Optical image capturing system

Abstract

An optical imaging system is provided. The optical image capturing system includes a first lens having a positive refractive power, a second lens having a negative refractive power, a third lens having a refractive index greater than 1.66, a fourth lens having a positive refractive power, a sixth lens having a negative refractive power, a seventh lens having a refractive index greater than 1.66, and an eighth lens disposed in order from an object side toward an image plane. And wherein the optical imaging system satisfies the following conditional expression: TTL / (2 * IMG HT) lt; tTL is the distance on the optical axis from the object side surface of the first lens to the imaging surface, and IMG HT is half the diagonal length of the imaging surface.

Description

[0001] Cross - reference to related applications

[0002] This application claims the benefit of priority to Korean Patent Application No. 10 - 2023 - 0171739, filed on November 30, 2023, with the Korean Intellectual Property Office, the entire disclosure of which is incorporated herein by reference for all purposes. Technical field

[0003] The following description relates to an optical imaging system. Background art

[0004] Portable terminals are equipped with cameras including an optical imaging system composed of a plurality of lenses to enable video calls and image capture.

[0005] In addition, as the functions implemented by cameras in portable terminals gradually increase, the demand for cameras with high resolution for portable terminals is also growing.

[0006] Recently, in order to achieve clearer image quality, image sensors with high pixels (e.g., 13 million to 100 million pixels) have been implemented in cameras for portable terminals.

[0007] In other words, the size of the image sensor has increased, and as a result, the total track length of the optical imaging system has also increased, which may ultimately cause the camera to protrude from the portable terminal.

[0008] As portable terminals are gradually becoming smaller and smaller, it is beneficial if the cameras for portable terminals have a thin form factor. Therefore, it is desirable to develop an optical imaging system that is both thin and capable of achieving high resolution. Summary of the invention

[0009] The Summary of the Invention section is intended to introduce, in a brief form, a selection of concepts that will be further described in the Detailed Description section below. The Summary of the Invention section is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to help determine the scope of the claimed subject matter.

[0010] In general, the optical imaging system includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, and an eighth lens arranged in sequence from the object side toward the imaging surface, where the first lens has a positive refractive power, and the second lens has a negative refractive power, where each of the second lens and the third lens has a refractive index greater than 1.66, and where the optical imaging system satisfies the following conditional expression: TTL / (2×IMG HT)<0.64, where TTL is the distance on the optical axis from the object side surface of the first lens to the imaging surface, and IMG HT is half of the diagonal length of the imaging surface.

[0011] Each of at least three lenses including the second lens and the third lens among the first lens to the eighth lens may have a refractive index greater than 1.66, and the absolute value of the focal length of the second lens among the at least three lenses having a refractive index greater than 1.66 is the smallest absolute value.

[0012] The fifth lens may have a refractive index greater than 1.66, and where the optical imaging system satisfies the following conditional expression: |v1-(v2+v3+v5)|<10, where v1 is the Abbe number of the first lens, v2 is the Abbe number of the second lens, v3 is the Abbe number of the third lens, and v5 is the Abbe number of the fifth lens.

[0013] The following conditional expressions may be satisfied: 25<v1-v2<45 and 25<v1-v3<45, where v1 is the Abbe number of the first lens, v2 is the Abbe number of the second lens, and v3 is the Abbe number of the third lens.

[0014] The following conditional expression may be satisfied: 15<v1-(v2+v3)<25, where v1 is the Abbe number of the first lens, v2 is the Abbe number of the second lens, and v3 is the Abbe number of the third lens.

[0015] The following conditional expression may be satisfied: 1.3<Fno<1.6, where Fno is the F-number of the optical imaging system.

[0016] The following conditional expression may be satisfied: 0.9<f1 / f<1.2, where f1 is the focal length of the first lens, and f is the total focal length of the optical imaging system.

[0017] The following conditional expression may be satisfied: -3<f2 / f<-1, where f2 is the focal length of the second lens, and f is the total focal length of the optical imaging system.

[0018] The following conditional expression may be satisfied: |f3 / f|>30, where f3 is the focal length of the third lens, and f is the total focal length of the optical imaging system.

[0019] It can satisfy the following conditional expression: 0.3 < |f1 / f2| < 0.6, where f1 is the focal length of the first lens and f2 is the focal length of the second lens.

[0020] It can satisfy the following conditional expression: |f1 / f3| < 0.05, where f1 is the focal length of the first lens and f3 is the focal length of the third lens.

[0021] It can satisfy the following conditional expression: |f2 / f3| < 0.08, where f2 is the focal length of the second lens and f3 is the focal length of the third lens.

[0022] It can satisfy the following conditional expression: 1.3 < f12 / f < 1.7, where f12 is the combined focal length of the first lens and the second lens, and f is the total focal length of the optical imaging system.

