Iris recognition lens

Abstract

The utility model discloses an iris recognition lens, which relates to the technical field of optical lens imaging and comprises an imaging lens which comprises a first lens, a first lens group, a diaphragm, a second lens group, a second lens, a third lens and a fourth lens which are sequentially arranged along an optical axis from an object side to an image side. The second lens group comprises a fifth lens, a double-liquid lens and a sixth lens, the first lens and the second lens have positive focal power, the third lens has negative focal power, the focal power of the fourth lens is zero, and the ratio of the focal power of the first lens group to the focal power of the imaging lens is smaller than or equal to-0.0716. The ratio of the focal power of the second lens group to the focal power of the imaging lens is larger than or equal to 0.315. The iris recognition lens of the utility model has high relative illumination, and can improve the adaptability and imaging quality of a system; the zoom lens can give consideration to parameters such as resolution and depth of field, and is wide in working range.

Description

Technical Field

[0001] The utility model relates to the technical field of optical lens imaging, in particular to an iris recognition lens. Background Art

[0002] Iris recognition technology has been widely used in identity verification due to its high security. However, existing iris recognition lenses are mostly fixed-focal-length, making them difficult to adapt to recognition requirements at varying distances, limiting their application in changing environments. Furthermore, the resolution and depth of field performance of fixed-focal-length lenses also make them difficult to meet the high standards of biometrics. Utility Model Content

[0003] The purpose of the utility model is to provide an iris recognition lens to solve the problems existing in the prior art. The relative illumination is high, and the adaptability and imaging quality of the system can be improved. The zoom lens can take into account parameters such as resolution and depth of field and has a wide working range.

[0004] To achieve the above purpose, the present invention provides the following solutions:

[0005] The utility model provides an iris recognition lens, including an imaging lens, wherein the imaging lens includes a first lens, a lens group 1, an aperture, a lens group 2, a second lens, a third lens, and a fourth lens, which are arranged in sequence along an optical axis from an object side to an image side. The lens group 2 includes a fifth lens, a double liquid lens, and a sixth lens. The first lens and the second lens have positive optical power, the third lens has negative optical power, and the optical power of the fourth lens is zero. The ratio of the optical power of the lens group 1 to the optical power of the imaging lens is less than or equal to -0.0716, and the ratio of the optical power of the lens group 2 to the optical power of the imaging lens is greater than or equal to 0.315.

[0006] Preferably, the lens group 1 includes a seventh lens and an eighth lens, the seventh lens has positive focal power, and the eighth lens has negative focal power.

[0007] Preferably, the imaging lens satisfies: 2.0≤TTL / EFL≤2.1, 0.70≤BFL / EFL≤0.75;

[0008] Among them, TTL is the distance from the object side surface of the first lens to the imaging surface on the optical axis, EFL is the focal length of the imaging lens, and BFL is the distance from the image side surface of the fourth lens to the imaging surface on the optical axis.

[0009] Preferably, the refractive index of the seventh lens is greater than that of the eighth lens, the refractive index of the eighth lens is greater than that of the third lens, the refractive index of the third lens is greater than that of the second lens, the refractive index of the fifth lens is greater than that of the fourth lens, the refractive index of the fifth lens is the same as that of the fifth lens, and the refractive index of the fifth lens is greater than that of the first lens.

[0010] Preferably, the double liquid lens includes a first liquid lens and a second liquid lens arranged in sequence along the optical axis from the object side to the image side, the refractive index of the first liquid lens is greater than or equal to 1.673, and the Abbe number of the first liquid lens is less than or equal to 25, the refractive index of the second liquid lens is greater than or equal to 1.472, and the Abbe number of the second liquid lens is less than or equal to 60.

[0011] Preferably, the object-side surface of the first lens is the first object-side surface, the image-side surface of the first lens is the first image-side surface, the first object-side surface is an even aspheric surface, and the first image-side surface is an even aspheric surface; the object-side surface of the second lens is the second object-side surface, the image-side surface of the second lens is the second image-side surface, the second object-side surface is convex, and the second object-side surface is an even aspheric surface, the second image-side surface is concave, and the second image-side surface is an even aspheric surface; the object-side surface of the third lens is the third object-side surface, the image-side surface of the third lens is the third image-side surface, the third object-side surface is concave, and the third image-side surface is concave; the object-side surface of the fourth lens is the fourth object-side surface, the image-side surface of the fourth lens is the fourth image-side surface, and the fourth object-side surface is The side surface of the lens is a plane, and the fourth image side surface is a plane; the object side surface of the fifth lens is the fifth object side surface, the image side surface of the fifth lens is the fifth image side surface, the fifth object side surface is a plane, and the fifth image side surface is a plane; the object side surface of the sixth lens is the sixth object side surface, the image side surface of the sixth lens is the sixth image side surface, the sixth object side surface is a plane, and the sixth image side surface is a concave surface; the object side surface of the seventh lens is the seventh object side surface, the image side surface of the seventh lens is the seventh image side surface, the seventh object side surface is a convex surface, and the seventh image side surface is a plane or a convex surface; the object side surface of the eighth lens is the eighth object side surface, the image side surface of the eighth lens is the eighth image side surface, the eighth object side surface is a plane or a convex surface, and the eighth image side surface is a convex surface.

