An optical imaging lens

Abstract

The present invention relates to the technical field of lenses. The present invention discloses an optical imaging lens, which sequentially includes a first lens, a second lens, a diaphragm, a third lens, and a fourth lens along an optical axis from the object side to the image side; the first lens is a convex-concave lens with a positive refractive power; the second lens is a concave-concave lens with a negative refractive power; the third lens is a plano-convex lens with a positive refractive power; the fourth lens has a positive refractive power, and the object side surface is convex. The first lens to the fourth lens are all glass lenses. The ratio of the edge thickness to the center thickness of the lenses of the first lens, the third lens, and the fourth lens is between 0.4 and 0.8, and the ratio of the edge thickness to the center thickness of the lens of the second lens is between 2.2 and 2.9, and satisfies: 1.67 < nd1, 1.75 < nd3, and 1.7 < nd4. The present invention has the advantages of low cost, easy processing; high resolution and good imaging quality; large light transmission and high relative illumination; compact structure, good seismic resistance, and high stability; and miniaturization.

Description

Technical Field

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

[0002] With the continuous advancement of science and technology and the continuous development of society, optical imaging lenses have also developed rapidly in recent years and are widely used in various fields such as smart phones, tablets, video conferencing, vehicle monitoring, security monitoring, machine vision, intelligent transportation systems, etc. Therefore, the requirements for optical imaging lenses are getting higher and higher.

[0003] In the vehicle-mounted LiDAR system, the performance of the LiDAR receiving lens is critical and will affect the reliability of the entire system. However, the existing LiDAR receiving lenses have difficult lens manufacturing processes, high material and processing costs, low imaging quality, and it is difficult to ensure the quality of signal reception; the aperture is generally small, and the edge signal-to-noise ratio of the receiving chip is not high; the structure is unstable, the anti-seismic performance is weak, and it is easily affected by vehicle body vibration; the structure is too long, which is not conducive to vehicle body installation and use. It can no longer meet the increasing requirements of vehicle-mounted LiDAR systems and is in urgent need of improvement. Summary of the invention

[0004] The object of the present invention is to provide an optical imaging lens to solve the above-mentioned technical problems.

[0005] To achieve the above object, the technical solution adopted by the present invention is: an optical imaging lens, comprising a first lens, a second lens, an aperture, a third lens and a fourth lens in sequence along an optical axis from the object side to the image side; the first lens to the fourth lens each include an object-side surface facing the object side and allowing imaging light to pass through, and an image-side surface facing the image side and allowing imaging light to pass through;

[0006] The first lens has a positive refractive power, the object side surface of the first lens is a convex surface, and the image side surface of the first lens is a concave surface;

[0007] The second lens has a negative refractive power, the object side surface of the second lens is a concave surface, and the image side surface of the second lens is a concave surface;

[0008] The third lens has a positive refractive power, the object side surface of the third lens is a flat surface, and the image side surface of the third lens is a convex surface;

[0009] The fourth lens element has a positive refractive power, and the object side surface of the fourth lens element is a convex surface;

[0010] The first lens to the fourth lens are all glass lenses. The ratios of the edge thickness to the center thickness of the lenses of the first lens, the third lens, and the fourth lens are all between 0.4 and 0.8, and the ratio of the edge thickness to the center thickness of the second lens is between 2.2 and 2.9, and satisfy: 1.67 < nd1, 1.75 < nd3, and 1.7 < nd4, where nd1 is the refractive index of the first lens, nd3 is the refractive index of the third lens, and nd4 is the refractive index of the fourth lens;

[0011] The lenses with refractive power in this optical imaging lens are only the above-mentioned first lens to the fourth lens.

[0012] Furthermore, this optical imaging lens further satisfies: 1 < ∣f1 / f∣ < 3, 0 < ∣f2 / f∣ < 3, 1 < ∣f3 / f∣ < 3, and 1 < ∣f4 / f∣ < 3, where f1 is the focal length of the first lens, f2 is the focal length of the second lens, f3 is the focal length of the third lens, f4 is the focal length of the fourth lens, and f is the focal length of this optical imaging lens.

