Optical lens

Abstract

The invention provides an optical lens, which sequentially comprises a first lens with negative focal power from an object side to an imaging surface along an optical axis, a second lens with negative focal power, a third lens with negative focal power and a fourth lens with negative focal power from the object side to the imaging surface, the object side surface of the second lens is a convex surface; the third lens has positive focal power, the object side surface of the third lens near the optical axis is a convex surface, and the image side surface of the third lens is a convex surface; the object side surface of the fourth lens is a concave surface, and the image side surface of the fourth lens is a convex surface; the fifth lens has positive focal power, the object side surface of the fifth lens is a convex surface near the optical axis, and the image side surface of the fifth lens is a concave surface; wherein the maximum field angle FOV of the optical lens and the aperture value Fno of the optical lens meet the following conditions: 136 degrees lt; an FOV / Fnot; 151 degrees. According to the optical lens provided by the invention, through specific surface shape setting and reasonable focal power distribution, the imaging quality of the optical lens can be improved, the aberration can be reduced, the imaging quality of the optical lens can be improved, and the lens has one or more advantages of large field angle, large aperture, large target surface and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of imaging lenses, and in particular to an optical lens. Background Art

[0002] Infrared lens is a lens specially used to capture infrared light. It plays an important role in the field of infrared photography and infrared sensing. The uses of infrared lens include: First, military intelligence personnel can use infrared lens for night vision surveillance, detect targets, and scout enemy movements. Infrared technology plays an important role in night operations, which can help combatants conduct reconnaissance and search operations in the dark, improve combat efficiency, and ensure the smooth execution of military operations. Second, security monitoring. Infrared lens is also widely used in the field of security monitoring. Security monitoring system can use infrared lens for night vision monitoring, and can clearly capture monitoring images even at night or in low light conditions. Infrared lens can help monitoring personnel to detect abnormal situations in time and protect people's lives and property safety. Third, thermal imaging. Infrared lens can also be used for thermal imaging, that is, using the infrared heat radiated by an object to display the temperature distribution of the object. Thermal imaging technology is widely used in medicine, construction, agriculture and other fields. In the medical field, thermal imaging technology can be used to diagnose diseases, in the construction field, thermal imaging technology can be used to detect the temperature distribution of building structures, and in the agricultural field, thermal imaging technology can be used to monitor the growth of crops. How to make infrared lenses compatible with both large aperture and large field of view is a problem that needs to be solved urgently. Summary of the invention

[0003] In view of the above problems, an object of the present invention is to provide an optical lens having advantages such as excellent imaging quality.

[0004] The technical solution adopted by the present invention is: An optical lens, comprising five lenses, which include: The first lens has a negative optical power, the object side surface of which is convex, and the image side surface of which is concave; a second lens having positive refractive power and a convex object-side surface; The third lens has positive refractive power, its object side surface is convex at the near optical axis, and its image side surface is convex; a fourth lens having negative optical power, whose object side surface is concave and whose image side surface is convex; A fifth lens having positive refractive power, whose object side surface is convex at the near optical axis and whose image side surface is concave; The maximum field of view FOV of the optical lens and the aperture value Fno of the optical lens satisfy: 136° <FOV / Fno<151°。

[0005] More preferably, the effective focal length f of the optical lens and the overall optical length TTL of the optical lens satisfy: 3.7 < TTL / f < 4; the overall optical length TTL of the optical lens and the true image height IH corresponding to the maximum field of view angle of the optical lens satisfy: 1.25 < TTL / IH < 1.4.

[0006] More preferably, the effective focal length f of the optical lens, the true image height IH corresponding to the maximum field of view angle of the optical lens, and the radian value θ of the maximum half field of view angle of the optical lens satisfy: 0.99 < (IH / 2) / (f×θ) < 1.02; the overall optical length TTL of the optical lens, the true image height IH corresponding to the maximum field of view angle of the optical lens, and the maximum field of view angle FOV of the optical lens satisfy: 1.4 < 180°×TTL / IH / FOV < 1.55.

[0007] More preferably, the true image height IH corresponding to the maximum field of view angle of the optical lens and the entrance pupil diameter EPD of the optical lens satisfy: 3.1 < IH / EPD < 3.5; the effective focal length f of the optical lens and the true image height IH corresponding to the maximum field of view angle of the optical lens satisfy: 2.8 < IH / f < 3.

[0008] More preferably, the effective focal length f of the optical lens and the focal length f1 of the first lens satisfy: -2.3 < f1 / f < -1.7; the effective focal length f of the optical lens and the object-side curvature radius R1 of the first lens satisfy: 13 < R1 / f < 446; the effective focal length f of the optical lens and the image-side curvature radius R2 of the first lens satisfy: 1.1 < R2 / f < 1.3.

