Optical imaging lens

Abstract

The invention relates to an optical imaging lens, which comprises a lens barrel, a lens group and a plurality of spacing elements, and is characterized in that the lens barrel is used for accommodating the lens group and the plurality of spacing elements; the lens group sequentially comprises a first lens with positive focal power, a second lens with negative focal power, a third lens with positive focal power, a fourth lens with negative focal power, a fifth lens with positive focal power and a sixth lens with negative focal power from the object side to the image side along the optical axis; the plurality of spacing elements comprise a fourth spacing element and a fifth spacing element; the optical imaging lens satisfies the following conditions: 9.10 lt; f / (f5 + f6) < = 15.50; 1.95 < = d0m / d5slt; 2.15, 2.15; 1.40 lt, 1.40 lt; eT6 / (EP45 + CP5) lt; and 2.00. According to the optical imaging lens, the lens forming process is optimized on the premise that mechanical aligning is met, the thickness of carrying equipment is greatly reduced, and meanwhile the lens machining feasibility is guaranteed.

Description

Technical Field

[0001] This invention relates to the field of imaging lens technology, and more particularly to an optical imaging lens. Background Technology

[0002] With the advancement of technology and the improvement of living standards, mobile phone photography has become an indispensable part of daily life. Currently, ultra-wide-angle, telephoto, large aperture, and large image sensor are gradually becoming standard features of mobile phone cameras. A single mobile phone will be equipped with multiple different types of lenses to achieve better imaging effects and a wider field of view, thereby meeting the diverse shooting needs of consumers. However, for conventional wide-angle lenses, when controlling the overall length and size of the lens, the thinner the lens, the smaller its shape, and the wider its field of view, the greater the curvature of the lens edge closest to the image side. This makes the manufacturing process more difficult and increases the risk of weld lines due to uneven lens shape and excessive thickness ratio, affecting image quality. Summary of the Invention

[0003] To address the problems existing in the prior art, the present invention aims to provide an optical imaging lens that optimizes the lens forming process while satisfying mechanical alignment. This ensures the feasibility of lens processing and gives the lens good manufacturability while significantly reducing the thickness of the mounting device in the ultra-thin lens.

[0004] To achieve the above-mentioned objectives, the present invention provides an optical imaging lens comprising a lens barrel, a lens group, and a plurality of spacers. The lens barrel is used to accommodate the lens group and the plurality of spacers. The lens group, along the optical axis from the object side to the image side, consists of a first lens with positive optical power, a second lens with negative optical power, a third lens with positive optical power, a fourth lens with negative optical power, a fifth lens with positive optical power, and a sixth lens with negative optical power.

[0005] The object-side surface of the first lens is concave, and its image-side surface is convex; the object-side surface of the fifth lens is concave, and its image-side surface is convex; the object-side surface of the sixth lens is convex, and its image-side surface is concave; the absolute value of the curvature of the light-transmitting area of ​​the object-side and image-side surfaces of the sixth lens gradually increases from the center of the optical axis to the radial edge.

[0006] The plurality of spacer elements include:

[0007] A fourth spacer element is disposed between the fourth lens and the fifth lens and contacts the image side of the fourth lens;

[0008] A fifth spacer element is disposed between the fifth lens and the sixth lens and contacts the image side of the fifth lens; the fifth spacer element contacts the object side of the sixth lens;

[0009] The optical imaging lens satisfies:

[0010] 9.10 <f / (f5+f6)≤15.50;

[0011] 1.95≤d0m / d5s<2.15;

[0012] 1.40 <ET6 / (EP45+CP5)<2.00;

[0013] Wherein, f is the effective focal length of the optical imaging lens, f5 is the effective focal length of the fifth lens, d0m is the inner diameter of the image-side end face of the lens barrel, d5s is the inner diameter of the object-side side face of the fifth spacer element, EP45 is the spacing distance between the fourth spacer element and the fifth spacer element along the optical axis, CP5 is the maximum thickness of the fifth spacer element along the optical axis, and ET6 is the edge thickness of the light-transmitting area of ​​the sixth lens.

[0014] According to one technical solution of the present invention, the plurality of spacer elements further includes a second spacer element disposed between the second lens and the third lens and in contact with the image side surface of the second lens; the inner diameter of the second spacer element is the minimum value among the inner diameters of the image side surfaces of all spacer elements in the optical lens;

[0015] The optical imaging lens satisfies: 2.40 <d5s / d2s<3.65;

[0016] Wherein, d5s is the inner diameter of the object side of the fifth spacer element, and d2s is the inner diameter of the object side of the second spacer element.

[0017] According to one technical solution of the present invention, the optical imaging lens satisfies: 1.35 <d0m / d0s<2.25;

[0018] Wherein, d0m is the inner diameter of the image-side end face of the lens barrel, and d0s is the inner diameter of the object-side end face of the lens barrel.

[0019] According to one technical solution of the present invention, the optical imaging lens satisfies: -1.15 <f6 / (d0m-d5m)<-0.50;

[0020] Wherein, f6 is the effective focal length of the sixth lens, d0m is the inner diameter of the image-side end face of the lens barrel, and d5m is the inner diameter of the image-side surface of the fifth spacer element.

[0021] According to one technical solution of the present invention, the optical imaging lens satisfies: 0.35 <EP45 / (d5s-d4m)<0.55;

[0022] Wherein, EP45 is the distance between the fourth spacer element and the fifth spacer element along the optical axis, d5s is the inner diameter of the object side of the fifth spacer element, and d4m is the inner diameter of the image side of the fourth spacer element.

[0023] According to one technical solution of the present invention, the optical imaging lens satisfies: 2.65 <EP50 / CT6<3.15;

[0024] Wherein, EP50 is the distance along the optical axis from the image side of the fifth spacer element to the image side end face of the lens barrel, and CT6 is the center thickness of the sixth lens.

[0025] According to one technical solution of the present invention, the plurality of spacers further includes a third spacer element, which is disposed between the third lens and the fourth lens and contacts the image side of the third lens; the optical imaging lens satisfies: 0.50≤T45 / (CT4+CT5)≤0.55; 0.85 <EP34 / (CP4+EP45)≤1.50;

[0026] Wherein, T45 is the air gap between the fourth lens and the fifth lens on the optical axis, CT4 is the center thickness of the fourth lens, CT5 is the center thickness of the fifth lens, EP34 is the spacing distance between the third spacer element and the fourth spacer element along the optical axis, CP4 is the maximum thickness of the fourth spacer element along the optical axis, and EP45 is the spacing distance between the fourth spacer element and the fifth spacer element along the optical axis.

