Optical system

Abstract

The optical system disclosed in the embodiments may include a first lens to a fifth lens arranged continuously along the optical axis in a direction from the object side to the image side, wherein each of the first lens to the fifth lens includes an object-side surface and an image-side surface, the effective aperture size of the image-side surface of the first lens is larger than the effective aperture size of the object-side surface of the first lens, and the thickness of the first lens is smaller than the thickness of the second lens.

Description

Technical Field

[0001] The implementation methods relate to optical devices for improving optical performance. Background Technology

[0002] Camera modules capture objects and store them as images or videos, and are installed in a variety of applications. In particular, camera modules are manufactured in very small sizes and are used not only in portable devices such as smartphones, tablets, and laptops, but also in drones and vehicles to provide a variety of functions. For example, the optical system of a 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 can perform autofocus (AF) by automatically adjusting the distance between the image sensor and the imaging lens to align the focal length of the lens, and can perform zoom functions by increasing or decreasing the magnification of distant objects via a zoom lens. Furthermore, the camera module employs image stabilization (IS) technology to correct or prevent image instability caused by unstable mounting or camera movement due to user movement. The most important element in this camera module for acquiring images is the imaging lens that forms the image. Recently, there has been increasing interest in high performance, such as high image quality and high resolution, and research is being conducted on optical systems including multiple lenses to achieve such high performance. For example, research is underway on achieving efficient optical systems using multiple imaging lenses with positive (+) and / or (-) refractive power. However, with multiple lenses involved, it is difficult to obtain excellent optical and aberration characteristics.

[0003] Typically, optical systems comprising multiple lenses can have a set effective focal length (EFL). In this case, when the EFL value is relatively large, the lens closest to the object has a large aperture or the largest aperture among the multiple lenses. Therefore, due to the relatively large size of the lens closest to the object, it is difficult to miniaturize the optical system. Optical systems comprising multiple lenses may also have a relatively high height. For example, as the number of lenses increases, the distance from the image sensor to the object surface of the lens closest to the object may increase. Therefore, the overall thickness of devices with optical systems, such as smartphones, may increase, and miniaturization becomes difficult. Therefore, a new optical system capable of solving the above problems is needed. Summary of the Invention

[0004] Technical issues

[0005] The embodiments provide optical systems with improved optical properties. The embodiments provide optical systems that can be implemented in a small and compact manner. The embodiments provide optical systems suitable for folding cameras with a thin profile.

[0006] Solution

[0007] An optical system according to an embodiment includes a first lens to a fifth lens arranged sequentially along an optical axis from the object side to the image side, wherein each of the first lens to the fifth lens includes an object-side surface and an image-side surface, wherein the effective aperture size of the image-side surface of the first lens can be larger than the effective aperture size of the object-side surface of the first lens, and the thickness of the first lens can be smaller than the thickness of the second lens.

[0008] According to embodiments of the present invention, the first lens may have positive (+) refractive power, and the object-side surface of the first lens may have a negative (-) radius of curvature. The thickness of the first lens may be thinner than the thickness of the third lens and thicker than the thickness of the fourth or fifth lens. The thickness of the first lens may be less than the distance between the first and second lenses. The thickness of the second lens may be greater than the thicknesses of the first, third, fourth, and fifth lenses.

[0009] The optical system according to the embodiment includes a first lens to a fifth lens arranged sequentially along the optical axis from the object side to the image side, wherein the first lens has positive (+) refractive power and a concave shape relative to the optical axis. The second lens may have a surface with an effective aperture larger than the effective aperture of the object-side surface of the first lens.

[0010] The second lens may have positive (+) refractive power, and the focal length of the first lens may be greater than the focal length of the second lens. Furthermore, the effective focal length (EFL) of the optical system may be less than the focal length of the first lens and greater than the focal length of the second lens. The image-side surface of the first lens may have a convex shape, and the image-side surface of the second lens may have a concave shape.

[0011] The optical system according to this embodiment includes a first lens to a fifth lens arranged sequentially along the optical axis from the object side to the image side, wherein the thickness of the first lens is thinner than the thickness of the second and third lenses and thicker than the thickness of the fourth and fifth lenses, and the thickness of the second lens is thicker than the thickness of the third lens, wherein the object-side surface or image-side surface of one of the lenses selected from the first and second lenses may have the largest effective aperture among the object-side surfaces and image-side surfaces of the first to fifth lenses.

[0012] Beneficial effects

[0013] The optical system according to this embodiment can have improved optical characteristics. Specifically, the optical system may include multiple lenses and may include at least one lens surface having an effective aperture larger than the object-side surface of the first lens closest to the object. Therefore, improved optical characteristics can be obtained when designing an optical system including multiple lenses.

[0014] The optical system according to this embodiment can be provided to be thin. For example, in the optical system, a lens with a relatively large effective diameter (e.g., at least one lens adjacent to the object side) can have a D-cut shape. Therefore, light loss during the processing of incident light can be minimized, and a thinner shape can be achieved.

[0015] The optical system according to this embodiment may include, for example, the optical system capable of changing light incident in a direction perpendicular to the surface of the device or apparatus including the light path changing member, to a direction parallel to the surface of the device or apparatus. Therefore, the optical system including multiple lenses can have a smaller thickness within the device or apparatus, and the overall thickness of the device or apparatus can be reduced. Attached Figure Description

[0016] Figure 1 This is a diagram showing a side cross-section of the optical system according to the first embodiment along the first direction (X).

[0017] Figure 2 This is a diagram showing a side cross-section of the optical system according to the first embodiment along the second direction (Y).

[0018] Figure 3 This is a diagram illustrating the D-shaped cut shape of at least one lens in an optical system according to the first embodiment.

[0019] Figure 4 It is a graph showing the MTF characteristics and aberration characteristics of the optical system according to the first embodiment.

[0020] Figure 5 This is a graph showing the aberration characteristics of the optical system according to the first embodiment.

[0021] Figure 6 This is a diagram showing a side cross-section of the optical system according to the second embodiment along the first direction (X).

[0022] Figure 7 This is a diagram showing a side cross-section of the optical system according to the second embodiment along the second direction (Y).

[0023] Figure 8This is a diagram illustrating the D-shaped cut shape of at least one lens in the optical system according to the second embodiment.

[0024] Figure 9 This is a graph showing the MTF characteristics of the optical system according to the second embodiment.

[0025] Figure 10 This is a graph showing the aberration characteristics of the optical system according to the second embodiment. Detailed Implementation

[0026] Preferred embodiments of the invention will be described in detail below with reference to the accompanying drawings. The spirit of the invention is not limited to the embodiments described herein, but can be implemented in various other forms, and one or more components can be selectively combined and substituted within the scope of the spirit of the invention. Furthermore, unless explicitly defined and clearly described, the terminology (including technical and scientific terms) used in the embodiments of the invention can be interpreted in the sense that is generally understood by one of ordinary skill in the art to which this invention pertains, and commonly used terms, such as those defined in dictionaries, should be interpretable in the context of the relevant art. Moreover, the terminology used in the embodiments of the invention is descriptive and not intended to limit the invention. In this specification, singular forms may also include plural forms, and unless otherwise specifically stated in the phrase, when referring to at least one (or more) of A and / or B, C, it may include one or more combinations of all combinations that can be combined with A, B, and C. In describing components of embodiments of the invention, terms such as first, second, A, B, (a), and (b) may be used. These terms are only used to distinguish components from other components and should not determine the nature, order, or process of the corresponding constituent elements. Furthermore, when describing a component as "connected," "coupled," or "joined" to another component, the description can include not only direct connection, coupling, or joining to the other component, but also connection, coupling, or joining via other components between the component and the other component. Additionally, when described as being formed or disposed "above" or "below" each component, the description includes not only cases where the two components are in direct contact with each other, but also cases where one or more other components are formed or disposed between the two components. Furthermore, when expressed as "above" or "below," it can refer to both the downward and upward directions relative to a single element.