[0009] More preferably, the effective focal length f of the optical lens and the focal length f3 of the third lens satisfy: 1 < f3 / f < 1.4; the effective focal length f of the optical lens and the object-side curvature radius R5 of the third lens satisfy: 1.1 < R5 / f < 2.7; the effective focal length f of the optical lens and the image-side curvature radius R6 of the third lens satisfy: -1.3 < R6 / f < -1.1.

[0010] More preferably, the effective focal length f of the optical lens and the focal length f4 of the fourth lens satisfy: -25.5 < f4 / f < -4.5; the effective focal length f of the optical lens and the object-side curvature radius R7 of the fourth lens satisfy: -0.9 < R7 / f < -0.4; the effective focal length f of the optical lens and the image-side curvature radius R8 of the fourth lens satisfy: -1.1 < R8 / f < -0.6.

[0011] More preferably, the effective focal length f of the optical lens and the focal length f5 of the fifth lens satisfy: 4 < f5 / f < 8; the effective focal length f of the optical lens and the curvature radius R9 of the object side surface of the fifth lens satisfy: 0.7 < R9 / f < 1.3; the effective focal length f of the optical lens and the curvature radius R10 of the image side surface of the fifth lens satisfy: 0.8 < R10 / f < 1.4.

[0012] More preferably, the focal length f1 of the first lens and the combined focal length f2345 of the second lens, the third lens, the fourth lens, and the fifth lens satisfy: -2.1 < f1 / f2345 < -1.7; the clear aperture radius d1 of the object side surface of the first lens and the clear aperture radius d10 of the image side surface of the fifth lens satisfy: 0.95 < d1 / d10 < 1.

[0013] More preferably, the focal length f3 of the third lens and the focal length f4 of the fourth lens satisfy: -0.35 < f3 / f4 < 0; the central thickness CT3 of the third lens and the central thickness CT4 of the fourth lens satisfy: 1 < CT3 / CT4 < 3.

[0014] Compared with the prior art, the optical lens provided by the present invention can improve the imaging quality of the optical lens, reduce aberration, and improve the imaging quality of the optical lens by setting a specific surface shape and reasonably distributing the optical power, so that the lens has one or more advantages such as a large field of view angle, a large aperture, and a large target surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The above and / or additional aspects and advantages of the present invention will become apparent and be readily understood from the following description of the embodiments in conjunction with the accompanying drawings, where: Figure 1 is a schematic structural diagram of the optical lens in Embodiment 1 of the present invention.

[0016] Figure 2 is a field curvature curve diagram of the optical lens in Embodiment 1 of the present invention.

[0017] Figure 3 is an F-Theta distortion curve diagram of the optical lens in Embodiment 1 of the present invention.

[0018] Figure 4 is a lateral chromatic aberration curve diagram of the optical lens in Embodiment 1 of the present invention.

[0019] Figure 5 is a relative illumination curve diagram of the optical lens in Embodiment 1 of the present invention.

[0020] Figure 6 is a schematic structural diagram of the optical lens in Embodiment 2 of the present invention.

[0021] Figure 7 Graph showing the field curvature of the optical lens in Embodiment 2 of the present invention.

[0022] Figure 8 Graph showing the F-Theta distortion of the optical lens in Embodiment 2 of the present invention.

[0023] Fig. 9 Graph showing the vertical axis chromatic aberration of the optical lens in Example 2 of the present invention.

[0024] Fig.10 This is a relative illumination curve diagram of the optical lens in Example 2 of the present invention.

[0025] Fig.11 Schematic diagram of the structure of the optical lens in Example 3 of the present invention.

[0026] Fig.12 4 is a field curvature curve diagram of the optical lens in Example 3 of the present invention.

[0027] Fig.13 Graph showing the F-Theta distortion of the optical lens in Embodiment 3 of the present invention.

[0028] Fig.14 Graph showing the vertical axis chromatic aberration of the optical lens in Example 3 of the present invention.

[0029] Fig.15 This is a relative illumination curve diagram of the optical lens in Example 3 of the present invention.

[0030] The following specific implementation manner will further illustrate the present invention in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0031] In order to better understand the present application, a more detailed description will be made of various aspects of the present application with reference to the accompanying drawings. It should be understood that these detailed descriptions are only descriptions of the embodiments of the present application, and are not intended to limit the scope of the present 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.