[0027] According to one technical solution of the present invention, the object-side surface and the image-side surface of the sixth lens each have at least one critical point; the optical imaging lens satisfies: -1.55 <f6 / f<-0.65,3.00<D5m / YC62<4.35;

[0028] Where f is the effective focal length of the optical imaging lens, f6 is the effective focal length of the sixth lens, D5m is the outer diameter of the image-side surface of the fifth spacer element, and YC62 is the vertical distance from the image-side surface of the sixth lens to the optical axis from the nearest critical point on the optical axis.

[0029] According to one technical solution of the present invention, the optical imaging lens satisfies: 0.75≤(OD6-YC62) / OD6<0.80;

[0030] Wherein, OD6 is the maximum outer diameter of the sixth lens, and YC62 is the vertical distance from the image-side surface of the sixth lens to the optical axis from the nearest critical point on the optical axis.

[0031] According to a technical solution of the present invention, the optical imaging lens satisfies: 0.45 ≤ EP45 / (T45 + CT5) ≤ 0.60;

[0032] Wherein, EP45 is the spacing distance between the fourth spacer element and the fifth spacer element along the optical axis direction, T45 is the air gap between the fourth lens and the fifth lens on the optical axis, and CT5 is the central thickness of the fifth lens.

[0033] According to a technical solution of the present invention, the optical imaging lens satisfies: 0.35 < SP6 / CTs < 0.55;

[0034] Wherein, SP6 is the length of the outer peripheral surface of the sixth lens parallel to the optical axis direction, and CT6 is the central thickness of the sixth lens.

[0035] Advantages of the present invention:

[0036] The optical imaging lens of the present application is a six-piece large image plane and wide-angle lens. The effective focal lengths of the fifth lens and the sixth lens and the effective focal length of the optical imaging lens satisfy 9.10 < f / (f5 + f6) ≤ 15.50, and the inner diameter of the image side end surface of the lens barrel and the inner diameter of the object side surface of the fifth spacer element satisfy 1.95 ≤ d0m / d5s < 2.15. It can be seen that the refractive powers of the fifth lens and the sixth lens are relatively strong. After the light passes through the fifth lens and the sixth lens and is refracted, the required image plane size is finally achieved. To control the overall length and volume of the lens in optical design, the optical imaging lens has a relatively thin thickness, a relatively large field angle, and a relatively large image plane. The absolute value of the curvature of the sixth lens in the optical imaging lens will increase more and more from the optical axis to the periphery, and the bending degree of the sixth lens will be greater, resulting in the problem that the sixth lens is prone to uneven thickness. When the lens is injection molded, the uneven cavity will force the molten plastic melt to flow separately, and at the same time cause the attenuation of the material flow pressure transmission and the significant temperature difference of the melt in different regions, so that the separated melt cannot be fully fused at the confluence, resulting in the problem of weld lines easily appearing on the lens. By controlling the ratio of the sum of the spacing distance between the fourth spacer element and the fifth spacer element and the maximum thickness of the fifth spacer element along the optical axis direction to the inner diameter of the image side surface of the fifth spacer element to satisfy the range of 1.40 < ET6 / (EP45 + CP5) < 2.00, the thickness of the non-light-passing area on the fifth lens, the maximum thickness of the fifth spacer element bearing between the fifth lens and the sixth lens, and the maximum thickness of the non-light-passing area on the edge of the sixth lens can be restricted, thereby ensuring the uniformity of the overall thickness of the sixth lens, reducing the risk of weld lines caused by the uneven thickness of the sixth lens, avoiding the appearance risk of the sixth lens and the risk of stray light generated by the light passing through the sixth lens at the weld line position, and thus improving the imaging quality. Description of the Drawings

[0037] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly described below. Obviously, the drawings described below are merely some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without creative effort.

[0038] Figure 1A , Figure 1B and Figure 1C The diagrams show the lens structure layout, optical structure layout, and schematic diagram of the parameters of the sixth lens portion of an optical imaging lens according to the present invention.

[0039] Figure 2A , Figure 2B and Figure 2C A schematic diagram of the structure of three optical imaging lenses according to Embodiment 1 of this application is shown;

[0040] Figures 3A to 3B The on-axis chromatic aberration curve and distortion curve of the optical imaging lens according to Embodiment 1 of this application are shown respectively;

[0041] Figure 4A , Figure 4B and Figure 4C A schematic diagram of the structure of three optical imaging lenses according to Embodiment 2 of this application is shown;

[0042] Figures 5A to 5B The on-axis chromatic aberration curve and distortion curve of the optical imaging lens according to Embodiment 2 of this application are shown respectively;

[0043] Figure 6A , Figure 6B and Figure 6C A schematic diagram of the structure of three optical imaging lenses according to Embodiment 3 of this application is shown;

[0044] Figures 7A to 7B The on-axis chromatic aberration curve and distortion curve of the optical imaging lens according to Embodiment 3 of this application are shown respectively;

[0045] Figure 8 The overall wavefront curve of the sixth lens of an optical imaging lens is shown when f / (f5+f6)=15.33, d0m / d5s=2.11, and ET6 / (EP45+CP5)=2.15.

[0046] Figure 9 The overall wavefront curve of the sixth lens of an optical imaging lens is shown when f / (f5+f6)=15.33, d0m / d5s=2.11, and ET6 / (EP45+CP5)=1.25.

[0047] Figure 10 The overall wavefront curve of the sixth lens of the optical imaging lens of this application is shown when f / (f5+f6)=15.33, d0m / d5s=2.11, and ET6 / (EP45+CP5)=1.87. Detailed Implementation

[0048] To better understand this application, various aspects of this application will be described in more detail with reference to the accompanying drawings. It should be understood that these detailed descriptions are merely illustrative of exemplary embodiments of this application and are not intended to limit the scope of this application in any way. Throughout the specification, the same reference numerals refer to the same elements. The expression "and / or" includes any and all combinations of one or more of the associated listed items.