[0023] It can satisfy the following conditional expression: 1.3 < f123 / f < 1.7, where f123 is the combined focal length from the first lens to the third lens.

[0024] The fourth lens can have a positive refractive power, and the fifth lens can have a negative refractive power.

[0025] The sixth lens can have a positive refractive power, the seventh lens can have a positive refractive power, and the eighth lens can have a negative refractive power.

[0026] Based on the accompanying drawings and the following detailed description, other features and aspects will be apparent. Description of the Drawings

[0027] Figure 1 A configuration diagram of an exemplary optical imaging system according to a first exemplary embodiment is shown.

[0028] Figure 2 Shows Figure 1 The aberration characteristics of the exemplary optical imaging system shown in

[0029] Figure 3 A configuration diagram of an exemplary optical imaging system according to a second exemplary embodiment is shown.

[0030] Figure 4 Shows Figure 3 The aberration characteristics of the exemplary optical imaging system shown in

[0031] Figure 5 A configuration diagram of an exemplary optical imaging system according to a third exemplary embodiment is shown.

[0032] Figure 6 Shows Figure 5 The aberration characteristics of the exemplary optical imaging system shown in

[0033] Throughout the drawings and the detailed description, unless otherwise described or specified, it is to be understood that the same reference numerals may refer to the same or similar elements, features, and structures. For clarity, illustration, and convenience purposes, the drawings may not be drawn to scale, and the relative dimensions, proportions, and descriptions of the elements in the drawings may be exaggerated. Detailed Description

[0034] The following detailed description is provided to assist the reader in obtaining a comprehensive understanding of the methods, apparatuses, and / or systems described herein. However, various changes, modifications, and equivalents of the methods, apparatuses, and / or systems described herein will be apparent after understanding the disclosure of this application. For example, the order of operations described herein and / or the order of the operations described herein are merely examples and, except for the order of operations and / or the order of operations that must occur in a particular sequence, are not limited to the sequences set forth herein and may be changed, which will be apparent after understanding the disclosure of this application. As another example, the order of operations and / or the order of operations may be performed in parallel, except for the order of operations and / or the order of operations that must occur in a sequence (e.g., a particular sequence). Additionally, descriptions of features known after understanding the disclosure of this application may be omitted for greater clarity and conciseness.

[0035] The features described herein may be implemented in different forms and should not be construed as limited to the examples described herein. Rather, the examples described herein are provided only to illustrate some of the many possible ways of implementing the methods, apparatuses, and / or systems described herein that will be apparent after understanding the disclosure of this application. In this document, the term "may" (e.g., with respect to what an example or embodiment may include or implement) means that there is at least one example or embodiment in which such a feature is included or implemented, while all examples or embodiments are not so limited. The terms "example" or "embodiment" used herein have the same meaning. For example, the phrase "in one example" has the same meaning as "in one embodiment," and "in one or more examples" has the same meaning as "in one or more embodiments."

[0036] The terms used herein are for describing various examples only and are not intended to limit the disclosure. Unless the context clearly indicates otherwise, the words "a", "an", and "the" are intended to include the plural forms as well. As used herein, the phrase "and / or" includes any one of the associated listed items and any combination of any two or more of them. As a non-limiting example, the phrases "comprising", "including", and "having" indicate the presence of the stated features, quantities, operations, components, elements, and / or combinations thereof, but do not preclude the presence or addition of one or more other features, quantities, operations, components, elements, and / or combinations thereof, or the presence of alternative stated features, quantities, operations, components, elements, and / or combinations thereof. Additionally, although one embodiment may state that the phrases "comprising", "including", and "having" indicate the presence of the stated features, quantities, operations, components, elements, and / or combinations thereof, there may be other embodiments in which one or more of the stated features, quantities, operations, components, elements, and / or combinations thereof are absent.

[0037] Throughout the specification, when a component, element, or layer is described as "on another component, element, or layer", "connected to", "coupled to", or "joined to" another component, element, or layer, it can be directly "on another component, element, or layer", "connected to", "coupled to", or "joined to" another component, element, or layer (e.g., in contact with another component, element, or layer), or there can reasonably be one or more other components, elements, or layers between that component, element, or layer and that other component, element, or layer. When a component, element, or layer is described as "directly on another component, element, or layer", "directly connected to", "directly coupled to", or "directly joined to" another component, element, or layer, then there are no other components, elements, or layers between that component, element, or layer and that other component, element, or layer. Similarly, expressions such as "between" and "directly between" and "adjacent" and "directly adjacent" can also be interpreted as described previously.

[0038] Although terms such as "first", "second", and "third" or A, B, (a), (b), etc. may be used herein to describe various components, parts, regions, layers, or portions, these components, parts, regions, layers, or portions are not limited by these terms. None of these terms is used to define, for example, the importance, sequence, or order of the corresponding components, parts, regions, layers, or portions, but are only used to distinguish the corresponding components, parts, regions, layers, or portions from other components, parts, regions, layers, or portions. Thus, without departing from the teachings of the examples described herein, the first component, first part, first region, first layer, or first portion mentioned in these examples can also be referred to as the second component, second part, second region, second layer, or second portion.