[0013] Even further, this optical imaging lens further satisfies: 10mm < f1 < 22mm, -8mm < f2 < -5mm, 7mm < f3 < 11mm, 10mm < f4 < 15mm, where f1 is the focal length of the first lens, f2 is the focal length of the second lens, f3 is the focal length of the third lens, and f4 is the focal length of the fourth lens.

[0014] Furthermore, antireflection films with a wavelength of 900nm are coated on both the object side and the image side of the first lens to the fourth lens.

[0015] Furthermore, this optical imaging lens further satisfies: 7mm < R11 < 15mm, 30mm < R12 < 62mm, -8mm < R21 < -5mm, 13mm < R22 < 17mm, -10mm < R32 < -7mm, 7mm < R41 < 10mm, where R11, R21, and R41 are the curvature radii of the object sides of the first lens, the second lens, and the fourth lens, and R12, R22, and R32 are the curvature radii of the image sides of the first lens, the second lens, and the third lens, respectively.

[0016] Furthermore, this optical imaging lens further satisfies: 1.67 < nd1 < 1.9, 20 < vd1 < 56; 1.5 < nd2 < 1.76, 35 < vd2 < 57, 1.75 < nd3 < 2.0, 20 < vd3 < 48, 1.7 < nd4 < 1.93, 20 < vd4 < 40, where nd1, nd2, nd3, and nd4 are the refractive indices of the first lens to the fourth lens respectively, and vd1, vd2, vd3, and vd4 are the dispersion coefficients of the first lens to the fourth lens respectively.

[0017] Furthermore, the optical imaging lens further satisfies: 0.6<(D11 / R11)<1.2, 0.1<(D12 / R12)<0.7, 0.7<|(D21 / R21)|<1.1, 0.1<(D22 / R22)<0.7, 1<|(D32 / R32)|<1.3, 0.8<(D41 / R41)≤1.2, 0.01<|(D42 / R42)|≤0.5, wherein D11, D12, D21, D22, D31, D32, D41 and D42 are first The clear aperture of the object side surface of the lens, the image side surface of the first lens, the object side surface of the second lens, the image side surface of the second lens, the object side surface of the third lens, the image side surface of the third lens, the object side surface of the fourth lens and the image side surface of the fourth lens, and R11, R12, R21, R22, R31, R32, R41 and R42 are the curvature radii of the object side surface of the first lens, the image side surface of the first lens, the object side surface of the second lens, the image side surface of the second lens, the object side surface of the third lens, the image side surface of the third lens, the object side surface of the fourth lens and the image side surface of the fourth lens respectively.

[0018] Beneficial technical effects of the present invention:

[0019] The present invention adopts four lenses and designs each lens accordingly, so that the material and processing costs are low and the industrial mass production is feasible; the demand for high resolution is met and the signal reception quality is guaranteed; large light transmission and the edge signal-to-noise ratio are greatly improved, so that the light spot uniformity is high and the noise interference is low; the relative illumination is high and the overall brightness uniformity of the picture is high; the structure is compact, the shock resistance is good, the stability is high, and the miniaturization is advantageous. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 This is a schematic diagram of the structure of Embodiment 1 of the present invention;

[0022] Figure 2 This is the infrared 0.840μm MTF diagram of the first embodiment of the present invention;

[0023] Figure 3 This is a defocus curve diagram of infrared 900nm at 10lp / mm according to the first embodiment of the present invention;

[0024] Figure 4 Graphs of field curvature and distortion according to Embodiment 1 of the present invention;

[0025] Figure 5 This is a relative illumination curve of infrared 900nm of Example 1 of the present invention;

[0026] Figure 6 is a point diagram of the first embodiment of the present invention;

[0027] Figure 7 This is a schematic diagram of the structure of Embodiment 2 of the present invention;

[0028] Figure 8 This is the infrared 0.840μm MTF diagram of the second embodiment of the present invention;

[0029] Fig. 9 This is a defocus curve diagram of infrared 900nm at 10lp / mm according to the second embodiment of the present invention;