[0049] It should be noted that in this specification, the terms "first," "second," "third," etc., are used only to distinguish one feature from another and do not imply any limitation on the features. Therefore, without departing from the teachings of this application, the first lens discussed below may also be referred to as the second lens or the third lens.

[0050] In the accompanying drawings, the thickness, size, and shape of the lenses have been slightly exaggerated for ease of illustration. Specifically, the shapes of the spherical or aspherical surfaces shown in the drawings are illustrated by way of example. That is, the shapes of the spherical or aspherical surfaces are not limited to those shown in the drawings. The drawings are for illustrative purposes only and are not strictly to scale.

[0051] The surface of each lens that connects its object side to its image side is called the outer peripheral surface of the lens. Each lens's object side or image side has a light-transmitting area and a non-light-transmitting area. The light-transmitting area is the effective light-transmitting area that directly participates in imaging, allows effective light to pass through, and participates in the imaging of the optical system. The non-light-transmitting area is the area that does not participate in imaging and does not perform the function of effective light transmission imaging; it is mostly the edge, light-blocking, or structural assembly area.

[0052] It should also be understood that the terms "comprising," "including," "having," "containing," and / or "comprising," when used in this specification, indicate the presence of the stated features, elements, and / or components, but do not exclude the presence or addition of one or more other features, elements, components, and / or combinations thereof. Furthermore, when expressions such as "at least one of..." appear after a list of listed features, they modify the entire list of features, not individual elements in the list. Additionally, when describing embodiments of this application, the word "may" is used to mean "one or more embodiments of this application." And the term "exemplary" is intended to refer to an example or illustration.

[0053] Unless otherwise specified, all terms used herein (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. It should also be understood that terms (e.g., those defined in common dictionaries) shall be interpreted as having the meaning consistent with their meaning in the context of the relevant art and shall not be interpreted in an idealized or overly formal sense, unless expressly so specified herein.

[0054] It should be noted that, unless otherwise specified, the embodiments and features described in the embodiments of this application can be combined with each other. The following embodiments only illustrate several implementation methods of this application, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the patent application. It should be pointed out that, for those skilled in the art, several modifications and improvements can be made without departing from the concept of this application, and these all fall within the protection scope of this application.

[0055] like Figure 1A , Figure 1B and Figure 1C As shown, according to a first aspect of the present invention, an optical imaging lens is provided, comprising a lens barrel, a lens group, and a plurality of spacer elements. The lens group comprises six lenses: a first lens having positive optical power, with its object-side surface being concave and its image-side surface being convex; a second lens having negative optical power, with its object-side surface being convex and its image-side surface being concave; a third lens having positive optical power, with both its object-side surface and image-side surface being convex; a fourth lens having negative optical power, with its object-side surface being concave; a fifth lens having positive optical power, with its object-side surface being concave and its image-side surface being convex; and a sixth lens having negative optical power, with its object-side surface being convex and its image-side surface being concave.

[0056] The first to sixth lenses are arranged sequentially along the optical axis from the subject side to the imaging plane side. Each lens has at least one object side facing the subject side and one image side facing the imaging plane side, and there is an air gap between adjacent lenses.

[0057] The plurality of spacer elements includes at least: a first spacer element disposed between the first lens and the second lens and in contact with the image side of the first lens; a second spacer element disposed between the second lens and the third lens and in contact with the image side of the second lens; a third spacer element disposed between the third lens and the fourth lens and in contact with the image side of the third lens; a fourth spacer element disposed between the fourth lens and the fifth lens and in contact with the image side of the fourth lens; a fifth spacer element disposed between the fifth lens and the sixth lens and in contact with the image side of the fifth lens; and a fifth spacer element in contact with the object side of the sixth lens. The inner diameter of the second spacer element is the minimum value among the inner diameters of the object side of all spacer elements in the optical lens.

[0058] The lens group and multiple spacer elements are accommodated in the lens barrel. The lens barrel includes an object-side end face, an image-side end face, and an inner annular surface. Along the optical axis direction of the optical imaging lens, the inner annular surface of the lens barrel is stepped.

[0059] Each lens in the lens group includes an object side face, an image side face, and an outer peripheral surface for connecting the object side face and the image side face.

[0060] In some embodiments of the present invention, the optical imaging lens may further include a color filter for correcting color deviation and / or a protective glass for protecting the photosensitive element located on the imaging surface.

[0061] In some embodiments of the present invention, the optical imaging lens satisfies: 9.10 < f / (f5 + f6) ≤ 15.50; 1.95 ≤ d0m / d5s < 2.15; 1.40 < ET6 / (EP45 + CP5) < 2.00, where f is the effective focal length of the optical imaging lens, f5 is the effective focal length of the fifth lens, f6 is the effective focal length of the sixth lens, d0m is the inner diameter of the image-side end face of the lens barrel, EP45 is the axial distance between the fourth spacer element and the fifth spacer element, CP5 is the maximum axial thickness of the fifth spacer element, and ET6 is the edge thickness of the light-passing area of the sixth lens.

[0062] In this application, the optical imaging lens is a six-piece large image plane and wide-angle lens. The effective focal lengths of the fifth lens and the sixth lens and the effective focal length of the optical imaging lens satisfy 9.10 < f / (f5 + f6) ≤ 15.50, and the inner diameter of the image-side end face of the lens barrel and the fifth spacer element satisfy 1.95 ≤ d0m / d5s < 2.15. It can be seen that the refractive power of the fifth lens and the sixth lens is relatively strong. After the light passes through the fifth lens and the sixth lens and is refracted, the required image plane size is finally achieved. To control the overall length and volume of the lens in optical design, the optical imaging lens has a relatively thin thickness, a relatively large field angle, and a relatively large image plane. The absolute value of the curvature of the sixth lens in the optical imaging lens will increase more and more around the optical axis, and the curvature of the sixth lens will become larger and larger, resulting in the problem that the sixth lens is prone to uneven thickness. When the lens is injection-molded, the uneven-thickness cavity will force the molten plastic melt to split, and at the same time cause the attenuation of the pressure transfer of the material flow and the significant temperature difference of the melt temperature in different regions, so that the split melt cannot be fully fused at the confluence, resulting in the problem that weld lines are prone to appear on the lens. By controlling the ratio of the sum of the spacing distance between the fourth spacer element and the fifth spacer element and the maximum thickness of the fifth spacer element to the inner diameter of the image-side surface of the fifth spacer element to satisfy the range of 1.40 < ET6 / (EP45 + CP5) < 2.00, the thickness of the non-light-transmitting area on the fifth lens, the maximum thickness of the fifth spacer element supported between the fifth lens and the sixth lens, and the maximum thickness of the non-light-transmitting area on the edge of the sixth lens can be restricted, thereby ensuring the uniformity of the overall thickness of the sixth lens, reducing the risk of weld lines caused by the uneven thickness of the sixth lens, avoiding the appearance risk of the sixth lens and the risk of stray light generated by the light passing through the sixth lens at the weld line position, and thus improving the imaging quality.