[0039] As used herein, the phrase "and / or" includes any one of the associated listed items and any combination of any two or more of them. Phrases such as "at least one of A, B, and C" are intended to have a disjunctive meaning, and such phrases as "at least one of A, B, and C" also include examples where one or more of A, B, and C may be present (e.g., any combination of one or more of A, B, and C), unless the corresponding description and implementation require the enumeration (e.g., "at least one of A, B, and C") to be interpreted as having a conjunctive meaning.

[0040] One or more examples can provide an optical imaging system capable of achieving high resolution and having a small total length.

[0041] In one or more exemplary embodiments of the following lens configurations, for illustrative purposes, the thickness, size, and shape of the lenses are slightly exaggerated. In particular, the spherical or aspherical shapes shown in the lens configuration diagrams are illustrative but not limited thereto.

[0042] The first lens refers to the lens closest to the object side, and the eighth lens refers to the lens closest to the imaging surface (or image sensor).

[0043] In addition, in one or more examples, the units of values such as the radius of curvature, thickness, distance, focal length, etc. of the lenses are all millimeters (mm), and the unit of the field of view (FOV) is degrees.

[0044] In addition, in the description of the shape of each lens, a shape with a convex surface means that the paraxial region of one surface is convex, and a shape with a concave surface means that the paraxial region of one surface is concave. Therefore, even if one surface of the lens is described as having a convex shape, the edge portion of the lens may be concave. Similarly, even if one surface of the lens is described as having a concave shape, the edge portion of the lens may be convex.

[0045] The paraxial region refers to a very narrow region close to the optical axis.

[0046] The imaging surface may refer to a virtual plane on which the optical imaging system forms a focal point. Alternatively, the imaging surface may refer to a surface of the image sensor that receives light.

[0047] An optical imaging system according to one or more exemplary embodiments may include eight lenses.

[0048] In an example, an optical imaging system according to an embodiment may include a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, and an eighth lens sequentially arranged from an object side toward an imaging surface. The first lens to the eighth lens are spaced apart from each other by a predetermined distance along an optical axis.

[0049] An optical imaging system according to one or more embodiments may include not only eight lenses, and may further include other components as needed.

[0050] In an example, the exemplary optical imaging system may further include an image sensor that converts an incident image of an object into an electrical signal.

[0051] In addition, the exemplary optical imaging system may further include an infrared filter (hereinafter referred to as "filter") that blocks infrared rays. The filter may be disposed between the eighth lens and the image sensor.

[0052] In addition, the exemplary optical imaging system may further include a diaphragm for controlling the amount of light.

[0053] The first lens to the eighth lens constituting the exemplary optical imaging system according to one or more exemplary embodiments may be formed of a plastic material.

[0054] In addition, at least one of the first lens to the eighth lens may have an aspherical surface. In addition, each of the first lens to the eighth lens may have at least one aspherical surface.

[0055] In an example, at least one of the object side surface and the image side surface of the first lens to the eighth lens may be aspherical. In this example, the aspherical surface of the first lens to the eighth lens is represented by Equation 1 below:

[0056] Equation 1:

[0057]

[0058] In Equation 1, c is the curvature of the lens (the reciprocal of the radius of curvature), K is the conic constant, and Y represents the distance from a specific point on the aspherical surface of the lens to the optical axis. In addition, the constants A to H, J, and L to P refer to aspherical coefficients. Z (SAG) represents the distance in the optical axis direction between a specific point on the aspherical surface of the lens and the vertex of the aspherical surface.

[0059] An optical imaging system according to one or more exemplary embodiments may satisfy at least one of the following conditional expressions.

[0060] According to an embodiment, the optical imaging system can satisfy the conditional expression TTL / (2×IMG HT) < 0.64. In this example, TTL is the distance from the object side surface of the first lens to the imaging surface on the optical axis, and IMG HT is half of the diagonal length of the imaging surface. Therefore, the optical imaging system can be miniaturized.

[0061] According to an embodiment, the optical imaging system can satisfy the conditional expression 1.3 < Fno < 1.6. In this example, Fno is the F-number of the optical imaging system. Therefore, the image brightness and resolution can be improved.

[0062] According to an embodiment, the optical imaging system can satisfy the conditional expression 25 < v1 - v2 < 45. In this example, v1 is the Abbe number of the first lens, and v2 is the Abbe number of the second lens.

[0063] According to an embodiment, the optical imaging system can satisfy the conditional expression 25 < v1 - v3 < 45. In this example, v3 is the Abbe number of the third lens.

[0064] According to an embodiment, the optical imaging system can satisfy the conditional expression 15 < v1 - (v2 + v3) < 25.