[0027] A convex lens surface can refer to a lens surface with a convex shape in the region corresponding to the optical axis, while a concave lens surface refers to a lens surface with a concave shape in the region corresponding to the optical axis. Furthermore, "object-side surface" can refer to the surface of the lens facing the object relative to the optical axis, while "image-side surface" can refer to the surface of the lens facing the imaging surface relative to the optical axis. Additionally, "vertical direction" can refer to a direction perpendicular to the optical axis, and the end of the lens or lens surface can refer to the end of the effective region of the lens through which incident light passes. The center thickness of the lens can refer to the thickness of the region overlapping the optical axis along the optical axis direction of the lens.

[0028] An optical system 1000 according to an embodiment of the present invention may include a plurality of lenses arranged sequentially from the object side to the image side. The optical system 1000 may include a filter 500 and an image sensor 300 on the image side of the plurality of lenses. The plurality of lenses may include four or more lenses. Specifically, the plurality of lenses may include five or more lenses. These lenses may be arranged sequentially along the optical axis OA of the optical system 1000. Light corresponding to image information of the object may sequentially pass through the plurality of lenses and the filter 500 and be incident on the image sensor 300.

[0029] Each of the plurality of lenses may include an effective region and an ineffective region. The effective region can be the area through which light incident on the lens passes. That is, the effective region can be the area where incident light is refracted to achieve optical properties. The ineffective region may be arranged around the effective region. The ineffective region can be the area where light does not incident. That is, the ineffective region can be the area unrelated to optical properties. Additionally, the ineffective region may be the area fixed to a lens barrel (not shown) that houses the lens. The optical system 1000 according to this embodiment may include an aperture stop for adjusting the amount of incident light. The aperture stop may be disposed between two lenses selected from the plurality of lenses. At least one of the plurality of lenses may be used as the aperture stop. For example, the lens surface of one lens selected from the plurality of lenses may be used as the aperture stop to adjust the amount of light incident on the optical system 1000.

[0030] A filter 500 may be disposed between multiple lenses and the image sensor 300. The filter 500 may include at least one of an infrared filter and a filter such as a cover glass. The filter 500 allows light with a defined wavelength band to pass through and filters light with different wavelength bands. When the filter 500 includes an infrared filter, radiation emitted from external light can be prevented from being transmitted to the image sensor 300. Furthermore, the filter 500 may transmit visible light and reflect infrared light. The image sensor 300 can detect light. Specifically, the image sensor 300 can detect light passing sequentially through the first to fifth lenses 110, 120, 130, 140, and 150. The image sensor 300 may include a charge-coupled device (CCD) or a complementary metal-oxide-semiconductor (CMOS) sensor.

[0031] The optical system 1000 may further include a light path changing member (not shown). The light path changing member can change the light path by reflecting light incident from the outside. The light path changing member may include a reflector or a prism. For example, the light path changing member may include a right-angle prism. When the light path changing member includes a right-angle prism, the light path changing member can change the path of the incident light by reflecting the path of the incident light at a 90-degree angle. The light path changing member can be positioned closer to the object side than the multiple lenses. That is, the optical system 1000 may include a light path changing member, multiple lenses, a filter 500, and an image sensor 300 arranged sequentially along the optical axis OA from the object side to the image side. The light path changing member can change the path of the light in a set direction by reflecting light incident from the outside. That is, the light path changing member can change the path of the light incident on the light path changing member to be directed toward the multiple lenses. Therefore, the optical system 1000 according to this embodiment can be applied to a folding camera that can reduce the camera thickness. Specifically, the optical system 1000 may include a light path changing member that changes the direction of light incident on the device in a direction perpendicular to the surface of the device to a direction parallel to the surface of the device. Therefore, the optical system 1000, which includes multiple lenses, can have a thinner thickness within the device, and thus can provide a thinner device.

[0032] More specifically, when the optical system 1000 does not include a light path changing component, multiple lenses can be arranged to extend in the device in a direction perpendicular to the surface of the device. Therefore, the optical system 1000 including multiple lenses may have a high height in the direction perpendicular to the device surface. However, when the optical system 1000 is applied to a folding camera including a light path changing component, the multiple lenses can be arranged to extend in a direction parallel to the surface of the device. Accordingly, the optical system 1000 including multiple lenses can have a low height in the direction perpendicular to the device surface. Therefore, the folding camera including the optical system 1000 can have a thinner thickness within the device, and the thickness of the device can also be reduced.

[0033] <First Implementation Method>

[0034] The optical system according to the first embodiment will be described in detail below. Figure 1 and Figure 2 This is a configuration diagram showing the side cross-sections of the optical system according to the first embodiment along different directions. Figure 3 This is a diagram showing the D-shaped cut shape in the optical system according to the first embodiment, and Figure 4 and Figure 5 It is a graph showing the MTF characteristics and aberration characteristics of the optical system according to the first embodiment.

[0035] Reference Figures 1 to 5 The optical system 1000 according to the first embodiment may include a plurality of lenses. For example, the optical system 1000 may include four or more lenses. Specifically, the optical system 1000 may include five or more lenses.

[0036] The optical system 1000 may include a first lens 110, a second lens 120, a third lens 130, a fourth lens 140, a fifth lens 150, a filter 500, and an image sensor 300, arranged sequentially along the optical axis OA from the object side towards the image side. The first to fifth lenses 110, 120, 130, 140, and 150 can be arranged sequentially along the optical axis OA of the optical system 1000. In this case, among the multiple lenses 110, 120, 130, 140, and 150, the first lens 110 can be arranged closest to the object side, and the fifth lens 150 can be arranged closest to the image side. Furthermore, the first lens 110 and the second lens 120 can be arranged continuously along the optical axis OA. More specifically, the first to fifth lenses 110, 120, 130, 140, and 150 can be arranged continuously along the optical axis OA.

[0037] The first lens 110 may have positive (+) refractive power. The first lens 110 may comprise a plastic or glass material. For example, the first lens 110 may be made of a plastic material. The first lens 110 may comprise a first surface S1 defined as the object-side surface and a second surface S2 defined as the image-side surface. The first surface S1 may be concave, and the second surface S2 may be convex. That is, the first lens 110 may have a meniscus shape that convexes along the image-side direction. At least one of the first surface S1 and the second surface S2 may be aspherical. For example, both the first surface S1 and the second surface S2 may be aspherical.

[0038] The second lens 120 may have positive (+) refractive power. The second lens 120 may comprise a plastic or glass material. For example, the second lens 120 may be made of a plastic material. The second lens 120 may include a third surface S3 defined as the object-side surface and a fourth surface S4 defined as the image-side surface. The third surface S3 may be convex, and the fourth surface S4 may be concave. That is, the second lens 120 may have a meniscus shape convex toward the object side. At least one of the third surface S3 and the fourth surface S4 may be aspherical. For example, both the third surface S3 and the fourth surface S4 may be aspherical.

[0039] The third lens 130 may have negative (-) refractive power. The third lens 130 may comprise a plastic or glass material. For example, the third lens 130 may be made of a plastic material. The third lens 130 may include a fifth surface S5 defined as the object-side surface and a sixth surface S6 defined as the image-side surface. The fifth surface S5 may be convex, and the sixth surface S6 may be concave. That is, the third lens 130 may have a meniscus shape convex toward the object side. At least one of the fifth surface S5 and the sixth surface S6 may be aspherical. For example, both the fifth surface S5 and the sixth surface S6 may be aspherical.