[0032] It should be noted that in this specification, the expressions of first, second, third, etc. are only used to distinguish one feature from another feature, and do not represent any limitation on the features. Therefore, without departing from the teaching of the present invention, the first lens discussed below may also be referred to as the second lens or the third lens.

[0033] In the drawings, the thickness, size and shape of the lenses have been slightly exaggerated for ease of explanation. Specifically, the shapes of the spherical or aspherical surfaces shown in the drawings are shown by way of example. That is, the shapes of the spherical or aspherical surfaces are not limited to the shapes of the spherical or aspherical surfaces shown in the drawings. The drawings are only examples and are not drawn strictly to scale.

[0034] In this article, the paraxial region refers to the region near the optical axis. If the lens surface is convex and the position of the convex surface is not defined, it means that the lens surface is convex at least in the paraxial region; if the lens surface is concave and the position of the concave surface is not defined, it means that the lens surface is concave at least in the paraxial region. The surface of each lens closest to the object is called the object side of the lens, and the surface of each lens closest to the imaging plane is called the image side of the lens.

[0035] It should also be understood that the terms "comprises", "including", "having", "includes" 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. In addition, when expressions such as "at least one of..." appear after a list of listed features, they modify the entire listed features rather than modifying the individual elements in the list. In addition, when describing embodiments of the present application, "may" is used to mean "one or more embodiments of the present application". And, the term "exemplary" is intended to refer to an example or illustration.

[0036] Unless otherwise defined, all terms (including technical terms and scientific terms) used in this article have the same meaning as commonly understood by ordinary technicians in the field to which this application belongs. It should also be understood that terms (such as terms defined in commonly used dictionaries) should be interpreted as having the same meaning as their meaning in the context of the relevant technology, and will not be interpreted in an idealized or overly formal sense unless explicitly defined in this article.

[0037] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0038] The optical lens provided by the embodiment of the present invention has five lenses in total, which are the first lens, the second lens, the third lens, the fourth lens and the fifth lens in order from the object side to the imaging surface along the optical axis. The optical lens provided by the present invention is an infrared lens, which is a lens specially used to capture infrared light.

[0039] In some embodiments, the first lens may have a negative focal power, with its object side being convex and its image side being concave. The second lens may have a positive focal power, with its object side being convex and its image side being either concave or convex. The third lens may have a positive focal power, with its object side being convex near the optical axis and its image side being convex. The fourth lens may have a negative focal power, with its object side being concave and its image side being convex. The fifth lens may have a positive focal power, with its object side being convex near the optical axis and its image side being concave.

[0040] In some embodiments, the optical lens may further include a diaphragm, and the diaphragm may be located between the first lens and the second lens. It can be understood that the diaphragm is used to limit the amount of incident light to change the brightness of the imaging. When the diaphragm is located between the first lens and the second lens, it is convenient for the correction of diaphragm aberration.

[0041] In some embodiments, the optical lens may further include a filter, and the filter may be disposed between the fifth lens and the imaging surface. The filter is used to filter out interfering light to prevent the interfering light from reaching the imaging surface of the optical lens and affecting normal imaging.

[0042] In some embodiments, the maximum field of view FOV of the optical lens and the f-number Fno of the optical lens satisfy: 136° < FOV / Fno < 151°. Meeting the above range defines that the optical lens has a suitable field of view and f-number, can collect light at large angles and obtain good imaging quality. More specifically, 136.66° < FOV / Fno < 150.19°.

[0043] In some embodiments, the effective focal length f of the optical lens and the total optical length TTL of the optical lens satisfy: 3.7 < TTL / f < 4. Meeting the above conditions can not only achieve the characteristics of large target surface and large viewing angle of the lens, so as to meet the local shooting requirements and be able to match larger-sized chips, but also achieve high-pixel imaging of the lens, improving the lens resolution and the receiving field of view. More specifically, 3.72 < TTL / f < 3.98.

[0044] In some embodiments, the total optical length TTL of the optical lens and the true image height IH corresponding to the maximum field of view of the optical lens satisfy: 1.25 < TTL / IH < 1.4. Meeting the above range is beneficial to achieving the balance between the volume of the optical lens and the large image surface. More specifically, 1.29 < TTL / IH < 1.39.

[0045] In some embodiments, the effective focal length f of the optical lens, the true image height IH corresponding to the maximum field of view angle of the optical lens, and the radian value θ of the maximum half field of view angle of the optical lens satisfy: 0.99 < (IH / 2) / (f×θ) < 1.02. When the above range is satisfied, the optical distortion of the optical lens is better controlled, the resolution of the optical lens is improved, and a better imaging effect can be obtained.

