Image capturing lens

Abstract

An image capturing lens includes a first lens, a second lens, and a third lens arranged in order from an object side to an image side of the image capturing lens, the first lens having a negative diopter, and one of the plurality of lenses having diopters being a graded index lens. The gradient refractive index lens satisfies 1lt; d / Tlt; d is the maximum outer diameter of the graded-index lens, and T is the thickness of the graded-index lens on the optical axis of the imaging lens.

Description

Technical Field

[0001] The present invention relates to an imaging lens. Background Art

[0002] In recent years, electronic products with imaging functions have been applied to various fields, such as security monitoring, in-vehicle camera systems, and action cameras. In this context, an optical imaging lens that can balance wide viewing angle, miniaturization, and high imaging quality is required. However, due to limitations in lens shape, material, etc., existing wide-angle lenses require a larger number of lenses or need to switch the thickness of the filter to achieve achromatic aberration and use the infrared band. Therefore, there is an urgent need for an imaging lens that can simultaneously meet the requirements of a wide viewing angle, achromatic aberration, and provide high-quality imaging of visible light and infrared light without switching the thickness of the filter. Summary of the Invention

[0003] Other objects and advantages of the present invention can be further understood from the technical features disclosed in the embodiments of the present invention.

[0004] An embodiment of the present invention provides an imaging lens, which includes a first lens, a second lens, and a third lens arranged in sequence from the object side to the image side of the imaging lens. The first lens has a negative refractive power, and the number of lenses with refractive power in the imaging lens does not exceed 9. Among the lenses with refractive power, one is a specified lens, and the specified lens is a gradient refractive index lens. An aperture stop is disposed between the two outermost lenses at both ends of the imaging lens. The gradient refractive index lens satisfies the condition of 1 < D / T < 32, where D is the maximum outer diameter of the gradient refractive index lens, and T is the thickness of the gradient refractive index lens on the optical axis of the imaging lens.

[0005] Another embodiment of the present invention provides an imaging lens, which includes a first lens, a second lens, and a third lens arranged in sequence from the object side to the image side of the imaging lens. The first lens has a negative refractive power, and the number of lenses with refractive power in the imaging lens does not exceed 9. Among the lenses with refractive power, one is a specified lens, and the specified lens is a lens with inhomogeneous material, and the refractive indices of the two surfaces of the lens with inhomogeneous material on the optical axis of the lens are different. The aperture stop is disposed between the two outermost lenses at both ends of the imaging lens. The lens with inhomogeneous material satisfies the condition of 1 < D / T < 32, where D is the maximum outer diameter of the lens with inhomogeneous material, and T is the central thickness of the lens with inhomogeneous material.

[0006] Another embodiment of the present invention provides an imaging lens, comprising a first lens, a second lens, and a third lens arranged in sequence from the object side to the image side of the imaging lens, the first lens having a negative refractive power, and the number of lenses with refractive power of the imaging lens does not exceed 9, one of the multiple lenses with refractive power is a designated lens, and the designated lens is a flat plate lens with a smooth surface and no microstructure and refractive power. An aperture stop is arranged between the two outermost lenses at the two ends of the imaging lens.

[0007] Through the design of each embodiment of the present invention, a good achromatic effect can be provided while meeting the requirements of wide viewing angle, and high-quality imaging of visible light and infrared light can be provided without switching the thickness of the filter. In addition, the imaging lens of the embodiment of the present invention, by appropriately matching glass and plastic lenses with spherical and aspherical surfaces, can reduce the manufacturing cost and take into account the image quality while being able to withstand the high temperature and temperature changes of the use environment. Furthermore, the imaging lens includes at least one single-piece gradient refractive index lens or material inhomogeneous lens, which can provide an achromatic effect similar to that of a cemented lens. Therefore, while meeting the requirements of achromatic and infrared band imaging, the use of cemented lenses can be reduced to obtain the effect of reducing the lens volume, the number of lenses or the total length.

[0008] In order to make the above features and advantages of the present invention more clearly understood, embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 FIG. 4 is a schematic diagram of an imaging lens according to an embodiment of the present invention.

[0010] Figure 2A , Figure 2B and Figure 2C They are Figure 1 The longitudinal spherical aberration diagram, field curvature aberration diagram and distortion aberration diagram of the imaging lens.

[0011] Figure 3 FIG. 4 is a schematic diagram of an imaging lens according to another embodiment of the present invention.

[0012] Figure 4A , Figure 4B and Figure 4C They are Figure 3 The longitudinal spherical aberration diagram, field curvature aberration diagram and distortion aberration diagram of the imaging lens.

[0013] Figure 5 FIG. 4 is a schematic diagram of an imaging lens according to another embodiment of the present invention.

[0014] Fig. 6A , Figure 6B and Figure 6C They are Figure 5The longitudinal spherical aberration diagram, field curvature aberration diagram and distortion aberration diagram of the imaging lens.

[0015] Figure 7 FIG. 4 is a schematic diagram of an imaging lens according to another embodiment of the present invention.

[0016] Fig. 8A , Figure 8B and Figure 8C They are Figure 7 The longitudinal spherical aberration diagram, field curvature aberration diagram and distortion aberration diagram of the imaging lens.

[0017] Fig. 9 FIG. 4 is a schematic diagram of an imaging lens according to another embodiment of the present invention.

[0018] Fig. 10A , Fig. 10B and Fig. 10C They are Fig. 9 The longitudinal spherical aberration diagram, field curvature aberration diagram and distortion aberration diagram of the imaging lens.

[0019] Fig.11 FIG. 4 is a schematic diagram of an imaging lens according to another embodiment of the present invention.

