Optical system and camera module including the same

Abstract

An optical system disclosed in an embodiment of the present invention includes first to eighth lenses disposed in a direction from an object side to a sensor side along an optical axis, in which the first lens has positive (+) or negative (-) refractive power at the optical axis, the second lens has positive (+) refractive power at the optical axis, the third lens has negative (-) refractive power at the optical axis, and the fourth lens has positive (-) refractive power at the optical axis. The seventh lens has a positive (+) refractive power at the optical axis, the eighth lens has a negative (-) refractive power at the optical axis, at least one of an object-side surface and a sensor-side surface of the seventh lens has at least one critical point, each of an object-side surface and a sensor-side surface of the eighth lens has a critical point, at least one of an object-side surface and a sensor-side surface of the eighth lens has a free-form surface shape in which a lens surface orthogonal to the optical axis in the first direction and a lens surface orthogonal to the optical axis in the second direction are asymmetric. The free-form surface may have a lens surface having a shape symmetrical about the optical axis on both sides in the first direction and a lens surface having a shape symmetrical about the optical axis on both sides in the second direction.

Description

Technical Field

[0001] Embodiments relate to an optical system for improving optical performance and a camera module including the optical system. Background Art

[0002] Camera modules capture objects and store them as images or videos, and are installed in various applications. In particular, camera modules are manufactured in very small sizes and are applied not only to portable devices such as smartphones, tablets, and notebook computers, but also to drones and vehicles to provide various functions.

[0003] For example, the optical system of the camera module may include an imaging lens for forming an image and an image sensor for converting the formed image into an electrical signal. In this case, the camera module may perform an auto focus (AF) function of aligning the focal length of the lens by automatically adjusting the distance between the image sensor and the imaging lens, and may perform a zoom function of zooming in or out by increasing or decreasing the magnification of a remote object through a zoom lens. In addition, the camera module employs an image stabilization (IS) technology to correct or prevent image instability caused by an unstable fixture or camera movement caused by a user's action.

[0004] The most important element of a camera module for obtaining an image is an imaging lens that forms an image. Recently, interest in high performance such as high image quality and high resolution has been increasing, and research on an optical system including a plurality of lenses is being conducted to achieve such high performance. For example, research is being conducted to achieve a high performance optical system using a plurality of imaging lenses having positive (+) and / or negative (-) refractive power.

[0005] However, when multiple lenses are included, there is a problem in that it is difficult to obtain excellent optical characteristics and aberration characteristics. In addition, when multiple lenses are included, the thickness, spacing, size, etc. of the multiple lenses may cause the total length, height, etc. to increase, thereby increasing the total size of the module including the multiple lenses.

[0006] In addition, in order to achieve high resolution and high definition, the size of image sensors is increasing. However, when the size of the image sensor increases, the TTL (Total Track Length) of the optical system including multiple lenses will also increase, resulting in an increase in the thickness of the camera and mobile terminal including the optical system.

[0007] Therefore, a new optical system that can solve the above problems is needed. Summary of the invention

[0008]

Technical issues

[0009] Embodiments of the present invention provide an optical system with improved optical characteristics.

[0010] The embodiment provides an optical system having excellent optical performance in both the central and peripheral portions of a field of view.

[0011] The embodiment provides an optical system capable of having a slim structure.

[0012]

Technical solution

[0013] An optical system according to an embodiment of the present invention includes first to eighth lenses, which are arranged along the optical axis from the object side to the sensor side, wherein the first lens has positive (+) or negative (-) refractive power on the optical axis, the second lens has positive (+) refractive power on the optical axis, the third lens has negative (-) refractive power on the optical axis, the seventh lens has positive (+) refractive power on the optical axis, the eighth lens has negative (-) refractive power on the optical axis, at least one of the object side surface and the sensor side surface of the seventh lens has at least one critical point, each of the object side surface and the sensor side surface of the eighth lens has a critical point, at least one of the object side surface and the sensor side surface of the eighth lens has a freeform surface shape, in which a lens surface orthogonal to the optical axis in a first direction and a lens surface orthogonal to the optical axis in a second direction are asymmetric, and the freeform surface can have lens surfaces that are symmetric about the optical axis on both sides of the first direction, and lens surfaces that are symmetric about the optical axis on both sides of the second direction.

[0014] According to an embodiment of the present invention, each of the object-side surface and the sensor-side surface of the seventh lens has a critical point, and the critical point of the object-side surface of the seventh lens can be positioned closer to the optical axis than the critical point of the sensor-side surface of the seventh lens.

[0015] According to an embodiment of the present invention, an object-side surface of the seventh lens may have a convex shape on the optical axis, and a sensor-side surface of the seventh lens may have a concave shape on the optical axis.

[0016] According to an embodiment of the present invention, a sensor-side surface of the third lens may have a concave shape on the optical axis, and an object-side surface of the fourth lens may have a concave shape on the optical axis.

[0017] According to an embodiment of the present invention, an object-side surface of the fifth lens may have a concave shape on the optical axis, and may have a maximum value among absolute values ​​of radii of curvature of lens surfaces of the optical system.

[0018] According to an embodiment of the present invention, the object side surface of the second lens may have a convex shape on the optical axis, the sensor side surface of the second lens has a convex shape on the optical axis, and the thickness of the second lens on the optical axis may be the maximum value among the lens thicknesses of the optical system.

[0019] According to an embodiment of the present invention, the sensor side surface of the eighth lens has a free-form surface, and the distance from the optical axis to the critical point of the sensor side surface of the eighth lens in the first direction may be different from the distance from the optical axis to the critical point of the sensor side surface of the eighth lens in the second direction.

[0020] According to an embodiment of the present invention, the object side surface of the eighth lens may have an aspherical shape.

[0021] According to an embodiment of the present invention, the optical axis distance between the seventh lens and the eighth lens is greater than the sum of the center thickness of the seventh lens and the center thickness of the eighth lens, and may be 1.8 times or more of the thickness having the maximum thickness among the first lens to the eighth lens.

[0022] According to an embodiment of the present invention, the straight-line distance InfX82 from the optical axis to the critical point of the sensor side surface of the eighth lens in the first direction is different from the straight-line distance InfY82 from the optical axis to the critical point of the sensor side surface of the eighth lens in the second direction, and may satisfy the following mathematical equation: -0.1 < InfX82 - InfY82 < 0.1 and 0.4 < TTL / (Imgh*2) < 0.7 (the total lens length (TTL) is the distance on the optical axis from the vertex of the object side surface of the first lens to the image surface of the image sensor, and Imgh is 1 / 2 of the maximum diagonal length of the image sensor).

[0023] An optical system according to an embodiment of the present invention includes: a first lens group on the object side, which has three or fewer lenses; and a second lens group on the sensor side of the first lens group, which has five or fewer lenses, wherein the first lens group has a positive (+) refractive power on the optical axis, the second lens group has a negative (-) refractive power on the optical axis, the number of lenses in the second lens group is less than twice the number of lenses in the first lens group, the lens surface of the first lens group and the second lens group that is closest to the second lens group has the smallest effective diameter, the last lens of the first lens group and the second lens group that is closest to the image sensor has the largest effective diameter, the sensor-side surface of the first lens group that is closest to the second lens group has a concave shape, the object-side surface of the second lens group that is closest to the first lens group has a concave shape, the sensor-side surface of the last lens has a free-form surface shape with a critical point, the sensor-side surface that is closest to the image sensor has a free-form surface shape, in which the lens surface orthogonal to the optical axis in the first direction and the lens surface orthogonal to the optical axis in the second direction are asymmetric, and the free-form surface may have lens surfaces that are symmetric on both sides of the optical axis in the first direction, and lens surfaces that are symmetric on both sides of the optical axis in the second direction.

[0024] According to an embodiment of the present invention, the straight-line distance InfX82 from the optical axis to the critical point of the sensor-side surface of the last lens in the first direction is different from the straight-line distance InfY82 from the optical axis to the critical point of the sensor-side surface of the last lens in the second direction, and may satisfy the following mathematical formula:

[0025] Mathematical formula: -0.1 < InfX82 - InfY82 < 0.1.

[0026] According to an embodiment of the present invention, the total focal length FX in the first direction is different from the total focal length FY in the second direction, and may satisfy the following mathematical formula:

[0027] Mathematical formula: -0.1 < FX - FY < 0.1.

[0028] According to an embodiment of the present invention, the following mathematical formula is satisfied: 0.4 < TTL / (Imgh*2) < 0.7 (TTL (total lens length) is the distance on the optical axis from the vertex of the object-side surface of the first lens to the image surface of the image sensor, and Imgh is 1 / 2 of the maximum diagonal length of the image sensor).

[0029] According to an embodiment of the present invention, the first lens group includes a first lens to a third lens arranged along the optical axis from the object side toward the sensor side, the second lens group includes a fourth lens to an eighth lens arranged along the optical axis from the object side toward the sensor side, each of the object-side surface and the sensor-side surface of the seventh lens may have a critical point, and the object-side surface of the eighth lens may have a critical point.

[0030] According to an embodiment of the present invention, the linear distance Inf71 from the optical axis to the critical point of the object-side surface of the seventh lens and the linear distance Inf72 from the optical axis to the critical point of the sensor-side surface of the seventh lens may satisfy the following mathematical formula:

[0031] 0.7 < Inf71 / Inf72 < 1.2 (mathematical formula).

[0032] According to an embodiment of the present invention, the linear distance Inf71 from the optical axis to the critical point of the object-side surface of the seventh lens and the average value Inf82 of the linear distances InfX82 and InfY82 from the optical axis to the critical points in the X direction and the Y direction of the sensor-side surface of the eighth lens may satisfy the following mathematical formula:

[0033] Mathematical formula: 0.7 < Inf71 / Inf82 < 1.2.

[0034] According to an embodiment of the present invention, the seventh lens has a positive (+) refractive power and has a convex object-side surface and a concave sensor-side surface, and the eighth lens has a negative (-) refractive power and has a convex object-side surface and a concave sensor-side surface.

[0035] According to an embodiment of the present invention, the average value Inf82 of the linear distances InfX82 and InfY82 from the optical axis to the critical points in the X direction and the Y direction of the sensor-side surface of the eighth lens and the linear distance D82 from the optical axis of the eighth lens to the end of the effective area may satisfy the following mathematical formula:

[0036] Mathematical formula: 0.2 < Inf82 / D82 < 0.8.

[0037] According to an embodiment of the present invention, the central thickness L2_CT of the second lens and the central thickness L3_CT of the third lens may satisfy the following mathematical formula:

[0038] 1 < L2_CT / L3_CT < 5 (mathematical formula).

[0039] According to an embodiment of the present invention, the optical axis distance between the seventh lens and the eighth lens may be 1.8 times or more of the central thickness of the second lens.

[0040] A camera module according to an embodiment of the present invention includes: an image sensor; and a filter between the image sensor and the last lens of the optical system, wherein the optical system includes the optical system disclosed above and can satisfy the following mathematical formula:

[0041] 0.5 < F / TTL < 1.2 (mathematical formula)

[0042] (F is the average value of the total focal lengths in two directions orthogonal to the optical axis of the optical system, and TTL (Total track length, lens total length) is the distance on the optical axis from the vertex of the object-side surface of the first lens to the image surface of the image sensor).

[0043]

Advantageous Effects

[0044] The optical system and the camera module according to the embodiment can have improved optical characteristics. Specifically, according to the surface shape, refractive power, thicknesses of multiple lenses, and distances between adjacent lenses among multiple lenses, the optical system can have improved aberration characteristics and resolution.

[0045] The optical system and the camera module according to the embodiment can have improved distortion and aberration characteristics, and can have good optical performance at the center and peripheral portions of the FOV.

[0046] The optical system according to the embodiment can have improved optical characteristics and a smaller lens total length (TTL), so that the optical system and the camera module including the optical system can be provided in a thin and compact structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 is a configuration diagram of an optical system and a camera module according to an embodiment of the present invention.

[0048] Figure 2 is a diagram showing Figure 1 the relationship in the first direction Y between the image sensor, the nth lens, and the (n - 1)th lens of the optical system.

[0049] Figure 3 is a diagram showing Figure 1 the relationship in the second direction X between the image sensor, the nth lens, and the (n - 1)th lens of the optical system.

[0050] Figure 4 is a table showing lens data according to a first embodiment of an optical system having Figure 1 the optical system.

[0051] Figure 5 is an example of the aspherical coefficient of a lens according to a first embodiment of the present invention.

[0052] Figure 6 : is a graph showing light aberration characteristics in the second direction X of the optical system according to the first embodiment of the present invention.

[0053] Figure 7 : is a graph showing light aberration characteristics in the first direction Y of the optical system according to the first embodiment.

[0054] Figure 8 It is shown that according to Figure 1 A table of lens data of a second embodiment of the optical system.

[0055] Fig. 9 ∠ ... is an example of the aspherical coefficient of the lens according to the second embodiment of the present invention.

[0056] Fig.10 : is a graph showing light aberration characteristics in the second direction X of the optical system according to the second embodiment of the present invention.

[0057] Fig.11 : is a graph showing light aberration characteristics in the first direction Y of the optical system according to the first embodiment.

[0058] Fig.12 It is shown that according to Figure 1 A table of lens data of a third embodiment of the optical system.

[0059] Fig.13 ⊥ ...

[0060] Fig.14 : is a graph showing light aberration characteristics in the second direction X of the optical system according to the third embodiment of the present invention.

[0061] Fig.15 : is a graph showing light aberration characteristics in the first direction Y of the optical system according to the third embodiment.

[0062] Fig.16 : is a table showing the Zernike coefficient of the sensor-side surface of the n-th lens of the optical system according to the first embodiment, the second embodiment, and the third embodiment of the present invention.