[0065] According to an embodiment, the optical imaging system can satisfy the conditional expression |v1 - (v2 + v3 + v5)| < 10. In this example, v5 is the Abbe number of the fifth lens.

[0066] According to an embodiment, the optical imaging system can satisfy the conditional expression 0.9 < f1 / f < 1.2. In this example, f1 is the focal length of the first lens, and f is the total focal length of the optical imaging system.

[0067] According to an embodiment, the optical imaging system can satisfy the conditional expression -3 < f2 / f < -1. In this example, f2 is the focal length of the second lens.

[0068] According to an embodiment, the optical imaging system can satisfy the conditional expression |f3 / f| > 30. In this example, f3 is the focal length of the third lens.

[0069] According to an embodiment, the optical imaging system can satisfy the conditional expression 2.5 < f4 / f < 5. In this example, f4 is the focal length of the fourth lens.

[0070] According to an embodiment, the optical imaging system can satisfy the conditional expression -10 < f5 / f < -4. In this example, f5 is the focal length of the fifth lens.

[0071] According to an embodiment, the optical imaging system can satisfy the conditional expression 0.3 < |f1 / f2| < 0.6.

[0072] According to an embodiment, the optical imaging system may satisfy the conditional expression |f1 / f3| < 0.05.

[0073] According to an embodiment, the optical imaging system may satisfy the conditional expression |f2 / f3| < 0.08.

[0074] According to an embodiment, the optical imaging system may satisfy the conditional expression 1.3 < f12 / f < 1.7. In this example, f12 is the combined focal length of the first lens and the second lens.

[0075] According to an embodiment, the optical imaging system may satisfy the conditional expression 1.3 < f123 / f < 1.7. In this example, f123 is the combined focal length of the first lens, the second lens, and the third lens.

[0076] The first lens to the eighth lens constituting an exemplary optical imaging system according to one or more embodiments will be described.

[0077] The first lens may have a positive refractive power. In addition, the first lens may have a meniscus shape convex toward the object side. Additionally, the object side surface of the first lens may be convex, and the image side surface of the first lens may be concave.

[0078] At least one of the object side surface and the image side surface of the first lens may be aspherical. In the example, both the object side surface and the image side surface of the first lens may be aspherical.

[0079] The second lens may have a negative refractive power. In addition, the second lens may have a meniscus shape convex toward the object side. Additionally, the object side surface of the second lens may be convex, and the image side surface of the second lens may be concave.

[0080] At least one of the object side surface and the image side surface of the second lens may be aspherical. In the example, both the object side surface and the image side surface of the second lens may be aspherical.

[0081] The third lens may have a positive or negative refractive power. In addition, the third lens may have a meniscus shape convex toward the object side. In addition, the object side surface of the third lens may be convex, and the image side surface of the third lens may be concave.

[0082] At least one of the object side surface and the image side surface of the third lens may be aspherical. In the example, both the object side surface and the image side surface of the third lens may be aspherical.

[0083] The fourth lens may have a positive refractive power. In addition, the fourth lens may have a meniscus shape convex toward the image side. Additionally, the object side surface of the fourth lens may be concave, and the image side surface of the fourth lens may be convex.

[0084] At least one of the object side and the image side of the fourth lens may be aspherical. For example, both the object side and the image side of the fourth lens may be aspherical.

[0085] The fifth lens may have a negative refractive power. In addition, the fifth lens may have a meniscus shape convex toward the image side. The object side of the fifth lens may be concave, and the image side of the fifth lens may be convex.

[0086] At least one of the object side and the image side of the fifth lens may be aspherical. For example, both the object side and the image side of the fifth lens may be aspherical.

[0087] The sixth lens may have a positive refractive power. In addition, the sixth lens may have a meniscus shape convex toward the object side. Additionally, the object side of the sixth lens may be convex, and the image side of the sixth lens may be concave.

[0088] At least one of the object side and the image side of the sixth lens may be aspherical. For example, both the object side and the image side of the sixth lens may be aspherical.

[0089] The sixth lens may have at least one anastigmatic point formed on at least one of its object side and image side. For example, the object side of the sixth lens may be convex in the paraxial region and concave in the portion other than the paraxial region. The image side of the sixth lens may be concave in the paraxial region and convex in the portion other than the paraxial region.

[0090] The seventh lens may have a positive refractive power. In addition, the seventh lens may have a shape with both of its surfaces convex. Additionally, the object side and the image side of the seventh lens may be convex.

[0091] At least one of the object side and the image side of the seventh lens may be aspherical. In an example, both the object side and the image side of the seventh lens may be aspherical.

[0092] Additionally, the seventh lens may have at least one anastigmatic point formed on at least one of its object side and image side. For example, the object side of the seventh lens may be convex in the paraxial region and concave in the portion other than the paraxial region. The image side of the seventh lens may be convex in the paraxial region and concave in the portion other than the paraxial region.