[0046] In some embodiments, the total optical length TTL of the optical lens, the true image height IH corresponding to the maximum field of view angle of the optical lens, and the field of view angle FOV of the optical lens satisfy: 1.4 < 180°×TTL / IH / FOV < 1.55. When the above range is satisfied, it is beneficial to balance the relationship among the total length, image height, and field of view angle of the optical lens. More specifically, 1.42 < 180°×TTL / IH / FOV < 1.51.

[0047] In some embodiments, the true image height IH corresponding to the maximum field of view angle of the optical lens and the entrance pupil diameter EPD of the optical lens satisfy: 3.1 < IH / EPD < 3.5. When the above range is satisfied, the width of the light beam incident on the optical lens can be increased, the relative illumination can be improved, and vignetting can be avoided. More specifically, 3.14 < IH / EPD < 3.49.

[0048] In some embodiments, the effective focal length f of the optical lens and the true image height IH corresponding to the maximum field of view angle of the optical lens satisfy: 2.8 < IH / f < 3. When the above range is satisfied, it is helpful to achieve a large image plane and improve the imaging quality of the optical lens. More specifically, 2.85 < IH / f < 2.91.

[0049] In some embodiments, the effective focal length f of the optical lens and the focal length f1 of the first lens satisfy: -2.3 < f1 / f < -1.7; the effective focal length f of the optical lens and the object-side curvature radius R1 of the first lens satisfy: 13 < R1 / f < 446; the effective focal length f of the optical lens and the image-side curvature radius R2 of the first lens satisfy: 1.1 < R2 / f < 1.3. When the above range is satisfied, the first lens can have an appropriate negative optical power, the degree of deflection of the incident light can be reduced, it is helpful for light to enter the optical system within a larger range, and it is beneficial to expand the field of view angle of the lens. More specifically, -2.21 < f1 / f < -1.78; 13.64 < R1 / f < 445.2; 1.1 < R2 / f < 1.26.

[0050] In some embodiments, the effective focal length f of the optical lens and the focal length f3 of the third lens satisfy: 1 < f3 / f < 1.4; the effective focal length f of the optical lens and the curvature radius R5 of the object side surface of the third lens satisfy: 1.1 < R5 / f < 2.7; the effective focal length f of the optical lens and the curvature radius R6 of the image side surface of the third lens satisfy: -1.3 < R6 / f < -1.1. The third lens is relatively sensitive in the entire optical system. Meeting the above ranges and reasonably defining the proportion of the optical power of the third lens and its surface shape are beneficial to improving the relative illumination of the optical lens. More specifically, 1.03 < f3 / f < 1.38; 1.14 < R5 / f < 2.64; -1.24 < R6 / f < -1.11.

[0051] In some embodiments, the effective focal length f of the optical lens and the focal length f4 of the fourth lens satisfy: -25.5 < f4 / f < -4.5; the effective focal length f of the optical lens and the curvature radius R7 of the object side surface of the fourth lens satisfy: -0.9 < R7 / f < -0.4; the effective focal length f of the optical lens and the curvature radius R8 of the image side surface of the fourth lens satisfy: -1.1 < R8 / f < -0.6. The fourth lens is relatively sensitive in the entire optical system. Meeting the above ranges and reasonably defining the proportion of the optical power of the fourth lens and its surface shape can be beneficial to controlling the field curvature and reducing the difficulty of aberration correction of the optical lens. More specifically, -25.44 < f4 / f < -4.57; -0.85 < R7 / f < -0.46; -1.09 < R8 / f < -0.67.

[0052] In some embodiments, the effective focal length f of the optical lens and the focal length f5 of the fifth lens satisfy: 4 < f5 / f < 8; the effective focal length f of the optical lens and the curvature radius R9 of the object side surface of the fifth lens satisfy: 0.7 < R9 / f < 1.3; the effective focal length f of the optical lens and the curvature radius R10 of the image side surface of the fifth lens satisfy: 0.8 < R10 / f < 1.4. Meeting the above ranges and reasonably defining the proportion of the optical power of the fifth lens and its surface shape are beneficial to converging light while reducing the light deflection angle, enabling the light to transition smoothly, and improving the imaging quality of the optical lens. More specifically, 4.04 < f5 / f < 7.96; 0.77 < R9 / f < 1.27; 0.87 < R10 / f < 1.31.

[0053] In some embodiments, the focal length f1 of the first lens and the combined focal length f2345 of the second, third, fourth, and fifth lenses satisfy: -2.1 < f1 / f2345 < -1.7. Meeting the above range is beneficial to balancing the aberrations generated by the lens groups before and after the aperture and improving the imaging quality of the optical lens. More specifically, -2.08 < f1 / f2345 < -1.77.