[0063] Fig.17 is a diagram showing a distortion grid in an optical system according to an embodiment of the present invention.

[0064] Fig.18 is a diagram showing that a camera module according to an embodiment is applied to a mobile terminal. DETAILED DESCRIPTION

[0065] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The technical concept of the present invention is not limited to some embodiments to be described, but can be implemented in various other forms, and one or more components can be selectively combined or replaced to be used within the scope of the technical concept of the present invention. In addition, unless specifically defined and clearly described, the terms (including technical terms and scientific terms) used in the embodiments of the present invention can be interpreted according to the meanings commonly understood by ordinary technicians in the field to which the present invention belongs, and the meanings of commonly used terms (such as terms defined in dictionaries) can be interpreted in the context of considering the contextual meaning of the relevant technology.

[0066] In addition, the terms used in the embodiments of the present invention are used to explain the embodiments and are not intended to limit the present invention. In this specification, unless specifically described with a sentence, the singular form may also include the plural form, and when stated as at least one (or one or more) of A, B and C, may include one or more of all combinations that can be combined with A, B and C. When describing the components of the embodiments of the present invention, terms such as the first, second, A, B, (a) and (b) may be used. These terms are only used to distinguish the component from other components, and these terms may not be determined by the nature, sequence, process, etc. of the corresponding constituent elements. Moreover, when describing that a component is "connected", "coupled" or "combined" to another component, the description may include not only directly connecting, coupling or combining to other components, but also "connecting", "coupling" or "combining" by other components between the component and the other component. In addition, in the case of being described as being formed or arranged on "above (up)" or "below (below)" of each component, the description includes not only the situation that two components are in direct contact with each other, but also the situation that one or more other components are formed or arranged between the two components. In addition, when expressed as “above” or “below”, it can refer to a downward direction as well as an upward direction with respect to one element.

[0067] In the description of the present invention, "object side surface" may refer to the surface of the lens facing the object side relative to the optical axis OA, and "sensor side surface" may refer to the surface of the lens facing the imaging surface (image sensor) relative to the optical axis. The convex surface of the lens may mean that the lens surface on the optical axis has a convex shape, and the concave surface of the lens may mean that the lens surface on the optical axis has a concave shape. The radius of curvature, the center thickness, and the distance between the lenses described in the lens data table may mean the value on the optical axis, and the unit is millimeter. The vertical direction may mean the direction perpendicular to the optical axis, and the end of the lens or the lens surface may mean the end or edge of the effective area of ​​the lens through which the incident light passes. Depending on the measurement method, the size of the effective diameter of the lens surface may have a measurement error of up to ±0.4mm. The paraxial area refers to a very narrow area near the optical axis, and is an area where the distance of the light from the optical axis OA is almost zero. In the following, the concave shape or convex shape of the lens surface is described as the optical axis, and the paraxial area may also be included.

[0068] Figure 1 1 and 2 are diagrams showing an optical system 1000 and a camera module having the optical system 1000 according to first to third embodiments of the present invention.

[0069] refer to Figure 1 , the optical system 1000 may include a plurality of lens groups G1 and G2. In detail, each of the plurality of lens groups G1 and G2 includes at least one lens. For example, the optical system 1000 may include a first lens group G1 and a second lens group G2 sequentially arranged along the optical axis OA from the object side toward the image sensor 300. Among the plurality of lens groups G1 and G2, the number of lenses in the second lens group G2 may be greater than the number of lenses in the first lens group G1, for example, greater than 1 times the number of lenses in the first lens group G1 and less than 2 times the number of lenses in the first lens group G1.

[0070] The first lens group G1 may include at least one lens. The first lens group G1 may include three or less lenses. For example, the first lens group G1 may include three lenses. The second lens group G2 may include at least two or more lenses. The second lens group G2 may include more lenses than the first lens group G1, for example, 1.5 times or more of the number of lenses of the first lens group G1. The second lens group G2 may include 7 or less lenses, or 6 or less lenses. The number of lenses of the second lens group G2 may have a difference of 3 or more and 6 or less compared to the number of lenses of the first lens group G1. For example, the second lens group G2 may include five lenses.

[0071] In the optical system 1000, the total length of the lens (TTL) can be less than 70% of the diagonal length of the image sensor 300, for example, it can be in the range of 40% to 69% or 50% to 61%. TTL is the distance from the object side surface of the first lens closest to the object side on the optical axis OA to the image surface of the image sensor, the diagonal length of the image sensor 300 is the maximum diagonal length of the image sensor 300, and can be twice the distance Imgh from the optical axis OA to the end of the diagonal. Therefore, a slim optical system and a camera module having the optical system can be provided. The total number of lenses of the first lens group G1 and the second lens group G2 is 7 to 9.

[0072] The first lens group G1 may have a positive (+) refractive power. The second lens group G2 may have a negative (-) refractive power different from that of the first lens group G1. The first lens group G1 and the second lens group G2 have different focal lengths and opposite refractive powers, thereby providing good optical performance in the center and peripheral portions of the FOV (field of view).

[0073] When expressed as an absolute value, the focal length of the second lens group G2 may be greater than the focal length of the first lens group G1. For example, the absolute value of the focal length f_G2 of the second lens group G2 may be 1.4 times or more of the absolute value of the focal length f_G1 of the first lens group G1, for example, in the range of 1.4 to 3.5 times. Therefore, the optical system 1000 according to the embodiment can improve aberration control characteristics such as chromatic aberration and distortion aberration by controlling the refractive power and focal length of each lens group, and can have good optical performance in the center and peripheral parts of the FOV.

[0074] On the optical axis OA, the first lens group G1 and the second lens group G2 may have a set distance. The optical axis distance between the first lens group G1 and the second lens group G2 on the optical axis OA is a separation distance on the optical axis OA, and may be an optical axis distance between a sensor-side surface of a lens closest to the sensor side among the lenses of the first lens group G1 and an object-side surface of a lens closest to the object side among the lenses of the second lens group G2. The optical axis distance between the first lens group G1 and the second lens group G2 may be greater than a center thickness of a last lens among the lenses of the first lens group G1 and a center thickness of a first lens among the lenses of the second lens group G2. The optical axis distance between the first lens group G1 and the second lens group G2 is less than the optical axis distance of the first lens group G1, and may be 20% or more of the optical axis distance of the first lens group G1, for example, in the range of 23% to 53% or 23% to 43% of the optical axis distance of the first lens group G1. Here, the optical axis distance of the first lens group G1 is the distance along the optical axis between the object-side surface of the lens closest to the object side and the sensor-side surface of the lens closest to the sensor side in the first lens group G1 .

[0075] The optical axis distance between the first lens group G1 and the second lens group G2 may be 21% or less of the optical axis distance of the second lens group G2, for example, in the range of 5% to 21%. The optical axis distance of the second lens group G2 is the distance along the optical axis between the object side surface of the lens closest to the object side in the second lens group G2 and the sensor side surface of the lens closest to the sensor side. The lens with the smallest average effective diameter in the first lens group G1 may be the lens closest to the second lens group G2. The lens with the smallest average effective diameter in the second lens group G2 may be the lens closest to the first lens group G1. Here, the average effective diameter is the average of the effective diameter of the object side surface of the lens and the effective diameter of the sensor side surface. Therefore, the optical system 1000 may have good optical performance not only in the central part of the FOV but also in the peripheral part, and may improve chromatic aberration and distortion aberration. The size of the lens with the smallest effective diameter in the first lens group G1 may be smaller than the size of the lens with the smallest effective diameter in the second lens group G2.

[0076] The optical system 1000 may include 10 or less lenses, or 9 or less lenses. The first lens group G1 refracts light incident through the object side to converge, and the second lens group G2 refracts light emitted from the first lens group G1 to diffuse to the peripheral portion of the image sensor 300.

[0077] The lens closest to the object side among the lenses of the first lens group G1 has a positive (+) refractive power, and the lens closest to the sensor side among the lenses of the second lens group G2 may have a negative (-) refractive power. In the optical system 1000, the number of lenses having a positive (+) refractive power may be greater than the number of lenses having a negative (-) refractive power. In the first lens group G1, the number of lenses having a positive (+) refractive power may be greater than the number of lenses having a negative (-) refractive power. In the second lens group G2, the number of lenses having a positive (+) refractive power may be greater than the number of lenses having a negative (-) refractive power.

[0078] Each of the plurality of lenses 100 may include an effective area and an ineffective area. The effective area may be an area through which light incident on each lens 100 passes. That is, the effective area may be an effective area in which the incident light is refracted to achieve optical characteristics. The ineffective area may be arranged around the effective area. The ineffective area may be an area in which effective light from the plurality of lenses 100 is not incident. That is, the ineffective area may be an area that is not related to the optical characteristics. In addition, the end of the ineffective area may be an area fixed to a lens barrel (not shown) that houses the lens.

[0079] The optical system 1000 may include an image sensor 300. The image sensor 300 may detect light and convert it into an electrical signal. The image sensor 300 may detect light that sequentially passes through a plurality of lenses 100. The image sensor 300 may include a device capable of sensing incident light, such as a charge coupled device (CCD) or a complementary metal oxide semiconductor (CMOS).

[0080] The optical system 1000 may include an optical filter 500. The optical filter 500 may be disposed between the second lens group G2 and the image sensor 300. The optical filter 500 may be disposed between a lens closest to the sensor side among the plurality of lenses 100 and the image sensor 300. For example, when the optical system 100 has eight lenses, the optical filter 500 may be disposed between the eighth lens 110 and the image sensor 300.

[0081] The optical filter 500 may include at least one of an infrared filter and a cover glass optical filter. The filter 500 may allow light of a set wavelength band to pass through and filter out light of a different wavelength band. When the optical filter 500 includes an infrared filter, radiant heat emitted from external light may be prevented from being transferred to the image sensor 300. In addition, the optical filter 500 may allow visible light to pass through and reflect infrared light.

[0082] The optical system 1000 according to an embodiment may include an aperture stop ST. The aperture stop ST may control the amount of light incident on the optical system 1000. The aperture stop ST may be disposed around the lenses of the first lens group G1. For example, the aperture stop ST may be disposed around the object-side surface or the sensor-side surface of the first lens 101 closest to the object side. The aperture stop ST may be disposed between two adjacent lenses 101 and 102 among the lenses of the first lens group G1. For example, the aperture stop ST may be located around the sensor side of the first lens 101 closest to the object side. Alternatively, at least one lens selected from the plurality of lenses 100 may be used as an aperture stop. In detail, the object-side surface or the sensor-side surface of one lens selected from the lenses of the first lens group G1 may be used as an aperture stop for adjusting the amount of light.

[0083] The optical system 1000 according to the embodiment may further include a reflective member (not shown) for changing the optical path. The reflective member may be implemented as a prism that reflects the incident light of the first lens group G1 toward the lens. The optical system according to the embodiment will be described in detail below.

[0084] Figure 1 is a structural diagram of an optical system and a camera module according to an embodiment of the present invention, Figure 2 yes Figure 1 The relationship between the image sensor, the n-th lens and the n-1-th lens of the optical system in the first direction Y, Figure 3 It is shown Figure 1 An explanatory diagram of the relationship in the second direction X between the image sensor, the nth lens and the n-1th lens of the optical system.

[0085] refer to Figures 1 to 3 The optical system 1000 according to the first to third embodiments includes a plurality of lenses 100, and the plurality of lenses 100 may include a first lens 101 to an eighth lens 108. The first to eighth lenses 101-108 may be sequentially arranged along an optical axis OA of the optical system 1000. Light corresponding to object information may pass through the first to eighth lenses 101-108 and be incident on the image sensor 300.

[0086] The first lens 101 may have a positive (+) refractive power on the optical axis OA. The first lens 101 may include a plastic or glass material. For example, the first lens 101 may be made of a plastic material.

[0087] The first lens 101 may include a first surface S1 defined as an object side surface and a second surface S2 defined as a sensor side surface. On the optical axis OA, the first surface S1 may have a convex shape and the second surface S2 may have a concave shape. That is, the first lens 101 may have a meniscus shape convex toward the object side on the optical axis OA. At least one of the first surface S1 and the second surface S2 may be an aspherical surface. For example, both the first surface S1 and the second surface S2 may be aspherical surfaces. The aspherical coefficients of the first surface S1 and the second surface S2 are provided as follows Figure 5 , Fig. 9 and Fig.13 As shown, L1 is the first lens 101.

[0088] The second lens 102 may have positive (+) or negative (-) refractive power on the optical axis OA. The second lens 102 may have positive (+) refractive power. The second lens 102 may include a plastic or glass material. For example, the second lens 102 may be made of a plastic material.

[0089] The second lens 102 may include a third surface S3 defined as an object-side surface and a fourth surface S4 defined as a sensor-side surface. On the optical axis OA, the third surface S3 may have a concave shape and the fourth surface S4 may have a convex shape. That is, the second lens 102 may have a convex shape on both sides of the optical axis OA. Alternatively, on the optical axis OA, the third surface S3 may have a convex shape and the fourth surface S4 may have a concave shape. At least one of the third surface S3 and the fourth surface S4 may be an aspherical surface. For example, both the third surface S3 and the fourth surface S4 may be aspherical surfaces. The aspherical coefficients of the third surface S3 and the fourth surface S4 are provided as follows Figure 5 , Fig. 9 and Fig.13 As shown, L2 is the second lens 102.

[0090] The third lens 103 may have positive (+) or negative (-) refractive power on the optical axis OA, and may preferably have positive (+) refractive power. The third lens 103 may include a plastic or glass material. For example, the third lens 103 may be made of a plastic material.