[0093] The eighth lens may have a negative refractive power. In addition, the eighth lens may have a shape with both of its surfaces concave. Additionally, the object side and the image side of the eighth lens may be concave.

[0094] At least one of the object side and the image side of the eighth lens may be aspherical. For example, both the object side and the image side of the eighth lens may be aspherical.

[0095] In addition, the eighth lens may have at least one inflection point formed on at least one of its object side and image side. In an example, the object side of the eighth lens may be concave in the paraxial region and convex in the portion other than the paraxial region. The image side of the eighth lens may be concave in the paraxial region and convex in the portion other than the paraxial region.

[0096] The second lens and the third lens may each be configured to have a refractive index greater than that of the first lens.

[0097] In an embodiment, the second lens and the third lens may each have a refractive index greater than 1.66.

[0098] Among the first lens to the eighth lens, at least three lenses including the second lens and the third lens may have a refractive index greater than 1.66. In an example, the second lens, the third lens, and the fifth lens may each have a refractive index greater than 1.66.

[0099] In an embodiment, the refractive index of the fifth lens may be greater than the refractive indices of the second lens and the third lens, respectively. In an example, the fifth lens may have a refractive index greater than 1.68.

[0100] In an exemplary optical imaging system, among the lenses having a refractive index greater than 1.66, at least two lenses may be configured to have a negative refractive power.

[0101] In an exemplary optical imaging system, among the lenses having a refractive index greater than 1.66, the absolute value of the focal length of the second lens may be the smallest.

[0102] The Abbe number of the third lens may be less than 50, the Abbe number of the fourth lens may be greater than 50, and the Abbe number of the fifth lens may be less than 50.

[0103] In addition, the Abbe numbers of the seventh lens and the eighth lens may each be greater than 50.

[0104] Reference will be made to Figure 1 and Figure 2 to describe an exemplary optical imaging system according to the first embodiment.

[0105] The exemplary optical imaging system 100 according to the first embodiment may include a first lens 110, a second lens 120, a third lens 130, a fourth lens 140, a fifth lens 150, a sixth lens 160, a seventh lens 170, and an eighth lens 180, and may further include a filter 190 and an image sensor.

[0106] The optical imaging system according to the first embodiment may form a focal point (or a focused image) on the imaging surface 191. The imaging surface 191 may refer to the surface on which the optical imaging system forms a focal point. As an example, the imaging surface 191 may refer to one surface of the image sensor that receives light.

[0107] The lens characteristics (radius of curvature, thickness of the lens or distance between lenses, refractive index, Abbe number, and effective radius) of each lens are shown in Table 1 below.

[0108] Table 1

[0109] Face number Component Radius of curvature Thickness or distance Refractive index Abbe number Effective radius S1 First lens 2.833 1.022 1.5463 55.99 2.060 S2 13.581 0.030 1.955 S3 Second lens 6.308 0.230 1.6789 19.24 1.853 S4 3.804 0.518 1.671 S5 Third lens 24.920 0.282 1.6789 19.24 1.660 S6 26.058 0.242 1.660 S7 Fourth lens -224.294 0.633 1.5463 55.99 1.730 S8 -11.048 0.143 1.932 S9 Fifth lens -10.328 0.239 1.6892 18.15 2.154 S10 -14.338 0.362 2.228 S11 Sixth lens 3.999 0.366 1.5707 37.40 2.843 S12 4.482 0.647 3.267 S13 Seventh lens 6.378 0.640 1.5371 55.74 3.463 S14 -9.640 0.988 3.877 S15 Eighth lens -10.942 0.353 1.5371 55.74 4.357 S16 3.067 0.200 4.729 S17 Filter Infinity 0.210 5.724 S18 Infinity 0.662 5.814 S19 Imaging plane Infinity 6.335

[0110] In the first embodiment, the first lens 110 may have a positive refractive power, the object side surface of the first lens 110 may be convex, and the image side surface of the first lens 110 may be concave.

[0111] The second lens 120 may have a negative refractive power, the object side surface of the second lens 120 may be convex, and the image side surface of the second lens 120 may be concave.

[0112] The third lens 130 may have a positive refractive power, the object side surface of the third lens 130 may be convex, and the image side surface of the third lens 130 may be concave.

[0113] The fourth lens 140 may have a positive refractive power, the object side surface of the fourth lens 140 may be concave, and the image side surface of the fourth lens 140 may be convex.

[0114] The fifth lens 150 may have a negative refractive power, the object side surface of the fifth lens 150 may be concave, and the image side surface of the fifth lens 150 may be convex.

[0115] The sixth lens 160 may have a positive refractive power, the object side surface of the sixth lens 160 may be convex, and the image side surface of the sixth lens 160 may be concave.