[0040] The fourth lens 140 may have positive (+) refractive power. The fourth lens 140 may comprise a plastic or glass material. For example, the fourth lens 140 may be made of a plastic material. The fourth lens 140 may include a seventh surface S7 defined as the object-side surface and an eighth surface S8 defined as the image-side surface. The seventh surface S7 may be convex, and the eighth surface S8 may be concave. That is, the fourth lens 140 may have a meniscus shape convex toward the object side. At least one of the seventh surface S7 and the eighth surface S8 may be aspherical. For example, both the seventh surface S7 and the eighth surface S8 may be aspherical.

[0041] The fifth lens 150 may have positive (+) refractive power. The fifth lens 150 may comprise a plastic or glass material. For example, the fifth lens 150 may be made of a plastic material. The fifth lens 150 may include a ninth surface S9 defined as the object-side surface and a tenth surface S10 defined as the image-side surface. The ninth surface S9 may be convex, and the tenth surface S10 may be concave. That is, the fifth lens 150 may have a meniscus shape convex toward the object side. At least one of the ninth surface S9 and the tenth surface S10 may be aspherical. For example, both the ninth surface S9 and the tenth surface S10 may be aspherical.

[0042] The optical system 1000 may include an aperture stop (not shown). The aperture stop may be disposed between the object and the first lens 110, or between the first lens and the third lenses 110, 120, 130. For example, the object-side surface (fifth surface S5) of the third lens 130 may be used as the aperture stop.

[0043] The first to fifth lenses 110, 120, 130, 140, and 150 may have a predetermined effective aperture (light transmission aperture). For example, the first to tenth surfaces S1, S2, S3, S4, S5, S6, S7, S8, S9, and S10 may each have a predetermined effective aperture (light transmission aperture). The object-side surface or image-side surface of one of the lenses selected from the first lens 110 and the second lens 120 may have the largest effective aperture among the first to tenth surfaces S1, S2, S3, S4, S5, S6, S7, S8, S9, and S10 of the first to fifth lenses 110, 120, 130, 140, and 150. For example, the optical system 1000 may include at least one lens surface having an effective aperture larger than the object-side surface (first surface S1) of the first lens 110. Specifically, the optical system 1000 may include a lens surface with an effective aperture larger than the first surface S1. The effective aperture of the image-side surface (second surface S2) of the first lens 110 can be larger than the effective aperture of the object-side surface (first surface S1) of the first lens 110. The effective aperture of the second surface S2 can be the largest among the first to tenth surfaces S1, S2, S3, S4, S5, S6, S7, S8, S9, and S10. Furthermore, among the first to tenth surfaces S10, the effective aperture of the first surface S1 can be second only to the effective aperture of the second surface S2. The effective aperture of the second lens 120 can be smaller than the effective aperture of the first lens 110. For example, the effective apertures of the object-side surface (third surface S3) and image-side surface (fourth surface S4) of the second lens 120 can be smaller than the effective apertures of the object-side surface (first surface S1) and image-side surface (second surface S2) of the first lens 110. Among the first to tenth surfaces S10, the effective aperture of the third surface S3 can be second only to the effective aperture of the first surface S1. Furthermore, among the first to tenth surfaces S1, S2, S3, S4, S5, S6, S7, S8, S9, and S10, the effective aperture size of the fourth surface S4 can be second only to the effective aperture size of the third surface S3.

[0044] Alternatively, the effective aperture of the second lens 120 may be larger than the effective aperture of the first lens 110. For example, the effective aperture of the object-side surface (third surface S3) of the second lens 120 may be larger than the effective aperture of one of the surfaces selected from the object-side surface (first surface S1) and the image-side surface (second surface S2) of the first lens 110. Specifically, the effective aperture of the third surface S3 may be larger than the effective apertures of the first surface S1 and the second surface S2. In this case, the effective aperture of the third surface S3 may be larger than the sizes of the first surface S1 and the second surface S2, but within 1.5 times the effective aperture of the second surface S2.

[0045] Reference Figure 3 At least one of the first to fifth lenses 110, 120, 130, 140, and 150 may have a non-circular shape. For example, the first lens 110, the second lens 120, and the third lens 130 may each have a non-circular shape. When each of the first to third lenses 110, 120, and 130 is viewed from the front corresponding to the optical axis OA, the effective area of ​​each lens may have a non-circular shape. Specifically, the effective area of ​​each of the first to third lenses 110, 120, and 130 may include a first corner to a fourth corner A1, A2, A3, and A4. The first edge A1 and the second edge A2 may be edges facing each other in a first direction (x-axis direction) perpendicular to the optical axis OA. The first edge A1 and the second edge A2 may have a curved shape. The third edge A3 and the fourth edge A4 may be edges facing each other in a second direction (y-axis direction) perpendicular to both the optical axis OA and the first direction. The third edge A3 and the fourth edge A4 may be edges connecting the ends of the first edge A1 and the second edge A2. The third edge A3 and the fourth edge A4 can have a straight line shape. That is, the first lens to the third lens 110, 120, 130 can have a D-shaped cut shape.

[0046] The first lens to the third lens 110, 120, 130 may have the aforementioned non-circular shape during manufacturing. For example, in the case where the first lens to the third lens 110, 120, 130 include a plastic material, they can be manufactured into a non-circular shape during an injection molding process. Alternatively, the first lens to the third lens 110, 120, 130 can be manufactured into a circular shape through an injection molding process, and a partial region can be cut in a subsequent cutting process to form the third edge A3 and the fourth edge A4. Thus, the effective area of each of the first lens to the third lens 110, 120, 130 can have a set size. For example, the length CA of a virtual first straight line passing through the optical axis OA and connecting the first edge A1 and the second edge A2 can be longer than the length CH of a virtual second straight line passing through the optical axis OA and connecting the third edge A3 and the fourth edge A4. Here, the length CA of the first straight line can represent the maximum clear aperture CA of the effective aperture of each of the first lens to the third lens 110, 120, 130, and the length CH of the second straight line can represent the minimum clear height CH of the effective aperture of each of the first lens to the third lens 110, 120, 130. In the above description, it has been described that the effective area of the first lens to the third lens 110, 120, 130 has a non-circular shape, but it is not limited thereto. The effective area of each lens can have a circular shape, and the ineffective area can have a non-circular shape.

[0047] The optical system 1000 according to the first embodiment can satisfy at least one of the following expressions described below. Therefore, when the optical system 1000 according to the first embodiment satisfies at least one of the following expressions, it can have improved optical characteristics. In addition, when the optical system 1000 satisfies at least one or two or more of the expressions, it can be implemented to be smaller and more compact. In addition, when the optical system 1000 satisfies at least one of the expressions, it can be applied to a foldable camera having a smaller thickness, so that a device including the camera can be manufactured to have a thin thickness.

[0048] [Equation 1]

[0049] 9 < EFL < 40

[0050] In Equation 1, EFL represents the effective focal length (mm) of the optical system 1000. Specifically, the EFL of the optical system 1000 can be 11 < EFL < 30. More specifically, the EFL of the optical system 1000 can be < 13 < EFL < 26.

[0051] [Equation 2]

[0052] 0.95 < L1S1 / L1S2 < 1

[0053] In Equation 2, L1S1 represents the effective aperture (mm) of the object side surface (the first surface S1) of the first lens 110, and L1S2 represents the effective aperture (mm) of the image side surface (the second surface S2) of the first lens 110. Specifically, L1S1 / L1S2 can satisfy 0.96 < L1S1 / L1S2 < 1. Specifically, L1S1 / L1S2 can satisfy 0.99 < L1S1 / L1S2 < 1.