[0054] In some embodiments, the clear aperture semi-diameter d1 of the object side surface of the first lens and the clear aperture semi-diameter d10 of the image side surface of the fifth lens satisfy: 0.95 < d1 / d10 < 1. Meeting the above range and reasonably matching the aperture ratio of the first lens and the fifth lens is convenient for structural design and helps to improve the imaging quality of the optical lens.

[0055] In some embodiments, the focal length f3 of the third lens and the focal length f4 of the fourth lens satisfy: -0.35 < f3 / f4 < 0; the central thickness CT3 of the third lens and the central thickness CT4 of the fourth lens satisfy: 1 < CT3 / CT4 < 3. Meeting the above range can reduce the light deflection angle, make the light path more stable, correct coma and field curvature at the same time, improve the flatness of imaging, and enhance the imaging quality of the optical lens. More specifically, -0.31 < f3 / f4 < -0.03; 1.04 < CT3 / CT4 < 2.97.

[0056] In some embodiments, the overall optical length TTL of the optical lens and the sum ∑CT of the central thicknesses of the first lens to the fifth lens along the optical axis satisfy: 0.5 < ∑CT / TTL < 0.7. Meeting the above range can effectively compress the overall length of the optical lens and is beneficial to the structural design and production process of the optical lens. More specifically, 0.55 < ∑CT / TTL < 0.67.

[0057] In some embodiments, the sum ∑CT of the central thicknesses of the first lens to the fifth lens along the optical axis and the effective focal length f of the optical lens satisfy: 2.2 < ∑CT / f < 2.6. Meeting the above range can effectively correct the field curvature and distortion of the optical lens and improve the imaging quality of the optical lens. More specifically, 2.23 < ∑CT / f < 2.6.

[0058] In some embodiments, the effective focal length f of the optical lens and the focal length f2 of the second lens satisfy: 3.1 < f2 / f < 22.8. Meeting the above range can effectively converge light, ensure that the lens reduces the difficulty of correcting edge field distortion while achieving a large field of view angle, and improve the overall imaging quality. More specifically, 3.13 < f2 / f < 22.75.

[0059] In some embodiments, the sagittal height Sag2 of the clear aperture semi-diameter of the image side surface of the first lens and the clear aperture semi-diameter d2 of the image side surface of the first lens satisfy: 0.45 < Sag2 / d2 < 0.51; the sagittal height Sag3 of the clear aperture semi-diameter of the object side surface of the second lens and the clear aperture semi-diameter d3 of the object side surface of the second lens satisfy: 0 < |Sag3 / d3| < 0.04. Meeting the above range helps to control the light path of the edge field and highlight the detailed information of the central field of the optical lens.

[0060] In some embodiments, the optical lens satisfies the conditional expressions: 1.4 mm < f < 1.5 mm, 1.2 mm < EPD < 1.4 mm, 5.5 mm < TTL < 5.8 mm, 1.05 < Fno < 1.25, 26° < CRA < 30°, 0.9 mm < BFL < 1.2 mm, 163° < FOV < 166°, 4 mm < IH < 4.3 mm; where f represents the effective focal length of the optical lens, EPD represents the entrance pupil diameter of the optical lens, TTL represents the total optical length of the optical lens, Fno represents the f-number of the optical lens, CRA represents the chief ray angle of incidence at the maximum image height of the optical lens, BFL represents the back focal length of the optical lens, FOV represents the maximum field of view angle of the optical lens, and IH represents the true image height corresponding to the maximum field of view angle of the optical lens. Meeting the above conditions indicates that the optical lens provided by the embodiments of the present invention has at least the characteristics of a large aperture, a large field of view angle, a large target surface, etc. More specifically, 1.41 mm < f < 1.5 mm, 1.2 mm < EPD < 1.36 mm, 5.53 mm < TTL < 5.72 mm, 1.09 < Fno < 1.21, 26.69° < CRA < 29.28°, 0.98 mm < BFL < 1.18 mm, 163.9° < FOV < 165.3°, 4.08 mm < IH < 4.26 mm.

[0061] In some embodiments, the lens material in the optical lens provided by the present invention can be glass or plastic. When the lens material is plastic, the production cost can be effectively reduced. Additionally, when the lens material is glass, the geometric chromatic aberration of the optical system can be effectively corrected due to the low dispersion characteristic of the glass itself. The optical lens provided by the present invention can adopt an all-plastic lens structure, which not only enables the lens to have excellent imaging performance, but also makes the structure of the lens relatively compact, and can better achieve the balance between the miniaturization of the lens and high image quality.