[0091] The third lens 103 may include a fifth surface S5 defined as an object-side surface and a sixth surface S6 defined as a sensor-side surface. On the optical axis OA, the fifth surface S5 may have a convex shape and the sixth surface S6 may have a concave shape. That is, the third lens 103 may have a meniscus shape convex toward the object side on the optical axis OA. Alternatively, on the optical axis OA, the fifth surface S5 may have a convex shape and the sixth surface S6 may have a convex shape. At least one of the fifth surface S5 and the sixth surface S6 may be an aspherical surface. For example, both the fifth surface S5 and the sixth surface S6 may be aspherical surfaces. The aspherical coefficients of the fifth surface S5 and the sixth surface S6 are provided as follows Figure 5 , Fig. 9 and Fig.13 As shown, L3 is the third lens 103.

[0092] The first lens group G1 may include first to third lenses 101, 102, and 103. Among the thicknesses of the first to third lenses 101, 102, and 103 on the optical axis OA (i.e., among the center thicknesses of the lenses), the second lens 102 may have the thickest thickness, and the third lens 103 may have the thinnest thickness. Therefore, the optical system 1000 may control incident light, and may have improved aberration characteristics and resolution.

[0093] In the average value of the effective diameter (CA: clear aperture) among the first to third lenses 101, 102, and 103, the third lens 103 may have the minimum value, and the first lens 101 may have the maximum value. In detail, among the first to third lenses 101, 102, and 103, the effective radius D11 of the first surface S1 may be the largest, and the effective radius of the sixth surface S6 of the third lens 103 may be the smallest. In addition, the effective diameter of the second lens 102 may be smaller than the effective diameter of the first lens 101 and larger than the effective diameter of the third lens 103. The effective diameter of the third lens 103 may be the smallest among the lenses of the optical system 1000. The size of the effective diameter is the average value of the effective diameter of the object side surface and the effective diameter of the sensor side surface of each lens. Therefore, the optical system 1000 may have an improved chromatic aberration control characteristic, and the vignetting characteristic of the optical system 1000 may be improved by controlling the incident light.

[0094] The refractive index of the third lens 103 may be greater than the refractive index of at least one or all of the first lens 101 and the second lens 102. The refractive index of the third lens 103 may be greater than 1.6, for example, 1.65 or greater, and the refractive indexes of the first lens 101 and the second lens 102 may be less than 1.6. The Abbe number of the third lens 103 may be less than the Abbe number of at least one or both of the first lens 101 and the second lens 102. For example, the Abbe number of the third lens 103 may be less than the Abbe number of the first lens 101 and the second lens 102, with a difference of 20 or more. In detail, the Abbe number of the first lens 101 and the second lens 102 may be greater than the Abbe number of the third lens 103 by 30 or more. Therefore, the optical system 1000 may have improved chromatic aberration control characteristics.

[0095] When the radius of curvature on the optical axis OA is expressed as an absolute value, the radius of curvature of the fourth surface S4 of the second lens 102 may be the largest among the first to third lenses 101, 102, and 103. The radius of curvature of the second surface S2 of the first lens 101 may be the smallest. In the first lens group G1, the difference between the lens surface having the largest radius of curvature and the lens surface having the smallest radius of curvature may be 50 times or more.

[0096] The fourth lens 104 may have positive (+) or negative (-) refractive power on the optical axis OA. The fourth lens 104 may have positive (+) refractive power. The fourth lens 104 may include a plastic or glass material. For example, the fourth lens 104 may be made of a plastic material.

[0097] The fourth lens 104 may include a seventh surface S7 defined as an object side surface and an eighth surface S8 defined as a sensor side surface. On the optical axis OA, the seventh surface S7 may have a concave shape, and the eighth surface S8 may have a convex shape. That is, the fourth lens 104 may have a meniscus shape convex toward the sensor side on the optical axis OA. Alternatively, the seventh surface S7 may have a convex shape on the optical axis OA, and the eighth surface S8 may have a convex shape on the optical axis OA. That is, the fourth lens 104 may have a convex shape on both sides of the optical axis OA. Alternatively, the seventh surface S7 may have a convex shape on the optical axis OA, and the eighth surface S8 may have a concave shape on the optical axis OA. That is, the fourth lens 104 may have a meniscus shape convex toward the object side on the optical axis OA. Alternatively, the seventh surface S7 may have a concave shape on the optical axis OA, and the eighth surface S8 may have a concave shape on the optical axis OA. That is, the fourth lens 104 may have a concave shape on both sides of the optical axis OA.

[0098] At least one of the seventh surface S7 and the eighth surface S8 may be an aspherical surface. For example, both the seventh surface S7 and the eighth surface S8 may be aspherical surfaces. The aspherical coefficients of the seventh surface S7 and the eighth surface S8 are provided as follows: Figure 5 , Fig. 9 and Fig.13 As shown, L4 is the fourth lens 104.

[0099] The refractive index of the fourth lens 104 may be smaller than that of the third lens 103. The Abbe number of the fourth lens 104 may be greater than that of the third lens 103 and smaller than that of the first lens 101. Therefore, the optical system 1000 may have improved chromatic aberration control characteristics.

[0100] The fifth lens 105 may have a positive (+) or negative (-) refractive power on the optical axis OA. The fifth lens 105 may have a positive (+) refractive power. The fifth lens 105 may include a plastic or glass material. For example, the fifth lens 105 may be made of a plastic material. The focal length of the fifth lens 105 may be greater than the focal length of the fourth lens 104.

[0101] The fifth lens 105 may include a ninth surface S9 defined as an object side surface and a tenth surface S10 defined as a sensor side surface. The ninth surface S9 may have a concave shape on the optical axis OA, and the tenth surface S10 may have a convex shape on the optical axis OA. That is, the fifth lens 105 may have a meniscus shape convex toward the sensor on the optical axis OA. The ninth surface S9 and the tenth surface S10 of the fifth lens 105 may be arranged from the optical axis OA to the end of the effective area without a critical point. When expressed in absolute values, the radius of curvature of the tenth surface S10 of the fifth lens 105 may be the largest in the optical system 1000. In addition, when expressed in absolute values, the average value of the radius of curvature of the ninth surface S9 and the tenth surface S10 of the fifth lens 105 is less than the radius of curvature of the twelfth surface S12 of the sixth lens 106, and may be greater than 120 mm.

[0102] At least one of the ninth surface S9 and the tenth surface S10 may be an aspherical surface. For example, both the ninth surface S9 and the tenth surface S10 may be aspherical surfaces. The aspherical coefficients of the ninth surface S9 and the tenth surface S10 are provided as follows: Figure 5 , Fig. 9 and Fig.13 As shown, L5 is the fifth lens 105.

[0103] The sixth lens 106 may have a positive (+) or negative (-) refractive power on the optical axis OA. The sixth lens 106 may have a negative (-) refractive power. The sixth lens 106 may include a plastic or glass material. For example, the sixth lens 106 may be made of a plastic material.

[0104] The sixth lens 106 may include an eleventh surface S11 defined as an object side surface and a twelfth surface S12 defined as a sensor side surface. The eleventh surface S11 may have a concave shape on the optical axis OA, and the twelfth surface S12 may have a concave shape on the optical axis OA. That is, the sixth lens 106 may have a concave shape on both sides of the optical axis OA. Alternatively, the eleventh surface S11 may have a concave shape on the optical axis OA, and the twelfth surface S12 may have a convex shape on the optical axis OA. That is, the sixth lens 106 may have a meniscus shape convex toward the sensor side. When the radius of curvature on the optical axis OA is expressed in absolute value, the radius of curvature of the twelfth surface S12 may be 15 times or more of the radius of curvature of the eleventh surface S11. The refractive index of the sixth lens 106 may be 1.6 or more, for example, 1.65 or more, and may be greater than the refractive indexes of the fourth lens 104, the fifth lens 105, the seventh lens 107, and the eighth lens 108.

[0105] From the optical axis OA to the end of the effective radius, the eleventh surface S11 may not be provided with a critical point, and the twelfth surface S12 may have a critical point. At least one of the eleventh surface S11 and the twelfth surface S12 may be an aspherical surface. For example, both the eleventh surface S11 and the twelfth surface S12 may be aspherical surfaces. The aspherical coefficients of the eleventh surface S11 and the twelfth surface S12 are provided as follows: Figure 5 , Fig. 9 and Fig.13 As shown, L6 is the sixth lens 106.

[0106] The seventh lens 107 may have positive (+) or negative (-) refractive power on the optical axis OA. The seventh lens 107 may have positive (+) refractive power. The seventh lens 107 may include a plastic or glass material. For example, the seventh lens 107 may be made of a plastic material.

[0107] The seventh lens 107 may include a thirteenth surface S13 defined as an object-side surface and a fourteenth surface S14 defined as a sensor-side surface. The thirteenth surface S13 may have a convex shape on the optical axis OA, and the fourteenth surface S14 may have a concave shape on the optical axis OA. That is, the seventh lens 107 may have a meniscus shape convex toward the object side on the optical axis OA. Alternatively, the thirteenth surface S13 may have a concave shape on the optical axis OA, or the fourteenth surface S14 may have a convex shape on the optical axis OA, that is, the seventh lens 107 may have a concave shape or a convex shape on both sides of the optical axis OA. Alternatively, the seventh lens 107 may have a meniscus shape convex toward the sensor.

[0108] like Figure 2As shown, the thirteenth surface S13 and the fourteenth surface S14 of the seventh lens 107 may have at least one critical point from the optical axis OA to the end of the effective area. The critical point P1 of the thirteenth surface S13 may be located at a distance Inf71 of 49% or more of the effective radius D71, for example, in the range of 49% to 69% or in the range of 54% to 64%, and the effective radius D71 is the distance from the optical axis OA to the end of the effective radius. The critical point P2 of the fourteenth surface S14 may be located at a distance Inf72 of 40% or more of the effective radius D72 based on the optical axis OA, for example, in the range of 40% to 60% or in the range of 45% to 55%. The position of the critical point P2 of the fourteenth surface S14 may be farther from the optical axis OA than the critical point P1 of the thirteenth surface S13. Therefore, the fourteenth surface S14 can cause the light incident through the thirteenth surface S13 to diverge. The critical points P1 and P2 may refer to points where the sign of the optical axis OA and the slope value relative to the direction perpendicular to the optical axis OA changes from positive (+) to negative (-) or from negative (-) to positive (+), and may refer to points where the slope value is 0. In addition, the critical point may be a point where the slope value of a tangent line passing through the lens surface becomes smaller after increasing, or may be a point where the slope value becomes smaller and then increases. Considering the optical characteristics of the optical system 1000, it is preferred that the positions of the critical points P1 and P2 of the seventh lens 107 are set at positions satisfying the above range. In detail, the positions of the critical points preferably satisfy the above range to control the optical characteristics of the optical system 1000, such as chromatic aberration, distortion characteristics, aberration characteristics, and resolution. Therefore, the optical path emitted to the image sensor 300 through the lens can be effectively controlled. Therefore, the optical system 1000 according to the embodiment can have improved optical characteristics even in the center and peripheral parts of the FOV.

[0109] At least one of the thirteenth surface S13 and the fourteenth surface S14 may be an aspherical surface. For example, both the thirteenth surface S13 and the fourteenth surface S14 may be aspherical surfaces. The aspherical coefficients of the thirteenth surface S13 and the fourteenth surface S14 are provided as follows: Figure 5 , Fig. 9 and Fig.13 As shown, L7 is the seventh lens 107.

[0110] The eighth lens 108 may have a negative (-) refractive power on the optical axis OA. The eighth lens 108 may include a plastic or glass material. For example, the eighth lens 108 may be made of a plastic material. The eighth lens 108 may be the lens closest to the sensor side or the last lens in the optical system 1000.

[0111] The eighth lens 108 may include a fifteenth surface S15 defined as an object-side surface and a sixteenth surface S16 defined as a sensor-side surface. The fifteenth surface S15 may have a convex shape on the optical axis OA, and the sixteenth surface S16 may have a concave shape on the optical axis OA. That is, the eighth lens 108 may have a convex shape from the optical axis OA toward the object side. Alternatively, the fifteenth surface S15 of the eighth lens 108 may have a concave shape, and the sixteenth surface S16 may have a concave shape or a convex shape.

[0112] The fifteenth surface S15 may be an aspherical surface. The sixteenth surface S16 may be a free-form surface. The aspherical coefficients of the fifteenth surface S15 are as follows: Figure 5 , Fig. 9 and Fig.13 As shown, L8 is the eighth lens 108, and S15 of L8 is set. In addition, the Zernike polynomial coefficients C1-C66 representing the free-form surface of the sixteenth surface S16 can be obtained according to the first embodiment to the third embodiment, as shown in Fig.17 Therefore, the eighth lens 108 may be a free-form surface lens.

[0113] like Figure 2 and Figure 3 As shown, the eighth lens 108 may have at least one critical point extending from the optical axis OA to the end of the effective area between the fifteenth surface S15 and the sixteenth surface S16. The critical point P3 of the fifteenth surface S15 may be located at a distance Inf81 of 45% or less of the effective radius D81, for example, in the range of 10% to 45% or in the range of 10% to 40%, and the effective radius D81 is the distance from the optical axis OA to the end of the effective radius. The critical points P4 and P6 of the sixteenth surface S16 are the first distance InfX82 and the second distance InfY82 in the first direction X and the second direction Y of 46% or less (for example, in the range of 26% to 46% or in the range of 31% to 41%) of the effective radius D82 based on the optical axis OA. The critical points P4 and P6 of the fourteenth surface S16 may be located farther from the optical axis OA than the critical point P3 of the fifteenth surface S15, and therefore, the sixteenth surface S16 may diverge the light incident through the fifteenth surface S15.