[0054] [Equation 3]

[0055] -8 < R_L1 / R_L3 < 0.98

[0056] In Equation 3, R_L1 represents the radius of curvature (mm) of the object side surface (the first surface S1) of the first lens 110, and R_L3 represents the radius of curvature (mm) of the object side surface (the third surface S3) of the second lens 120. Specifically, R_L1 and R_L3 can satisfy -8 < R_L1 / R_L3 < -2.

[0057] [Equation 4]

[0058] [[ID=仃]]0.1 < TH_L1 / TH_L2 < 0.75

[0059] In Equation 4, TH_L1 represents the center thickness (mm) of the first lens 110, and TH_L2 represents the center thickness (mm) of the second lens 120. Specifically, TH_L1 and TH_L2 can satisfy 0.2 < TH_L1 / TH_L2 < 0.65. More specifically, TH_L1 and TH_L2 can satisfy 0.3 < TH_L1 / TH_L2 < 0.55.

[0060] [Equation 5]

[0061] 0.52 < CH n(n<4) / CA n(n<4) <0.98

[0062] In Equation 5, CH n(n<4) represents the minimum net height (mm) of the effective aperture of the nth lens. Specifically, CH n(n<4) represents the minimum size (mm) of the effective aperture of one lens selected from the first lens to the third lenses 110, 120, 130. In addition, CA n(n<4) represents the maximum clear aperture (mm) of the nth lens. Specifically, CA n(n<4) represents the maximum size (mm) of the effective aperture of one lens selected from the first lens to the third lenses 110, 120, 130.

[0063] [Formula 6]

[0064] 20<|f1|-|f2|<150

[0065] In Equation 6, f1 represents the focal length (mm) of the first lens 110, and f2 represents the focal length (mm) of the second lens 120.

[0066] [Formula 7]

[0067] 2 <BFL / ImgH<5

[0068] In Equation 7, BFL (back focal length) represents the distance (mm) along the optical axis from the image-side surface of the lens closest to the image sensor 300 among the multiple lenses to the image sensor 300. Furthermore, ImgH represents half the diagonal length (mm) of the effective area of ​​the image sensor 300. That is, ImgH represents the vertical distance (mm) from the optical axis on the upper surface of the image sensor 300 to a region of a field.

[0069] [Formula 8]

[0070] 0.35 <BFL / EFL<0.75

[0071] In Equation 8, BFL (back focal length) represents the distance (mm) from the image-side surface of the lens closest to the image sensor 300 among the multiple lenses to the image sensor 300 along the optical axis. Furthermore, EFL represents the effective focal length (mm) of the optical system 1000.

[0072] [Formula 9]

[0073] 1.5 <TTL / BFL<2.5

[0074] In Equation 9, TTL (Total track length) represents the distance (mm) along the optical axis from the object-side surface (first surface S1) of the lens (first lens 110) closest to the object side among the multiple lenses to the image sensor 300. Furthermore, BFL (back focal length) represents the distance (mm) along the optical axis from the image-side surface of the lens (first lens 110) closest to the image sensor 300 among the multiple lenses to the image sensor 300.

[0075] [Formula 10]

[0076] 0.75 <DL2 / TTL<0.9

[0077] In Equation 10, DL2 represents the distance (mm) from the object-side surface (third surface S3) of the second lens (second lens 120) closest to the object side among the multiple lenses to the image sensor 300. Furthermore, TTL (total optical length) represents the distance (mm) from the object-side surface (first surface S1) of the lens (first lens 110) closest to the object side among the multiple lenses to the image sensor 300.

[0078] In the case where the optical system 1000 includes 5 lenses as in the first embodiment, the following formulas 11 to 14 can be additionally satisfied.

[0079] [Equation 11]

[0080] |f3|<|f2|<|f5|<|f1|<|f4|

[0081] In Equation 11, f1 represents the focal length of the first lens 110, and f2 represents the focal length of the second lens 120. Additionally, f3 represents the focal length of the third lens 130, f4 represents the focal length of the fourth lens 140, and f5 represents the focal length of the fifth lens 150.

[0082] [Equation 12]

[0083] 0.5 <TH_L1 / d12<1

[0084] In Equation 12, TH_L1 represents the center thickness (mm) of the first lens 110, and d12 is the distance (mm) between the first lens 110 and the second lens 120 along the optical axis OA.

[0085] [Equation 13]

[0086] 2 <f1 / EFL<4

[0087] In Equation 13, f1 represents the focal length (mm) of the first lens 110, and EFL represents the effective focal length (mm) of the optical system 1000.

[0088] [Formula 14]

[0089]

[0090] In Equation 14, Z is the sagitta (Sag), which can represent the distance from any position on the aspherical surface to the vertex of the aspherical surface along the optical axis. Furthermore, Y can represent the distance from any position on the aspherical surface to the optical axis along a direction perpendicular to the optical axis. Additionally, c can represent the curvature of the lens, and K can represent the conic constant. Furthermore, A, B, C, D, E, and F can represent aspherical constants.

[0091] The optical system 1000 according to the first embodiment can satisfy at least one or two or more of Equations 1 to 13. Specifically, the optical system 1000 may include at least one lens surface with an effective aperture larger than the effective aperture of the first surface S1, and may have improved optical properties. In the optical system 1000, the first to third lenses 110, 120, 130 may have a non-circular shape, such as a D-shaped cut. Therefore, compared to a circular shape, the optical system 1000 can be implemented in a smaller size and can be provided in a compact form. When the optical system 1000 satisfies at least one of Equations 1 to 13, it can be applied to a folding camera. Specifically, the optical system 1000 may include a light path changing member, and changes light incident on the device in a direction perpendicular to the device surface to a direction parallel to the device surface. Therefore, the optical system 1000 including multiple lenses can have a thinner thickness within the device, and thus the device can be provided thinner.

[0092] [Table 1]

[0093]

[0094] [Table 2]

[0095] item First Implementation Method TTL 17.4958 EFL 17.1422 BFL 10.0731 ImgH 3.2 f1 37.9952 f2 9.0840 f3 -5.6663 f4 47.0826 f5 23.3461

[0096] Table 1 shows the radii of curvature, center thickness (mm) of each lens, distance between lenses (mm), effective aperture size, refractive index, and Abbe number of the first to fifth lenses 110, 120, 130, 140, and 150 according to the first embodiment. Table 2 relates to the TTL (total optical length), EFL (effective focal length), BFL (back focal length), and focal length of the lenses in the optical system 1000 according to the first embodiment.

[0097] Referring to Table 1, the refractive indices of the first lens 110, the second lens 120, and the fourth lens 140 can be the same. Furthermore, the refractive indices of the first lens 110, the second lens 120, and the fourth lens 140 can be less than the refractive index of the third lens 130. Furthermore, the refractive index of the third lens 130 can be less than the refractive index of the fifth lens 150. The Abbe numbers of the first lens 110, the second lens 120, and the fourth lens 140 can be equal to each other. Furthermore, the Abbe numbers of the first lens 110, the second lens 120, and the fourth lens 140 can be greater than the Abbe number of the third lens 130. Furthermore, the Abbe number of the third lens 130 can be greater than the Abbe number of the fifth lens 150. Surfaces S1, S2, S3, S4, S5, S6, S7, S8, S9, and S10 of the first to fifth lenses 110, 120, 130, 140, and 150 can each have a predetermined effective aperture (light transmission aperture). Specifically, in the optical system 1000, the effective aperture of the second surface S2 can be larger than that of the first surface S1, and the effective aperture of the first surface S1 can be larger than that of the third surface S3. Although not disclosed in Table 1, the second lens 120 may include at least one surface with an effective aperture larger than that of the first lens 110. For example, the effective aperture of the third surface S3 can be larger than that of the first surface S1. Furthermore, the effective aperture of the third surface S3 can be larger than that of the first surface S1 and the second surface S2.