[0062] In some embodiments, the first lens, the second lens, the third lens, the fourth lens, and the fifth lens can adopt spherical lenses or aspherical lenses. Compared with the spherical structure, the aspherical structure can effectively reduce the aberration of the optical system, thereby reducing the number of lenses and the size of the lenses, and better realizing the miniaturization of the lens. More specifically, the first lens, the second lens, the third lens, the fourth lens, and the fifth lens of the present invention can all adopt aspherical lenses.

[0063] In each embodiment of the present invention, when the lens adopts an aspherical lens, the shapes of the aspherical surfaces of the optical lens satisfy the following equation: ; Among them, z is the distance between the surface and the vertex of the surface in the direction of the optical axis, h is the distance from the optical axis to the surface, c is the curvature of the surface vertex, K is the quadratic surface coefficient, B, C, D, E, F, G, and H are the fourth-order, sixth-order, eighth-order, tenth-order, twelfth-order, fourteenth-order, and sixteenth-order surface coefficients respectively.

[0064] The present invention is further described below in multiple embodiments. In each embodiment, the thickness, radius of curvature, and material selection of each lens in the optical lens are different. For specific differences, please refer to the parameter table of each embodiment. The following embodiments are only preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the following embodiments. Any other changes, substitutions, combinations or simplifications that do not deviate from the innovative points of the present invention should be regarded as equivalent replacement methods and are included in the protection scope of the present invention.

[0065] Example 1 See also Figure 1 , which is a schematic diagram of the structure of the optical lens 100 provided in Embodiment 1 of the present invention, wherein the optical lens includes, in sequence from the object side to the imaging surface along the optical axis: a first lens L1, an aperture ST, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5 and a filter G1.

[0066] The first lens L1 has negative refractive power, its object side surface S1 is convex, and its image side surface S2 is concave; The second lens L2 has positive refractive power, its object side surface S3 is convex, and its image side surface S4 is concave at the near optical axis; The third lens L3 has positive refractive power, its object side surface S5 is convex at the near optical axis, and its image side surface S6 is convex; The fourth lens L4 has negative refractive power, its object-side surface S7 is concave, and its image-side surface S8 is convex; The fifth lens L5 has positive refractive power, its object-side surface S9 is convex at the near optical axis, and its image-side surface S10 is concave; The object side surface S11 and the image side surface S12 of the filter G1 are both planes; The imaging surface S13 is a plane.

[0067] The first lens L1, the second lens L2, the third lens L3, the fourth lens L4 and the fifth lens L5 are all plastic aspherical lenses.

[0068] The relevant parameters of each lens in the optical lens 100 in Example 1 are shown in Table 1-1.

[0069] Table 1-1 The surface parameters of the aspheric lens of the optical lens 100 in Example 1 are shown in Table 1-2.

[0070] Table 1-2 In this embodiment, the field curvature curve, F-Theta distortion curve, vertical axis chromatic aberration curve, and relative illumination curve of the optical lens 100 are shown as follows: Figure 2 , Figure 3 , Figure 4 , Figure 5 shown.

[0071] Figure 2 The field curvature curve of Example 1 is shown, which represents the field curvature of light on the meridional image plane and the sagittal image plane, the horizontal axis represents the offset (unit: mm), and the vertical axis represents the half field angle (unit: °). It can be seen from the figure that the field curvature of the meridional image plane and the sagittal image plane is controlled within ±0.17mm, indicating that the optical lens 100 can well correct the field curvature in the infrared band.

[0072] Figure 3 The F-Theta distortion curve of Example 1 is shown, which represents the F-Theta distortion at different image heights on the imaging surface, the horizontal axis represents the F-Theta distortion value (unit: %), and the vertical axis represents the half field angle (unit: °). It can be seen from the figure that the F-Theta distortion of the optical lens 100 is controlled within 0-5%, indicating that the distortion of the optical lens 100 in the infrared band is well corrected.

[0073] Figure 4 The vertical chromatic aberration curve of Example 1 is shown, which represents the chromatic aberration of each wavelength relative to the central wavelength (0.94 μm) at different image heights on the imaging surface, the horizontal axis represents the vertical chromatic aberration value of each wavelength relative to the central wavelength (unit: μm), and the vertical axis represents the field angle. It can be seen from the figure that the vertical chromatic aberration of the longest wavelength and the shortest wavelength is controlled within ±3 μm, indicating that the optical lens 100 can extremely well correct the chromatic aberration of each field of view in the infrared band.