[0116] In addition, the sixth lens 160 may have at least one inflection point formed on at least one of its object side and image side. In an example, the object side of the sixth lens 160 may be convex in the paraxial region and concave in portions other than the paraxial region. Additionally, the image side of the sixth lens 160 may be concave in the paraxial region and convex in portions other than the paraxial region.

[0117] The seventh lens 170 may have a positive refractive power, and the object side and image side of the seventh lens 170 may be convex in the paraxial region.

[0118] In addition, the seventh lens 170 may have at least one inflection point formed on at least one of its object side and image side. For example, the object side of the seventh lens 170 may be convex in the paraxial region and concave in portions other than the paraxial region. Additionally, the image side of the seventh lens 170 may be convex in the paraxial region and concave in portions other than the paraxial region.

[0119] The eighth lens 180 may have a negative refractive power, and the object side and image side of the eighth lens 180 may be concave in the paraxial region.

[0120] In addition, the eighth lens 180 may have at least one inflection point formed on at least one of its object side and image side. In an example, the object side of the eighth lens 180 may be concave in the paraxial region and convex in portions other than the paraxial region. Additionally, the image side of the eighth lens 180 may be concave in the paraxial region and convex in portions other than the paraxial region.

[0121] Each surface of the first lens 110 to the eighth lens 180 may have an aspherical coefficient as shown in Table 2 below. In an example, both the object side and image side of the first lens 110 to the eighth lens 180 may be aspherical.

[0122] Table 2

[0123]

[0124]

[0125]

[0126] In addition, the exemplary optical imaging system configured as described above may have aberration characteristics as shown in Figure 2 The aberration characteristics will be described with reference to

[0127] The exemplary optical imaging system according to the second embodiment will be described with reference to Figure 3 and Figure 4 ​

[0128] The exemplary optical imaging system 200 according to the second embodiment may include a first lens 210, a second lens 220, a third lens 230, a fourth lens 240, a fifth lens 250, a sixth lens 260, a seventh lens 270, and an eighth lens 280, and may further include a filter 290 and an image sensor.

[0129] The exemplary optical imaging system according to the second embodiment may form a focal point (or a focused image) on the imaging surface 291. The imaging surface 291 may refer to the surface on which the optical imaging system forms a focal point. In an example, the imaging surface 291 may refer to a surface of the image sensor that receives light.

[0130] The lens characteristics (radius of curvature, thickness of the lens or distance between lenses, refractive index, Abbe number, and effective radius) of each lens are shown in Table 3 below.

[0131] Table 3

[0132]

[0133]

[0134] In the second embodiment, the first lens 210 may have a positive refractive power, the object side surface of the first lens 210 may be convex, and the image side surface of the first lens 210 may be concave.

[0135] The second lens 220 may have a negative refractive power, the object side surface of the second lens 220 may be convex, and the image side surface of the second lens 220 may be concave.

[0136] The third lens 230 may have a negative refractive power, the object side surface of the third lens 230 may be convex, and the image side surface of the third lens 230 may be concave.

[0137] The fourth lens 240 may have a positive refractive power, the object side surface of the fourth lens 240 may be concave, and the image side surface of the fourth lens 240 may be convex.

[0138] The fifth lens 250 may have a negative refractive power, the object side surface of the fifth lens 250 may be concave, and the image side surface of the fifth lens 250 may be convex.

[0139] The sixth lens 260 may have a positive refractive power, the object side surface of the sixth lens 260 may be convex, and the image side surface of the sixth lens 260 may be concave.

[0140] In addition, the sixth lens 260 may have at least one inflection point formed on at least one of its object side and image side. In an example, the object side of the sixth lens 260 may be convex in the paraxial region and concave in a portion other than the paraxial region. Additionally, the image side of the sixth lens 260 may be concave in the paraxial region and convex in a portion other than the paraxial region.

[0141] The seventh lens 270 may have a positive refractive power, and the object side and the image side of the seventh lens 270 may be convex in the paraxial region.

[0142] In addition, the seventh lens 270 may have at least one inflection point formed on at least one of its object side and image side. In an example, the object side of the seventh lens 270 may be convex in the paraxial region and concave in a portion other than the paraxial region. The image side of the seventh lens 270 may be convex in the paraxial region and concave in a portion other than the paraxial region.

[0143] The eighth lens 280 may have a negative refractive power, and the object side and the image side of the eighth lens 280 may be concave in the paraxial region.

[0144] In addition, the eighth lens 280 may have at least one inflection point formed on at least one of its object side and image side. In an example, the object side of the eighth lens 280 may be concave in the paraxial region and convex in a portion other than the paraxial region. The image side of the eighth lens 280 may be concave in the paraxial region and convex in a portion other than the paraxial region.

[0145] Each surface of the first lens 210 to the eighth lens 280 may have an aspherical coefficient as shown in Table 4 below. In an example, both the object side and the image side of the first lens 210 to the eighth lens 280 may be aspherical.