[0098] Referring to Table 2, the effective focal length EFL of the optical system 1000 can be less than the focal length f1 of the first lens 110. Furthermore, the effective focal length EFL of the optical system 1000 can be greater than the focal length f2 of the second lens 120.

[0099] [Table 3]

[0100]

[0101]

[0102] Table 3 shows the result values ​​of the optical system 1000 according to the first embodiment for the above-described equations. Referring to Table 3, it can be seen that the optical system 1000 according to the first embodiment satisfies at least one or two or more of equations 1 to 13. Specifically, it can be seen that the optical system 1000 satisfies all of equations 1 to 13. Accordingly, the optical system 1000 according to the first embodiment can have the following characteristics: Figure 4 and Figure 5 The MTF (modulation transfer function) characteristics and aberration characteristics are shown. Specifically, Figure 5This is a graph of the aberration diagram of the optical system 1000 according to the first embodiment, and from left to right, it shows the measured spherical aberration, astigmatic field curve, and distortion. Figure 5 In the diagram, the X-axis can represent focal length (mm) or distortion (%), and the Y-axis can represent the height of the image sensor. Additionally, the spherical aberration graph is a graph of light in the wavebands of approximately 435 nm, approximately 486 nm, approximately 546 nm, approximately 587 nm, and approximately 656 nm, and the astigmatism and distortion graph is a graph of light in the 546 nm waveband. The optical system 1000 according to the first embodiment can have improved optical characteristics. Specifically, the optical system 1000 can include at least one lens surface having an effective aperture larger than the first surface S1 of the first lens 110, and can have improved optical characteristics. In the optical system 1000, the first to third lenses 110, 120, 130 can have non-circular shapes, such as D-shaped cuts. Therefore, compared to circular shapes, the optical system 1000 can be implemented in a smaller size and can be provided in a compact form. The optical system 1000 can include multiple lenses and optical path changing components (not shown). Therefore, the optical system 1000 can be applied to a folding camera that can have a small thickness, and the device including the camera can be manufactured to have a small thickness.

[0103] <Second Implementation Method>

[0104] The optical system according to the second embodiment will be described in detail below. Figure 6 and Figure 7 It is a configuration diagram of the optical system according to the second embodiment, and Figure 8 This is a diagram illustrating the D-shaped cut shape in the optical system according to the second embodiment. Figure 9 and Figure 10 This is a graph showing the MTF characteristics and aberration characteristics of the optical system according to the second embodiment.

[0105] Reference Figures 6 to 10 The optical system 1000 according to the second embodiment may include a plurality of lenses. For example, the optical system 1000 may include four or more lenses. Specifically, the optical system 1000 may include six or more lenses.

[0106] The optical system 1000 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 filter 500, and an image sensor 300, arranged sequentially along the optical axis OA from the object side to the image side. The first to sixth lenses 210, 220, 230, 240, 250, and 260 can be arranged sequentially along the optical axis OA of the optical system 1000. In this case, among the multiple lenses 210, 220, 230, 240, 250, and 260, the first lens 210 can be arranged closest to the object side, and the sixth lens 260 can be arranged closest to the image side. Furthermore, the first lens 210 and the second lens 220 can be arranged continuously along the optical axis OA. More specifically, the first to sixth lenses 210, 220, 230, 240, 250, and 260 can be arranged continuously along the optical axis OA.

[0107] The first lens 210 may have positive (+) refractive power. The first lens 210 may comprise a plastic or glass material. For example, the first lens 210 may be made of a plastic material. The first lens 210 may comprise a first surface S1 defined as the object-side surface and a second surface S2 defined as the image-side surface. The first surface S1 may be concave, and the second surface S2 may be convex. That is, the first lens 210 may have a meniscus shape that convexes along the image-side direction. At least one of the first surface S1 and the second surface S2 may be aspherical. For example, both the first surface S1 and the fourth surface S4 may be aspherical.

[0108] The second lens 220 may have positive (+) refractive power. The second lens 220 may comprise a plastic or glass material. For example, the second lens 220 may be made of a plastic material. The second lens 220 may include a third surface S3 defined as the object-side surface and a fourth surface S4 defined as the image-side surface. The third surface S3 may be convex, and the fourth surface S4 may also be convex. That is, the second lens 220 may have a convex shape on both sides. At least one of the third surface S3 and the fourth surface S4 may be aspherical. For example, both the third surface S3 and the fourth surface S4 may be aspherical.

[0109] The third lens 230 may have negative (-) refractive power. The third lens 230 may comprise a plastic or glass material. For example, the third lens 230 may be made of a plastic material. The third lens 230 may include a fifth surface S5 defined as the object-side surface and a sixth surface S6 defined as the image-side surface. The fifth surface S5 may be concave, and the sixth surface S6 may also be concave. That is, the third lens 230 may have a concave shape on both sides. At least one of the fifth surface S5 and the sixth surface S6 may be aspherical. For example, both the fifth surface S5 and the sixth surface S6 may be aspherical.

[0110] The fourth lens 240 may have positive (+) refractive power. The fourth lens 240 may comprise a plastic or glass material. For example, the fourth lens 240 may be made of a plastic material. The fourth lens 240 may include a seventh surface S7 defined as the object-side surface and an eighth surface S8 defined as the image-side surface. The seventh surface S7 may be convex, and the eighth surface S8 may be concave. That is, the fourth lens 240 may have a meniscus shape convex toward the object side. At least one of the seventh surface S7 and the eighth surface S8 may be aspherical. For example, both the seventh surface S7 and the eighth surface S8 may be aspherical.

[0111] The fifth lens 250 may have positive (+) refractive power. The fifth lens 250 may comprise a plastic or glass material. For example, the fifth lens 250 may be made of a plastic material. The fifth lens 250 may include a ninth surface S9 defined as the object-side surface and a tenth surface S10 defined as the image-side surface. The ninth surface S9 may be convex, and the tenth surface S10 may be concave. That is, the fifth lens 250 may have a meniscus shape convex toward the object side. At least one of the ninth surface S9 and the tenth surface S10 may be aspherical. For example, both the ninth surface S9 and the tenth surface S10 may be aspherical.

[0112] The sixth lens 260 may have positive (+) refractive power. The sixth lens 260 may comprise a plastic or glass material. For example, the sixth lens 260 may be made of a plastic material. The sixth lens 260 may comprise an eleventh surface S11 defined as the object-side surface and a twelfth surface S12 defined as the image-side surface. The eleventh surface S11 may be convex, and the twelfth surface S12 may be concave. That is, the sixth lens 260 may have a meniscus shape convex toward the object side. At least one of the eleventh surface S11 and the twelfth surface S12 may be aspherical. For example, both the eleventh surface S11 and the twelfth surface S12 may be aspherical.

[0113] The optical system 1000 may include an aperture stop (not shown). The aperture stop may be positioned between the object and the first lens 210, or between the first lens and the third lenses 210, 220, 230. For example, the aperture stop may be positioned between the second lens 220 and the third lens 230.

