim 8 , wherein the sensor-side surface of the second lens has a concave shape on the optical axis,
wherein the object-side surface of the third lens faces the sensor-side surface of the second lens and has a convex shape on the optical axis,
wherein the maximum effective diameter is the sensor-side surface of the ninth lens, and
wherein the minimum effective diameter is the object-side surface of the third lens.
10 . The optical system of claim 9 , wherein a center thickness of the first lens and the third lens satisfies the following equation,
Equation:1< L 1_ CT/L 3_ CT< 5
(L1_CT is the thickness on the optical axis of the first lens, and L3_CT is the thickness on the optical axis of the third lens).
11 . The optical system of claim 1 , comprising an aperture stop disposed on an outer periphery between the second lens and the third lens,
wherein a relationship between effective radii of the first to ninth lenses and an effective radius of the aperture stop satisfies the following equation,
Equation:1.5<ΣSemi_ CA/ST _Semi_ CA< 50
(ΣSemi_CA is a sum of all effective radii, and ST_Semi_CA is the effective radius of the aperture stop).
12 . The optical system of claim 1 , wherein a relationship between effective diameters of the first to ninth lenses and the total number of lenses satisfies the following equation,
Equation:1<Σ CA /lens number<10
(ΣCA is a sum of the effective diameters of object-side surfaces and sensor-side surfaces of the first to ninth lenses, and the lens number is 9).
13 . A camera module comprising:
an optical system according to claim 1 ;
an image sensor; and
a filter between the image sensor and a last lens of the optical system,
wherein the camera module satisfies the following equation,
Equation:0.7≤ F/EPD< 2.6
(F is a total focal length of the optical system, and EPD is an entrance pupil diameter of the optical system).
14 . An optical system comprising:
a first lens group having a plurality of lenses on an object side; and
a second lens group having a plurality of lenses on a sensor side of the first lens group,
wherein the first lens group has a positive (+) refractive power on an optical axis,
wherein the second lens group has a positive (+) refractive power on the optical axis,
wherein a number of lenses in the second lens group is three times or more than a number of lenses in the first lens group,
wherein an object-side surface closest to the first lens group in the second lens group has a smallest effective diameter,
wherein a sensor-side surface closest to an image sensor among lens surfaces of the second lens group has a largest effective diameter,
wherein the sensor-side surface closest to the image sensor among the lens surfaces of the second lens group has a minimum distance between a center of the sensor-side surface and the image sensor, and the distance gradually increases toward an end of an effective region of the sensor-side surface, and
wherein the optical system satisfies the following equations,
Equations:
0.6 <TTL /ImgH<3.2
0.7 <F/EPD< 2.6
(Total track length (TTL) is a distance on the optical axis from an apex of an object-side surface of the first lens group to an upper surface of the image sensor, ImgH is ½ of a maximum diagonal length of the image sensor, and F is a total focal length of the first and second lens groups, and EPD is a size of an entrance pupil diameter of the optical system).
15 . The optical system of claim 14 , wherein a focal length of each of the first and second lens groups is greater in the first lens group than in the second lens group.
16 . The optical system of claim 14 , wherein the first lens group comprises a first lens and a second lens aligned with the optical axis from the object side toward the image sensor,
wherein the second lens group includes third to ninth lenses aligned from the first lens group toward the image sensor,
wherein an average effective diameter of the third lens is a smallest among that of the first to ninth lenses, and
wherein an average effective diameter of the ninth lens is a largest that of the first to ninth lenses.
17 . The optical system of claim 16 , wherein a sensor-side surface of the ninth lens has a critical point and satisfies the following equation,
Equation:0.5< L 9 S 2_max_ sag to Sensor<2
(L9S2_max_sag to Sensor is a distance in a direction of the optical axis from a maximum Sag value of the sensor-side surface of the ninth lens to the image sensor).
18 . The optical system of claim 16 , wherein a number of lenses having critical points on both object-side surfaces and sensor-side surfaces in the second lens group is 50% or more of lenses in the second lens group, and
wherein a thickness of the first lens on the optical axis and a distance between the first and second lenses satisfy the following equation,
Equation:20< L 1 CT/d 12
(L1 CT is the thickness on the optical axis of the first lens, and d12 is the distance on the optical axis between the first and second lenses).
19 . The optical system of claim 18 , wherein a distance between the eighth lens and the ninth lens satisfies the following equation,
Equation:0< d 89_ CT/d 89_ ET< 3
(d89_CT is a distance on the optical axis between the eighth lens and the ninth lens, and d89_ET is a distance on the optical axis between an end of an effective region of a sensor-side surface of the eighth lens and an end of an effective region of an object-side surface of the ninth lens).
20 . The optical system of claim 14 , wherein a focal length f_G1 of the first lens group and a focal length f_G2 of the second lens group satisfy the following equation,
Equation:−1.5< f _ G 1/ f _ G 2<1.7.