[0074] Figure 5 The relative illumination curve of Example 1 is shown, which represents the relative illumination values ​​at different field angles on the imaging surface, with the horizontal axis representing the field angle (unit: °) and the vertical axis representing the relative illumination. It can be seen from the figure that the relative illumination value of the optical lens is still greater than 35% at the maximum half field angle, indicating that the optical lens 100 has good relative illumination in the infrared band.

[0075] Example 2 See also Figure 6 , shown is a schematic diagram of the structure of the optical lens 200 provided in Example 2 of the present invention. Compared with Example 1, the main difference between this embodiment and Example 1 is that the optical parameters such as the curvature radius of each lens surface and the lens thickness are different.

[0076] The relevant parameters of each lens in the optical lens 200 in Example 2 are shown in Table 2-1.

[0077] Table 2-1 The surface parameters of the aspheric lens of the optical lens 200 in Example 2 are shown in Table 2-2.

[0078] Table 2-2 In this embodiment, the field curvature curve, F-Theta distortion curve, vertical axis chromatic aberration curve, and relative illumination curve of the optical lens 200 are shown as follows: Figure 7 , Figure 8 , Fig. 9 , Fig.10 shown.

[0079] from Figure 7 It can be seen that the field curvature of the meridian image plane and the sagittal image plane is controlled within ±0.15 mm, indicating that the optical lens 200 can well correct the field curvature in the infrared band.

[0080] from Figure 8 It can be seen that the F-Theta distortion of the optical lens 200 is controlled within -2%~4%, indicating that the distortion of the optical lens 200 in the infrared band is well corrected.

[0081] from Fig. 9 It can be seen that the vertical axis chromatic aberration of the longest wavelength and the shortest wavelength is controlled within ±4 μm, indicating that the optical lens 200 can extremely well correct the chromatic aberration of each field of view in the infrared band.

[0082] from Fig.10 It can be seen that the relative illumination value of the optical lens is still greater than 30% at the maximum half field of view, indicating that the optical lens 200 has good relative illumination in the infrared band.

[0083] Example 3 See also Fig.11 , shown is a schematic diagram of the structure of the optical lens 300 provided in Example 3 of the present invention. Compared with Example 1, the main differences of this embodiment are: the image side surface S4 of the second lens L2 is a convex surface; the optical parameters such as the curvature radius of each lens surface and the lens thickness are different.

[0084] The relevant parameters of each lens in the optical lens 300 in Example 3 are shown in Table 3-1.

[0085] Table 3-1 The surface parameters of the aspheric lens of the optical lens 300 in Example 3 are shown in Table 3-2.

[0086] Table 3-2 In this embodiment, the field curvature curve, F-Theta distortion curve, vertical axis chromatic aberration curve, and relative illumination curve of the optical lens 300 are shown as follows: Fig.12 , Fig.13 , Fig.14 , Fig.15 shown.

[0087] from Fig.12 It can be seen that the field curvature of the meridian image plane and the sagittal image plane is controlled within ±0.15 mm, indicating that the optical lens 300 can well correct the field curvature in the infrared band.

[0088] from Fig.13 It can be seen that the F-Theta distortion of the optical lens 300 is controlled within -2%~8%, indicating that the distortion of the optical lens 300 in the infrared band is well corrected.

[0089] from Fig.14 It can be seen that the vertical axis chromatic aberration of the longest wavelength and the shortest wavelength is controlled within ±2μm, indicating that the optical lens 300 can extremely well correct the chromatic aberration of each field of view in the infrared band.

[0090] from Fig.15 It can be seen that the relative illumination value of the optical lens is still greater than 38% at the maximum half field of view, indicating that the optical lens 300 has good relative illumination in the infrared band.

[0091] Please refer to Table 4, which shows the optical characteristics corresponding to the above embodiments, including the effective focal length f of the optical lens, the total optical length TTL, the aperture value Fno, the real image height IH corresponding to the maximum field of view angle, the chief ray incident angle CRA at the maximum image height, the maximum field of view angle FOV, and the numerical value corresponding to each conditional expression in each embodiment.

[0092] Table 4 In summary, the optical lens provided by the present invention has at least the following advantages: (1) Through specific surface shape settings and reasonable optical focal length distribution, the lens has a large aperture. When the optical lens is imaging in a dark environment, the noise caused by weak light can be reduced, thereby improving the image quality; ensuring large target surface imaging, while controlling the number of lenses (5p), reducing the difficulty of lens processing and improving mass production.