[0114] The first to sixth lenses 210, 220, 230, 240, 250, and 260 can each have a set effective aperture (light transmission aperture). For example, the first to twelfth surfaces S1, S2, S3, S4, S5, S6, S7, S8, S9, S10, S11, and S12 can each have a set effective aperture. The object-side surface or image-side surface of one of the lenses selected from the first lens 210 and the second lens 220 can have the largest effective aperture among the first to twelfth surfaces S1, S2, S3, S4, S5, S6, S7, S8, S9, S10, S11, and S12 of the first to sixth lenses 210, 220, 230, 240, 250, and 260. For example, the optical system 1000 may include at least one lens surface having an effective aperture larger than the object-side surface (first surface S1) of the first lens 210. Specifically, the optical system 1000 may include a lens surface having an effective aperture larger than the first surface S1.

[0115] The effective aperture of the image-side surface (second surface S2) of the first lens 210 can be larger than the effective aperture of the object-side surface (first surface S1) of the first lens 210. The effective aperture of the second surface S2 can be the largest among the first surface S1 to the twelfth surface S12. In addition, among the first surface S1 to the twelfth surface S12, the effective aperture of the first surface S1 can be second only to the second surface S2.

[0116] The effective aperture of the second lens 220 can be smaller than that of the first lens 210. For example, the effective apertures of the object-side surface (third surface S3) and image-side surface (fourth surface S4) of the second lens 220 can be smaller than those of the object-side surface (first surface S1) and image-side surface (second surface S2) of the first lens 110. Among the first surfaces S1 to the twelfth surfaces S12, the effective aperture of the third surface S3 can be second only to that of the first surface S1. Furthermore, among the first surfaces S1 to the twelfth surfaces S12, the effective aperture of the fourth surface S4 can be larger than that of the third surface S3. Furthermore, among the first surfaces S1 to the twelfth surfaces S12, the effective aperture of the image-side surface (eighth surface S8) of the fourth lens 240 can be the smallest. Alternatively, the effective aperture of the second lens 220 can be larger than that of the first lens 210. For example, the effective aperture of the object-side surface (third surface S3) of the second lens 220 can be larger than the effective aperture of one of the surfaces selected from the object-side surface (first surface S1) and the image-side surface (second surface S2) of the first lens 210. Specifically, the effective aperture of the third surface S3 can be larger than the effective apertures of the first surface S1 and the second surface S2. In this case, the effective aperture of the third surface S3 can be larger than the sizes of the first surface S1 and the second surface S2, but within 1.5 times the effective aperture of the second surface S2.

[0117] Reference Figure 8 At least one or more of the first to sixth lenses 210, 220, 230, 240, 250, and 260 may have a non-circular shape. For example, the first lens 210, the second lens 220, and the third lens 230 may each have a non-circular shape. When each of the first to third lenses 210, 220, and 230 is viewed from the front corresponding to the optical axis OA, the effective area of ​​each lens may have a non-circular shape. Specifically, the effective area of ​​each of the first to third lenses 210, 220, and 230 may include a first corner to a fourth corner A1, A2, A3, and A4. The first edge A1 and the second edge A2 may be edges facing each other in a first direction (x-axis direction) perpendicular to the optical axis OA. The first edge A1 and the second edge A2 may have a curved shape. The third edge A3 and the fourth edge A4 may be edges facing each other in a second direction (y-axis direction) perpendicular to the optical axis OA and the first direction. The third edge A3 and the fourth edge A4 may be edges connecting the ends of the first edge A1 and the second edge A2. The third edge A3 and the fourth edge A4 can have a straight line shape. That is, the first lens to the third lens 210, 220, 230 can have a D-shaped cut shape.

[0118] The first lens to the third lens 210, 220, 230 may have the aforementioned non-circular shape during the manufacturing process. For example, when the first lens to the third lens 210, 220, 230 include a plastic material, they can be manufactured into a non-circular shape during an injection molding process. Alternatively, the first lens to the third lens 210, 220, 230 can be manufactured into a circular shape by an injection molding process, and a partial area can be cut in a subsequent cutting process to form the third edge A3 and the fourth edge A4. Thus, the effective area of each of the first lens to the third lens 210, 220, 230 can have a set size. For example, the length CA of a virtual first straight line passing through the optical axis OA and connecting the first edge A1 and the second edge A2 can be longer than the length CH of a virtual second straight line passing through the optical axis OA and connecting the third edge A3 and the fourth edge A4. Here, the length CA of the first straight line can represent the maximum clear aperture CA of each of the first lens to the third lens 210, 220, 230, and the length CH of the second straight line can represent the minimum net height CH of the effective aperture of each of the first lens to the third lens 210, 220, 230.

[0119] In the above description, it has been described that the effective area of the first lens to the third lens 210, 220, 230 has a non-circular shape, but it is not limited thereto. The effective area of each lens can have a circular shape, and the ineffective area can have a non-circular shape.

[0120] The optical system 1000 according to the second embodiment can satisfy at least one or two or more of the following formulas described below. Therefore, when the optical system 1000 according to the second embodiment satisfies at least one or two or more of the following formulas, it can have improved optical characteristics. In addition, when the optical system 1000 satisfies at least one or two or more of the following formulas, it can be implemented smaller and more compact. In addition, when the optical system 1000 satisfies at least one or two or more of the following formulas, it can be applied to a foldable camera with a smaller thickness, so that a device including the camera can be manufactured to have a thin thickness.

[0121] [Formula 14]

[0122] 9 < EFL < 40

[0123] In Formula 14, EFL represents the effective focal length (mm) of the optical system 1000. Specifically, the EFL of the optical system 1000 can be 11 < EFL < 30. More specifically, the EFL of the optical system 1000 can be 13 < EFL < 26.

[0124] [Formula 15]

[0125] 0.95 < L1S1 / L1S2 < 1

[0126] In Equation 15, L1S1 represents the effective aperture (mm) of the object side surface (the first surface S1) of the first lens 210, and L1S2 represents the effective aperture (mm) of the image side surface (the second surface S2) of the first lens 210. Specifically, L1S1 / L1S2 can satisfy 0.96 < L1S1 / L1S2 < 1. Specifically, L1S1 / L1S2 can satisfy 0.99 < L1S1 / L1S2 < 1.

[0127] [Equation 16]

[0128] -8 < R_L1 / R_L3 < 0.98

[0129] In Equation 16, R_L1 represents the radius of curvature (mm) of the object side surface (the first surface S1) of the first lens 210, and R_L3 represents the radius of curvature (mm) of the object side surface (the third surface S3) of the second lens 220. Specifically, R_L1 and R_L3 can satisfy -8 < R_L1 / R_L3 < -2.

[0130] [Equation 17]

[0131] 0.1 < TH_L1 / TH_L2 < 0.75

[0132] In Equation 17, TH_L1 represents the center thickness (mm) of the first lens 210, and TH_L2 represents the center thickness (mm) of the second lens 220. Specifically, TH_L1 and TH_L2 can satisfy 0.2 < TH_L1 / TH_L2 < 0.65. More specifically, TH_L1 and TH_L2 can satisfy 0.3 < TH_L1 / TH_L2 < 0.55.

[0133] [Equation 18]

[0134] 0.52 < CH n(n<4) / CA n(n<4) < 0.98

[0135] In Equation 18, CH n(n<4) represents the minimum net height (mm) of the effective aperture of the nth lens. Specifically, CH n(n<4) represents the minimum dimension (mm) of the effective aperture of one lens selected from the first lens to the third lens 210, 220, 230. In addition, CA n(n<4) represents the maximum clear aperture (mm) of the nth lens. Specifically, CA n(n<4) represents the maximum dimension (mm) of the effective aperture of one lens selected from the first lens to the third lens 210, 220, 230.