[0114] At least one of the fifteenth surface S15 and the sixteenth surface S16 of the eighth lens 108 may be set as a free-form surface. For example, the sixteenth surface S16 of the eighth lens 108 is a free-form surface and has a shape (+X, -X) symmetrical in a first direction X orthogonal to the optical axis OA based on the optical axis OA, and may have a shape (+Y, -Y) symmetrical in a second direction Y orthogonal to the optical axis OA. That is, as Figure 2 and Figure 3As shown, the lens surfaces in the +Y and -Y directions are symmetrical about the XZ plane or the optical axis OA on both sides of the second direction Y, and the lens surfaces in the +X and -X directions are symmetrical about the YZ plane or the optical axis OA on both sides of the first direction X. Here, the Z-axis direction is the optical axis direction. The first direction X and the second direction Y may be orthogonal to each other and may have an asymmetric shape relative to the optical axis OA. The effective radius D82 of the sixteenth surface S16 in the first direction X and the second direction Y may be the same or different. When there is a difference in the effective radius D82 of the sixteenth surface S16 in the first direction X and the second direction Y, it may be the same as the difference between the critical points P4 and P6. The first distance InfX82 is the distance from the optical axis OA of the sixteenth surface S16 to the critical point P4 in the first direction X, and the second distance InfY82 is the distance from the optical axis OA to the critical point P6 in the second direction Y, and the following conditions may be satisfied: InfX82>InfY82. The difference between the first distance InfX82 and the second distance InfY82 may be 0.5% or less, for example, in the range of 0.01% to 0.5%. The first distance InfX82 and the second distance InfY82 may be set within a range of 1.5 mm or more from the optical axis OA, for example, 1.5 mm to 2.1 mm. In view of the optical characteristics of the optical system 1000, it is preferred that the positions of the critical points P3, P4, and P6 of the eighth lens 108 are set at positions satisfying the above range. In detail, the positions of the critical points preferably satisfy the above range to control the optical characteristics of the optical system 1000, such as chromatic aberration, distortion characteristics, aberration characteristics, and resolution. Therefore, the path of light emitted to the image sensor 300 through the lens can be effectively controlled. Therefore, the optical system 1000 according to the embodiment can have improved optical characteristics even in the center and peripheral parts of the FOV.

[0115] The sixteenth surface S16 of the eighth lens 108 may have different distances ZX82, XY82 from the critical points P4, P6 in the first direction X and the second direction Y to the end of the effective diameter, for example, satisfying the condition: ZX82>ZY82, and the range may be from 1.5 mm to 2.2 mm.

[0116] In addition, normals K2 and K4, which are straight lines perpendicular to tangent lines K1 and K3 in the first direction X and the second direction Y at any point on the sensor-side sixteenth surface S16 passing through the last lens (eighth lens 108), may have predetermined angles θ1 and θ2 with the optical axis OA, and the angles θ1 and θ2 in the first direction X and the second direction Y may be different from each other, and the maximum angle may be less than 60 degrees, for example, in the range of 5 to 59 degrees or in the range of 10 to 50 degrees. Therefore, since the optical axis or paraxial region of the sixteenth surface S16 has the minimum Sag value, a slim optical system can be provided.

[0117] The second lens group G2 may include fourth to eighth lenses 104, 105, 106, 107, and 108. Among the fourth to eighth lenses 104, 105, 106, 107, and 108, a lens having a maximum center thickness may be greater than a center distance between the third lens 103 and the fourth lens 104. In the second lens group G2, a lens having a maximum center thickness may be the eighth lens 105, and a lens having a minimum center thickness may be the fifth lens 105. Therefore, the optical system 1000 may control incident light and may have improved aberration characteristics and resolution.

[0118] Among the fourth to eighth lenses 104, 105, 106, 107, and 108, the fourth lens 104 may have the smallest effective diameter (CA: clear aperture) among the lenses, and the effective diameter of the eighth lens 108 may be the largest. In detail, in the second lens group G2, the size of the effective diameter of the seventh surface S7 of the fourth lens 104 may be the smallest, and the size of the effective diameter of the sixteenth surface S16 may be the largest. The size of the effective diameter of the sixteenth surface S16 may be the largest effective diameter in the optical system, and may be 2.2 times the size of the effective diameter of the seventh surface S7. The size of the effective diameter of the eighth lens 108 is the largest, so that incident light can be effectively refracted toward the image sensor 300. Therefore, the optical system 1000 may have an improved chromatic aberration control characteristic, and the vignetting characteristic of the optical system 1000 may be improved by controlling the incident light.

[0119] In the second lens group G2, the number of lenses having a refractive index exceeding 1.6 may be smaller than the number of lenses having a refractive index less than 1.6. In the second lens group G2, the number of lenses having an Abbe number greater than 50 may be smaller than the number of lenses having an Abbe number less than 50.

[0120] like Figure 2 and Figure 3As shown, BFL (back focal length) is the distance from the image sensor 300 to the last lens on the optical axis. That is, BFL is the optical axis distance between the image sensor 300 and the sensor-side sixteenth surface S16 of the eighth lens 108. L7_CT is the center thickness or optical axis thickness of the seventh lens 107, and L7_ET is the end or edge thickness of the effective area of ​​the seventh lens 107. L8_CT is the center thickness or optical axis thickness of the eighth lens 108. D78_CT is the optical axis distance (i.e., center distance) from the center of the sensor-side surface of the seventh lens 107 to the center of the object-side surface of the eighth lens 108. That is, the optical axis distance D78_CT from the center of the sensor-side surface of the seventh lens 107 to the center of the object-side surface of the eighth lens 108 is the distance between the fourteenth surface S14 and the fifteenth surface S15 on the optical axis OA. D78_CT may be greater than the optical axis distance between the third lens 103 and the fourth lens 104. D78_CT may be greater than the sum of the center thicknesses of the seventh lens 107 and the eighth lens 108. D78_CT may be 1.8 times or more, for example, 1.8 times to 2.5 times, the central thickness of the thickest lens in the optical system 1000 (ie, the second lens 102 ).

[0121] The center thickness of the second lens 102 is the largest among the lenses, and the center distance D78_CT between the seventh lens 107 and the eighth lens 108 is the largest among the distances between the lenses. The center thickness of the third lens 103 is the smallest among the lenses, and the center distance between the second lens 102 and the third lens 103 is the smallest among the distances between the lenses. Among the distances between the lenses, the center distance between the fourth lens 104 and the fifth lens 105 may be 2.5 times or less, for example, 2 times or less, of the center distance between the second lens 102 and the third lens 103.

[0122] The refractive index of the sixth lens 106 may be greater than the refractive indexes of the seventh lens 107 and the eighth lens 108, and may exceed 1.6. The Abbe number of the sixth lens 106 may be less than the Abbe number of the seventh lens 107 and the eighth lens 108. For example, the Abbe number of the sixth lens 106 may be 20 or more smaller than the Abbe number of the seventh lens 107 and the eighth lens 108. In detail, the Abbe number of the seventh lens 107 and the eighth lens 108 may be greater than the Abbe number of the sixth lens 106 by 30 or more, for example, by 50 or more. Therefore, the optical system 1000 may have improved chromatic aberration control characteristics.

[0123] In the lenses 101 to 108, the maximum center thickness may be 2.5 times or more, for example, 2.5 times to 5 times, the minimum center thickness. The third lens 103 having the maximum center thickness may be 2.5 times or more, for example, 2.5 times to 4 times, the second lens 102 having the minimum center thickness. In the plurality of lenses 100, the number of lenses having a center thickness less than 0.5 mm may be equal to the number of lenses having a center thickness of 0.5 mm or more. Therefore, the optical system 1000 may be provided with a structure having a slim thickness. In the plurality of lens surfaces S1 to S16, the number of surfaces having an effective radius less than 2 mm may be equal to or greater than the number of surfaces having an effective radius of 2 mm or more. Describing the radius of curvature as an absolute value, the radius of curvature of the third surface S3 of the second lens 102 in the plurality of lenses 100 may be the largest among the lens surfaces on the optical axis OA, and the radius of curvature of the fifteenth surface S15 of the eighth lens 108 may be the smallest among the lens surfaces on the optical axis OA.

[0124] When the focal length is described in absolute values, the focal length of the sixth lens 106 among the plurality of lenses 100 may be the largest among the lenses, the focal length of the eighth lens 108 may be the smallest, and the maximum focal length may be greater than 100 times the minimum focal length.

[0125] The optical system 1000 according to the embodiment disclosed above may satisfy at least one or two or more of the following mathematical formulas. Therefore, the optical system 1000 according to the embodiment may have improved optical characteristics. For example, when the optical system 1000 satisfies at least one mathematical formula, the optical system 1000 may effectively control aberration characteristics such as chromatic aberration and distortion, and may have good optical performance not only in the central part of the FOV but also in the peripheral part. The optical system 1000 may have improved resolution and may have a thinner and more compact structure.

[0126] [Mathematical formula 1]1 <L1_CT / L3_CT<5

[0127] In Math 1, L1_CT represents the thickness (mm) of the first lens 101 on the optical axis OA, and L3_CT represents the thickness (mm) of the third lens 103 on the optical axis OA. When the optical system 1000 satisfies Math 1, the optical system 1000 can improve aberration characteristics. Preferably, the above Math 1 can satisfy: <L1_CT / L3_CT≤3。

[0128] [Math 2] 0.5 <L3_CT / L4_CT<2

[0129] In Math 2, L3_CT represents the thickness (mm) of the third lens 103 on the optical axis OA, and L4_CT represents the thickness (mm) of the fourth lens 104 on the optical axis OA. When the optical system 1000 satisfies Math 2, the optical system 1000 may have improved chromatic aberration control characteristics. Preferably, the above Math 2 may satisfy: 0.5 <L3_CT / L4_CT≤1.5。

[0130] [Mathematical formula 2-1] (L1_CT+L3_CT) <L2_CT

[0131] In Math 2-1, L2_CT represents the thickness of the second lens 102 on the optical axis OA, and may be greater than the sum of the center thickness L1_CT of the first lens 101 and the center thickness L3_CT of the third lens 103. When the optical system 1000 satisfies Math 2-1, the optical system 1000 may have improved chromatic aberration control characteristics.

[0132] [Mathematical formula 3]1 <L8_CT / L7_CT<2

[0133] In Math 3, L8_CT represents the thickness (mm) of the eighth lens 108 on the optical axis OA, and L7_CT represents the thickness (mm) of the seventh lens 107 on the optical axis OA. In detail, when the optical system 1000 satisfies Math 3, the optical system 1000 may have improved chromatic aberration control characteristics.

[0134] [Math 4] 0.1 <L1_CT / L8_CT<1

[0135] [Mathematical formula 5]1 <L2_CT / L8_CT<3

[0136] When the optical system 1000 satisfies Math. 4 and 5, the optical system 1000 may have improved chromatic aberration control characteristics. Therefore, the thicknesses of the first lens 101, the second lens 102, and the eighth lens 108 may satisfy: L1_CT <L8_CT<L2_CT。

[0137] [Math 6] 0.01 <D12_CT / D78_CT<1

[0138] In Mathematical Formula 11, D12_CT represents the optical axis distance (mm) between the first lens 101 and the second lens 102. In detail, D12_CT represents the distance (mm) between the second surface S2 of the first lens 101 and the third surface S3 of the second lens 102 along the optical axis OA. D78_CT represents the optical axis distance (mm) between the center of the fourteenth surface S14 of the seventh lens 107 and the center of the fifteenth surface S15 of the eighth lens 108. When the optical system 1000 according to the embodiment satisfies Mathematical Formula 6, the optical system 1000 can improve the aberration characteristics and control the size of the optical system 1000, for example, the TTL (total length of the lens) is reduced. Preferably, Mathematical Formula 6 can satisfy: 0.01 <D12_CT / D78_CT≤0.5。

[0139] [Mathematical formula 7]1 <G1_TD / D34_CT<5

[0140] In Math 7, G1_TD represents the distance on the optical axis between the first object-side surface S1 of the first lens 101 and the sensor-side sixth surface S6 of the third lens 103 (mm). D34_CT represents the optical axis distance between the third lens 103 and the fourth lens 104 (mm). In detail, D34_CT represents the distance on the optical axis OA between the sixth surface S6 of the third lens 103 and the seventh surface S7 of the fourth lens 104 (mm). When the optical system 1000 satisfies Math 7, the thickness of the first lens group G1 and the optical axis distance between the second lens group G2 can be set, and the aberration characteristics of the optical system 1000 can be improved, and the reduction of TTL (total lens length) can be controlled.

[0141] [Mathematical formula 8]1 <G2_TD / D78_CT<5

[0142] In Math 8, G2_TD represents the distance on the optical axis between the object-side seventh surface S7 of the fourth lens 104 and the sensor-side sixteenth surface S16 of the eighth lens 108 (mm). D78_CT represents the optical axis distance (mm) between the seventh lens 107 and the eighth lens 108. In detail, D78_CT represents the distance (mm) between the fourteenth surface S14 of the seventh lens 107 and the fifteenth surface S15 of the eighth lens 108 on the optical axis OA. Math 8 can set the total optical axis distance of the second lens group G2 and the maximum interval within the second lens group G2. When the optical system 1000 according to the embodiment satisfies Math 8, the optical system 1000 can improve the aberration characteristics and control the size of the optical system 1000, such as TTL reduction. Preferably, the value of Math 8 can be 2 or more and 4 or less.

[0143] In addition, Mathematical Formula 7 and / or Mathematical Formula 8 may also satisfy at least one of the following Mathematical Formulas 8-1 to 8-7.