[0012] Preferably, the object side surface of the first liquid lens is the ninth object side surface, the image side surface of the first liquid lens is the ninth image side surface, the ninth object side surface is a plane, and the ninth image side surface is a convex surface; the image side surface of the second liquid lens is the tenth image side surface, and the tenth image side surface is a plane.

[0013] Preferably, the fifth lens is adhesively bonded to the first liquid lens, and the sixth lens is adhesively bonded to the second liquid lens.

[0014] Preferably, the seventh lens is adhesively bonded to the eighth lens.

[0015] Preferably, the imaging lens satisfies: 0.5 < f7 / f < 0.6, 0.7 < f2 / f < 0.9, 1.2 < |f3| / f < 1.3, where f7 is the focal length of the seventh lens, f2 is the focal length of the second lens, |f3| is the absolute value of the focal length of the third lens, and f is the focal length of the imaging lens.

[0016] The present utility model has achieved the following technical effects compared with the prior art:

[0017] The present utility model provides an iris recognition lens, which includes an imaging lens. The imaging lens includes a first lens, a lens group one, an aperture stop, a lens group two, a second lens, a third lens, and a fourth lens arranged in sequence along the optical axis from the object side to the image side. The lens group two includes a fifth lens, a dual liquid lens, and a sixth lens. The first lens and the second lens have positive optical powers, the third lens has a negative optical power, the optical power of the fourth lens is zero, the ratio of the optical power of the lens group one to the optical power of the imaging lens is less than or equal to -0.0716, and the ratio of the optical power of the lens group two to the optical power of the imaging lens is greater than or equal to 0.315. The zoom function can be realized through the dual liquid lens, which can adapt to the recognition requirements at different distances, can be applied in a variable environment, enables the position of the recognition object not to be fixed, can realize contactless access, can improve the adaptability and imaging quality of the system; and the zoom lens can take into account parameters such as resolution and depth of field, and has a wide working range. By setting the optical powers of the first lens, the lens group one, the lens group two, the second lens, the third lens, and the fourth lens, the light passing amount of the imaging lens is ensured, and the relative illumination is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present utility model or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present utility model. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0019] Figure 1 Schematic diagram of the structure of the iris recognition lens provided in Embodiment 1:

[0020] Figure 2 Optical path diagram of the iris recognition lens provided in Embodiment 1;

[0021] Figure 3MTF curve of the iris recognition lens provided in Example 1 at a working object distance of 1600mm and light of 780nm-860nm;

[0022] Figure 4 This is a spot diagram of the iris recognition lens provided in Example 1 at a working object distance of 1600mm and a wavelength of 780nm-860nm;

[0023] Figure 5 Field curvature and distortion diagram of the iris recognition lens provided in Example 1 at a working object distance of 1600mm and 780nm-860nm light;

[0024] Figure 6 Relative illumination diagram of the iris recognition lens provided in Example 1 at a working object distance of 1600mm and 780nm-860nm light;

[0025] Figure 7 The defocus MTF curve of the iris recognition lens provided in Example 1 at a working object distance of 1600mm and a light range of 780nm-860nm;

[0026] Figure 8 Schematic diagram of the structure of the iris recognition lens provided in Example 2:

[0027] Figure 9 Light path diagram of the iris recognition lens provided in Example 2;

[0028] Figure 10 This is an MTF curve of the iris recognition lens provided in Example 2 at an object distance of 800mm and light of 780nm-860nm;

[0029] Figure 11 This is a spot diagram of the iris recognition lens provided in Example 2 at a working object distance of 800mm and a wavelength of 780nm-860nm;

[0030] Figure 12 Field curvature and distortion diagram of the iris recognition lens provided in Example 2 at a working object distance of 800mm and 780nm-860nm light;

[0031] Figure 13 Relative illumination diagram of the iris recognition lens provided in Example 2 at a working object distance of 800mm and 780nm-860nm light;

[0032] Figure 14 The defocus MTF curve of the iris recognition lens provided in Example 2 at an object distance of 800mm and a light range of 780nm-860nm;

[0033] Figure 15 Schematic diagram of the structure of the iris recognition lens provided in Example 3:

[0034] Figure 16 Light path diagram of the iris recognition lens provided in Example 3;

[0035] Figure 17 This is an MTF curve of the iris recognition lens provided in Example 3 at a working object distance of 200mm and 780nm-860nm light;

[0036] Figure 18 This is a spot diagram of the iris recognition lens provided in Example 3 at a working object distance of 200mm and a wavelength of 780nm-860nm;

[0037] Figure 19 Field curvature and distortion diagram of the iris recognition lens provided in Example 3 at a working object distance of 200mm and 780nm-860nm light;