[0020] Fig. 12A , Fig. 12B and Fig. 12C They are Fig.11 The longitudinal spherical aberration diagram, field curvature aberration diagram and distortion aberration diagram of the imaging lens.

[0021] Fig.13 FIG. 4 is a schematic diagram of an imaging lens according to another embodiment of the present invention.

[0022] Fig.14A , Fig. 14B and Fig. 14C They are Fig.13 The longitudinal spherical aberration diagram, field curvature aberration diagram and distortion aberration diagram of the imaging lens.

[0023] Reference numerals:

[0024] 10a, 10b, 10c, 10d, 10e, 10f, 10g: Imaging lenses

[0025] 12: Optical axis

[0026] 14: Aperture stop

[0027] 16: Filter

[0028] 18: Cover

[0029] 22: Imaging surface

[0030] L1 to L8: Lens

[0031] S1 to S21: Surface

[0032] G1, G2: lens group

[0033] OS: Physical side

[0034] IS: Image side DETAILED DESCRIPTION

[0035] The terms "first" and "second" used in the following embodiments are intended to identify the aforementioned and other technical contents, features and functions of the same or similar invention, which will be clearly presented in the detailed description of the embodiments with reference to the drawings below. The directional terms mentioned in the following embodiments, such as up, down, left, right, front or back, etc., are only referenced to the directions of the attached drawings. Therefore, the directional terms used are used to illustrate and not to limit the present invention. In order to show the characteristics of this embodiment, only the structures related to this embodiment are shown, and the other structures are omitted.

[0036] The lens referred to in the present invention refers to a component that is partially or completely made of a transparent material and has refractive power, and is usually made of glass or plastic.

[0037] When a lens is used in an imaging system, the magnification side (object side) of the lens refers to the side on the optical path closer to the object being photographed, while the image reduction side (image side) refers to the side on the optical path closer to the image sensor.

[0038] The object-side surface (or image-side surface) of a lens has a convex portion (or concave portion) located in a certain area, which means that the area is more "convex outwardly" (or "concave inwardly") in a direction parallel to the optical axis than the outer area adjacent to the area in the radial direction.

[0039] Figure 1 Schematic diagram of the imaging lens of the first embodiment of the present invention. Figure 1, the imaging lens 10a includes a lens L1, a lens L4, a lens L5 (the lens L1, the lens L4, and the lens L5 constitute the first lens group G1), a lens L2, a lens L6, a lens L3 (the lens L2, the lens L6, and the lens L3 constitute the second lens group G2), a filter 16, and a cover plate 18, which are arranged in sequence from the object side OS to the image side IS of the imaging lens 10a and have refractive powers, and an aperture stop 14 provided between the lens L5 and the lens L2. The aperture stop 14 is a light-shielding element such as an aperture. In some embodiments, the aperture stop 14 may not be an independent optical element, but the inner diameter of the lens barrel may be used as the aperture stop 14. In other embodiments, the aperture stop 14 may be provided at other positions between the lens L1 and the lens L2. Light from the side of the object to be photographed can enter the imaging lens 10a and sequentially pass through the L1, the lens L4, the lens L5, the aperture stop 14, the lens L2, the lens L6, the lens L3, the filter 16, and the cover plate 18 to form an image on the imaging surface 22. The object side OS is the side facing the object to be photographed, and the image side IS is the side facing the imaging surface 22. In this embodiment, the refractive power of the first lens group G1 is negative and the refractive power of the second lens group G2 is positive. The filter 16 is, for example, an infrared filter, which can allow light of a required wavelength band (such as infrared light and visible light) to pass through and filter out light of other wavelength bands. The cover plate 18 may be made of any suitable light-transmitting material, such as glass material, and the cover plate 18 can be used to adjust the overall length of the imaging lens and can also provide a protection effect for the imaging lens.

[0040] In each specific embodiment of the present invention, the number of lenses with refractive powers in the imaging lens does not exceed 9, and among all the lenses with refractive powers in the imaging lens, at least one is a gradient refractive index lens or a lens with inhomogeneous material. A gradient refractive index lens is an optical lens in which the refractive index distribution of the internal material changes gradually along the radial or axial direction. A lens with inhomogeneous material refers to a lens that uses two or more different refractive index materials to cause a refraction effect when light travels through it. The gradient refractive index lens / lens with inhomogeneous material may have different refractive indices on the two surfaces on the optical axis of the lens, and the gradient refractive index lens / lens with inhomogeneous material may have a spherical, aspherical structure, or may be a flat lens with a smooth surface without microstructures and with refractive power. Furthermore, in the specific embodiment of the present invention, the specified lens with a gradient refractive index (gradient refractive index lens, lens with inhomogeneous material, or flat lens with a smooth surface without microstructures and with refractive power) satisfies the condition of 1 < D / T < 32, and preferably satisfies the condition of 5 < D / T < 13, where D is the maximum outer diameter of the specified lens with a gradient refractive index, and T is the thickness (lens center thickness) of the specified lens with a gradient refractive index on the optical axis of the imaging lens.