[0093] (2) The optical lens of the present invention can reasonably correct the overall aberration of the optical lens, the overall lens aberration is small, the structure is compact, and the imaging quality of the optical lens is improved.

[0094] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0095] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. An optical lens, comprising five lenses, characterized in that: It successively includes from the object side to the imaging surface along the optical axis: A first lens with negative optical power, whose object side is convex and whose image side is concave; A second lens with positive optical power, whose object side is convex; A third lens with positive optical power, whose object side is convex near the optical axis and whose image side is convex; A fourth lens with negative optical power, whose object side is concave and whose image side is convex; A fifth lens with positive optical power, whose object side is convex near the optical axis and whose image side is concave; Wherein, the maximum field of view angle FOV of the optical lens and the aperture value Fno of the optical lens satisfy: 136° < FOV / Fno < 151°.

2. The optical lens according to claim 1, characterized in that: The effective focal length f of the optical lens and the overall optical length TTL of the optical lens satisfy: 3.7 < TTL / f < 4; The overall optical length TTL of the optical lens and the true image height IH corresponding to the maximum field of view angle of the optical lens satisfy: 1.25 < TTL / IH < 1.

4.

3. The optical lens according to claim 1, characterized in that: The effective focal length f of the optical lens, the true image height IH corresponding to the maximum field of view angle of the optical lens and the radian value θ of the maximum half field of view angle of the optical lens satisfy: 0.99 < (IH / 2) / (f×θ) < 1.02; The overall optical length TTL of the optical lens, the true image height IH corresponding to the maximum field of view angle of the optical lens and the maximum field of view angle FOV of the optical lens satisfy: 1.4 < 180°×TTL / IH / FOV < 1.

55.

4. The optical lens according to claim 1, characterized in that: The true image height IH corresponding to the maximum field of view angle of the optical lens and the entrance pupil diameter EPD of the optical lens satisfy: 3.1 < IH / EPD < 3.5; The effective focal length f of the optical lens and the true image height IH corresponding to the maximum field of view angle of the optical lens satisfy: 2.8 < IH / f < 3.

5. The optical lens according to claim 1, characterized in that: The effective focal length f of the optical lens and the focal length f1 of the first lens satisfy: -2.3 < f1 / f < -1.7; The effective focal length f of the optical lens and the curvature radius R1 of the object side of the first lens satisfy: 13 < R1 / f < 446; The effective focal length f of the optical lens and the curvature radius R2 of the image side of the first lens satisfy: 1.1 < R2 / f < 1.

3.

6. The optical lens according to claim 1, characterized in that: The effective focal length f of the optical lens and the focal length f3 of the third lens satisfy: 1 < f3 / f < 1.4; The effective focal length f of the optical lens and the curvature radius R5 of the object side of the third lens satisfy: 1.1 < R5 / f < 2.7; The effective focal length f of the optical lens and the curvature radius R6 of the image side of the third lens satisfy: -1.3 < R6 / f < -1.

1.

7. The optical lens according to claim 1, characterized in that: The effective focal length f of the optical lens and the focal length f4 of the fourth lens satisfy: -25.5 < f4 / f < -4.5; The effective focal length f of the optical lens and the curvature radius R7 of the object side of the fourth lens satisfy: -0.9 < R7 / f < -0.4; The effective focal length f of the optical lens and the curvature radius R8 of the image side of the fourth lens satisfy: -1.1 < R8 / f < -0.

6.

8. The optical lens according to claim 1, characterized in that: The effective focal length f of the optical lens and the focal length f5 of the fifth lens satisfy: 4 < f5 / f < 8; the effective focal length f of the optical lens and the object-side curvature radius R9 of the fifth lens satisfy: 0.7 < R9 / f < 1.3; the effective focal length f of the optical lens and the image-side curvature radius R10 of the fifth lens satisfy: 0.8 < R10 / f < 1.

4.

9. The optical lens according to claim 1, characterized in that: The focal length f1 of the first lens and the combined focal length f2345 of the second lens, the third lens, the fourth lens, and the fifth lens satisfy: -2.1 < f1 / f2345 < -1.7; the object-side clear aperture radius d1 of the first lens and the image-side clear aperture radius d10 of the fifth lens satisfy: 0.95 < d1 / d10 < 1.

10. The optical lens according to claim 1, characterized in that: The focal length f3 of the third lens and the focal length f4 of the fourth lens satisfy: -0.35 < f3 / f4 < 0; the central thickness CT3 of the third lens and the central thickness CT4 of the fourth lens satisfy: 1 < CT3 / CT4 < 3.

Images