[0038] Figure 20 Relative illumination diagram of the iris recognition lens provided in Example 3 at a working object distance of 200mm and 780nm-860nm light;

[0039] Figure 21 The defocus MTF curve of the iris recognition lens provided in Example 3 at a working object distance of 200mm and a light source of 780nm-860nm;

[0040] In the figure: 100, iris recognition lens; 1, first lens element; 101, first object-side surface; 102, first image-side surface; 2, aperture; 3, second lens element; 301, second object-side surface; 302, second image-side surface; 4, third lens element; 401, third object-side surface; 402, third image-side surface; 5, fourth lens element; 501, fourth object-side surface; 502, fourth image-side surface; 6, fifth lens element; 601, fifth object-side surface; 602, fifth image-side surface; 7, double liquid lens; 701, first liquid lens; 702, second liquid lens; 703, ninth object-side surface; 704, ninth image-side surface; 705, tenth image-side surface; 8, sixth lens element; 801, sixth object-side surface; 802, sixth image-side surface; 9, seventh lens element; 901, seventh object-side surface; 902, seventh image-side surface; 10, eighth lens element; 1001, eighth object-side surface; 1002, eighth image-side surface; 11, imaging surface. DETAILED DESCRIPTION

[0041] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0042] The purpose of the utility model is to provide an iris recognition lens to solve the problems existing in the prior art. The relative illumination is high, and the adaptability and imaging quality of the system can be improved. The zoom lens can take into account parameters such as resolution and depth of field and has a wide working range.

[0043] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0044] Glossary of terms:

[0045] A lens having positive optical power (or negative optical power) means that the paraxial optical power of the lens calculated using Gaussian optical theory is positive (or negative).

[0046] The object side (or image side) of a lens is defined as the specific area of ​​the lens surface where imaging light rays pass.

[0047] The concave or convex shape of a lens can be determined by the sign of the radius of curvature (R value). R values ​​are commonly found in optical design software such as ZEMAX. Regarding the object side, a positive R value indicates a convex surface; a negative R value indicates a concave surface. Conversely, regarding the image side, a positive R value indicates a concave surface; a negative R value indicates a convex surface.

[0048] Example 1

[0049] like Figures 1 to 7 As shown, this embodiment provides an iris recognition lens 100, comprising an imaging lens. The imaging lens comprises a first lens 1, a lens group 1, an aperture 2, a lens group 2, a second lens 3, a third lens 4, and a fourth lens 5, arranged in sequence along the optical axis from the object side to the image side. The lens group 2 comprises a fifth lens 6, a double liquid lens 7, and a sixth lens 8. The first lens 1 and the second lens 3 have positive focal powers, the third lens 4 has negative focal power, and the fourth lens 5 has zero focal power. The ratio of the focal power of the lens group 1 to the focal power of the imaging lens is less than or equal to -0.0716, and the ratio of the focal power of the lens group 2 to the focal power of the imaging lens is greater than or equal to 0.315. The double liquid lens 7 enables a zoom function, adapting to recognition requirements at different distances and enabling application in diverse environments. This eliminates the need to fix the position of the recognized object, enabling seamless access and improving the adaptability and imaging quality of the system. Furthermore, the zoom lens can balance parameters such as resolution and depth of field, and has a wide operating range. By setting the optical power of the first lens 1, lens group 1, lens group 2, second lens 3, third lens 4 and fourth lens 5, the light throughput of the imaging lens is guaranteed and the relative illumination is high.

[0050] In this embodiment, the first lens group includes a seventh lens 9 and an eighth lens 10 . The seventh lens 9 has positive refractive power, and the eighth lens 10 has negative refractive power.

[0051] In this embodiment, the imaging lens satisfies the following conditions: 2.0≤TTL / EFL≤2.1, 0.70≤BFL / EFL≤0.75; wherein TTL is the distance on the optical axis from the object side surface of the first lens element 1 to the imaging surface 11, EFL is the focal length of the imaging lens, and BFL is the distance on the optical axis from the image side surface of the fourth lens element 5 to the imaging surface 11, thereby shortening the total length of the imaging system.

[0052] In this embodiment, the refractive index of the seventh lens element 9 is greater than that of the eighth lens element 10, the refractive index of the eighth lens element 10 is greater than that of the third lens element 4, the refractive index of the third lens element 4 is greater than that of the second lens element 3, the refractive index of the fifth lens element 6, the sixth lens element 8, and the fourth lens element 5 are the same, the refractive index of the second lens element 3 is greater than that of the fifth lens element 6, and the refractive index of the fifth lens element 6 is greater than that of the first lens element 1, thereby better eliminating aberrations and chromatic aberrations.