[0144] [Mathematical formula 8-1] G1_TD <G2_TD

[0145] [Mathematical formula 8-2]D34_CT <D78_CT

[0146] [Mathematical formula 8-3] G1_TD≤D78_CT

[0147] [Mathematical formula 8-4]1 <G2_TD / G1_TD<4

[0148] [Mathematical formula 8-5]3 <nL / D78_CT<5.5

[0149] Here, nL is the number of lenses in the optical system 1000 , and may be in the range of 7 to 9, or 8, for example.

[0150] [Mathematical formula 8-6]1 <nL / G2_TD<3

[0151] [Mathematical formula 8-7]3 <nL / G1_TD<5

[0152] [Mathematical formula 9] 0 < (L7_CT + L8_CT) / D78_CT < 1

[0153] In Math 9, the sum of the center thickness L7_CT of the seventh lens 107 and the center thickness L8_CT of the eighth lens 108 may be less than the optical axis distance D78_CT between the seventh lens 107 and the eighth lens 108. When the optical system 1000 satisfies Math 9, the optical system 1000 may improve aberration characteristics and control TTL slimness.

[0154] [Math 10]0 <L1R1 / L8R2<5

[0155] In Math 10, L1R1 represents a curvature radius (mm) of the first surface S1 of the first lens 101 on the optical axis OA, and L8R2 represents a curvature radius (mm) of the sixteenth surface S16 of the eighth lens 108 on the optical axis OA. When the optical system 1000 according to the embodiment satisfies Math 10, optical performance may be improved by controlling the shapes and refractive powers of the first lens and the eighth lens.

[0156] Regarding the surface shape, refractive power, and optical performance of the lens of the optical system 1000, Math. 10 may further include at least one of Math. 10-1 to 10-3.

[0157] [Mathematical formula 10-1] 100<|L5R1 / L8R2|<300

[0158] In Math 10-1, L5R1 represents a radius of curvature (mm) of a ninth surface S9 of the fifth lens 105 on the optical axis OA. When Math 10-1 is satisfied, shapes and refractive powers of the fifth and eighth lenses may be controlled, and optical performance of the second lens group G2 may be improved.

[0159] [Mathematical formula 10-2]1<|L5R1 / L6R2|<10

[0160] In Math. 10-2, L6R2 represents a radius of curvature (mm) of the twelfth surface S12 of the sixth lens 106 on the optical axis OA. When Math. 10-2 is satisfied, the shapes and refractive powers of the fifth and sixth lenses may be controlled.

[0161] [Mathematical formula 10-3]1<|L5R1 / L2R2|<10

[0162] In Math Formula 10-2, L2R2 represents a radius of curvature of the fourth surface S4 of the second lens 102 on the optical axis OA. When Math Formula 10-2 is satisfied, the shapes and refractive powers of the first lens and the fifth lens may be controlled.

[0163] Here, the absolute values ​​of the curvature radii of the fourth surface S4 of the second lens 102, the ninth surface S9 of the fifth lens 105, and the twelfth surface S12 of the sixth lens 106 may be greater than 100, and when expressed as absolute values, the following mathematical formula may be satisfied: L2R2 <L6R2<L5R1。

[0164] [Mathematical formula 11] 10<(|L5R1| / L2_CT) / nL<90

[0165] In Math Formula 11, L5R1 represents a radius of curvature (mm) of a ninth surface S9 of the fifth lens 105 on the optical axis OA, L2_CT represents a thickness of the second lens 102 on the optical axis, and nL represents the number of lenses of the optical system 1000. When Math Formula 11 is satisfied, the refractive powers of the second lens and the fifth lens may be controlled, and optical performance of incident light may be improved.

[0166] Math 11 may further include at least one of the following Math 11-1 and 11-2.

[0167] [Mathematical formula 11-1] 10<(|L_R_Max| / L_CT_Max) / nL<90

[0168] In Math Formula 11-1, L_R_Max is the maximum radius of curvature of the first to sixteenth surfaces 16 on the optical axis OA, and L_CT_Max is the maximum thickness of the first to eighth lenses 101 to 108 on the optical axis.

[0169] [Mathematical formula 11-2] 10<(|L_R2_Max| / L_CT_Max) / nL<90

[0170] In Math Formula 11-2, L_R2_Max is the maximum value of the curvature radius R2 of the sensor-side surface of the first to eighth lenses 101 to 108 , and nL is the number of lenses in the optical system 1000 .

[0171] [Mathematical formula 12] 11 <D6_CT / D67_CT<30

[0172] Math 12 may set the thickness D6_CT of the sixth lens 106 on the optical axis and the distance D67_CT between the sixth lens 106 and the seventh lens 107 on the optical axis. When the optical system satisfies Math 12, the optical system 1000 may improve aberration characteristics and control the size of the optical system 1000, such as TTL reduction.

[0173] [Math 13] 0 < (D78_CT) / InfX82 < 3

[0174] In Math 13, D78_CT is the optical axis distance between the seventh lens 107 and the eighth lens 108, and InfX82 is the straight line distance (mm) from the optical axis OA to the critical point P6 in the X-axis direction on the sensor side surface S16 of the eighth lens 108. The critical point P6 may be the first critical point adjacent to the optical axis OA in the X-axis direction. When the optical system satisfies Math 13, optical performance, for example, distortion aberration characteristics of the peripheral portion in the X-axis direction may be improved. Preferably, the value of Math 13 may be 0.5 or more and 2 or less.

[0175] [Equation 14] 0 < (D78_CT) / InfY82 < 3

[0176] In Mathematical Formula 14, InfY82 is a straight-line distance (mm) from the optical axis OA to the critical point P4 in the Y-axis direction on the sensor side surface S16 of the eighth lens 108. The critical point P4 may be the first critical point in the Y-axis direction adjacent to the optical axis OA. When the optical system satisfies Mathematical Formula 14, optical performance, such as distortion aberration characteristics of the peripheral part in the Y-axis direction, may be improved. Preferably, the value of Mathematical Formula 14 may be 0.5 or greater and 2 or less, and may be greater than the value of Mathematical Formula 13. In addition, InfX82 and InfY82 may be different from each other, and the difference may be less than 0.5 mm.

[0177] [Math 15] 0 < (D78_CT) / Inf82 < 3

[0178] In Math 15, Inf82 is an average of a straight-line distance (mm) from the optical axis OA to a critical point P4 in the Y-axis direction on the sensor-side surface S16 of the eighth lens 108 and a distance to a critical point P6 in the X-axis direction. When the optical system satisfies Math 15, optical performance, for example, distortion aberration characteristics of peripheral portions in the X-axis direction and the Y-axis direction can be improved.

[0179] [Math 16] 1.60 <n3

[0180] In Math 4, n3 represents the refractive index of the third lens 103 at the d-line. When the optical system 1000 according to the embodiment satisfies Math 16, the optical system 1000 may improve chromatic aberration characteristics.

[0181] Math 16 may include at least one of the following Math 16-1 to 16-2.

[0182] [Mathematical formula 16-1] 1.50 <n1<1.6

[0183] [Mathematical formula 16-2] 1.50 <n8<1.6

[0184] In Maths. 16-1 and 16-2, n1 is the refractive index of the first lens 101 at the d-line, and n8 is the refractive index of the eighth lens 108 at the d-line. When the optical system 1000 according to the embodiment satisfies Maths. 16-1 and 16-2, chromatic aberration characteristics may be improved.

[0185] [Math 17] 1.65 <AVR(n3,n6)<1.75

[0186] In Math 17, n6 represents the refractive index of the sixth lens 106 at the d-line, and AVR(n3, n6) represents the average refractive index of the third lens 103 and the sixth lens 106. When the optical system 1000 according to the embodiment satisfies Math 17, the optical system 1000 may improve chromatic aberration characteristics.

[0187] [Mathematical formula 18]1 <CA_L1S1 / CA_L3S1<2

[0188] In Math 18, CA_L1S1 represents the size (mm) of the effective diameter CA (clear aperture) of the first surface S1 of the first lens 101, and CA_L3S1 represents the size (mm) of the effective diameter CA of the fifth surface S5 of the third lens 103. When the optical system 1000 according to the embodiment satisfies Math 18, the optical system 1000 can control light incident to the first lens group G1 and can have improved aberration control characteristics. The value of Math 18 may be 1.5 or less.

[0189] [Mathematical formula 19]1 <CA_L8S2 / CA_L4S2<5

[0190] In Math 19, CA_L4S2 represents the size (mm) of the effective diameter CA of the eighth surface S8 of the fourth lens 104. When the optical system 1000 according to the embodiment satisfies Math 19, the optical system 1000 can control the path of light traveling through the second lens group G2 and can have improved aberration control characteristics. The value of Math 19 may be 4 or less.

[0191] [Math 20] 0.2 <CA_L3S2 / CA_L4S1<2

[0192] In Math 20, CA_L3S2 represents the size (mm) of the effective diameter CA of the sixth surface S6 of the third lens 103, and CA_L4S1 represents the size (mm) of the effective diameter CA of the seventh surface S7 of the fourth lens 104. When the optical system 1000 according to the embodiment satisfies Math 18, the optical system 1000 can improve chromatic aberration, and the lengths of the opposing lens surfaces of the first lens group G1 and the second lens group G2 can be set, and vignetting can be controlled for optical performance.

[0193] [Math 21] 0.1 <CA_L6S2 / CA_L8S2<2

[0194] In Math 21, CA_L6S2 represents the size (mm) of the effective diameter CA of the twelfth surface S12 of the sixth lens 106. When the optical system 1000 according to the embodiment satisfies Math 21, the optical system 1000 can control light traveling to the sixth to eighth lenses 106, 107, and 108, and can improve aberration characteristics.

[0195] [Mathematical formula 22]1 <L7R1 / L7_CT<10

[0196] In Math 22, L7R1 represents the radius of curvature (mm) of the second surface S2 of the seventh lens 107, and L7_CT represents the thickness of the seventh lens 107 on the optical axis. That is, Math 22 may satisfy: L7R1>L7_CT, and the value of Math 22 may be 2 or greater. When the optical system 1000 according to the embodiment satisfies Math 22, the aberration characteristics of the optical system 1000 may be improved.

[0197] [Math 23] 1<|L6R1 / L8R1|<5

[0198] In Math 14, L6R1 represents the curvature radius (mm) of the eleventh surface S11 of the sixth lens 106, and L8R1 represents the curvature radius (mm) of the fifteenth surface S15 of the eighth lens 108. When the optical system 1000 according to the embodiment satisfies Math 23, the aberration characteristics of the optical system 1000 may be improved. The value of Math 23 may be 4 or less.

[0199] [Math 24]0 <L_CT_Max / Air_Max<5

[0200] In Math 24, L_CT_Max represents the thickest thickness (mm) of each of the plurality of lenses on the optical axis OA, and Air_Max represents the maximum value of the optical axis distance between the plurality of lenses. When the optical system 1000 according to the embodiment satisfies Math 24, the optical system 1000 has good optical performance at a set viewing angle and focal length, and the size of the optical system 1000 can be reduced, for example, TTL can be reduced. The value of Math 24 can be 3 or less, or can be 1 or less.

[0201] [Mathematical formula 25] 0.5 < ΣL_CT / ΣAir_CT < 2

[0202] In Mathematical Formula 25, ∑L_CT represents the sum of the thickness of each of the plurality of lenses on the optical axis OA (mm), and ∑Air_CT represents the sum of the distances between two adjacent lenses of the plurality of lenses on the optical axis OA (mm). When the optical system 1000 according to the embodiment satisfies Formula 25, the optical system 1000 has good optical performance at a set viewing angle and focal length, and the size of the optical system 1000 can be reduced, for example, TTL can be reduced.

[0203] [Mathematical formula 26] 10<∑Index<30

[0204] In Math 26, ΣIndex represents the sum of the refractive indices of the plurality of lenses 100 at the d-line. When the optical system 1000 according to the embodiment satisfies Math 26, the TTL of the optical system 1000 may be controlled and the resolution may be improved.

[0205] Mathematical formula 26 can also satisfy mathematical formulas 26-1 and 26-2.

[0206] [Mathematical formula 26-1] 1.5 < ∑ Index / nL < 1.6

[0207] [Mathematical formula 26-2]30<∑Abb / nL<50

[0208] ΣAbbe represents the sum of the Abbe numbers of each lens in the plurality of lenses 100 , and nL represents the number of lenses in the optical system, which may be 8, or 7 to 9, for example.

[0209] [Mathematical formula 27] 10<∑Abb / ∑Index<50

[0210] In Math 27, ΣAbbe represents the sum of the Abbe numbers of each of the plurality of lenses 100. When the optical system 1000 according to the embodiment satisfies Math 27, the optical system 1000 may have improved aberration characteristics and resolution.

[0211] Mathematical formula 27 can also satisfy mathematical formula 27-1.

[0212] [Mathematical formula 27-1] 20 < (∑Abb + ∑Index) / nL < 50

[0213] [Math 28] 0.5 <CA_L1S1 / CA_min<2

[0214] In Math 28, CA_L1S1 represents an effective diameter (mm) of the first surface S1 of the first lens 101, and CA_Min represents a minimum effective diameter (mm) among the first to sixteenth surfaces S1-S16. When the optical system 1000 according to the embodiment satisfies Math 28, light incident through the first lens 101 can be controlled, and a slim optical system can be provided while maintaining optical performance.