[0041] In a specific embodiment of the present invention, the aperture stop 14 is disposed between the two outermost lenses at the two ends of the imaging lens, and the object side OS is disposed on the left side of each figure, and the image side IS is disposed on the right side of each figure, which will not be described repeatedly below. In the present embodiment, the refractive powers of lens L1, lens L4, lens L5, lens L2, lens L6, and lens L3 are negative, negative, positive, positive, negative, and positive, respectively. In the present embodiment, lens L1 is a glass spherical lens, lens L2 is a glass molded aspherical lens, and lenses L4, L5, L6, and L3 are plastic aspherical lenses, but the present invention is not limited thereto. Lens L6 and lens L3 are bonded to each other to form a combined lens, for example, a double bonded lens is formed by bonding, but the present invention is not limited thereto. The bonding of lens L6 and lens L3 to form a bonded lens can improve the chromatic aberration problem of the imaging lens 10a, and can tolerate a higher manufacturing tolerance, thereby improving the yield rate. Furthermore, in this embodiment, the designated lens with a gradient refractive index is the filter 16. The filter 16 can be a flat lens with a smooth surface and no microstructure and a refractive power, and the D / T value of the filter 16 is 12.36. By mixing and matching the structure of the gradient refractive index lens with glass and plastic, chromatic aberration and spherical aberration can be further eliminated to improve the imaging quality.

[0042] The diagonal field of view DFOV refers to the light collection angle of the optical surface closest to the object side OS, that is, the field of view (diagonal field of view) measured diagonally. In this embodiment, the diagonal field of view DFOV of the imaging lens 10a is 170 degrees. Furthermore, according to the design of the embodiment, the total system length TTL of the imaging lens 10a on the optical axis (the length from the object side surface S1 of the lens L1 to the imaging surface 22 on the optical axis 12) is 13.4 mm, the total lens length LT of the outermost surfaces of the two ends of the imaging lens 10a on the optical axis 12 (the length from the object side surface S1 of the lens L1 to the image side surface S12 of the lens L3 on the optical axis) is 12.02 mm, the effective focal length EFL is 1.2 mm, the aperture number (F-number) is 1.8, and the maximum image height is 1.96 mm.

[0043] The lens design parameters and shape of the imaging lens 10a are shown in Table 1. However, the information listed in Table 1 below is not intended to limit the present invention. Any person skilled in the art may make appropriate changes to the parameters or settings after referring to the present invention, which should still fall within the scope of the present invention.

[0044] Table 1 records the values ​​of the optical parameters of each lens in the optical system. The units of the radius of curvature and the spacing in Table 1 are millimeters (mm). In Table 1, the radius of curvature refers to the reciprocal of the curvature. When the radius of curvature is positive, the center of the lens surface is on the image side of the lens. When the radius of curvature is negative, the center of the lens surface is on the object side of the lens. The spacing (mm) refers to the straight-line distance between two adjacent surfaces on the optical axis 12. For example, the spacing of surface S1 is the distance between surface S1 and surface S2, and the spacing of surface S2 is the distance between surface S2 and surface S3. For the spacing, refractive index and Abbe number corresponding to each lens and each optical element in the aperture, please refer to the corresponding values ​​of each spacing, refractive index and Abbe number in the same column. For the parameter values ​​of the radius of curvature, spacing, etc. of each surface, please refer to Table 1, which will not be repeated here.

[0045] Table 1

[0046]

[0047]

[0048] An aspheric lens refers to a lens whose front and rear surfaces have at least one surface whose radius of curvature changes with the central axis, and can be used to correct aberrations. In the following design examples of the present invention, the aspheric polynomial can be expressed by the following formula:

[0049]

[0050] In the above formula, Z is the offset (sag) in the direction of the optical axis, c is the reciprocal of the radius of the osculating sphere, that is, the reciprocal of the radius of curvature close to the optical axis, k is the quadratic coefficient (conic), and r is the aspheric height, that is, the height from the center of the lens to the edge of the lens. AG in Tables 2 and 3 represent the values ​​of the 4th, 6th, 8th, 10th, 12th, 14th, and 16th order terms of the aspheric polynomial, respectively. However, the data listed below are not intended to limit the present invention. Any person skilled in the art may make appropriate changes to the parameters or settings after referring to the present invention, which should still fall within the scope of the present invention.

[0051] Table 2

[0052] S3 S4 S5 S6 S8 S9 K 15.05715 -0.08822 13.67271 -98.7786 0 -6.51229 A 4.12E-02 3.68E-02 1.26E-02 -8.01E-03 2.16E-02 -5.10E-02 B -1.96E-02 6.20E-02 5.25E-03 5.50E-02 -3.29E-03 1.29E-02 C 6.18E-03 -1.30E-01 2.86E-04 -3.69E-02 -6.04E-03 -8.23E-03 D -1.39E-03 1.15E-01 -1.71E-05 1.67E-02 2.80E-03 1.72E-03 E 2.29E-04 -5.09E-02 0 1.87E-16 0 0 F -2.64E-05 1.09E-02 0 0 0 0 G 1.53E-06 -9.61E-04 0 0 0 0

[0053] Table 3

[0054]

[0055]

[0056] In a specific embodiment of the present invention, the change direction of the inhomogeneous material of a designated lens with a gradient refractive index may include both radial and axial directions, and the refractive index calculation formula is:

[0057] n(r,z)=n00+C01×z+C02×z 2 +C10×r 2 +C20×r 4 +C30×r 6

[0058] Where n is the refractive index, r is the radius from any point of the lens to the center of the lens, z is the axial distance, n(r,z) represents the refractive index of the gradient refractive index lens when the radius r is a certain value and the axial distance z is another value, n00 is the basic refractive index, and C01, C02, C10, C20, and C30 represent the correlation coefficients. Table 4 below discloses the design parameters of the gradient refractive index lens (filter 16) of lens 10a. Table 4 shows the values ​​of the basic refractive index and the correlation coefficients at different wavelengths, where the C-line of the horizontal stop is the wavelength of 656.27nm of the hydrogen C line (hydrogen red line), d-line is the wavelength of 587.56nm of the helium d line (helium yellow line), and F-line is the wavelength of 486.12nm of the hydrogen F line (hydrogen blue line), and the vertical stop is n00 as the basic refractive index; C01, C02, C10, C20, and C30 represent the correlation coefficients.