[0053] In this embodiment, the double liquid lens 7 includes a first liquid lens 701 and a second liquid lens 702 arranged in sequence along the optical axis from the object side to the image side. The refractive index of the first liquid lens 701 is greater than or equal to 1.673, and the Abbe number of the first liquid lens 701 is less than or equal to 25. The refractive index of the second liquid lens 702 is greater than or equal to 1.472, and the Abbe number of the second liquid lens 702 is less than or equal to 60.

[0054] In this embodiment, the object side of the first lens 1 is the first object side 101, and the image side of the first lens 1 is the first image side 102. The first object side 101 is an even aspherical surface, and the first image side 102 is an even aspherical surface; the object side of the second lens 3 is the second object side 301, and the image side of the second lens 3 is the second image side 302. The second object side 301 is a convex surface and is an even aspherical surface, and the second image side 302 is a concave surface and is an even aspherical surface; the object side of the third lens 4 is the third object side 401, and the image side of the third lens 4 is the third image side 402. The third object side 401 is a concave surface, and the third image side 402 is a concave surface; the object side of the fourth lens 5 is the fourth object side 501, and the image side of the fourth lens 5 is the fourth image side 502. The fourth object side 501 is a flat surface, and the fourth image side 502 is a flat surface; the object side of the fifth lens 6 is the fifth object side 601, and the image side of the fifth lens 6 is the fifth image side 602. The fifth object side 601 is a flat surface, and the fifth image side 602 is a flat surface; the object side of the sixth lens 8 is the sixth object side 801, and the image side of the sixth lens 8 is the sixth image side 802. The sixth object side 801 is a flat surface, and the sixth image side 802 is a concave surface; the object side of the seventh lens 9 is the seventh object side 901, and the image side of the seventh lens 9 is the seventh image side 902. The seventh object side 901 is a convex surface, and the seventh image side 902 is a flat surface or a convex surface; the object side of the eighth lens 10 is the eighth object side 1001, and the image side of the eighth lens 10 is the eighth image side 1002. The eighth object side 1001 is a flat surface or a convex surface, and the eighth image side 1002 is a convex surface.

[0055] In this embodiment, the object side of the first liquid lens 701 is the ninth object side 703, and the image side of the first liquid lens 701 is the ninth image side 704. The ninth object side 703 is a flat surface, and the ninth image side 704 is a convex surface; the image side of the second liquid lens 702 is the tenth image side 705, and the tenth image side 705 is a flat surface. As a preferred embodiment, the ninth image side 704 is a flat surface.

[0056] In this embodiment, the fifth lens 6 and the first liquid lens 701 are adhesively bonded to each other, and the sixth lens 8 and the second liquid lens 702 are adhesively bonded to each other; the seventh lens 9 and the eighth lens 10 are adhesively bonded to each other; which is convenient for assembly and has a good yield.

[0057] In this embodiment, the imaging lens satisfies: 0.5 < f7 / f < 0.6, 0.7 < f / f < 0.9, 1.2 < |f3| / f < 1.3, where f7 is the focal length of the seventh lens 9, f2 is the focal length of the second lens 3, |f3| is the absolute value of the focal length of the third lens 4, and f is the focal length of the imaging lens, so that the focal length of the imaging lens is about 24 mm.

[0058] The specific optical parameters of the iris recognition lens 100 of this embodiment are shown in Table 1:

[0059] Table 1

[0060]

[0061] The iris recognition lens 100 of this embodiment has an effective focal length (EFL) of 20.1765 mm, a back focal length (BFL) of 4.4345 mm, a working F / # of 2.2135 mm, an entrance pupil diameter (ENPD) of 9.1772 mm, and a distance (TTL) from the object side of the first lens 1 to the imaging plane 11 on the optical axis of 38.6115 mm. The theoretical system resolution (NL) of this imaging lens is 550 lp / mm. When using an OV2744 CMOS sensor, the chip cutoff frequency (NR) is 166 lp / mm. This embodiment of the iris recognition lens 100 can meet the requirements of 2K resolution sensors, balancing resolution, depth of field, and magnification.

[0062] Figure 3 This is the MTF curve of the imaging lens at a working object distance of 1600mm and 780nm-860nm light. The MTF value is ≥0.4 in the full field of view up to the cutoff frequency, and the imaging quality is good.

[0063] Figure 4 This is the spot diagram of the imaging lens at a working object distance of 1600mm and 780nm-860nm light. The diffuse spot distribution is relatively uniform and concentrated under the full field of view. The RMS radius of the reference chief ray is smaller than the Airy disk radius, which can reach the diffraction limit.

[0064] Figure 5 The field curvature and distortion diagrams of the imaging lens at a working object distance of 1600mm and 780nm-860nm light are small, with distortion <2.5%.

[0065] Figure 6 This is the relative illumination of the imaging lens at a working object distance of 1600mm and 780nm-860nm light. The curve descends smoothly, the relative illumination is >0.9 at the maximum field of view, and the imaging image is bright.

[0066] Figure 7 This is the through-focus MTF curve of the imaging lens at a working object distance of 1600mm, 780nm-860nm light, a spatial frequency of 50lp / mm, and a defocus range of -0.1mm to 0.1mm. The graph reflects the field curvature correction, which is good.