[0063] For example, when f / (f5 + f6) = 15.33 and d0m / d5s = 2.11, the above relationship is satisfied. At this time, when d5m / (EP45 + CP5) = 2.15, as Figure 8 shown, during the filling process of the plastic melt, the curves on the left side are densely distorted and interlaced, and the phenomenon of curve convergence and wrapping is obvious. The wavefront curves in the edge area of the lens are significantly converged. The simulation results show that there is a risk of weld lines; when d5m / (EP45 + CP5) = 1.25, as Figure 9 shown, during the filling process of the plastic melt, the curves on the left side converge and are distorted, and there is also a certain disorder in the middle curves. The phenomenon of curve convergence and wrapping is obvious. The wavefront curves in the edge area of the lens are significantly converged. The simulation results show that there is a risk of weld lines; when d5m / (EP45 + CP5) = 1.87, as Figure 10 shown, when the molten glue flows through the lens area, the wavefront is flat, there is no phenomenon of convergence and wrapping, and there is a slight difference in the speed between the edge and the center. The simulation results show no distribution of weld lines.

[0064] In some embodiments of the present invention, the optical imaging lens satisfies: 2.40 < d5s / d2s < 3.65; where d5s is the inner diameter of the object side surface of the fifth spacer element, and d2s is the inner diameter of the object side surface of the second spacer element.

[0065] After the lens light passes through the aperture of the second spacer element, it diverges. By the above conditional formula, controlling the inner diameters of the object sides of the second spacer element and the fifth spacer element can ensure sufficient light input to the system, and at the same time restrict the overall propagation angle of the light, reducing the problem of stray light caused by excessive light angles.

[0066] In some embodiments of the present invention, the optical imaging lens satisfies: 1.35 < d0m / d0s < 2.25; where d0m is the inner diameter of the image side end surface of the lens barrel, and d0s is the inner diameter of the object side end surface of the lens barrel.

[0067] By the above conditional formula, controlling the inner diameter of the object side surface and the inner diameter of the image side surface of the lens barrel can balance the weight distribution of the lens barrel under the condition of meeting the imaging design conditions of the optical imaging lens, and尽可能 ensure that the external shape structure tends to be miniaturized, reducing the product volume and weight.

[0068] In some embodiments of the present invention, the optical imaging lens satisfies: -1.15 < f6 / (d0m - d5m) < -0.50; where f6 is the effective focal length of the sixth lens, d0m is the inner diameter of the image side end surface of the lens barrel, and d5m is the inner diameter of the image side surface of the fifth spacer element.

[0069] By the above conditional formula, controlling the relationship between the effective focal length of the sixth lens, the inner diameter of the image side end surface of the lens barrel, and the inner diameter of the image side surface of the fifth spacer element can help the end of the lens barrel avoid the outgoing light and prevent stray light at the end under the condition that the light reaches the required image surface size after refraction by the sixth lens and the sixth lens has sufficient mechanical components.

[0070] In some embodiments of the present invention, the optical imaging lens satisfies: 0.35 < EP45 / (d5s - d4m) < 0.55; where EP45 is the axial spacing distance between the fourth spacer element and the fifth spacer element, d5s is the inner diameter of the object side surface of the fifth spacer element, and d4m is the inner diameter of the image side surface of the fourth spacer element.

[0071] By the above conditional formula, the angles of the incident light and the outgoing light before and after passing through the fifth lens and the inner diameter gradient of the object side surfaces of the fourth spacer element and the fifth spacer element can be effectively controlled, thereby controlling the light drop, intercepting the excess light in the outer field of view, and improving the imaging quality.

[0072] In some embodiments of the present invention, the optical imaging lens satisfies: 2.65 < EP50 / CT6 < 3.15; where EP50 is the distance from the image side surface of the fifth spacer element to the image side end face of the lens barrel along the optical axis direction, and CT6 is the central thickness of the sixth lens.

[0073] Through the above conditional formula, the thickness of the non-light-passing area of the sixth lens can be controlled not to be too large, ensuring the overall thickness ratio of the sixth lens. At the same time, it can also control the image side surface of the sixth lens not to protrude from the image side end face of the lens barrel, effectively reducing the appearance loss during the lens production process and improving the overall yield and performance.

[0074] In some embodiments of the present invention, the optical imaging lens satisfies: 0.50 ≤ T45 / (CT4 + CT5) ≤ 0.55; 0.85 < EP34 / (CP4 + EP45) ≤ 1.50; where T45 is the air gap between the fourth lens and the fifth lens on the optical axis, CT4 is the central thickness of the fourth lens, CT5 is the central thickness of the fifth lens, EP34 is the interval distance between the third spacer element and the fourth spacer element along the optical axis direction, CP4 is the maximum thickness of the fourth spacer element along the optical axis direction, and EP45 is the interval distance between the fourth spacer element and the fifth spacer element along the optical axis direction.

[0075] Through the above conditional formula, while restricting the relationship between the air gap between the fourth lens and the fifth lens and the thicknesses of the two lenses, it is ensured that the air gap between the fourth lens and the fifth lens is not too large. By reasonably designing the thicknesses of the non-light-passing areas of the fourth spacer element, the fourth lens, and the fifth lens, the risk of deformation of the fourth spacer element after high temperature can be reduced from the design, improving the reliability stability of the lens.

[0076] In some embodiments of the present invention, there is at least one critical point on the object side surface and the image side surface of the sixth lens respectively. The optical imaging lens satisfies: -1.55 < f6 / f < -0.65, 3.00 < D5m / YC62 < 4.35; where f is the effective focal length of the optical imaging lens, f6 is the effective focal length of the sixth lens, D5m is the outer diameter of the image side surface of the fifth spacer element, and YC62 is the perpendicular distance from the closest critical point on the image side surface of the sixth lens to the optical axis.