[0059] Table 4

[0060]

[0061] Figure 2A , Figure 2B , Figure 2C is an imaging optical simulation data diagram of the imaging lens 10a of this embodiment, wherein Figure 2A , Figure 2B , Figure 2C The longitudinal spherical aberration diagram, the field curvature aberration diagram and the distortion aberration diagram on the imaging surface 22 of the imaging lens 10a at wavelengths of 486nm, 546nm and 656nm are shown respectively. The figures shown in these optical simulation data diagrams are all within the standard range, which verifies that the imaging lens 10a of this embodiment can indeed provide good optical imaging quality.

[0062] Figure 3Schematic diagram of an imaging lens according to a second embodiment of the present invention. The imaging lens 10b of this embodiment includes lenses L1, L4, L5 (lens L1, L4 and L5 constitute a first lens group G1 with negative refractive power), L2, L6, L3 (lens L2, L6 and L3 constitute a second lens group G2 with positive refractive power), a filter 16 and a cover plate 18, and an aperture stop 14 disposed between lens L5 and lens L2, which are arranged in order from the object side OS to the image side IS of the imaging lens 10b and have refractive power. In this embodiment, lens L4 is a material inhomogeneous lens with a gradient refractive index. In this embodiment, the refractive powers of lens L1, lens L4, lens L5, lens L2, lens L6 and lens L3 are negative, negative, positive, positive, negative and positive, respectively. In the present embodiment, lens L1 is a glass spherical lens, lens L4 is a material inhomogeneous lens with a gradient refractive index and is an aspherical lens, lens L2 is a glass molded aspherical lens, and lenses L5, L6, and L3 are plastic aspherical lenses, but the present invention is not limited thereto. Lens L6 and lens L3 are bonded to each other to form a combined lens, for example, a double bonded lens is formed by bonding, but the present invention is not limited thereto. Lens L6 and lens L3 are bonded to form a bonded lens, which can improve the chromatic aberration problem of the imaging lens 10a and can tolerate higher manufacturing tolerances, thereby improving the yield rate. Furthermore, by mixing and matching the structure of the gradient refractive index lens with glass and plastic, chromatic aberration and spherical aberration can be further eliminated to improve the imaging quality.

[0063] In this embodiment, the effective focal length EFL of the imaging lens 10b is 1.2 mm, the aperture number (F-number) is 1.8, the diagonal field of view DFOV is 170 degrees, the total system length TTL is 14.2 mm, the total lens length LT is 11.68 mm, the maximum image height is 2.03 mm, the designated lens with a gradient refractive index is lens L4, and the D / T value of lens L4 is 9.19.

[0064] Detailed optical data of the imaging lens 10 b of the second embodiment are shown in Table 5 below.

[0065] Table 5

[0066]

[0067]

[0068] The quadratic surface coefficients of each aspherical surface of the imaging lens 10 b and various aspherical coefficients are shown in Table 6 and Table 7.

[0069] Table 6

[0070] S3 S4 S5 S6 S8 S9 K 29.361932 -0.09205 13.63001 -98.8063 0 -6.51451 A 4.18E-02 3.47E-02 1.25E-02 -7.99E-03 2.16E-02 -5.10E-02 B -1.96E-02 6.18E-02 5.23E-03 5.51E-02 -3.33E-03 1.29E-02 C 6.19E-03 -1.30E-01 2.82E-04 -3.69E-02 -6.08E-03 -8.21E-03 D -1.39E-03 1.15E-01 -1.80E-05 1.67E-02 2.76E-03 1.73E-03 E 2.29E-04 -5.09E-02 0 1.87E-16 0 0 F -2.64E-05 1.09E-02 0 0 0 0 G 1.53E-06 -9.61E-04 0 0 0 0

[0071] Table 7

[0072] S10 S11 S12 K -98.8838 -3.46957 -1.89383 A -4.61E-03 7.50E-02 -3.99E-03 B -9.43E-03 -3.12E-02 -5.45E-03 C -5.68E-04 8.54E-03 3.63E-03 D 8.65E-04 -1.13E-03 -1.24E-03 E -1.64E-14 1.28E-13 1.78E-04 F 0 0 0 G 0 0 0

[0073] Table 8 below discloses the design parameters of the gradient index lens (lens L4) of lens 10b.

[0074] Table 8

[0075]

[0076] Figure 4A , Figure 4B and Figure 4C The longitudinal spherical aberration diagram, the field curvature aberration diagram and the distortion aberration diagram on the imaging surface 22 of the imaging lens 10b at wavelengths of 486nm, 546nm and 656nm are shown respectively. The figures shown in these optical simulation data diagrams are all within the standard range, which verifies that the imaging lens 10b of this embodiment can indeed provide good optical imaging quality.

[0077] Figure 5 Schematic diagram of an imaging lens according to a third embodiment of the present invention. The imaging lens 10c of this embodiment comprises a lens L1, a lens L4, a lens L7, a lens L5 (constituting a first lens group G1 with negative refractive power), a lens L2, a lens L6, a lens L3 (constituting a second lens group G2 with positive refractive power), a filter 16 and a cover plate 18, which are arranged in order from the object side OS to the image side IS of the imaging lens 10c and have refractive power, and an aperture stop 14 disposed between the lens L5 and the lens L2. In this embodiment, the filter 16 uses an inhomogeneous material to produce a gradient refractive index, and is a flat lens with a smooth surface and no microstructure and refractive power. In this embodiment, the refractive powers of the lens L1, the lens L4, the lens L7, the lens L5, the lens L2, the lens L6, and the lens L3 are negative, negative, negative, positive, positive, negative, and positive, respectively. In the present embodiment, lenses L1 and L7 are glass spherical lenses, lens L2 is a glass molded aspherical lens, and lenses L4, L5, L6, and L3 are plastic aspherical lenses, but the present invention is not limited thereto. Lens L6 and lens L3 are bonded to each other to form a combined lens, for example, a double bonded lens is formed by bonding, but the present invention is not limited thereto. Lens L6 and lens L3 are bonded to form a bonded lens, which can improve the chromatic aberration problem of the imaging lens 10c and can tolerate higher manufacturing tolerances, thereby improving the yield rate. Furthermore, by mixing and matching the structure of the gradient refractive index lens with glass and plastic, chromatic aberration and spherical aberration can be further eliminated to improve the imaging quality.