[0067] Example 2

[0068] like Figures 8 to 14As shown, this embodiment provides an iris recognition lens 100, including an imaging lens. The imaging lens includes a first lens 1, a lens group 1, an aperture 2, a lens group 2, a second lens 3, a third lens 4, and a fourth lens 5, arranged in sequence along the optical axis from the object side to the image side. The lens group 2 includes a fifth lens 6, a double liquid lens 7, and a sixth lens 8. The first lens 1 and the second lens 3 have positive focal powers, the third lens 4 has negative focal power, and the fourth lens 5 has zero focal power. The ratio of the focal power of the lens group 1 to the focal power of the imaging lens is less than or equal to -0.0716, and the ratio of the focal power of the lens group 2 to the focal power of the imaging lens is greater than or equal to 0.315. The double liquid lens 7 enables a zoom function, can adapt to recognition requirements at different distances, and can be used in changing environments. The zoom lens has better performance in terms of resolution and depth of field, and has a wide range of applications. By setting the optical power of the first lens 1, lens group 1, lens group 2, second lens 3, third lens 4 and fourth lens 5, the light transmission of the imaging lens is guaranteed, making the imaging image of the imaging lens bright.

[0069] In this embodiment, the first lens group includes a seventh lens 9 and an eighth lens 10 . The seventh lens 9 has positive refractive power, and the eighth lens 10 has negative refractive power.

[0070] In this embodiment, the imaging lens satisfies the following conditions: 2.0≤TTL / EFL≤2.1, 0.70≤BFL / EFL≤0.75; wherein TTL is the distance on the optical axis from the object side surface of the first lens element 1 to the imaging surface 11, EFL is the focal length of the imaging lens, and BFL is the distance on the optical axis from the image side surface of the fourth lens element 5 to the imaging surface 11, thereby shortening the total length of the imaging system.

[0071] In this embodiment, the refractive index of the seventh lens element 9 is greater than that of the eighth lens element 10, the refractive index of the eighth lens element 10 is greater than that of the third lens element 4, the refractive index of the third lens element 4 is greater than that of the second lens element 3, the refractive index of the fifth lens element 6, the sixth lens element 8, and the fourth lens element 5 are the same, the refractive index of the second lens element 3 is greater than that of the fifth lens element 6, and the refractive index of the fifth lens element 6 is greater than that of the first lens element 1, thereby better eliminating aberrations and chromatic aberrations.

[0072] In this embodiment, the double liquid lens 7 includes a first liquid lens 701 and a second liquid lens 702 arranged in sequence along the optical axis from the object side to the image side. The refractive index of the first liquid lens 701 is greater than or equal to 1.673, and the Abbe number of the first liquid lens 701 is less than or equal to 25. The refractive index of the second liquid lens 702 is greater than or equal to 1.472, and the Abbe number of the second liquid lens 702 is less than or equal to 60.

[0073] In this embodiment, the object side of the first lens 1 is the first object side 101, and the image side of the first lens 1 is the first image side 102. The first object side 101 is an even aspherical surface, and the first image side 102 is an even aspherical surface; the object side of the second lens 3 is the second object side 301, and the image side of the second lens 3 is the second image side 302. The second object side 301 is a convex surface, and the second object side 301 is an even aspherical surface. The second image side 302 is a concave surface, and the second image side 302 is an even aspherical surface; the object side of the third lens 4 is the third object side 401, and the image side of the third lens 4 is the third image side 402. The third object side 401 is a concave surface, and the third image side 402 is a concave surface; the object side of the fourth lens 5 is the fourth object side 501, and the image side of the fourth lens 5 is the fourth image side 502. The fourth object side 501 is a plane, and the fourth image side 502 is a plane; the object side of the fifth lens 6 is the fifth object side 601, and the image side of the fifth lens 6 is the fifth image side 602. The fifth object side 601 is a plane, and the fifth image side 602 is a plane; the object side of the sixth lens 8 is the sixth object side 801, and the image side of the sixth lens 8 is the sixth image side 802. The sixth object side 801 is a plane, and the sixth image side 802 is a concave surface; the object side of the seventh lens 9 is the seventh object side 901, and the image side of the seventh lens 9 is the seventh image side 902. The seventh object side 901 is a convex surface, and the seventh image side 902 is a plane or a convex surface; the object side of the eighth lens 10 is the eighth object side 1001, and the image side of the eighth lens 10 is the eighth image side 1002. The eighth object side 1001 is a plane or a convex surface, and the eighth image side 1002 is a convex surface.

[0074] In this embodiment, the object side of the first liquid lens 701 is the ninth object side 703, and the image side of the first liquid lens 701 is the ninth image side 704. The ninth object side 703 is a plane, and the ninth image side 704 is a convex surface; the image side of the second liquid lens 702 is the tenth image side 705, and the tenth image side 705 is a plane. As a preferred embodiment, the ninth image side 704 is a plane.