[0077] By controlling the above conditional formula to restrict the distribution of the effective focal length of the sixth lens in the system, it is beneficial to obtain a large field angle. Further restricting the position of the outer diameter of the image side of the fifth spacer element and the critical point on the image side of the sixth lens reduces the deformation of the lens caused by assembly stress.

[0078] In some embodiments of the present invention, the optical imaging lens satisfies: 0.75 ≤ (OD6 - YC62) / OD6 < 0.80; where OD6 is the maximum outer diameter of the sixth lens, and YC62 is the vertical distance from the nearest critical point on the image side surface of the sixth lens to the optical axis.

[0079] Through the above conditional formula, the position of the critical point on the image side surface of the sixth lens can be controlled, the emission path of the light rays passing through the sixth lens can be constrained, the possibility of stray light appearing at the end of the lens barrel can be reduced, and at the same time, it is ensured that the imaging light rays of the optical imaging lens can match the chip size after passing through the sixth lens.

[0080] In some embodiments of the present invention, the optical imaging lens satisfies: 0.45 ≤ EP45 / (T45 + CT5) ≤ 0.60; where EP45 is the interval distance between the fourth spacer element and the fifth spacer element along the optical axis direction, T45 is the air gap between the fourth lens and the fifth lens on the optical axis, and CT5 is the central thickness of the fifth lens.

[0081] Through the above conditional formula, the ratio of the thickness of the fifth lens from the edge to the center can be constrained, which is beneficial to the molding process of the fifth lens.

[0082] In some embodiments of the present invention, the optical imaging lens satisfies: 0.35 < SP6 / CT6 < 0.55; where SP6 is the length of the outer peripheral surface of the sixth lens parallel to the optical axis direction, and CT6 is the central thickness of the sixth lens.

[0083] Through the above conditional formula, the length of the outer peripheral surface of the sixth lens parallel to the optical axis and the central thickness are controlled within a reasonable range, ensuring that the sixth lens has sufficient outer peripheral parallel length to contact the inner wall of the lens barrel. By contacting the inner wall of the lens barrel through the outer peripheral parallel length of the sixth lens, stable positioning support is provided for the sixth lens, ensuring that the optical axis of the sixth lens coincides with the optical axes of the lens barrel and other lenses without deviation, thereby reducing the eccentricity error.

[0084] The second aspect of the present application provides an optical imaging lens. The optical imaging lens may include a lens barrel, a lens group, and a plurality of spacer elements disposed within the lens barrel. The lens group includes: a first lens having a positive optical power; a second lens having a negative optical power; a third lens having a positive optical power; a fourth lens having a negative optical power; a fifth lens having a positive optical power; a sixth lens having a negative optical power. At least among the plurality of spacer elements include: a second spacer element disposed between the second lens and the third lens and in contact with the image side surface of the second lens; a third spacer element disposed between the third lens and the fourth lens and in contact with the image side surface of the third lens; a fourth spacer element disposed between the fourth lens and the fifth lens and in contact with the image side surface of the fourth lens; a fifth spacer element disposed between the fifth lens and the sixth lens and in contact with the image side surface of the fifth lens; the fifth spacer element is in contact with the object side surface of the sixth lens.

[0085] The optical imaging lens satisfies: 10.4mm ≤ d0m / tan(Semi-FOV) < 11.15mm; -1.15 < f6 / (d0m - d5m) < -0.50; where, d0m is the inner diameter of the image side end face of the lens barrel, Semi-FOV is half of the maximum field angle of the optical imaging lens, f6 is the effective focal length of the sixth lens, and d5m is the inner diameter of the image side surface of the fifth spacer element.

[0086] Through the above ratio relationship between the inner diameter of the image side of the lens barrel and the tangent of the field angle, a constraint is formed on the aperture of the light finally exiting the lens barrel. Since the inner diameter of the image side end face of the lens barrel is to match the size of the final image plane, stray light is likely to occur at the tail end of the lens barrel. For example, multiple reflections caused by redundant reflection areas on the inner wall of the image side end face of the lens barrel, or beam blockage and scattering caused by insufficient inner diameter, and then secondary reflection occurs on the surface of the sixth lens, finally deviating from the effective imaging optical path and projecting onto the image plane, thus generating stray light. By controlling the relationship between the effective focal length of the sixth lens and the inner diameters of the image side surface of the lens barrel and the image side surface of the fifth spacer element, it is beneficial for the light to refract along the effective optical path of wide angle and large image plane, and at the same time, it can meet the condition of leaving enough mechanical assembly space for the sixth lens, and enable the tail end of the lens barrel to effectively avoid the outgoing light and prevent stray light at the tail end.

[0087] The optical imaging lens according to the above embodiment of the present application uses six lenses. By reasonably distributing the optical powers, surface shapes of each lens, and the arrangements of each spacer element, etc., the span of each gear in the cooperation between the lens and the lens barrel is relatively uniform, enhancing the ability of light convergence and improving the imaging quality of the optical imaging lens.

[0088] In some embodiments of the present invention, the lens material in the optical imaging lens provided by the present invention can be glass or plastic. When the lens material is plastic, production costs can be effectively reduced. Conversely, when the lens material is glass, the low dispersion characteristic of glass itself can effectively correct geometric chromatic aberration of the optical imaging lens. The optical imaging lens provided by the present invention can adopt an all-plastic lens structure, which not only gives the lens excellent imaging performance but also allows for a more compact lens structure, achieving a better balance between lens miniaturization and high image quality.

[0089] In some embodiments of the present invention, the first lens, second lens, third lens, fourth lens, fifth lens, and sixth lens can be spherical lenses or aspherical lenses. Compared with spherical structures, aspherical structures can effectively reduce the aberrations of optical imaging lenses, thereby reducing the number of lenses and the size of the lenses, and better achieving lens miniaturization. More specifically, the first lens, second lens, third lens, fourth lens, fifth lens, and sixth lens of the present invention can all be aspherical lenses, which can effectively reduce the aberrations of optical imaging lenses, thereby reducing the number of lenses and the size of the lenses, and achieving lens miniaturization.