[0078] In this embodiment, the effective focal length EFL of the imaging lens 10c is 1.0 mm, the aperture number (F-number) is 1.8, the diagonal field of view DFOV is 170 degrees, the total system length TTL is 13.0 mm, the total lens length LT is 11.02 mm, the maximum image height is 1.98 mm, the designated lens with a gradient refractive index is the filter 16, and the D / T value of the filter 16 is 11.34.

[0079] Detailed optical data of the imaging lens 10c of the third embodiment are shown in Table 9 below.

[0080] Table 9

[0081]

[0082]

[0083] The quadratic surface coefficients of each aspherical surface of the imaging lens 10c and various aspherical coefficients are shown in Table 10 and Table 11.

[0084] Table 10

[0085] S3 S4 S7 S8 S10 S11 K 33.704698 -0.1617 5.323173 -250.784 0 -5.5038 A 7.75E-02 9.29E-02 2.48E-02 5.00E-02 3.06E-02 -7.10E-02 B -2.89E-02 7.10E-02 8.11E-03 4.85E-02 -2.69E-02 8.26E-03 C 7.31E-03 -1.40E-01 -9.94E-04 -2.65E-02 4.33E-03 -6.89E-03 D -1.45E-03 1.15E-01 5.35E-04 3.32E-02 1.00E-03 9.83E-04 E 2.29E-04 -5.09E-02 0 1.87E-16 0 0 F -2.64E-05 1.09E-02 0 0 0 0 G 1.53E-06 -9.61E-04 0 0 0 0

[0086] Table 11

[0087]

[0088]

[0089] Table 12 below discloses the design parameters of the gradient index lens (filter 16) of the lens 10c.

[0090] Table 12

[0091]

[0092] Fig. 6A , Figure 6B and Figure 6C The longitudinal spherical aberration diagram, the field curvature aberration diagram and the distortion aberration diagram on the imaging surface 22 of the imaging lens 10c at wavelengths of 486nm, 546nm and 656nm are shown respectively. The figures shown in these optical simulation data diagrams are all within the standard range, which verifies that the imaging lens 10c of this embodiment can indeed provide good optical imaging quality.

[0093] Figure 7Schematic diagram of an imaging lens according to a fourth embodiment of the present invention. The imaging lens 10d of this embodiment comprises a lens L1, a lens L4, a lens L7, a lens L5 (constituting a first lens group G1 with negative refractive power), a lens L2, a lens L6, a lens L8, a lens L3 (constituting a second lens group G2 with positive refractive power), a filter 16 and a cover plate 18, which are arranged in order from the object side OS to the image side IS of the imaging lens 10d and have refractive power, and an aperture stop 14 disposed between the lens L5 and the lens L2. In this embodiment, the filter 16 uses an inhomogeneous material to produce a gradient refractive index, and is a flat lens with a smooth surface and no microstructure and refractive power. In this embodiment, the refractive powers of the lens L1, the lens L4, the lens L7, the lens L5, the lens L2, the lens L6, the lens L8, and the lens L3 are negative, negative, negative, positive, positive, positive, negative, positive, positive, respectively. In the present embodiment, lenses L1 and L7 are glass spherical lenses, lens L2 is a glass molded aspherical lens, and lenses L4, L5, L6, L8, and L3 are plastic aspherical lenses, but the present invention is not limited thereto. Lens L6 and lens L8 are bonded to each other to form a combined lens, for example, a double bonded lens is formed by bonding, but the present invention is not limited thereto. Lens L6 and lens L8 are bonded to form a bonded lens, which can improve the chromatic aberration problem of the imaging lens 10d and can tolerate higher manufacturing tolerances, thereby improving the yield rate. Furthermore, by mixing and matching the structure of the gradient refractive index lens with glass and plastic, chromatic aberration and spherical aberration can be further eliminated to improve the imaging quality.

[0094] In this embodiment, the effective focal length EFL of the imaging lens 10d is 0.4 mm, the aperture number (F-number) is 1.8, the diagonal field of view DFOV is 170 degrees, the total system length TTL is 13.0 mm, the total lens length LT is 11.24 mm, the maximum image height is 2.01 mm, the designated lens with a gradient refractive index is the filter 16, and the D / T value of the filter 16 is 31.21.

[0095] Detailed optical data of the imaging lens 10d of the fourth embodiment are shown in Table 13 below.

[0096] Table 13

[0097]

[0098]

[0099] The quadratic surface coefficients and various aspherical coefficients of each aspherical surface of the imaging lens 10d are shown in Table 14 and Table 15.