[0075] In this embodiment, the fifth lens 6 and the first liquid lens 701 are adhesively bonded to each other, and the sixth lens 8 and the second liquid lens 702 are adhesively bonded to each other; the seventh lens 9 and the eighth lens 10 are adhesively bonded to each other; which is convenient for assembly and has a good yield.

[0076] In this embodiment, the imaging lens satisfies: 0.5 < f7 / f < 0.6, 0.7 < f2 / f < 0.9, 1.2 < |f3| / f < 1.3, where f7 is the focal length of the seventh lens 9, f2 is the focal length of the second lens 3, |f3| is the absolute value of the focal length of the third lens 4, and f is the focal length of the imaging lens, so that the focal length of the imaging lens is about 24 mm.

[0077] The specific optical parameters of the iris recognition lens 100 of this embodiment are shown in Table 2:

[0078] Table 2

[0079]

[0080] The iris recognition imaging lens of this embodiment has an effective focal length (EFL) of 19.8957 mm, a back focal length (BFL) of 4.1964 mm, a working F / # of 2.2426 mm, an entrance pupil diameter (ENPD) of 9.0435 mm, and a distance (TTL) from the object side of the first lens 1 to the imaging plane 11 on the optical axis of 38.6115 mm. This imaging lens system has a theoretical resolution (NL) of 543 lp / mm. When using an OV2744 CMOS sensor, the chip cutoff frequency (NR) is 166 lp / mm. This embodiment can meet the requirements of 2K resolution sensors, balancing resolution, depth of field, and magnification.

[0081] Figure 10 This is the MTF curve of the imaging lens at an object distance of 800mm and 780nm-860nm light. The MTF value is ≥0.4 in the full field of view up to the cutoff frequency, and the imaging quality is good.

[0082] Figure 11 This is the spot diagram of the imaging lens at an object distance of 800mm and 780nm-860nm light. The diffuse spot distribution is relatively uniform and concentrated in the full field of view. The RMS radius of the reference chief ray is smaller than the Airy disk radius, which can reach the diffraction limit.

[0083] Figure 12 The field curvature and distortion diagrams of the imaging lens at an object distance of 800mm and a light range of 780nm-860nm are shown. The distortion and field curvature are small, with a distortion of <2.5%.

[0084] Figure 13 This is the relative illumination of the imaging lens at an object distance of 800mm and light of 780nm-860nm. The curve descends smoothly, the relative illumination is >0.9 at the maximum field of view, and the imaging image is bright.

[0085] Figure 14 This is the through-focus MTF curve of the imaging lens at an object distance of 800mm, 780nm-860nm light, a spatial frequency of 50lp / mm, and a defocus range of -0.1mm to 0.1mm. The graph reflects the field curvature correction, which is good.

[0086] Example 3

[0087] like Figures 15-21As shown, this embodiment provides an iris recognition lens 100, including an imaging lens. The imaging lens includes a first lens 1, a lens group 1, an aperture 2, a lens group 2, a second lens 3, a third lens 4, and a fourth lens 5, arranged in sequence along the optical axis from the object side to the image side. The lens group 2 includes a fifth lens 6, a double liquid lens 7, and a sixth lens 8. The first lens 1 and the second lens 3 have positive focal powers, the third lens 4 has negative focal power, and the fourth lens 5 has zero focal power. The ratio of the focal power of the lens group 1 to the focal power of the imaging lens is less than or equal to -0.0716, and the ratio of the focal power of the lens group 2 to the focal power of the imaging lens is greater than or equal to 0.315. The double liquid lens 7 enables a zoom function, can adapt to recognition requirements at different distances, and can be used in changing environments. The zoom lens has better performance in terms of resolution and depth of field, and has a wide range of applications. By setting the optical power of the first lens 1, lens group 1, lens group 2, second lens 3, third lens 4 and fourth lens 5, the light transmission of the imaging lens is guaranteed, making the imaging image of the imaging lens bright.

[0088] In this embodiment, the first lens group includes a seventh lens 9 and an eighth lens 10 . The seventh lens 9 has positive refractive power, and the eighth lens 10 has negative refractive power.

[0089] In this embodiment, the imaging lens satisfies the following conditions: 2.0≤TTL / EFL≤2.1, 0.70≤BFL / EFL≤0.75; wherein TTL is the distance on the optical axis from the object side surface of the first lens element 1 to the imaging surface 11, EFL is the focal length of the imaging lens, and BFL is the distance on the optical axis from the image side surface of the fourth lens element 5 to the imaging surface 11, thereby shortening the total length of the imaging system.

[0090] In this embodiment, the refractive index of the seventh lens element 9 is greater than that of the eighth lens element 10, the refractive index of the eighth lens element 10 is greater than that of the third lens element 4, the refractive index of the third lens element 4 is greater than that of the second lens element 3, the refractive index of the fifth lens element 6, the sixth lens element 8, and the fourth lens element 5 are the same, the refractive index of the second lens element 3 is greater than that of the fifth lens element 6, and the refractive index of the fifth lens element 6 is greater than that of the first lens element 1. This can eliminate aberrations and chromatic aberrations to a certain extent.