[0215] [Mathematical formula 29]1 <CA_max / CA_min<5

[0216] In Math 29, CA_max represents the maximum effective diameter (mm) among the object-side surface and the sensor-side surface of the plurality of lenses, and represents the maximum effective diameter (mm) among the first to sixteenth surfaces S1-S16. When the optical system 1000 according to the embodiment satisfies Math 29, the optical system 1000 can provide a slim and compact optical system while maintaining optical performance. The effective diameter of the sixteenth surface S16 can have the maximum effective diameter, and the effective diameter of the sixth surface S6 can have the minimum effective diameter.

[0217] Math 29 may include at least one of Math 29-1 to 29-4.

[0218] [Mathematical formula 29-1]1 <CA_L8 / CA_L3<5

[0219] [Mathematical formula 29-2]1 <CA_L8 / CA_L4<5

[0220] [Mathematical formula 29-3]2 <CA_L8 / CA_L2<4

[0221] [Mathematical formula 29-4]CA_L3 <CA_L4<CA_L2<CA_L5

[0222] Here, CA_L2, CA_L3, CA_L4, CA_L5, and CA_L8 are average values ​​of effective diameters of the object-side surface and the sensor-side surface of each lens. When the optical system satisfies Mathematical Formulas 29-1 to 29-4, the optical system 1000 can provide a slim and compact optical system while maintaining optical performance.

[0223] [Mathematical formula 30]1 <CA_max / CA_AVR<3

[0224] In Math 30, CA_max represents the maximum effective diameter (mm) among the object-side surface and the sensor-side surface of the plurality of lenses, and CA_AVR represents the average of the effective diameters of the object-side surface and the sensor-side surface of the plurality of lenses. When the optical system 1000 according to the embodiment satisfies Math 30, a slim and compact optical system can be provided.

[0225] [Math 31] 0.1 <CA_min / CA_AVR<1

[0226] In Math 31, CA_min represents the smallest effective diameter (mm) among the object-side surface and the sensor-side surface of the plurality of lenses. When the optical system 1000 according to the embodiment satisfies Math 31, a slim and compact optical system may be provided.

[0227] [Math 32] 0.1 <CA_max / (2*ImgH)<1

[0228] In Math 32, CA_max represents the largest effective diameter among the object side surface and the sensor side surface of the plurality of lenses, and ImgH represents the distance (mm) from the center (0.0F) of the image sensor 300 overlapping the optical axis OA to the diagonal end. That is, ImgH represents 1 / 2 of the maximum diagonal length (mm) of the effective area of ​​the image sensor 300. When the optical system 1000 according to the embodiment satisfies Math 32, the optical system 1000 has good optical performance in the center and peripheral portions of the FOV, and a slim and compact optical system can be provided. The symbol * represents multiplication.

[0229] Mathematical formula 32 may include the following mathematical formula 32-2.

[0230] [Mathematical formula 32-1] 0.5 <ImgH / nL<2

[0231] [Mathematical formula 32-1] 0.5 <TTL / nL<2

[0232] nL is the number of lenses of the optical system, for example, 7 to 9, preferably 8, and TTL represents the distance (mm) from the vertex of the first surface S1 of the first lens 101 to the image surface of the image sensor 300 on the optical axis OA.

[0233] [Math 33] 0.5 <TD / CA_max<1.5

[0234] In Math 39, TD is the optical axis distance (mm) from the object-side surface of the first lens 101 to the n-th lens (i.e., the sensor-side surface of the eighth lens 108 group). For example, it is the distance from the first surface S1 to the sixteenth surface S16 on the optical axis OA. When the optical system 1000 according to the embodiment satisfies Math 33, a slim and compact optical system can be provided.

[0235] [Math 34]0 <F / L8R2<10

[0236] In Math 34, F represents the total focal length of the optical system 1000 (mm), and L8R2 represents the curvature radius (mm) of the sixteenth surface S16 of the eighth lens 108 having a free-form surface. When the optical system 1000 according to the embodiment satisfies Math 34, the optical system 1000 can reduce the size of the optical system 1000, for example, reduce TTL.

[0237] [Mathematical formula 35]1 <F / L1R1<10

[0238] In Math 35, L1R1 represents the radius of curvature (mm) of the first surface S1 of the first lens 101. When the optical system 1000 according to the embodiment satisfies Math 35, the size of the optical system 1000 can be reduced, for example, TTL can be reduced. The value of Math 35 may be 5 or less, for example, 3 or less.

[0239] [Math 36]0 <EPD / L8R2<10

[0240] In Math 36, EPD represents the size (mm) of the entrance pupil of the optical system 1000, and L8R2 represents the radius of curvature (mm) of the sixteenth surface S14 of the eighth lens 108 having a free-form surface. When the optical system 1000 according to the embodiment satisfies Math 36, the optical system 1000 can control the overall brightness and can have good optical performance in the center and peripheral parts of the FOV. The value of Math 36 may be 5 or less, for example, 3 or less.

[0241] [Math 37] 0.5 <EPD / L1R1<8

[0242] Math 37 represents the relationship between the size of an entrance pupil (EPD) of the optical system and the radius of curvature of the first surface S1 of the first lens 101 and can control incident light. The value of Math 37 may be 5 or less, for example, 3 or less.

[0243] [Mathematical formula 38]-3 <F1 / F3<0

[0244] In Math Formula 38, F1 represents the focal length (mm) of the first lens 101, and F3 represents the focal length (mm) of the third lens 103. When the optical system 1000 according to the embodiment satisfies Math Formula 38, it may have an appropriate refractive power to control the optical path traveling through the first lens 101 and the third lens 103, and may improve the resolution.

[0245] [Math 39]0 <F13 / F<5

[0246] In Math 39, F13 represents the combined focal length of the first to third lenses (mm), and F represents the effective focal length (mm) in two directions X and Y orthogonal to the optical axis OA in the optical system 1000. That is, the effective focal length Fx in the X direction and the effective focal length Fy in the Y direction are different from each other, and their average value can be defined as F. Math 39 establishes a relationship between the focal length of the first lens group G1 and the total effective focal length. When the optical system 1000 according to the embodiment satisfies Math 39, the optical system 1000 can control the TTL of the optical system 1000.

[0247] [Math 40] 0<|F48 / F13|<10

[0248] In Math 40, F13 represents the composite focal length (mm) of the first lens to the third lens, and F48 represents the composite focal length (mm) of the fourth lens to the eighth lens. Math 40 establishes the relationship between the focal length of the first lens group G1 and the focal length of the second lens group G2. In an embodiment, the composite focal length of the first lens to the third lens may have a positive (+) value, and the composite focal length of the fourth lens to the eighth lens may have a negative (-) value. When the optical system 1000 according to an embodiment satisfies Math 40, the optical system 1000 may improve aberration characteristics such as chromatic aberration and distortion aberration. The value of Math 40 may be 8 or less, for example, 5 or less.

[0249] At least one of Math 39 and Math 40 may include Math 40 - 1 to 40 - 4 .

[0250] [Mathematical formula 40-1]-10 <F48 / F<0

[0251] [Mathematical formula 40-2]0 <F / nL<2

[0252] [Mathematical formula 40-3]1<(F13+|F48|+F) / nL<5

[0253] [Mathematical formula 40-4] 0.5 < (F13 + |F48|) / nL < 4

[0254] Here, nL is the number of lenses in the optical system and may be in the range of 7 to 9, or 8.

[0255] [Mathematical formula 41]2 <TTL<20

[0256] In Math 41, TTL represents a distance (mm) on the optical axis OA from the center of the first surface S1 of the first lens 101 to the image surface of the image sensor 300. By setting TTL to less than 20 in Math 41, a slim and compact optical system can be provided.

[0257] Mathematical formula 41 may also include mathematical formula 41-1.

[0258] [Mathematical formula 41-1]1≤(TTL+Imgh) / nL<5

[0259] Here, nL is the number of lenses in the optical system and may be 7 to 9, preferably 8.

[0260] [Mathematical formula 42]2 <ImgH

[0261] Equation 42 enables the diagonal dimension of the image sensor 300 to exceed 4 mm, thereby providing an optical system with high resolution.

[0262] [Math 43] BFL < 2.5

[0263] Mathematical formula 43 makes BFL (back focal length) less than 2.5 mm, thereby ensuring the installation space of the filter 500, improving the assembly of components by the distance (mm) between the image sensor 300 and the last lens, and improving the coupling reliability. That is, when there is no critical point on the sensor side surface of the last lens, the BFL value can be set to less than 2.5 mm, for example, 2 mm or less.

[0264] [Mathematical formula 44]2 <F<20

[0265] In Mathematical Formula 44, the total focal length F can be set according to the optical system.

[0266] [Math 45] FOV<120

[0267] In Math 45, FOV represents the viewing angle of the optical system 1000, and an optical system with a viewing angle of less than 120 degrees may be provided. The FOV may be 100 degrees or less.

[0268] [Math 46] 0.5 <TTL / CA_max<2

[0269] In Math 46, CA_max represents the maximum effective diameter (mm) among the object-side surface and the sensor-side surface of the plurality of lenses, and TTL represents the distance on the optical axis OA from the vertex of the first surface S1 of the first lens 101 to the image surface of the image sensor 300. Math 46 establishes a relationship between the total optical axis length and the maximum effective diameter of the optical system, thereby providing a slim and compact optical system.

[0270] Mathematical formula 46 may also include mathematical formula 46-1. Here, nL is the number of lenses in the optical system, which may be 7 to 9, preferably 8.

[0271] [Mathematical formula 46-1] 0<(TTL / CA_max) / nL<0.2

[0272] [Math 47] 0.4 <TTL / (2*ImgH)<0.7

[0273] Mathematical formula 47 can set the total optical axis length (TTL) of the optical system and the diagonal length (2*Imgh) of the image sensor 300. When the optical system 1000 according to the embodiment satisfies mathematical formula 47, the optical system 1000 ensures a BFL (back focal length) to apply a relatively large image sensor 300, for example, a large image sensor 300 of about 1 inch, and can have a small TTL, thereby achieving high image quality and having a slim structure.

[0274] Math 47 may also include Math 47-1. Here, nL is the number of lenses in the optical system, which may be 7 to 9, preferably 8.

[0275] [Mathematical formula 47-1] 0 < (TTL / (2 * ImgH)) / nL < 0.2

[0276] [Mathematical formula 48]

[0277] 0.01 <BFL / ImgH<0.5

[0278] Mathematical formula 48 can set the optical axis distance between the image sensor 300 and the last lens and the length of the image sensor 300 from the optical axis in the diagonal direction. When the optical system 1000 according to the embodiment satisfies mathematical formula 48, the optical system 1000 can ensure the BFL to apply a relatively large image sensor 300, for example, a larger image sensor 300 of about 1 inch, and can minimize the distance between the last lens and the image sensor 300, so that good optical characteristics can be obtained in the center and peripheral parts of the FOV.

[0279] Math 48 may further include Math 48-1. Here, nL is the number of lenses in the optical system, which may be 7 to 9, preferably 8.

[0280] [Mathematical formula 48-1] 0 < (BFL / ImgH) / nL < 0.1

[0281] [Mathematical formula 49]4 <TTL / BFL<10

[0282] Mathematical formula 49 can set the total optical axis length (TTL) of the optical system and the optical axis distance (BFL) between the image sensor 300 and the last lens (unit: mm). In the present invention, since the sensor side surface of the last lens has no critical point, the value of mathematical formula 55 can be 5 mm or more, or 6 mm or more. When the optical system 1000 according to the embodiment satisfies mathematical formula 49, the optical system 1000 ensures the BFL and can be set to be slim and compact.

[0283] Math 49 may further include Math 49-1. Here, nL is the number of lenses in the optical system, which may be 7 to 9, preferably 8.

[0284] [Mathematical formula 49-1] 0.3 < (TTL / BFL) / nL < 1

[0285] [Math 50] 0.5 <F / TTL<1.5

[0286] Math 50 can set the total focal length (F) and the total optical axis length (TTL) of the optical system 1000. Therefore, a slim and compact optical system can be provided.

[0287] Math 50 may further include Math 50-1. Here, nL is the number of lenses in the optical system, which may be 7 to 9, preferably 8.

[0288] [Mathematical formula 50-1] 0<(F / TTL) / nL<0.3

[0289] [Mathematical formula 51]3 <F / BFL<10

[0290] Mathematical formula 51 can set the total focal length F of the optical system 1000 and the optical axis distance (BFL) between the image sensor 300 and the last lens (unit: mm). In the present invention, since there is no critical point on the sensor side surface of the last lens, the BFL value is further reduced, so the value of mathematical formula 51 can be 5 mm or more. When the optical system 1000 according to the embodiment satisfies mathematical formula 51, the optical system 1000 can have a set viewing angle, can have an appropriate focal length, and can provide a slim and compact optical system. In addition, the optical system 1000 can minimize the distance between the last lens and the image sensor 300, so that it can have good optical characteristics in the peripheral part of the FOV.

[0291] Mathematical formula 51 may also include mathematical formula 51-1. Here, nL is the number of lenses in the optical system, which may be 7 to 9, preferably 8.

[0292] [Mathematical formula 51-1] 0.2 < (F / TTL) / nL < 3

[0293] [Math 52] 0.1 <F / ImgH<3

[0294] Math 52 may set the total focal length (F, mm) of the optical system 1000 and the diagonal length Imgh at the optical axis of the image sensor 300. By applying a relatively large image sensor 300, for example, a larger image sensor 300 of about 1 inch, the optical system 1000 may have improved aberration characteristics.

[0295] Mathematical formula 52 may further include mathematical formula 52-1. Here, nL is the number of lenses in the optical system, which may be 7 to 9, preferably 8.