[0100] Table 14

[0101] S3 S4 S7 S8 S10 S11 K 4.1614917 -0.36146 4.189562 -183.22 0 -5.60256 A 6.50E-02 1.06E-01 3.60E-02 5.13E-02 1.95E-02 -6.20E-02 B -2.77E-02 6.65E-02 1.68E-02 7.31E-02 -3.47E-02 2.67E-03 C 7.38E-03 -1.34E-01 -1.95E-03 -4.85E-02 -1.93E-04 -1.31E-02 D -1.46E-03 1.18E-01 9.82E-03 4.65E-02 -4.74E-04 -1.60E-03 E 2.29E-04 -5.09E-02 0 1.87E-16 0 0 F -2.64E-05 1.09E-02 0 0 0 0 G 1.53E-06 -9.61E-04 0 0 0 0

[0102] Table 15

[0103] S12 S13 S14 S15 S16 K -94.13485 -2.45163 -9.003E+18 -4.2E+18 -83.2796 A -1.64E-02 1.65E-01 1.73E-02 -8.25E-04 -1.38E-02 B 6.33E-03 -2.63E-02 1.41E-02 5.49E-03 1.57E-02 C -4.11E-03 3.96E-02 2.66E-03 -1.05E-03 -4.26E-03 D -1.66E-03 8.45E-03 6.45E-04 4.09E-03 1.64E-03 E -1.64E-14 1.28E-13 1.78E-04 F G

[0104] Table 16 below discloses the design parameters of the gradient index lens (filter 16) of lens 10d.

[0105] Table 16

[0106]

[0107] Fig. 8A , Figure 8B and Figure 8C The longitudinal spherical aberration diagram, the field curvature aberration diagram and the distortion aberration diagram on the imaging surface 22 of the imaging lens 10d at wavelengths of 486nm, 546nm and 656nm are shown respectively. The figures shown in these optical simulation data diagrams are all within the standard range, which verifies that the imaging lens 10d of this embodiment can indeed provide good optical imaging quality.

[0108] Fig. 9 Schematic diagram of the imaging lens of the fifth embodiment of the present invention. The imaging lens 10e of this embodiment includes a lens L1, a lens L4, a lens L5 (constituting a first lens group G1 with negative refractive power), a lens L2, a lens L3 (constituting a second lens group G2 with positive refractive power), a filter 16 and a cover plate 18, which are arranged in order from the object side OS to the image side IS of the imaging lens 10e and have refractive power, and an aperture stop 14 disposed between the lens L5 and the lens L2. In this embodiment, the lens L4 is a material inhomogeneous lens with a gradient refractive index. In other embodiments, the material inhomogeneous lens with a gradient refractive index can also be one of the lens L5, the lens L2 or the lens L3. In this embodiment, the refractive powers of the lens L1, the lens L4, the lens L5, the lens L2 and the lens L3 are negative, negative, positive, positive and positive, respectively. In this embodiment, lens L1 is a glass spherical lens, lens L4 is a material inhomogeneous lens with a gradient refractive index and is an aspherical lens, lens L2 is a glass molded aspherical lens, and lenses L5 and L3 are plastic aspherical lenses, but the present invention is not limited thereto. By mixing and matching the structure of the gradient refractive index lens with glass and plastic, chromatic aberration and spherical aberration can be further eliminated to improve the imaging quality.

[0109] In this embodiment, the effective focal length EFL of the imaging lens 10e is 0.8 mm, the aperture number (F-number) is 1.8, the diagonal field of view DFOV is 170 degrees, the total system length TTL is 12.2 mm, the total lens length LT is 8.85 mm, the maximum image height is 1.33 mm, the designated lens with a gradient refractive index is lens L4, and the D / T value of lens L4 is 8.86.

[0110] Detailed optical data of the imaging lens 10e of the fifth embodiment are shown in Table 17 below.

[0111] Table 17

[0112]

[0113]

[0114] The quadratic surface coefficients of each aspherical surface of the imaging lens 10e and various aspherical coefficients are shown in Tables 18 and 19.

[0115] Table 18

[0116]

[0117]

[0118] Table 19

[0119] S10 S11 K -1.89383 -1.89383 A -3.99E-03 -3.99E-03 B -5.45E-03 -5.45E-03 C 3.63E-03 3.63E-03 D -1.24E-03 -1.24E-03 E 1.78E-04 1.78E-04 F 0 0 G 0 0

[0120] Table 20 below discloses the design parameters of the gradient index lens (lens L4) of lens 10e.

[0121] Table 20

[0122]

[0123] Fig. 10A , Fig. 10B and Fig. 10C The longitudinal spherical aberration diagram, the field curvature aberration diagram and the distortion aberration diagram on the imaging surface 22 of the imaging lens 10e at wavelengths of 486nm, 546nm and 656nm are shown respectively. The figures shown in these optical simulation data diagrams are all within the standard range, which verifies that the imaging lens 10e of this embodiment can indeed provide good optical imaging quality.

[0124] Fig.11Schematic diagram of an imaging lens according to a sixth embodiment of the present invention. The imaging lens 10f of this embodiment includes a lens L1, a lens L4, a lens L5 (constituting a first lens group G1 with negative refractive power), a lens L2, a lens L6, a lens L3 (constituting a second lens group G2 with positive refractive power), a filter 16 and a cover plate 18, which are arranged in order from the object side OS to the image side IS of the imaging lens 10f and have refractive power, and an aperture stop 14 disposed between the lens L5 and the lens L2. In this embodiment, the lens L6 is a material inhomogeneous lens with a gradient refractive index. In this embodiment, the refractive powers of the lens L1, the lens L4, the lens L5, the lens L2, the lens L6, and the lens L3 are negative, negative, positive, positive, negative, and positive, respectively. In the present embodiment, lens L1 is a glass spherical lens, lens L6 is a material inhomogeneous lens with a gradient refractive index and is an aspherical lens, lens L2 is a glass molded aspherical lens, and lenses L4, L5, and L3 are plastic aspherical lenses, but the present invention is not limited thereto. Lens L6 and lens L3 are bonded to each other to form a combined lens, for example, a double bonded lens is formed by bonding, but the present invention is not limited thereto. Lens L6 and lens L3 are bonded to form a bonded lens, which can improve the chromatic aberration problem of the imaging lens 10a and can tolerate higher manufacturing tolerances, thereby improving the yield rate. Furthermore, by mixing and matching the structure of the gradient refractive index lens with glass and plastic, chromatic aberration and spherical aberration can be further eliminated to improve the imaging quality.