[0030] Fig.10 Graphs showing field curvature and distortion according to Embodiment 2 of the present invention;

[0031] Fig.11 This is a relative illumination curve of infrared 900nm of the second embodiment of the present invention;

[0032] Fig.12 is a point diagram of the second embodiment of the present invention;

[0033] Fig.13 This is a schematic diagram of the structure of Embodiment 3 of the present invention;

[0034] Fig.14 This is the infrared 0.840μm MTF diagram of the third embodiment of the present invention;

[0035] Fig.15 This is a defocus curve diagram of infrared 900nm at 10lp / mm according to the third embodiment of the present invention;

[0036] Fig.16 Graphs of field curvature and distortion according to Embodiment 3 of the present invention;

[0037] Fig.17 This is a relative illumination curve diagram of infrared 900nm of embodiment 3 of the present invention;

[0038] Fig.18 This is a point diagram of Embodiment 3 of the present invention;

[0039] Fig.19 This is a schematic diagram of the structure of Embodiment 4 of the present invention;

[0040] Fig. 20 This is the infrared 0.840μm MTF diagram of the fourth embodiment of the present invention;

[0041] Fig.21 This is a defocus curve diagram of infrared 900nm at 10lp / mm according to the fourth embodiment of the present invention;

[0042] Fig. 22 Graphs of field curvature and distortion according to Embodiment 4 of the present invention;

[0043] Fig.23 This is a relative illumination curve of infrared 900nm of the fourth embodiment of the present invention;

[0044] Fig.24 This is a point diagram of the fourth embodiment of the present invention;

[0045] Fig.25 This is a schematic diagram of the structure of Embodiment 5 of the present invention;

[0046] Fig.26 This is the infrared 0.840μm MTF diagram of Example 5 of the present invention;

[0047] Fig. 27 This is a defocus curve diagram of infrared 900nm at 10lp / mm according to Embodiment 5 of the present invention;

[0048] Fig.28 Graphs of field curvature and distortion according to Embodiment 5 of the present invention;

[0049] Fig.29 This is a relative illumination curve of infrared 900nm of Example 5 of the present invention;

[0050] Fig.30 This is a point diagram of Embodiment 5 of the present invention; DETAILED DESCRIPTION

[0051] To further illustrate the various embodiments, the present invention provides drawings. These drawings are part of the disclosure of the present invention, which are mainly used to illustrate the embodiments and can be used in conjunction with the relevant descriptions in the specification to explain the operating principles of the embodiments. With reference to these contents, a person of ordinary skill in the art should be able to understand other possible implementations and advantages of the present invention. The components in the figures are not drawn to scale, and similar component symbols are generally used to represent similar components.

[0052] The present invention will now be further described with reference to the accompanying drawings and specific implementation methods.

[0053] When it is said that "a lens has a positive refractive power (or negative refractive power)", it means that the paraxial refractive power of the lens calculated by Gaussian optical theory is positive (or negative). The so-called "object side (or image side) of the lens" is defined as a specific range through which the imaging light passes through the lens surface. The concavity and convexity of the lens surface can be judged by the judgment method of those with ordinary knowledge in this field, that is, by the positive and negative signs of the radius of curvature (abbreviated as R value) to judge the concavity and convexity of the lens surface. The R value is commonly used in optical design software, such as Zemax or CodeV. The R value is also commonly found in the lens data sheet of optical design software. Taking the object side as an example, when the R value is positive, it is determined that the object side is a convex surface; when the R value is negative, it is determined that the object side is a concave surface. Conversely, taking the image side as an example, when the R value is positive, it is determined that the image side is a concave surface; when the R value is negative, it is determined that the image side is a convex surface.

[0054] The present invention provides an optical imaging lens, which sequentially includes a first lens, a second lens, a diaphragm, a third lens, and a fourth lens along an optical axis from the object side to the image side; the first lens to the fourth lens each include an object side facing the object side and through which the imaging light passes and an image side facing the image side and through which the imaging light passes.

[0055] The first lens has a positive refractive power, the object side of the first lens is a convex surface, and the image side of the first lens is a concave surface.