[0146] Table 4

[0147]

[0148]

[0149]

[0150] In addition, the exemplary optical imaging system configured as described above may have aberration characteristics as shown in Figure 4 .

[0151] Reference will be made to Figure 5 and Figure 6 to describe the exemplary optical imaging system according to the third embodiment.

[0152] The exemplary optical imaging system 300 according to the third embodiment may include a first lens 310, a second lens 320, a third lens 330, a fourth lens 340, a fifth lens 350, a sixth lens 360, a seventh lens 370, and an eighth lens 380, and may further include a filter 390 and an image sensor.

[0153] The optical imaging system according to the third embodiment may form a focus (or a focused image) on the imaging surface 391. The imaging surface 391 may refer to the surface on which the optical imaging system forms a focus. In an example, the imaging surface 391 may refer to a surface of the image sensor that receives light.

[0154] The lens characteristics (radius of curvature, thickness of the lens or distance between lenses, refractive index, Abbe number, and effective radius) of each lens are shown in Table 5 below.

[0155] Table 5

[0156]

[0157]

[0158] In the third embodiment, the first lens 310 may have a positive refractive power, the object side surface of the first lens 310 may be convex, and the image side surface of the first lens 310 may be concave.

[0159] The second lens 320 may have a negative refractive power, the object side surface of the second lens 320 may be convex, and the image side surface of the second lens 320 may be concave.

[0160] The third lens 330 may have a negative refractive power, the object side surface of the third lens 330 may be convex, and the image side surface of the third lens 330 may be concave.

[0161] The fourth lens 340 may have a positive refractive power, the object side surface of the fourth lens 340 may be concave, and the image side surface of the fourth lens 340 may be convex.

[0162] The fifth lens 350 may have a negative refractive power, the object side surface of the fifth lens 350 may be concave, and the image side surface of the fifth lens 350 may be convex.

[0163] The sixth lens 360 may have a positive refractive power, the object side surface of the sixth lens 360 may be convex, and the image side surface of the sixth lens 360 may be concave.

[0164] In addition, the sixth lens 360 may have at least one inflection point formed on at least one of its object side and image side. For example, the object side of the sixth lens 360 may be convex in the paraxial region and concave in the portion other than the paraxial region. The image side of the sixth lens 360 may be concave in the paraxial region and convex in the portion other than the paraxial region.

[0165] The seventh lens 370 may have a positive refractive power, and the object side and image side of the seventh lens 370 may be convex in the paraxial region.

[0166] In addition, the seventh lens 370 may have at least one inflection point formed on at least one of its object side and image side. In an example, the object side of the seventh lens 370 may be convex in the paraxial region and concave in the portion other than the paraxial region. The image side of the seventh lens 370 may be convex in the paraxial region and concave in the portion other than the paraxial region.

[0167] The eighth lens 380 may have a negative refractive power, and the object side and image side of the eighth lens 380 may be concave.

[0168] In addition, the eighth lens 380 may have at least one inflection point formed on at least one of its object side and image side. In an example, the object side of the eighth lens 380 may be concave in the paraxial region and convex in the portion other than the paraxial region. The image side of the eighth lens 380 may be concave in the paraxial region and convex in the portion other than the paraxial region.

[0169] Each surface of the first lens 310 to the eighth lens 380 may have an aspherical coefficient as shown in Table 6 below. In an example, both the object side and image side of the first lens 310 to the eighth lens 380 may be aspherical.

[0170] Table 6

[0171]

[0172]

[0173]

[0174] In addition, the exemplary optical imaging system configured as described above may have aberration characteristics as shown in Figure 6 below.

[0175] Table 7

[0176] First embodiment Second embodiment Third embodiment Fno 1.522 1.535 1.561 TTL 7.767 7.808 7.880 IMG HT 6.329 6.329 6.329 FOV 89.12 88.25 87.358 f 6.114 6.262 6.357 f1 6.340 6.344 6.346 f2 -14.666 -15.917 -16.231 f3 763.536 -293.262 -336.893 f4 21.246 19.984 20.554 f5 -54.932 -33.597 -31.945 f6 51.018 40.583 40.389 f7 7.247 7.297 7.358 f8 -4.421 -4.300 -4.213 f12 9.766 9.356 9.271 f123 9.628 9.564 9.447

[0177] In Table 7, Fno is the F-number of an exemplary optical imaging system, TTL is the distance on the optical axis from the object side surface of the first lens to the imaging surface, IMG HT is half of the diagonal length of the imaging surface, and FOV is the field of view of the optical imaging system.

[0178] f is the total focal length of the optical imaging system, f1 is the focal length of the first lens, f2 is the focal length of the second lens, f3 is the focal length of the third lens, f4 is the focal length of the fourth lens, f5 is the focal length of the fifth lens, f6 is the focal length of the sixth lens, f7 is the focal length of the seventh lens, and f8 is the focal length of the eighth lens.