[0136] [Formula 19]

[0137] 20<|f1|-|f2|<150

[0138] In Equation 19, f1 represents the focal length (mm) of the first lens 210, and f2 represents the focal length (mm) of the second lens 220.

[0139] [Formula 20]

[0140] 2 <BFL / ImgH<5

[0141] In Equation 20, BFL (back focal length) represents the distance (mm) from the image side surface of the lens 260, the lens closest to the image sensor 300 among the multiple lenses, to the image sensor 300. Furthermore, ImgH represents half the diagonal length (mm) of the effective area of ​​the image sensor 300. That is, ImgH represents the vertical distance (mm) from the optical axis of the upper surface of the image sensor 300 to a region of a field.

[0142] [Equation 21]

[0143] 0.35 <BFL / EFL<0.75

[0144] In Equation 21, BFL (back focal length) represents the distance (mm) from the image-side surface of the lens 260, which is the closest of the multiple lenses to the image sensor 300, to the image sensor 300 along the optical axis. Furthermore, EFL represents the effective focal length (mm) of the optical system 1000.

[0145] [Equation 22]

[0146] 1.5 <TTL / BFL<2.5

[0147] In Equation 22, TTL (Total Optical Length) represents the distance (mm) from the object-side surface (first surface S1) of the first lens 210, which is closest to the object side among the multiple lenses, to the image sensor 300 along the optical axis. Furthermore, BFL represents the distance (mm) from the image-side surface of the lens 260, which is closest to the image sensor 300 among the multiple lenses, to the image sensor 300 along the optical axis.

[0148] [Equation 23]

[0149] 0.75 <DL2 / TTL<0.9

[0150] In Equation 23, DL2 represents the distance (mm) from the object-side surface (third surface S3) of the second adjacent object-side lens 220 among the plurality of lenses to the image sensor 300 along the optical axis. Furthermore, TTL (total optical length) represents the distance (mm) from the object-side surface (first surface S1) of the lens 210 closest to the object side among the plurality of lenses to the image sensor 300 along the optical axis.

[0151] In the case where the optical system 1000 includes 6 lenses as in the second embodiment, the following equations 24 to 29 can be additionally satisfied.

[0152] [Equation 24]

[0153] |f3|<|f2|<|f6|<|f4|<|f5|<|f1|

[0154] Equation 24 is an example of comparing the absolute values ​​of the focal lengths of each lens. In Equation 24, f1 represents the focal length of the first lens 210, and f2 represents the focal length of the second lens 220. Furthermore, f3 represents the focal length of the third lens 230, and f4 represents the focal length of the fourth lens 240. Additionally, f5 represents the focal length of the fifth lens 250, and f6 represents the focal length of the sixth lens 260.

[0155] [Equation 25]

[0156] |f1|>|f2|+|f3|+|f4|+|f5|+|f6|

[0157] In Equation 25, f1 represents the focal length of the first lens 110, and f2 represents the focal length of the second lens 220. Furthermore, f3 represents the focal length of the third lens 230, and f4 represents the focal length of the fourth lens 240. Additionally, f5 represents the focal length of the fifth lens 250, and f6 represents the focal length of the sixth lens 260.

[0158] [Equation 26]

[0159] 10 <TH_L1 / d12<15

[0160] In Equation 26, TH_L1 represents the center thickness (mm) of the first lens 210, and d12 represents the distance (mm) between the first lens 210 and the second lens 220 along the optical axis OA.

[0161] [Equation 27]

[0162] 0.05 <d12 / d23<0.08

[0163] In Equation 27, d12 represents the distance (mm) between the first lens 210 and the second lens 220 along the optical axis OA, and d23 represents the distance (mm) between the second lens 220 and the third lens 230 along the optical axis OA.

[0164] [Equation 28]

[0165] 8 <f1 / EFL<14

[0166] In Equation 28, f1 represents the focal length (mm) of the first lens 210, and EFL represents the effective focal length (mm) of the optical system 1000.

[0167] [Equation 29]

[0168]

[0169] In Equation 29, Z is the sagitta (Sag), which can represent the distance from any position on the aspherical surface to the vertex of the aspherical surface along the optical axis. Furthermore, Y can represent the distance from any position on the aspherical surface to the optical axis along a direction perpendicular to the optical axis. Additionally, c can represent the curvature of the lens, and K can represent the conic constant. Furthermore, A, B, C, D, E, and F can represent aspherical constants.

[0170] The optical system 1000 according to the second embodiment can satisfy at least one or two or more of Equations 14 to 28. Specifically, the optical system 1000 may include at least one lens surface with an effective aperture larger than the effective aperture of the first surface S1, and may have improved optical properties. In the optical system 1000, the first to third lenses 210, 220, 230 may have non-circular shapes, such as D-shaped cuts. Therefore, compared to circular shapes, the optical system 1000 can be implemented in a smaller size and can be provided in a compact form. When the optical system 1000 satisfies at least one or two or more of Equations 14 to 28, the optical system 1000 can be adapted to a folding camera. Specifically, the optical system 1000 may include a light path changing member, and changes light incident on the device in a direction perpendicular to the device surface to a direction parallel to the device surface. Therefore, the optical system 1000 including multiple lenses can have a thinner thickness within the device, and thus the device can be provided thinner.

[0171] [Table 4]

[0172]

[0173] [Table 5]

[0174] item First Implementation Method TTL 17.3614 EFL 17.1380 BFL 8.3614 ImgH 3.2000 f1 155.1162 f2 7.3685 f3 -4.8207 f4 32.8128 f5 68.0291 f6 19.8623

[0175] Table 4 shows the radii of curvature, center thickness (mm) of each lens, distance between lenses (mm), effective aperture size, refractive index, and Abbe number of the first to sixth lenses 210, 220, 230, 240, 250, and 260 according to the second embodiment. Table 5 relates to the total optical length (TTL), effective focal length (EFL), back focal length (BFL), and focal length of the lenses of the optical system 1000 according to the second embodiment. Referring to Table 4, the refractive indices of the first lens 210 and the third lens 230 can be the same, the refractive indices of the second lens 220 and the fifth lens 250 can be the same, and the refractive indices of the fourth lens 240 and the sixth lens 260 can be the same. Furthermore, the refractive index of the second lens 220 can be less than the refractive index of the first lens 210, and the refractive index of the first lens 210 can be less than the refractive index of the fourth lens 240. The Abbe numbers of the first lens 210 and the third lens can be equal, the Abbe numbers of the second lens 220 and the fifth lens 250 can be equal, and the Abbe numbers of the fourth lens 240 and the sixth lens 260 can be equal. Furthermore, the Abbe number of the fourth lens 240 can be less than the Abbe number of the first lens 210, and the Abbe number of the first lens 210 can be less than the Abbe number of the second lens 220. Each surface S1, S2, S3, S4, S5, S6, S7, S8, S9, S10, S11, and S12 of the first to sixth lenses 210, 220, 230, 240, 250, and 260 can have a set effective aperture (light transmission aperture). Specifically, in the optical system 1000, the size of the effective aperture of the second surface S2 can be larger than the size of the effective aperture of the first surface S1, and the size of the effective aperture of the first surface S1 can be larger than the size of the effective aperture of the third surface S3. Although not disclosed in Table 4, the second lens 220 may include at least one surface with an effective aperture larger than that of the first lens 210. For example, the effective aperture of the third surface S3 may be larger than that of the first surface S1. Furthermore, the effective aperture of the third surface S3 may be larger than that of the first surface S1 and the second surface S2.

[0176] Referring to Table 5, the effective focal length EFL of the optical system 1000 can be less than the focal length f1 of the first lens 210. Furthermore, the effective focal length EFL of the optical system 1000 can be greater than the focal length f2 of the second lens 220.