[0091] In this embodiment, the double liquid lens 7 includes a first liquid lens 701 and a second liquid lens 702 arranged in sequence along the optical axis from the object side to the image side. The refractive index of the first liquid lens 701 is greater than or equal to 1.673, and the Abbe number of the first liquid lens 701 is less than or equal to 25. The refractive index of the second liquid lens 702 is greater than or equal to 1.472, and the Abbe number of the second liquid lens 702 is less than or equal to 60.

[0092] In this embodiment, the object side of the first lens 1 is the first object side 101, and the image side of the first lens 1 is the first image side 102. The first object side 101 is an even aspherical surface, and the first image side 102 is an even aspherical surface; the object side of the second lens 3 is the second object side 301, and the image side of the second lens 3 is the second image side 302. The second object side 301 is a convex surface, and the second object side 301 is an even aspherical surface. The second image side 302 is a concave surface, and the second image side 302 is an even aspherical surface; the object side of the third lens 4 is the third object side 401, and the image side of the third lens 4 is the third image side 402. The third object side 401 is a concave surface, and the third image side 402 is a concave surface; the object side of the fourth lens 5 is the fourth object side 501, and the image side of the fourth lens 5 is the fourth image side 502. The fourth object side 501 is a plane, and the fourth image side 502 is a plane; the object side of the fifth lens 6 is the fifth object side 601, and the image side of the fifth lens 6 is the fifth image side 602. The fifth object side 601 is a plane, and the fifth image side 602 is a plane; the object side of the sixth lens 8 is the sixth object side 801, and the image side of the sixth lens 8 is the sixth image side 802. The sixth object side 801 is a plane, and the sixth image side 802 is a concave surface; the object side of the seventh lens 9 is the seventh object side 901, and the image side of the seventh lens 9 is the seventh image side 902. The seventh object side 901 is a convex surface, and the seventh image side 902 is a plane or a convex surface; the object side of the eighth lens 10 is the eighth object side 1001, and the image side of the eighth lens 10 is the eighth image side 1002. The eighth object side 1001 is a plane or a convex surface, and the eighth image side 1002 is a convex surface.

[0093] In this embodiment, the object side of the first liquid lens 701 is the ninth object side 703, and the image side of the first liquid lens 701 is the ninth image side 704. The ninth object side 703 is a plane, and the ninth image side 704 is a convex surface; the image side of the second liquid lens 702 is the tenth image side 705, and the tenth image side 705 is a plane. As a preferred embodiment, the ninth image side 704 is a plane.

[0094] In this embodiment, the fifth lens 6 and the first liquid lens 701 are glued together, and the sixth lens 8 and the second liquid lens 702 are glued together; the seventh lens 9 and the eighth lens 10 are glued together; which is convenient for assembly and has a good yield.

[0095] In this embodiment, the imaging lens satisfies: 0.5 < f7 / f < 0.6, 0.7 < f2 / f < 0.9, 1.2 < |f3| / f < 1.3, where f7 is the focal length of the seventh lens 9, f2 is the focal length of the second lens 3, |f3| is the absolute value of the focal length of the third lens 4, and f is the focal length of the imaging lens, so that the focal length of the imaging lens is about 24 mm.

[0096] The specific optical parameters of the iris recognition lens 100 of this embodiment are shown in Table 3:

[0097] Table 3

[0098]

[0099] The iris recognition imaging lens of this embodiment has an effective focal length (EFL) of 18.4372 mm, a back focal length (BFL) of 2.9599 mm, a working F / # of 2.4084 mm, an entrance pupil diameter (ENPD) of 8.3805 mm, and a distance (TTL) from the object side of the first lens element 1 to the imaging plane 11 on the optical axis of 38.6115 mm. The theoretical system resolution (NL) of this imaging lens is 506 lp / mm. When using the OV2744 CMOS sensor, the chip cutoff frequency (NR) is 166 lp / mm. This embodiment can meet the requirements of 2K resolution sensors, balancing resolution, depth of field, and magnification.

[0100] Figure 17 This is the MTF curve of the imaging lens at a working object distance of 200mm and 780nm-860nm light. The MTF value is ≥0.3 in the full field of view up to the cutoff frequency, and the imaging quality is good.

[0101] Figure 18 This is the spot diagram of the imaging lens at a working object distance of 200mm and 780nm-860nm light. The diffuse spot distribution is relatively uniform and concentrated in the full field of view. The RMS radius of the reference chief ray is smaller than the Airy disk radius, which can reach the diffraction limit.

[0102] Figure 19 The field curvature and distortion diagrams of the imaging lens at a working object distance of 200mm and 780nm-860nm light are small, with distortion <4.5%.