[0296] [Mathematical formula 52-1] 0 < (F / Imgh) / nL < 0.3

[0297] [Mathematical formula 53]1≤F / EPD<5

[0298] Equation 53 can set the overall focal length (F, mm) and entrance pupil size of the optical system 1000. Therefore, the overall brightness of the optical system can be controlled.

[0299] Mathematical formula 53 may also include mathematical formula 53-1. Here, nL is the number of lenses in the optical system, which may be 7 to 9, preferably 8.

[0300] [Mathematical formula 53-1] 0.1 < (F / EPD) / nL < 0.4

[0301] [Math 54] 0.5 <TTL / (D82x2)<1.5

[0302] In Math. 54, D82 is a straight line distance from the optical axis OA to the effective diameter of the sixteenth surface S16 of the sensor side of the eighth lens 108 and may be defined as an effective radius. The optical system may set the length in the optical axis direction and the maximum effective diameter by Math.

[0303] [Math 55] 0.5 <F2 / F<1.5

[0304] In Math 55, F2 is the focal length of the second lens 102, and F is the average of the effective focal lengths of the optical system in the X direction and the Y direction. When Math 55 is satisfied, the optical system and the camera module can improve the chromatic aberration characteristics by setting the ratio of the average effective focal lengths of the second lens in two directions X and Y orthogonal to the optical axis within a set range.

[0305] Mathematical formula 55 may include at least one of the following mathematical formulas 55-1 to 55-7.

[0306] [Mathematical formula 55-1] 1.5 <F1 / F<3.2

[0307] [Mathematical formula 55-2]-2.5 <F3 / F<0

[0308] [Mathematical formula 55-3] 5.5 <F4 / F<7

[0309] [Mathematical formula 55-4]21 <F5 / F<31

[0310] [Mathematical formula 55-5]-2.5 <F6 / F<0

[0311] [Mathematical formula 55-6] 0.5 <F7 / F<1.9

[0312] [Mathematical formula 55-7] -1.5 <F8 / F<0

[0313] In Math. Formulas 55-1 to 55-7, F1, F3, F4, F5, F6, F7, and F8 are focal lengths of the first lens, the second lens to the eighth lens, and F is an average value of the effective focal lengths of the optical system in the X direction and the Y direction. When the optical system satisfies Math. Formula 55 and Math. Formulas 55-1 to 55-7, the ratio of the average effective focal lengths of each lens in two directions X and Y orthogonal to the optical axis is set within a set range, and distortion and chromatic aberration characteristics can be improved.

[0314] [Mathematical formula 56]-5 <F2 / F3<0

[0315] When Math Formula 56 is satisfied, the optical system can improve distortion and chromatic aberration characteristics by setting the ratio of the focal lengths of the second lens and the third lens to a set range.

[0316] [Math 57] 0.8 <F2 / F12<1.8

[0317] In Math 57, F12 is a composite focal length of the first lens and the second lens. The optical system can improve distortion and chromatic aberration characteristics of the first lens group G1 by setting the ratio of the focal lengths of the first lens and the second lens to a set range according to Math 57.

[0318] [Math 58] 0.5 <F12 / F<1.5

[0319] When the optical system satisfies Math. 58, the ratio of the combined focal length of the first lens and the second lens to the average effective focal length in two directions X and Y orthogonal to the optical axis is set to a set range, distortion and chromatic aberration characteristics can be improved.

[0320] [Math 59]0 <L2R1 / |L2R2|<1

[0321] In Math. 59, L2R1 is the curvature radius of the third object-side surface of the second lens 102, and L2R2 is the curvature radius of the fourth side surface of the second lens 102 on the sensor. The optical system can improve aberration characteristics by satisfying Math. 59.

[0322] [Math 60]0 <L3R2 / |L3R1|<1

[0323] In Math 60, L3R1 is the curvature radius of the object-side fifth surface of the third lens 103, and L3R2 is the curvature radius of the sensor-side sixth surface of the third lens 103. By satisfying Math 60, the optical system can improve aberration characteristics. In addition, by satisfying Math 59 and Math 60, control can be performed with good optical performance at a set viewing angle.

[0324] [Math 61] 0.8 <n2 / n3<1.2

[0325] In Math 61, n2 is the refractive index of the second lens at the d-line, and n3 is the refractive index of the third lens 103 at the d-line. When Math 61 is satisfied, the chromatic aberration characteristic of the optical system can be improved.

[0326] [Mathematical formula 62]1 <L2_CT / L3_CT<5

[0327] By setting the center thicknesses of the second lens and the third lens within the above range in Math. 62, the optical system 1000 may have improved chromatic aberration control characteristics.

[0328] [Math 63] 0.7 <Inf71 / Inf72<1.2

[0329] In Mathematical Formula 63, Inf71 is a critical point P1 (see Figure 2 ), Inf72 is the straight-line distance from the optical axis OA to the critical point P2 of the sensor-side fourteenth surface S14 of the seventh lens 107 (see Figure 2 ). Here, the critical points P1 and P2 are critical points closest to the optical axis OA on the thirteenth surface S13 and the fourteenth surface S14 of the seventh lens 107. By satisfying the range of Mathematical Formula 63, the optical system can improve distortion aberration characteristics and provide good optical performance for the peripheral portion of the FOV.

[0330] [Math 64] 0.7 <Inf71 / Inf82<1.2

[0331] In Math. 64, Inf82 is the critical points P4 and P6 in the X direction and the Y direction from the optical axis OA to the sensor-side sixteenth surface S16 of the eighth lens 108 (see Figure 2 and Figure 3 That is, Inf82 is the average of the straight-line distances from the optical axis to the critical point P6 in the X direction from the optical axis to the sensor-side sixteenth surface S16 of the eighth lens 108 (see Figure 3 ) and the critical point P4 in the Y direction from the optical axis to the sixteenth surface S16 on the sensor side of the eighth lens 108 (see Figure 2 ) is an average of the straight-line distances InfY82 of the eighth lens 108. InfX82 and InfY82 may be different from each other, and the critical points P4 and P6 are critical points closest to the optical axis OA in the X direction and the Y direction on the sixteenth surface S16 of the eighth lens 108. By satisfying the range of mathematical formula 64, the optical system can improve the distortion aberration characteristics and provide good optical performance for the peripheral portion of the field of view.

[0332] [Math 65] 0.3 <Inf71 / D71<1.0

[0333] In Math 65, D71 is a straight-line distance from the optical axis OA to an effective diameter of the object-side thirteenth surface S13 of the seventh lens 107. By satisfying the range of Math 65, the optical system can refract light incident through the seventh lens 107 and the eighth lens 108 to the peripheral portion, improve distortion aberration characteristics, and can provide good optical performance for the peripheral portion of the FOV.

[0334] [Math 66] 0.3 <Inf72 / D72<1.0

[0335] In Math 66, D72 is a straight-line distance from the optical axis OA to the effective diameter of the sensor-side fourteenth surface S14 of the seventh lens 107. By satisfying the range of Math 66, the optical system can refract light incident through the seventh lens 107 and the eighth lens 108 to the peripheral portion, improve distortion aberration characteristics, and can provide good optical performance for the peripheral portion of the FOV.

[0336] [Math 67] 0.2 <Inf82 / D82<0.8

[0337] In Math 67, D82 is a straight-line distance from the optical axis OA to the effective diameter of the sensor-side sixteenth surface S16 of the eighth lens 108. By satisfying the range of Math 67, the optical system can refract the light passing through the eighth lens 108 to the peripheral portion, improve the distortion aberration characteristics, and can provide good optical performance for the peripheral portion of the FOV. The value of Math 67 may be 0.6 or less, for example, 0.5 or less.

[0338] [Math 68] -0.1 <FX-FY<0.1

[0339] In mathematical formula 68, FX is the effective focal length in the X direction, and FY is the effective focal length in the Y direction. That is, the effective focal lengths FX and FY in the two directions X and Y orthogonal to the optical axis OA may be different from each other. By satisfying mathematical formula 68, the optical system may have good optical performance under the set FOV and focal length. Here, FX>0, FY>0.

[0340] [Math 69] -0.1 <InfX82-InfY82<0.1

[0341] In Mathematical Formula 69, InfX82 is the critical point P6 (see Figure 3 ), InfY82 is the straight-line distance from the optical axis to the critical point P4 in the Y direction of the sixteenth surface S16 on the sensor side of the eighth lens 108 (see Figure 2 ) in a straight line distance. InfX82 and InfY82 may be different from each other. By satisfying the range of Mathematical Formula 69, the optical system can improve the distortion aberration characteristics and provide good optical performance for the peripheral part of the FOV. Here, InfX82>O, InfY82>0.

[0342] [Mathematical formula 70]

[0343] -0.5 <ZX82-ZY82<0.5

[0344] In Mathematical Formula 70, ZX82 is the critical point P6 in the X direction from the sensor-side sixteenth surface S16 of the eighth lens 108 (see Figure 3 ) to the end of the effective area (mm), ZY82 is the critical point P4 in the Y direction of the sixteenth surface S16 on the sensor side (see Figure 2 ) to the straight line distance (mm) from the end of the effective area. ZX82 and ZY82 may be different from each other. By satisfying the range of mathematical formula 70, the optical system can improve the distortion aberration characteristics and provide good optical performance for the peripheral part of the FOV.

[0345] [Mathematical formula 71]

[0346]

[0347] In mathematical formula 71, Z is the Sag value, which can represent the distance from any position on the aspheric surface to the vertex of the aspheric surface in the direction of the optical axis. Y can represent the distance from any position on the aspheric surface to the optical axis in a direction perpendicular to the optical axis. c can represent the curvature of the lens, and K can represent the cone constant. In addition, A, B, C, D, E and F can represent aspheric surface constants. In the practice of the present invention, an aspheric surface can be provided from the first surface S1 to the fifteenth surface S15.

[0348] [Mathematical formula 72]

[0349]

[0350] In Mathematical Formula 72, Z is the Sag value of the sixteenth surface S16 and can represent the distance from any position on the free-form surface to the vertex of the free-form sphere in the optical axis direction. C is the curvature value of the sixteenth surface S16 of the eighth lens 108, r is the effective diameter value of the sixteenth surface S16, k is the cone constant, Cj is the j-order Zernike function, and among the x and y polynomial coefficients, only the coefficients (m, n) of the 0th, 2nd, 4th, 6th, 8th, and 10th powers of x and y can be used, and x m y m is the j-th order Zernike basis in the x-direction and the y-direction. Fig.16 The Zernike coefficient of the sixteenth surface calculated by the above mathematical formula is shown. According to the first embodiment, the second embodiment, and the third embodiment, the sixteenth surface is a free-form surface.

[0351] The optical system 1000 according to the embodiment may satisfy at least one or two or more of Mathematical Formulas 1 to 70. In this case, the optical system 1000 may have improved optical characteristics. In detail, when the optical system 1000 satisfies at least one or two or more of Mathematical Formulas 1 to 70, the optical system 1000 has improved resolution, and may improve aberration and distortion characteristics. In addition, the optical system 1000 may ensure BFL (back focal length) to apply a large-size image sensor 300, and may minimize the distance between the last lens and the image sensor 300, so that it may have good optical performance in the center and peripheral parts of the FOV. In addition, when the optical system 1000 satisfies at least one of Mathematical Formulas 1 to 70, it may include a relatively large image sensor 300, have a relatively small TTL value, and be thinner, and provide a compact optical system and a camera module having the optical system.

[0352] In the optical system 1000 according to the embodiment, the distance between the plurality of lenses 100 may have a value set according to a region.

[0353] Figure 4 Is based on having Figure 1 An example of lens data of the first embodiment of the optical system, Figure 8 Is based on having Figure 1 An example of lens data of the second embodiment of the optical system, and Fig.12 Is based on having Figure 1 An example of lens data of the third embodiment of the optical system.

[0354] like Figure 4 , Figure 8 and Fig.12 As shown, the optical systems according to the first embodiment, the second embodiment and the third embodiment have the size of the curvature radius on the optical axis OA, the lens thickness, the distance between the lenses, the refractive index at the d line (588nm), the Abbe number of the first lens to the eighth lens 101 to 108, and the effective diameter (CA: clear aperture).

[0355] The sum of the refractive indexes of the plurality of lenses 100 is 10 or more, for example, in the range of 10 to 15, the sum of the Abbe numbers is 300 or more, for example, in the range of 300 to 350, the sum of the center thicknesses of all the lenses is 4.5 mm or less, for example, in the range of 3.5 mm to 4.5 mm, and the sum of the center distances between the first lens to the eighth lens on the optical axis may be 5 mm or less, which is less than the sum of the center thicknesses of the lenses, and may be in the range of 2.8 mm to 3.5 mm. In addition, the average value of the effective diameter of each lens surface of the plurality of lenses 100 may be 4 mm or more, for example, in the range of 4 mm to 6 mm, and the average value of the center thickness of each lens may be 0.55 mm or less, for example, in the range of 0.35 mm to 0.55 mm. The sum of the effective diameters of the plurality of lenses 100 is the effective diameter from the first surface S1 to the sixteenth surface S16, and may be 58 mm or more, for example, in the range of 58 mm to 78 mm.

[0356] like Figure 5 , Fig. 9 and Fig.13 As shown, at least one lens surface of the plurality of lenses 100 of the first embodiment, the second embodiment, and the third embodiment may include an aspheric surface having a 30th order aspheric coefficient. For example, the first to eighth lenses 101, 102, 103, 104, 105, 106, 107, 108 may include a lens surface having a 30th order aspheric coefficient from the first surface S1 to the fifteenth surface S15. As described above, an aspheric surface having a 30th order aspheric coefficient (a value other than "0") can particularly greatly change the aspheric shape of the peripheral portion, thereby being able to well correct the optical performance of the peripheral portion of the FOV.