[0179] In an exemplary optical imaging system according to one or more embodiments, the size can be reduced while achieving high resolution.

[0180] Although the present disclosure includes specific examples, it will be apparent after understanding the disclosure of the present application that various changes in form and detail can be made to these examples without departing from the spirit and scope of the claims and their equivalents. The examples described herein are to be understood in a descriptive sense only and not for purposes of limitation. The description of each feature or aspect in an example should be considered applicable to similar features or aspects in other examples. Appropriate results can still be achieved if the described techniques are performed in a different order, and / or if the components in the described systems, architectures, devices, or circuits are combined in a different manner and / or replaced or supplemented by other components or their equivalents.

[0181] Accordingly, in addition to the above and all the drawings disclosed, the scope of the present disclosure also includes the claims and their equivalents, that is, all variations within the scope of the claims and their equivalents should be understood to be included in the present disclosure.

Claims

1. An optical imaging system, comprising: a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, and an eighth lens arranged in sequence from the object side towards the imaging surface, wherein the first lens has a positive refractive power, and the second lens has a negative refractive power, wherein the second lens and the third lens each have a refractive index greater than 1.66, wherein the optical imaging system satisfies the following conditional expression: TTL / (2×IMG HT)<0.64, wherein TTL is the distance on the optical axis from the object side surface of the first lens to the imaging surface, and IMG HT is half of the diagonal length of the imaging surface, and wherein the optical imaging system has a total of eight lenses.

2. The optical imaging system according to claim 1, wherein: Each of at least three lenses including the second lens and the third lens among the first lens to the eighth lens has a refractive index greater than 1.66, and among the at least three lenses having a refractive index greater than 1.66, the absolute value of the focal length of the second lens is the smallest absolute value.

3. The optical imaging system according to claim 1, wherein: The fifth lens has a refractive index greater than 1.66, and wherein the optical imaging system satisfies the following conditional expression: |v1-(v2+v3+v5)|<10, wherein v1 is the Abbe number of the first lens, v2 is the Abbe number of the second lens, v3 is the Abbe number of the third lens, and v5 is the Abbe number of the fifth lens.

4. The optical imaging system according to claim 1, wherein: Satisfies the following conditional expression: 25<v1-v2<45; and 25<v1-v3<45, wherein v1 is the Abbe number of the first lens, v2 is the Abbe number of the second lens, and v3 is the Abbe number of the third lens.

5. The optical imaging system according to claim 1, wherein: Satisfies the following conditional expression: 15<v1-(v2+v3)<25, wherein v1 is the Abbe number of the first lens, v2 is the Abbe number of the second lens, and v3 is the Abbe number of the third lens.

6. The optical imaging system according to claim 1, wherein: Satisfies the following conditional expression: 1.3<Fno<1.6, wherein Fno is the F-number of the optical imaging system.

7. The optical imaging system according to claim 1, wherein: Satisfies the following conditional expression: 0.9<f1 / f<1.2, wherein f1 is the focal length of the first lens, and f is the total focal length of the optical imaging system.

8. The optical imaging system according to claim 1, wherein: Satisfies the following conditional expression: -3<f2 / f<-1, wherein f2 is the focal length of the second lens, and f is the total focal length of the optical imaging system.

9. The optical imaging system according to claim 1, wherein: Satisfies the following conditional expression: |f3 / f|>30, wherein f3 is the focal length of the third lens, and f is the total focal length of the optical imaging system.

10. The optical imaging system according to claim 1, wherein: Satisfies the following conditional expression: 0.3<|f1 / f2|<0.6, wherein f1 is the focal length of the first lens, and f2 is the focal length of the second lens.

11. The optical imaging system according to claim 1, wherein: Satisfies the following conditional expression: |f1 / f3|<0.05, wherein f1 is the focal length of the first lens, and f3 is the focal length of the third lens.

12. The optical imaging system according to claim 1, wherein: Satisfies the following conditional expression: |f2 / f3|<0.08, wherein f2 is the focal length of the second lens, and f3 is the focal length of the third lens.

13. The optical imaging system according to claim 1, wherein: The following conditional expressions are met: 1.3 <f12 / f<1.7, Wherein, f12 is the composite focal length of the first lens and the second lens, and f is the total focal length of the optical imaging system.

14. The optical imaging system according to claim 13, wherein: The following conditional expressions are met: 1.3 <f123 / f<1.7, Wherein, f123 is the composite focal length of the first lens to the third lens.

15. The optical imaging system of claim 1, wherein: The fourth lens has positive refractive power, and the fifth lens has negative refractive power.

16. The optical imaging system of claim 1, wherein: The sixth lens has positive refractive power, the seventh lens has positive refractive power, and the eighth lens has negative refractive power.

Images