[0090] When an aspherical lens is used, the shapes of each aspherical surface of the optical imaging lens satisfy the following equation:

[0091]

[0092] In the above formula, The height perpendicular to the optical axis is along the optical axis. The axial distance from the vertex to the surface at the location; This represents the curvature at the vertex of the aspherical surface. The conic coefficient; , , , , , , ...represent aspheric coefficients of the fourth, sixth, eighth, tenth, twelfth, fourteenth, and sixteenth orders, respectively.

[0093] The present invention will be further described below with reference to several embodiments. In each embodiment, the thickness, radius of curvature, and material selection of each lens in the optical imaging lens are different; for specific differences, please refer to the parameter tables of each embodiment. The following embodiments are merely preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the following embodiments. Any changes, substitutions, combinations, or simplifications made without departing from the innovative points of the present invention should be considered as equivalent substitutions and are included within the protection scope of the present invention.

[0094] Example 1

[0095] The following is for reference Figures 2A to 3B The optical imaging lens 1001, optical imaging lens 1002 and optical imaging lens 1003 according to Embodiment 1 of this application are described. Figure 2A , Figure 2B and Figure 2C Schematic diagrams of the optical imaging lens 1001, optical imaging lens 1002 and optical imaging lens 1003 according to Embodiment 1 of this application are shown respectively.

[0096] like Figure 2A , Figure 2B and Figure 2C As shown, the structural schematic diagrams of optical imaging lenses 1001, 1002, and 1003 all include a lens barrel P0, lens groups E1 to E6, and multiple spacer elements P1 to P5.

[0097] In Embodiment 1, the schematic diagrams of the optical imaging lens 1001, optical imaging lens 1002, and optical imaging lens 1003 use the same lens group. The lens group includes, in sequence from the object side to the image side: first lens E1, second lens E2, third lens E3, fourth lens E4, fifth lens E5, and sixth lens E6. Among them, the first lens E1, with positive optical power, has a concave object-side surface S1 and a convex image-side surface S2; the second lens E2, with negative optical power, has a convex object-side surface S3 and a concave image-side surface S4; the third lens E3, with positive optical power, has convex object-side surface S5 and image-side surface S6; the fourth lens E4, with negative optical power, has a concave object-side surface S7 and a convex image-side surface S8; the fifth lens E5, with positive optical power, has a concave object-side surface S9 and a convex image-side surface S10; and the sixth lens E6, with negative optical power, has a convex object-side surface S11 and a concave image-side surface S12. Light from the object passes sequentially through each surface S1 to S14 and is finally imaged on the imaging surface S15. In Table 1, S13 and S14 can be the object side and image side of the filter or protective glass, S15 is the imaging plane, OBJ (not shown in the figure) is the object plane, and STO is the aperture stop, which is located between the second lens and the third lens.

[0098] Table 1 lists the relevant parameters of each lens in the optical imaging lens of this embodiment, including: surface type, radius of curvature, center thickness / gap, refractive index of the material, Abbe number and conic coefficient.

[0099]

[0100] Table 1

[0101] Table 2 lists the aspherical coefficients of each aspherical lens in the optical imaging lens of this embodiment, including: A4, A6, A8, A... 10 A 12 A 14 A 16 A 18 A 20 A 22 A 24 A 26 A 28 and A 30 .

[0102]

[0103] Table 2

[0104] like Figure 2A , Figure 2B and Figure 2C As shown, optical imaging lenses 1001, 1002, and 1003 each include five spacer elements: a first spacer element P1, a second spacer element P2, a third spacer element P3, a fourth spacer element P4, and a fifth spacer element P5. Specifically, the first spacer element P1 is disposed between the first lens E1 and the second lens E2 and contacts the image-side surface of the first lens E1; the second spacer element P2 is disposed between the second lens E2 and the third lens E3 and contacts the image-side surface of the second lens E3; the third spacer element P3 is disposed between the third lens E3 and the fourth lens E4 and contacts the image-side surface of the third lens E3; the fourth spacer element P4 is disposed between the fourth lens E4 and the fifth lens E5 and contacts the image-side surface of the fourth lens E4; the fifth spacer element P5 is disposed between the fifth lens E5 and the sixth lens E6 and contacts the image-side surface of the fifth lens E5; and the fifth spacer element P5 contacts the object-side surface of the sixth lens E6. The aforementioned spacer elements P1 to P5 can intercept excess light from the edges and enhance the structural stability of optical imaging lenses 1001, 1002, and 1003.

[0105] Optical imaging lenses 1001, 1002, and 1003 have different lens structures. Table 3 shows the spacer elements and basic parameters of the lens barrels of optical imaging lenses 1001, 1002, and 1003 in Embodiment 1. As an example, optical imaging lenses 1001, 1002, and 1003 all have a lens barrel P0.

[0106]

[0107] Table 3

[0108] Figure 3A The on-axis chromatic aberration curve of the optical imaging lens of Embodiment 1 is shown, which represents the deviation of the focal point of light of different wavelengths after passing through the lens. Figure 3B The distortion curve of the optical imaging lens of Embodiment 1 is shown, representing the distortion magnitude values ​​corresponding to different image heights. According to... Figures 3A to 3B As can be seen, the optical imaging lens given in Example 1 can achieve good imaging quality.

[0109] Example 2

[0110] The following is for reference Figures 4A to 5B The optical imaging lens 2001, optical imaging lens 2002 and optical imaging lens 2003 according to Embodiment 2 of this application are described. Figure 4A , Figure 4B and Figure 4C Schematic diagrams of the optical imaging lens 2001, optical imaging lens 2002 and optical imaging lens 2003 according to Embodiment 2 of this application are shown respectively.

[0111] like Figure 4A , Figure 4B and Figure 4C As shown, the structural schematic diagrams of optical imaging lenses 2001, 2002, and 2003 all include a lens barrel P0, lens groups E1 to E6, and multiple spacer elements P1 to P5.