[0177] [Table 6]

[0178]

[0179]

[0180] Table 6 shows the result values ​​of the optical system 1000 according to the second embodiment for the above-described equations. Referring to Table 6, it can be seen that the optical system 1000 according to the second embodiment satisfies at least one or two or more of equations 14 to 28. Specifically, it can be seen that the optical system 1000 satisfies all of equations 14 to 28. Accordingly, the optical system 1000 according to the second embodiment can have the following characteristics: Figure 9 and Figure 10 The MTF (modulation transfer function) characteristics and aberration characteristics are shown. Specifically, Figure 10 This is an aberration diagram of the optical system 1000 according to the first embodiment, and from left to right are the measured spherical aberration, astigmatism curve, and distortion. Figure 10 In the diagram, the X-axis can represent focal length (mm) or distortion (%), and the Y-axis can represent the height of the image sensor. Additionally, the spherical aberration graph is a graph of light in the wavebands of approximately 435 nm, approximately 486 nm, approximately 546 nm, approximately 587 nm, and approximately 656 nm, and the astigmatism and distortion graph is a graph of light in the 546 nm waveband. The optical system 1000 according to the first embodiment can have improved optical characteristics. Specifically, the optical system 1000 can include at least one lens surface having an effective aperture larger than the first surface S1 of the first lens 210, and can have improved optical characteristics. In the optical system 1000, the first to third lenses 210, 220, 230 can have non-circular shapes, such as D-shaped cuts. Therefore, compared to circular shapes, the optical system 1000 can be implemented in a smaller size and can be provided in a compact form. The optical system 1000 can include multiple lenses and optical path changing components (not shown). Therefore, the optical system 1000 can be applied to a folding camera that can have a small thickness, and the device including the camera can be manufactured to have a small thickness.

[0181] The features, structures, effects, etc., described in the above embodiments are included in at least one embodiment of the present invention, and are not necessarily limited to one embodiment. Furthermore, the features, structures, effects, etc., shown in each embodiment can be combined or modified by those skilled in the art to which these embodiments pertain for use in other embodiments. Therefore, anything related to such combinations and modifications should be interpreted as being included within the scope of the present invention. Moreover, although embodiments have been described above, these embodiments are merely examples and do not limit the present invention, and the above description is intended to those skilled in the art to which the present invention pertains without departing from the essential characteristics of these embodiments. It can be seen that various modifications and applications that have not yet been made are possible. For example, each component specifically shown in the embodiments can be implemented by modification. Differences related to such modifications and applications should be interpreted as being included within the scope of the present invention as defined in the appended claims.

Claims

1. An optical system, comprising: A first lens spaced apart from the image sensor; A second lens is disposed between the first lens and the image sensor; A third lens is disposed between the second lens and the image sensor; A fourth lens is disposed between the third lens and the image sensor; as well as A fifth lens is disposed between the fourth lens and the image sensor; The first lens to the fifth lens are arranged sequentially along the optical axis. Each of the first to fifth lenses includes an object-side surface and an image-side surface. Wherein, the effective aperture on the image-side surface of the first lens is larger than the effective aperture on the object-side surface of the first lens. The center thickness of the first lens is thinner than the center thickness of the second lens. The object-side surface of the first lens has a negative (-) radius of curvature. The first lens has positive (+) refractive power, and The object-side surface of the third lens has a convex shape. The optical system satisfies the following conditions: (1) 2 <BFL / ImgH<5; (2) |f3|<|f2|<|f5|<|f1|<|f4|; and (3) 2 < f1 / EFL < 4, in, EFL represents the effective focal length of the optical system. BFL represents the back focal length of the optical system. ImgH represents half the diagonal length of the effective imaging area of ​​the image sensor, and f1, f2, f3, f4, and f5 represent the focal lengths of the first lens, the second lens, the third lens, the fourth lens, and the fifth lens, respectively.

2. The optical system according to claim 1, wherein, The fifth lens has positive (+) refractive power. The first lens has a meniscus shape that bulges out along the image side direction, and The image-side surface of the fourth lens has a concave shape.

3. The optical system according to claim 1, wherein, The second lens has positive (+) refractive power. The object-side surface of the second lens has a convex shape, and The image-side surface of the second lens has a concave shape.

4. The optical system according to any one of claims 1 to 3, wherein, The thickness of the first lens is less than the distance between the first lens and the second lens in the direction of the optical axis.

5. The optical system according to claim 4, wherein, The center thickness of the second lens is greater than the center thickness of the third lens, the fourth lens, and the fifth lens.

6. An optical system, comprising: A first lens spaced apart from the image sensor; A second lens is disposed between the first lens and the image sensor; A third lens is disposed between the second lens and the image sensor; A fourth lens is disposed between the third lens and the image sensor; as well as A fifth lens is disposed between the fourth lens and the image sensor; The first lens to the fifth lens are arranged sequentially along the optical axis. The first lens has positive (+) refractive power. The first lens includes an object-side surface, which has a concave shape relative to the optical axis. The second lens has a surface with an effective aperture larger than the effective aperture of the object-side surface of the first lens, and The object-side surface of the third lens has a convex shape. The optical system satisfies the following conditions: (1) 2 <BFL / ImgH<5; (2) |f3|<|f2|<|f5|<|f1|<|f4|; and (3) 2 < f1 / EFL < 4, in, EFL represents the effective focal length of the optical system. BFL represents the back focal length of the optical system. ImgH represents half the diagonal length of the effective imaging area of ​​the image sensor, and f1, f2, f3, f4, and f5 represent the focal lengths of the first lens, the second lens, the third lens, the fourth lens, and the fifth lens, respectively.

7. The optical system according to claim 6, wherein, The second lens has positive (+) refractive power. The fifth lens has positive (+) refractive power, and The focal length of the first lens is greater than the focal length of the second lens.

8. The optical system according to claim 6 or 7, wherein, The effective focal length (EFL) of the optical system is less than the focal length of the first lens and greater than the focal length of the second lens.

9. The optical system according to claim 8, wherein, The image-side surface of the first lens has a convex shape. The image-side surface of the second lens has a concave shape; and Wherein, the thickness of the first lens is less than the distance between the first lens and the second lens in the direction of the optical axis.

10. An optical system, comprising: A first lens spaced apart from the image sensor; A second lens is disposed between the first lens and the image sensor; A third lens is disposed between the second lens and the image sensor; A fourth lens is disposed between the third lens and the image sensor; as well as A fifth lens is disposed between the fourth lens and the image sensor; The first lens to the fifth lens are arranged sequentially along the optical axis. The center thickness of the first lens is less than the center thickness of the second and third lenses, but greater than the center thickness of the fourth and fifth lenses. Wherein, the center thickness of the second lens is greater than the center thickness of the third lens, and Wherein, the object-side surface or image-side surface of one of the lenses selected from the first lens and the second lens has the largest effective aperture among the object-side surfaces and image-side surfaces of the first lens to the fifth lens. The object-side surface of the first lens has a concave shape. The first lens has positive (+) refractive power, and The object-side surface of the third lens has a convex shape. The optical system satisfies the following conditions: (1) 2 <BFL / ImgH<5; (2) |f3|<|f2|<|f5|<|f1|<|f4|; and (3) 2 < f1 / EFL < 4, in, EFL represents the effective focal length of the optical system. BFL represents the back focal length of the optical system. ImgH represents half the diagonal length of the effective imaging area of ​​the image sensor, and f1, f2, f3, f4, and f5 represent the focal lengths of the first lens, the second lens, the third lens, the fourth lens, and the fifth lens, respectively.

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