[0125] In this embodiment, the effective focal length EFL of the imaging lens 10f is 0.9 mm, the aperture number (F-number) is 1.8, the diagonal field of view DFOV is 170 degrees, the total system length TTL is 12.2 mm, the total lens length LT is 10.23 mm, the maximum image height is 1.75 mm, the designated lens with a gradient refractive index is lens L6, and the D / T value of lens L6 is 5.77.

[0126] Detailed optical data of the imaging lens 10f of the sixth embodiment are shown in Table 21 below.

[0127] Table 21

[0128]

[0129]

[0130] The quadratic surface coefficients and various aspherical coefficients of each aspherical surface of the imaging lens 10f are shown in Table 22 and Table 23.

[0131] Table 22

[0132] S3 S4 S5 S6 S8 S9 K 98.74453 -0.06299 14.0909 -97.9931 0 -5.71019 A 3.43E-02 3.19E-02 1.28E-02 -1.61E-02 1.94E-02 -5.90E-02 B -1.58E-02 6.08E-02 -1.17E-03 4.51E-02 -3.36E-03 2.18E-02 C 5.54E-03 -1.29E-01 3.95E-03 -3.06E-02 -2.63E-03 -1.28E-02 D -1.34E-03 1.13E-01 -1.22E-03 1.28E-02 7.46E-03 2.42E-03 E 2.29E-04 -5.09E-02 0 1.87E-16 0 0 F -2.64E-05 1.09E-02 0 0 0 0 G 1.53E-06 -9.61E-04 0 0 0 0

[0133] Table 23

[0134]

[0135]

[0136] Table 24 below reveals the design parameters of the gradient index lens (lens L6) of lens 10f.

[0137] Table 24

[0138]

[0139] Fig. 12A , Fig. 12B and Fig. 12C The longitudinal spherical aberration diagram, the field curvature aberration diagram and the distortion aberration diagram on the imaging surface 22 of the imaging lens 10f at wavelengths of 486nm, 546nm and 656nm are shown respectively. The figures shown in these optical simulation data diagrams are all within the standard range, which verifies that the imaging lens 10f of this embodiment can indeed provide good optical imaging quality.

[0140] Fig.13 Schematic diagram of the imaging lens of the seventh embodiment of the present invention. The imaging lens 10g of this embodiment includes a lens L1 (constituting a first lens group G1 with negative refractive power), a lens L2, a lens L3 (constituting a second lens group G2 with positive refractive power), a filter 16 and a cover plate 18, which are arranged in sequence from the object side OS to the image side IS of the imaging lens 10g and have refractive power, and an aperture stop 14 disposed between the lens L1 and the lens L2. In this embodiment, the lens L3 is a material inhomogeneous lens with a gradient refractive index. In this embodiment, the refractive powers of the lens L1, the lens L2, and the lens L3 are negative, positive, and positive, respectively. In this embodiment, the lens L1 is a glass spherical lens, the lens L3 is a material inhomogeneous lens with a gradient refractive index and is an aspherical lens, and the lens L2 is a glass molded aspherical lens, but the present invention is not limited thereto. By mixing and matching the structure of the gradient refractive index lens with glass and plastic, chromatic aberration and spherical aberration can be further eliminated to improve the imaging quality.

[0141] In this embodiment, the effective focal length EFL of the imaging lens 10g is 0.4 mm, the aperture number (F-number) is 1.8, the diagonal field of view DFOV is 170 degrees, the total system length TTL is 8.1 mm, the total lens length LT is 7.03 mm, the maximum image height is 0.79 mm, the designated lens with a gradient refractive index is lens L3, and the D / T value of lens L3 is 2.33.

[0142] Detailed optical data of the imaging lens 10g of the seventh embodiment are shown in Table 25 below.

[0143] Table 25

[0144]

[0145] The quadratic surface coefficients of each aspherical surface of the imaging lens 10g and various aspherical coefficients are shown in Table 26.

[0146] Table 26

[0147]

[0148]

[0149] Table 27 below reveals the design parameters of the gradient index lens (lens L3) of lens 10g.

[0150] Table 27

[0151]

[0152] Fig.14A , Fig. 14B and Fig. 14C The longitudinal spherical aberration diagram, the field curvature aberration diagram and the distortion aberration diagram on the imaging surface 22 of the imaging lens 10g at wavelengths of 486nm, 546nm and 656nm are shown respectively. The figures shown in these optical simulation data diagrams are all within the standard range, which verifies that the imaging lens 10g of this embodiment can indeed provide good optical imaging quality.

[0153] In summary, the imaging lens of the embodiment of the present invention can provide a good achromatic effect while meeting the requirements of wide viewing angle by complying with the above-mentioned component characteristics and configuration conditions, and can provide high-quality imaging of visible light and infrared light without switching the thickness of the filter. In addition, the imaging lens of the embodiment of the present invention can reduce the manufacturing cost and take into account the image quality while being able to withstand the high temperature and temperature changes of the use environment by appropriately matching the glass and plastic lenses with the spherical surface and the aspherical surface. Furthermore, the imaging lens includes at least one single-piece gradient refractive index lens or material inhomogeneous lens, which can provide an achromatic effect similar to that of a cemented lens. Therefore, while meeting the requirements of achromatic and infrared band imaging, the use of cemented lenses can be reduced to obtain the effect of reducing the lens volume, the number of lenses or the total length.