[0112] In Embodiment 2, the schematic diagrams of the optical imaging lens 2001, optical imaging lens 2002, and optical imaging lens 2003 use the same lens group. The lens group includes, in sequence from the object side to the image side: first lens E1, second lens E2, third lens E3, fourth lens E4, fifth lens E5, and sixth lens E6. Among them, the first lens E1, with positive optical power, has a concave object-side surface S1 and a convex image-side surface S2; the second lens E2, with negative optical power, has a convex object-side surface S3 and a concave image-side surface S4; the third lens E3, with positive optical power, has convex object-side surface S5 and image-side surface S6; the fourth lens E4, with negative optical power, has a concave object-side surface S7 and a convex image-side surface S8; the fifth lens E5, with positive optical power, has a concave object-side surface S9 and a convex image-side surface S10; and the sixth lens E6, with negative optical power, has a convex object-side surface S11 and a concave image-side surface S12. Light from the object passes sequentially through each surface S1 to S14 and is finally imaged on the imaging surface S15. In Table 4, S13 and S14 can be the object side and image side of the filter or protective glass, S15 is the imaging plane, OBJ (not shown in the figure) is the object plane, and STO is the aperture stop, which is located between the second lens and the third lens.

[0113] Table 4 lists the relevant parameters of each lens in the optical imaging lens of this embodiment, including: surface type, radius of curvature, center thickness / gap, refractive index of the material, Abbe number and conic coefficient.

[0114]

[0115] Table 4

[0116] Table 5 lists the aspherical coefficients of each aspherical lens in the optical imaging lens of this embodiment, including: A4, A6, A8, A... 10 A 12 A 14 A 16 A 18 A 20 A 22 A 24 A 26 A 28 and A 30 .

[0117]

[0118] Table 5

[0119] like Figure 4A , Figure 4B and Figure 4C As shown, optical imaging lenses 2001, 2002, and 2003 each include five spacer elements, namely, the first spacer element P1, the second spacer element P2, the third spacer element P3, the fourth spacer element P4, and the fifth spacer element P5. Since the positions of these five spacer elements are the same as those of the spacer elements in optical imaging lenses 1001, 1002, and 1003 of Embodiment 1, they will not be described again.

[0120] Optical imaging lenses 2001, 2002, and 2003 have different lens structures. Table 6 shows the spacer elements and basic parameters of the lens barrels for optical imaging lenses 2001, 2002, and 2003 in Embodiment 2. As an example, optical imaging lenses 2001, 2002, and 2003 all have a single lens barrel P0.

[0121]

[0122] Table 6

[0123] Figure 5A The on-axis chromatic aberration curve of the optical imaging lens of Embodiment 2 is shown, which indicates the deviation of the focal point of light of different wavelengths after passing through the lens. Figure 5BThe distortion curve of the optical imaging lens in Embodiment 2 is shown, representing the distortion magnitude corresponding to different image heights. According to... Figures 5A to 5B It can be seen that the optical imaging lens given in Example 2 can achieve good imaging quality.

[0124] Example 3

[0125] The following is for reference Figures 6A to 7B The optical imaging lens 3001, optical imaging lens 3002 and optical imaging lens 3003 according to Embodiment 3 of this application are described. Figure 6A , Figure 6B and Figure 6C Schematic diagrams of the optical imaging lens 3001, optical imaging lens 3002 and optical imaging lens 3003 according to Embodiment 3 of this application are shown respectively.

[0126] like Figure 6A , Figure 6B and Figure 6C As shown, the structural schematic diagrams of optical imaging lenses 3001, 3002, and 3003 all include a lens barrel P0, lens groups E1 to E6, and multiple spacer elements P1 to P5.

[0127] In Embodiment 3, the schematic diagrams of the optical imaging lens 3001, optical imaging lens 3002 and optical imaging lens 3003 use the same lens group. The lens group includes, in sequence from the object side to the image side: first lens E1, second lens E2, third lens E3, fourth lens E4, fifth lens E5 and sixth lens E6. Among them, the first lens E1, with positive optical power, has a concave object-side surface S1 and a convex image-side surface S2; the second lens E2, with negative optical power, has a convex object-side surface S3 and a concave image-side surface S4; the third lens E3, with positive optical power, has convex object-side surface S5 and image-side surface S6; the fourth lens E4, with negative optical power, has a concave object-side surface S7 and a concave image-side surface S8; the fifth lens E5, with positive optical power, has a concave object-side surface S9 and a convex image-side surface S10; and the sixth lens E6, with negative optical power, has a convex object-side surface S11 and a concave image-side surface S12. Light from the object passes sequentially through each surface S1 to S14 and is finally imaged on the imaging surface S15. In Table 7, S13 and S14 can be the object side and image side of the filter or protective glass, S15 is the imaging plane, OBJ (not shown in the figure) is the object plane, and STO is the aperture stop, which is located between the second lens and the third lens.

[0128] Table 7 lists the relevant parameters of each lens in the optical imaging lens of this embodiment, including: surface type, radius of curvature, center thickness / gap, refractive index of the material, Abbe number and conic coefficient.

[0129]

[0130] Table 7

[0131] Table 8 lists the aspherical coefficients of each aspherical lens in the optical imaging lens of this embodiment, including: A4, A6, A8, A... 10 A 12 A 14 A 16 A 18 A 20 A 22 A 24 A 26 A 28 and A 30 .

[0132]

[0133] Table 8

[0134] like Figure 6A , Figure 6B and Figure 6C As shown, optical imaging lenses 3001, 3002, and 3003 each include five spacer elements, namely, the first spacer element P1, the second spacer element P2, the third spacer element P3, the fourth spacer element P4, and the fifth spacer element P5. Since the positions of the above two spacer elements are the same as those of the spacer elements in optical imaging lenses 1001, 1002, and 1003 of Embodiment 1, they will not be described again.

[0135] Optical imaging lenses 3001, 3002, and 3003 have different lens structures. Table 9 shows the spacer elements and basic parameters of the lens barrels of optical imaging lenses 3001, 3002, and 3003 in Embodiment 3. As an example, optical imaging lenses 3001, 3002, and 3003 all have a lens barrel P0.

[0136]

[0137] Table 9

[0138] Figure 7A The on-axis chromatic aberration curve of the optical imaging lens of Embodiment 3 is shown, which indicates the deviation of the focal point of light of different wavelengths after passing through the lens. Figure 7B The distortion curve of the optical imaging lens in Embodiment 3 is shown, representing the distortion magnitude corresponding to different image heights. According to... Figures 7A to 7B It can be seen that the optical imaging lens given in Example 3 can achieve good imaging quality.

[0139] In summary, the optical parameters of the optical imaging lenses 1001, 1002, 1003, 2001, 2002, 2003, 3001, 3002 and 3003 of Embodiments 1 to 3 are shown in Table 10 below.