[0357] Figure 6 is a graph showing light aberration characteristics of the optical system in the second direction X according to the first embodiment of the present invention, Figure 7 is a graph showing light aberration characteristics of the optical system in the first direction Y according to the first embodiment, Fig.10 is a graph showing light aberration characteristics of the optical system in the second direction X according to the second embodiment of the present invention, Fig.11 is a graph showing light aberration characteristics of an optical system in a first direction Y according to a second embodiment of the present invention, Fig.14 is a graph showing light aberration characteristics of the optical system in the second direction X according to the third embodiment of the present invention, and Fig.15 : is a graph showing light aberration characteristics in the first direction Y of the optical system according to the third embodiment of the present invention.

[0358] like Figure 6 , Figure 7 , Fig.10 , Fig.11 , Fig.14 and Fig.15 As shown, these graphs are analysis diagrams showing the lateral aberration in the first direction X and the second direction Y in the region where the relative field height on the optical axis in the tangential field curvature and the spherical field curvature is 0.0 to 1.0 according to the first to third embodiments, and it can be confirmed that an optical system with a good lateral aberration correction state can be obtained for light of wavelength bands of about 470nm, about 510nm, about 555nm, about 610nm, and about 650nm. That is, the optical system 1000 according to the embodiment can have improved resolution and good optical performance not only in the central part of the FOV but also in the peripheral part. As confirmed in the above examples, the lens system according to the first embodiment of the present invention is compact and lightweight, has an eight-lens configuration, and spherical aberration, astigmatism, distortion aberration, chromatic aberration, and coma aberration are all well corrected, so that high resolution can be achieved, so it can be used by being embedded in the optical device of the camera.

[0359] Table 1 relates to each of the above mathematical formulas in the optical system 1000 according to the first to third embodiments, and relates to TTL, BFL (back focal length), F value (which is the total effective focal length of the optical system 1000), ImgH, the focal length F1, F2, F3, F4, F5, F6, F7, F8 of each of the first to eighth lenses, the composite focal length, etc.

[0360]

Table 1

[0361]

[0362]

[0363] Table 2 shows the Figure 1 Table of effective radii (semi-apertures) (mm) of L1 to L8 and S1-S16 of the first to eighth lenses of the first embodiment, the second embodiment, and the third embodiment of the optical system 1000.

[0364]

Table 2

[0365]

[0366]

[0367] Table 3 involves Figure 1Result values ​​of the above mathematical formulas 1 to 70 in the optical system 1000. Referring to Table 3, it can be seen that the optical system 1000 satisfies at least one, two or more, or three or more of the mathematical formulas 1 to 70. In detail, it can be seen that the optical system 1000 according to the embodiment satisfies all of the above mathematical formulas 1 to 70. Therefore, the optical system 1000 can improve the optical performance and optical characteristics of the center and peripheral parts of the FOV.

[0368]

Table 3

[0369]

[0370]

[0371]

[0372]

[0373] Fig.17 It is shown Figure 1 This is a view of a distortion grid of the actual FOV and the paraxial FOV of the horizontal FOV (field of view) and the vertical FOV in the optical system of FIG. This is a distortion grid that occurs when light is emitted from the optical system according to the first to third embodiments, and it can be seen that the distortion occurs uniformly toward the left and right edges and the upper edge of the horizontal FOV and the vertical FOV.

[0374] Fig.18 is a diagram showing that a camera module according to an embodiment is applied to a mobile terminal.

[0375] refer to Fig.18 , the mobile terminal 1 may include a camera module 10 disposed at the rear side. The camera module 10 may include an image capture function. In addition, the camera module 10 may include at least one of an auto focus function, a zoom function, and an OIS function.

[0376] The camera module 10 can process still images or video frames obtained by the image sensor 300 in a shooting mode or a video call mode. The processed image frames can be displayed on a display unit (not shown) of the mobile terminal 1 and can be stored in a memory (not shown). In addition, although not shown in the figure, the camera module can also be set on the front side of the mobile terminal 1.

[0377] For example, the camera module 10 may include a first camera module 10A and a second camera module 10B. At this time, at least one of the first camera module 10A and the second camera module 10B may include the above-mentioned optical system 1000. Therefore, the camera module 10 may have a slim structure and may have improved distortion and aberration characteristics. In addition, the camera module 10 may have good optical performance even in the center and peripheral parts of the FOV.

[0378] In addition, the mobile terminal 1 may further include an autofocus device 31. The autofocus device 31 may include an autofocus function using a laser. The autofocus device 31 may be mainly used under conditions where the autofocus function of the image using the camera module 10 is degraded, such as a distance of 10 m or less or a dark environment. The autofocus device 31 may include a light emitting unit including a vertical cavity surface emitting laser (VCSEL) semiconductor device, and a light receiving unit that converts light energy into electrical energy, such as a photodiode.

[0379] In addition, the mobile terminal 1 may further include a flash module 33. The flash module 33 may include a light emitting element that emits light therein. The flash module 33 may be operated by a camera operation of the mobile terminal or a user's control.

[0380] The features, structures, effects, etc. described in the above embodiments are all included in at least one embodiment of the present invention, and are not necessarily limited to one embodiment. In addition, the features, structures, effects described in each embodiment can be combined or modified by a person skilled in the art of the embodiment relative to other embodiments. Therefore, the contents related to these combinations and modifications should be understood to be included in the scope of the present invention.

[0381] In addition, although described based on the embodiment, this is only an example, and the present invention is not limited thereto. It will be clear to those skilled in the art that various modifications and applications not described above can be made without departing from the essential features of the present embodiment. For example, each component specifically shown in the embodiment can be modified and implemented. Moreover, the differences associated with these modifications and applications should be understood to be included within the scope of the present invention defined in the appended claims.

Claims

1. An optical system, comprising: The first lens to the eighth lens are arranged along the optical axis from the object side toward the sensor side. Wherein, the first lens has positive (+) refractive power or negative (-) refractive power on the optical axis, wherein the second lens has positive (+) refractive power on the optical axis, The third lens has negative (-) refractive power on the optical axis. The seventh lens has positive (+) refractive power on the optical axis. The eighth lens has a negative (-) refractive power on the optical axis. At least one of the object-side surface and the sensor-side surface of the seventh lens has at least one critical point. wherein each of the object-side surface and the sensor-side surface of the eighth lens has a critical point, wherein at least one of the object-side surface and the sensor-side surface of the eighth lens has a free-form surface shape in which a lens surface orthogonal to the optical axis in a first direction and a lens surface orthogonal to the optical axis in a second direction are asymmetric, and The free-form surface has lens surfaces that are symmetrical about the optical axis on both sides of the first direction, and lens surfaces that are symmetrical about the optical axis on both sides of the second direction.

2. The optical system according to claim 1, in, Each of the object-side surface and the sensor-side surface of the seventh lens has a critical point, Wherein, a critical point of the object-side surface of the seventh lens is positioned closer to the optical axis than a critical point of the sensor-side surface of the seventh lens.

3. The optical system according to claim 1, in, The object-side surface of the seventh lens has a convex shape on the optical axis, Wherein, a sensor-side surface of the seventh lens has a concave shape on the optical axis.

4. The optical system according to claim 3, in, a sensor-side surface of the third lens has a concave shape on the optical axis, The object-side surface of the fourth lens has a concave shape on the optical axis.

5. The optical system according to claim 3, in, An object-side surface of the fifth lens has a concave shape on the optical axis, and has a maximum value among absolute values ​​of radii of curvature of lens surfaces of the optical system.

6. The optical system according to any one of claims 1 to 5, in, an object-side surface of the second lens has a convex shape on the optical axis, and a sensor-side surface of the second lens has a convex shape on the optical axis, The thickness of the second lens on the optical axis is the maximum value among the lens thicknesses of the optical system.

7. An optical system according to any one of claims 1 to 5, in, The sensor-side surface of the eighth lens has a free-form surface, The distance from the optical axis to the critical point of the sensor-side surface of the eighth lens in the first direction is different from the distance from the optical axis to the critical point of the sensor-side surface of the eighth lens in the second direction.

8. The optical system according to claim 7, in, The object-side surface of the eighth lens is aspherical.

9. The optical system according to any one of claims 1 to 5, in, An optical axis distance between the seventh lens and the eighth lens is greater than a sum of a center thickness of the seventh lens and a center thickness of the eighth lens, and is 1.8 times or more the thickness of a lens having a maximum thickness among the first to eighth lenses.

10. The optical system according to claim 7, in, A straight line distance InfX82 from the optical axis to a critical point of the sensor-side surface of the eighth lens in the first direction and a straight line distance InfY82 from the optical axis to a critical point of the sensor-side surface of the eighth lens in the second direction are different from each other, and Among them, the following mathematical formula is satisfied: Mathematical formula: -0.1 <InfX82-InfY82<0.1 Mathematical formula: 0.4 <TTL / (Imgh*2)<0.7 (TTL (total lens length) is the distance on the optical axis from the vertex of the object-side surface of the first lens to the image surface of the image sensor, and Imgh is 1 / 2 of the maximum diagonal length of the image sensor).

11. An optical system comprising: A first lens group on the object side having three or fewer lenses; as well as a second lens group on the sensor side of the first lens group having five or fewer lenses, Wherein, the first lens group has positive (+) refractive power on the optical axis, Wherein, the second lens group has negative (-) refractive power on the optical axis, The number of lenses in the second lens group is less than twice the number of lenses in the first lens group. Among them, on the lens surfaces of the first lens group and the second lens group, the lens closest to the second lens group has the smallest effective diameter, The last lens closest to the image sensor in the lens surfaces of the first lens group and the second lens group has the largest effective diameter, wherein a sensor-side surface of the first lens group closest to the second lens group has a concave shape, wherein the object-side surface of the second lens group closest to the first lens group has a concave shape, wherein the sensor side surface of the last lens has a free-form surface shape with a critical point, wherein a sensor side surface closest to the image sensor has a free-form surface shape in which a lens surface orthogonal to the optical axis in a first direction and a lens surface orthogonal to the optical axis in a second direction are asymmetric, and The free-form surface has lens surfaces that are symmetrical on both sides of the optical axis in the first direction, and lens surfaces that are symmetrical on both sides of the optical axis in the second direction.

12. The optical system according to claim 11, in, A straight line distance InfX82 from the optical axis to a critical point of the sensor side surface of the last lens in the first direction and a straight line distance InfY82 from the optical axis to a critical point of the sensor side surface of the last lens in the second direction are different from each other and satisfy the following mathematical formula: Mathematical formula: -0.1 <InfX82-InfY82<0.1。 13. The optical system according to claim 11 or 12, in, The total focal length FX in the first direction and the total focal length FY in the second direction are different from each other and satisfy the following mathematical formula: Mathematical formula: -0.1 <FX-FY<0.1。 14. The optical system according to claim 11 or 12, in, Satisfies the following mathematical formula: Mathematical formula: 0.4 <TTL / (Imgh*2)<0.7 (TTL (total lens length) is the distance on the optical axis from the vertex of the object-side surface of the first lens to the image surface of the image sensor, and Imgh is 1 / 2 of the maximum diagonal length of the image sensor).

15. The optical system according to claim 11 or 12, in, The first lens group includes first to third lenses arranged along the optical axis from the object side toward the sensor side, The second lens group includes fourth to eighth lenses arranged along the optical axis from the object side toward the sensor side. wherein each of an object-side surface and a sensor-side surface of the seventh lens has a critical point, and Wherein, the object-side surface of the eighth lens has a critical point.

16. The optical system according to claim 15, in, The straight-line distance Inf71 from the optical axis to the critical point of the object-side surface of the seventh lens and the straight-line distance Inf72 from the optical axis to the critical point of the sensor-side surface of the seventh lens satisfy the following mathematical formula: Mathematical formula: 0.7 <Inf71 / Inf72<1.2。 17. The optical system according to claim 15, in, The average value Inf82 of the straight-line distance Inf71 from the optical axis to the critical point of the object-side surface of the seventh lens and the straight-line distances InfX82 and InfY82 from the optical axis to the critical points in the X direction and the Y direction of the sensor-side surface of the eighth lens satisfies the following mathematical formula: Mathematical formula: 0.7 <Inf71 / Inf82<1.2。 18. The optical system according to claim 15, in, The seventh lens has positive (+) refractive power and has a convex object-side surface and a concave sensor-side surface, The eighth lens has negative (-) refractive power and has a convex object-side surface and a concave sensor-side surface.

19. The optical system according to claim 18, in, The average value Inf82 of the straight-line distances InfX82 and InfY82 to the critical points in the X and Y directions of the sensor-side surface of the eighth lens and the straight-line distance D82 from the optical axis of the eighth lens to the end of the effective area satisfy the following mathematical formula: Mathematical formula: 0.2 <Inf82 / D82<0.8。 20. The optical system according to claim 15, in, The center thickness L2_CT of the second lens and the center thickness L3_CT of the third lens satisfy the following mathematical formula: Mathematical formula: 1 <L2_CT / L3_CT<5。 21. The optical system according to claim 20, in, An optical axis distance between the seventh lens and the eighth lens is 1.8 times or more of a center thickness of the second lens.

22. A camera module, comprising: Image sensor; as well as a filter disposed between the image sensor and the last lens of the optical system, Wherein, the optical system comprises the optical system according to claim 1 or 11, Among them, the following mathematical formula is satisfied: Mathematical formula: 0.5 <F / TTL<1.2 (F is the average value of the total focal length in two directions orthogonal to the optical axis of the optical system, and TTL (total lens length) is the distance on the optical axis from the vertex of the object-side surface of the first lens to the image surface of the image sensor).

Images