[0154] Although the present invention has been disclosed as above by way of embodiments, it is not intended to limit the present invention. Any person skilled in the art may make some changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined by the attached claims.

Claims

1. An imaging lens, characterized in that: Comprising: A first lens, a second lens, and a third lens arranged in sequence from the object side to the image side of the imaging lens. The first lens has a negative refractive power, and the number of lenses with refractive power in the imaging lens does not exceed 9; among the lenses with refractive power, one is a specified lens, and the specified lens is a gradient-index lens; and An aperture stop, disposed between the two outermost lenses at both ends of the imaging lens; The gradient-index lens satisfies the condition of 1 < D / T < 32, where D is the maximum outer diameter of the gradient-index lens, and T is the thickness of the gradient-index lens on the optical axis of the imaging lens.

2. The imaging lens according to claim 1, wherein: The refractive index gradient direction of the gradient-index lens is axial and radial.

3. An imaging lens, characterized in that: Comprising: A first lens, a second lens, and a third lens arranged in sequence from the object side to the image side of the imaging lens. The first lens has a negative refractive power, and the number of lenses with refractive power in the imaging lens does not exceed 9. Among the lenses with refractive power, one is a specified lens, and the specified lens is a lens with inhomogeneous material, and the refractive indices are different on the two surfaces of the lens with inhomogeneous material on the optical axis of the lens; And An aperture stop, disposed between the two outermost lenses at both ends of the imaging lens; The lens with inhomogeneous material satisfies the condition of 1 < D / T < 32, where D is the maximum outer diameter of the lens with inhomogeneous material, and T is the central thickness of the lens with inhomogeneous material.

4. An imaging lens, characterized in that: Comprising: A first lens, a second lens, and a third lens arranged in sequence from the object side to the image side of the imaging lens. The first lens has a negative refractive power, and the number of lenses with refractive power in the imaging lens does not exceed 9. Among these lenses with refractive power, one is a specified lens, and the specified lens is a flat lens with a smooth surface without microstructures and with refractive power; and An aperture stop, disposed between the two outermost lenses at both ends of the imaging lens.

5. The imaging lens according to claim 4, wherein: D is the maximum outer diameter of the specified lens, T is the thickness of the specified lens on the optical axis of the imaging lens, and the specified lens satisfies the condition of 1 < D / T < 32.

6. The imaging lens according to claim 1, 3 or 5, characterized in that: The specified lens satisfies the condition of 5 < D / T < 13.

7. The imaging lens according to claim 1, 3 or 4, characterized in that: Among these lenses with refractive power, there is at least one aspherical lens.

8. The imaging lens according to claim 1, 3 or 4, characterized in that: The aperture stop is disposed between the first lens and the second lens.

9. The imaging lens according to claim 8, wherein: The second lens is a glass-molded aspherical lens.

10. The imaging lens according to claim 8, wherein: The third lens is the specified lens.

11. The imaging lens according to claim 8, wherein: It further includes a fourth lens and a fifth lens, and the fourth lens and the fifth lens are disposed between the first lens and the second lens.

12. The imaging lens according to claim 11, wherein: The fifth lens, the second lens, and the third lens are aspherical lenses.

13. The imaging lens according to claim 11, wherein: One of the fourth lens, the fifth lens, the second lens, and the third lens is the specified lens.

14. The imaging lens according to claim 11, wherein: It further includes a sixth lens, disposed between the second lens and the third lens.

15. The imaging lens according to claim 14, wherein: The fourth lens or the sixth lens is the specified lens.

16. The imaging lens according to claim 14, wherein: It further includes a filter, and the filter is disposed on the side of the third lens away from the object side and is the specified lens.

17. The imaging lens according to claim 14, wherein: The first lens, the fourth lens, and the fifth lens form a first lens group, the second lens, the sixth lens, and the third lens form a second lens group. The refractive power of the first lens group is negative, and the refractive power of the second lens group is positive.

18. The imaging lens according to claim 14, wherein: The invention also includes a seventh lens, which is arranged between the fourth lens and the fifth lens.

19. The imaging lens according to claim 18, wherein: The fourth lens, the fifth lens, the second lens, the sixth lens and the third lens are aspherical lenses.

20. The imaging lens according to claim 18, wherein: A filter is also included. The infrared filter is arranged on a side of the third lens away from the object side and is the designated lens.

21. The imaging lens according to claim 18, wherein: The first lens, the fourth lens, the seventh lens and the fifth lens form a first lens group, the second lens, the sixth lens and the third lens form a second lens group, the refractive power of the first lens group is negative, and the refractive power of the second lens group is positive.

22. The imaging lens according to claim 18, wherein: The invention also includes an eighth lens, which is arranged between the sixth lens and the third lens.

23. The imaging lens according to claim 22, wherein: The fourth lens, the fifth lens, the second lens, the sixth lens and the third lens are aspherical lenses.

24. The imaging lens according to claim 22, wherein: The invention also comprises a filter, which is arranged on a side of the third lens away from the object side, and the filter is the designated lens.

25. The imaging lens according to claim 22, wherein: The first lens, the fourth lens, the seventh lens and the fifth lens form a first lens group, the second lens, the sixth lens, the eighth lens and the third lens form a second lens group, the refractive power of the first lens group is negative, and the refractive power of the second lens group is positive.

Images