[0103] Figure 20 This is the relative illumination of the imaging lens at a working object distance of 200mm and 780nm-860nm light. The curve descends smoothly, the relative illumination is >0.9 at the maximum field of view, and the imaging image is bright.

[0104] Figure 21 This is the through-focus MTF curve of the imaging lens at a working object distance of 200mm, 780nm-860nm light, a spatial frequency of 50lp / mm, and a defocus range of -0.1mm to 0.1mm. This graph reflects the field curvature correction, which is good.

[0105] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. An iris recognition lens, characterized by: The imaging lens includes an imaging lens, which includes a first lens, a lens group 1, an aperture, a lens group 2, a second lens, a third lens, and a fourth lens, which are arranged in sequence along the optical axis from the object side to the image side. The lens group 2 includes a fifth lens, a double liquid lens, and a sixth lens. The first lens and the second lens have positive focal power, the third lens has negative focal power, and the fourth lens has zero focal power. The ratio of the focal power of the lens group 1 to the focal power of the imaging lens is less than or equal to -0.0716, and the ratio of the focal power of the lens group 2 to the focal power of the imaging lens is greater than or equal to 0.

315.

2. The iris recognition lens according to claim 1, characterized in that: The lens group 1 includes a seventh lens and an eighth lens, the seventh lens has positive optical power, and the eighth lens has negative optical power.

3. The iris recognition lens according to claim 1, wherein: The imaging lens satisfies the following conditions: 2.0≤TTL / EFL≤2.1, 0.70≤BFL / EFL≤0.75; Among them, TTL is the distance from the object side surface of the first lens to the imaging surface on the optical axis, EFL is the focal length of the imaging lens, and BFL is the distance from the image side surface of the fourth lens to the imaging surface on the optical axis.

4. The iris recognition lens according to claim 2, wherein: The refractive index of the seventh lens is greater than that of the eighth lens, the refractive index of the eighth lens is greater than that of the third lens, the refractive index of the third lens is greater than that of the second lens, the refractive index of the fifth lens, the sixth lens, and the fourth lens are the same, the refractive index of the second lens is greater than that of the fifth lens, and the refractive index of the fifth lens is greater than that of the first lens.

5. The iris recognition lens according to claim 1, wherein: The double liquid lens includes a first liquid lens and a second liquid lens arranged in sequence along the optical axis from the object side to the image side, the refractive index of the first liquid lens is greater than or equal to 1.673, and the Abbe number of the first liquid lens is less than or equal to 25, the refractive index of the second liquid lens is greater than or equal to 1.472, and the Abbe number of the second liquid lens is less than or equal to 60.

6. The iris recognition lens according to claim 2, wherein: The object side of the first lens is the first object side, and the image side of the first lens is the first image side. The first object side is an even aspherical surface, and the first image side is an even aspherical surface; the object side of the second lens is the second object side, and the image side of the second lens is the second image side. The second object side is a convex surface and is an even aspherical surface, and the second image side is a concave surface and is an even aspherical surface; the object side of the third lens is the third object side, and the image side of the third lens is the third image side. The third object side is a concave surface, and the third image side is a concave surface; the object side of the fourth lens is the fourth object side, and the image side of the fourth lens is the fourth image side. The fourth object side is a flat surface, and the fourth image side is a flat surface; the object side of the fifth lens is the fifth object side, and the image side of the fifth lens is the fifth image side. The fifth object side is a flat surface, and the fifth image side is a flat surface; the object side of the sixth lens is the sixth object side, and the image side of the sixth lens is the sixth image side. The sixth object side is a flat surface, and the sixth image side is a concave surface; the object side of the seventh lens is the seventh object side, and the image side of the seventh lens is the seventh image side. The seventh object side is a convex surface, and the seventh image side is a flat surface or a convex surface; the object side of the eighth lens is the eighth object side, and the image side of the eighth lens is the eighth image side. The eighth object side is a flat surface or a convex surface, and the eighth image side is a convex surface.

7. The iris recognition lens according to claim 5, characterized in that: The object side of the first liquid lens is the ninth object side, and the image side of the first liquid lens is the ninth image side. The ninth object side is a flat surface, and the ninth image side is a convex surface; the image side of the second liquid lens is the tenth image side, and the tenth image side is a flat surface.

8. The iris recognition lens according to claim 5, characterized in that: The fifth lens and the first liquid lens are adhesively bonded to each other, and the sixth lens and the second liquid lens are adhesively bonded to each other.

9. The iris recognition lens according to claim 2, wherein: The seventh lens and the eighth lens are adhesively bonded to each other.

10. The iris recognition lens according to claim 1, characterized in that: The imaging lens satisfies: 0.5 < f7 / f < 0.6, 0.7 < f2 / f < 0.9, 1.2 < |f3| / f < 1.3, where f7 is the focal length of the seventh lens, f2 is the focal length of the second lens, |f3| is the absolute value of the focal length of the third lens, and f is the focal length of the imaging lens.

Images