[0140]

[0141] Table 10

[0142] The optical imaging lenses 1001, 1002, 1003, 2001, 2002, 2003, 3001, 3002 and 3003 of Embodiments 1 to 3 satisfy the relationship shown in Table 11.

[0143]

[0144] Table 11

[0145] The above description is merely a preferred embodiment of this application and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the inventive concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions disclosed in this application.

Claims

1. An optical imaging lens, comprising a lens barrel, a lens group, and a plurality of spacer elements, wherein the lens barrel is used to house the lens group and the plurality of spacer elements; characterized in that, The lens group consists of, in sequence along the optical axis from the object side to the image side, a first lens with positive optical power, a second lens with negative optical power, a third lens with positive optical power, a fourth lens with negative optical power, a fifth lens with positive optical power, and a sixth lens with negative optical power. The object-side surface of the first lens is concave, and its image-side surface is convex; the object-side surface of the fifth lens is concave, and its image-side surface is convex; the object-side surface of the sixth lens is convex, and its image-side surface is concave; the absolute value of the curvature of the light-transmitting area of ​​the object-side and image-side surfaces of the sixth lens gradually increases from the center of the optical axis to the radial edge. The plurality of spacer elements include: A fourth spacer element is disposed between the fourth lens and the fifth lens and contacts the image side of the fourth lens; A fifth spacer element is disposed between the fifth lens and the sixth lens and contacts the image side of the fifth lens; the fifth spacer element contacts the object side of the sixth lens; The optical imaging lens satisfies: 9.10 <f / (f5+f6)≤15.50; 1.95≤d0m / d5s<2.15; 1.40 <ET6 / (EP45+CP5)<2.00; Wherein, f is the effective focal length of the optical imaging lens, f5 is the effective focal length of the fifth lens, f6 is the effective focal length of the sixth lens, d0m is the inner diameter of the image-side end face of the lens barrel, d5s is the inner diameter of the object-side side face of the fifth spacer element, EP45 is the spacing distance between the fourth spacer element and the fifth spacer element along the optical axis, CP5 is the maximum thickness of the fifth spacer element along the optical axis, and ET6 is the edge thickness of the light-transmitting area of ​​the sixth lens.

2. The optical imaging lens according to claim 1, characterized in that, The plurality of spacers also includes a second spacer element placed between the second lens and the third lens and in contact with the image side of the second lens; the inner diameter of the object side of the second spacer element is the minimum value among the inner diameters of the object side of all spacers in the optical lens. The optical imaging lens satisfies: 2.40 <d5s / d2s<3.65; Wherein, d5s is the inner diameter of the object side of the fifth spacer element, and d2s is the inner diameter of the object side of the second spacer element.

3. The optical imaging lens according to claim 1 or 2, characterized in that, The optical imaging lens satisfies: 1.35 <d0m / d0s<2.25; Wherein, d0m is the inner diameter of the image-side end face of the lens barrel, and d0s is the inner diameter of the object-side end face of the lens barrel.

4. The optical imaging lens according to claim 1 or 2, characterized in that, The optical imaging lens satisfies: -1.15 <f6 / (d0m-d5m)<-0.50; Wherein, f6 is the effective focal length of the sixth lens, d0m is the inner diameter of the image-side end face of the lens barrel, and d5m is the inner diameter of the image-side surface of the fifth spacer element.

5. The optical imaging lens according to claim 1 or 2, characterized in that, The optical imaging lens satisfies: 0.35 <EP45 / (d5s-d4m)<0.55; Wherein, EP45 is the distance between the fourth spacer element and the fifth spacer element along the optical axis, d5s is the inner diameter of the object side of the fifth spacer element, and d4m is the inner diameter of the image side of the fourth spacer element.

6. The optical imaging lens according to claim 1 or 2, characterized in that, The optical imaging lens satisfies: 2.65 <EP50 / CT6<3.15; Wherein, EP50 is the distance along the optical axis from the image side of the fifth spacer element to the image side end face of the lens barrel, and CT6 is the center thickness of the sixth lens.

7. The optical imaging lens according to claim 1 or 2, characterized in that, The plurality of spacers further includes a third spacer element, disposed between the third lens and the fourth lens and in contact with the image-side surface of the third lens; the optical imaging lens satisfies: 0.50≤T45 / (CT4+CT5)≤0.55; 0.85 <EP34 / (CP4+EP45) ≤1.50; Wherein, T45 is the air gap between the fourth lens and the fifth lens on the optical axis, CT4 is the center thickness of the fourth lens, CT5 is the center thickness of the fifth lens, EP34 is the spacing distance between the third spacer element and the fourth spacer element along the optical axis, CP4 is the maximum thickness of the fourth spacer element along the optical axis, and EP45 is the spacing distance between the fourth spacer element and the fifth spacer element along the optical axis.

8. The optical imaging lens according to claim 1 or 2, characterized in that, The object-side surface and the image-side surface of the sixth lens each have at least one critical point; the optical imaging lens satisfies: -1.55 <f6 / f<-0.65 ;3.00<D5m / YC62<4.35; Where f is the effective focal length of the optical imaging lens, f6 is the effective focal length of the sixth lens, D5m is the outer diameter of the image-side surface of the fifth spacer element, and YC62 is the vertical distance from the image-side surface of the sixth lens to the optical axis from the nearest critical point on the optical axis.

9. The optical imaging lens according to claim 1 or 2, characterized in that, The optical imaging lens satisfies: 0.75≤(OD6-YC62) / OD6<0.80; Wherein, OD6 is the maximum outer diameter of the sixth lens, and YC62 is the vertical distance from the image-side surface of the sixth lens to the optical axis from the nearest critical point on the optical axis.

10. The optical imaging lens according to claim 1 or 2, characterized in that, The optical imaging lens satisfies: 0.45≤EP45 / (T45+CT5)≤0.60; Wherein, EP45 is the distance between the fourth spacer element and the fifth spacer element along the optical axis, T45 is the air gap between the fourth lens and the fifth lens on the optical axis, and CT5 is the center thickness of the fifth lens.

11. The optical imaging lens according to claim 1 or 2, characterized in that, The optical imaging lens satisfies: 0.35 <SP6 / CT6<0.55; Wherein, SP6 is the length of the outer peripheral surface of the sixth lens in the direction parallel to the optical axis, and CT6 is the center thickness of the sixth lens.

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