[0056] The second lens has a negative refractive power, the object side of the second lens is a concave surface, and the image side of the second lens is a concave surface.

[0057] The third lens has a positive refractive power, the object side of the third lens is a flat surface, and the image side of the third lens is a convex surface.

[0058] The fourth lens has a positive refractive power, and the object side of the fourth lens is a convex surface.

[0059] The first lens to the fourth lens are all glass lenses, with low material and processing costs, having the feasibility of industrial mass production and good stability.

[0060] The ratio of the edge thickness to the center thickness of the lenses of the first lens, the third lens, and the fourth lens is all between 0.4 and 0.8, and the ratio of the edge thickness to the center thickness of the second lens is between 2.2 and 2.9, making the overall structure of the optical imaging lens more compact, with good stability, and still able to maintain good optical performance in a vibrating environment.

[0061] And it satisfies: 1.67 < nd1, 1.75 < nd3 and 1.7 < nd4, where nd1 is the refractive index of the first lens, nd3 is the refractive index of the third lens, and nd4 is the refractive index of the fourth lens, to achieve large light transmission.

[0062] The optical imaging lens with refractive power has only the above-mentioned first lens to fourth lens. The present invention adopts four lenses, and through corresponding designs for each lens, it has the advantages of low cost and feasibility of industrial mass production; it meets the requirements of high resolution and ensures signal reception quality; it has a large aperture, a significant improvement in the signal-to-noise ratio of the edge signal, resulting in a high spot uniformity and low noise interference; it has a relatively high relative illumination and a high overall brightness uniformity of the picture; it has a compact structure, good seismic resistance and high stability; and it has the advantage of miniaturization.

[0063] Preferably, the optical imaging lens further satisfies: 1 < ∣f1 / f∣ < 3, 0 < ∣f2 / f∣ < 3, 1 < ∣f3 / f∣ < 3 and 1 < ∣f4 / f∣ < 3, where f1 is the focal length of the first lens, f2 is the focal length of the second lens, f3 is the focal length of the third lens, f4 is the focal length of the fourth lens, and f is the focal length of the optical imaging lens.

[0064] More preferably, the optical imaging lens further satisfies: 10 mm < f1 < 22 mm, -8 mm < f2 < -5 mm, 7 mm < f3 < 11 mm, 10 mm < f4 < 15 mm, where f1 is the focal length of the first lens, f2 is the focal length of the second lens, f3 is the focal length of the third lens, and f4 is the focal length of the fourth lens.

[0065] Preferably, the object side and the image side of the first lens to the fourth lens are both coated with an antireflection film with a wavelength of 900 nm to increase the transmittance of the overall signal light.

[0066] Preferably, the optical imaging lens further satisfies: 7 mm < R11 < 15 mm, 30 mm < R12 < 62 mm, -8 mm < R21 < -5 mm, 13 mm < R22 < 17 mm, -10 mm < R32 < -7 mm, 7 mm < R41 < 10 mm, where R11, R21 and R41 are the curvature radii of the object sides of the first lens, the second lens and the fourth lens, and R12, R22 and R32 are the curvature radii of the image sides of the first lens, the second lens and the third lens respectively, which are easy to process and reduce the detection difficulty.

[0067] Preferably, the optical imaging lens further satisfies: 1.67 < nd1 < 1.9, 20 < vd1 < 56; 1.5 < nd2 < 1.76, 35 < vd2 < 57, 1.75 < nd3 < 2.0, 20 < vd3 < 48, 1.7 < nd4 < 1.93, 20 < vd4 < 40, where nd1, nd2, nd3 and nd4 are the refractive indices of the first lens to the fourth lens respectively, and vd1, vd2, vd3 and vd4 are the dispersion coefficients of the first lens to the fourth lens respectively, further balancing the chromatic aberration.

[0068] Preferably, the optical imaging lens further satisfies: 0.6<(D11 / R11)<1.2, 0.1<(D12 / R12)<0.7, 0.7<|(D21 / R21)|<1.1, 0.1<(D22 / R22)<0.7, 1<|(D32 / R32)|<1.3, 0.8<(D41 / R41)≤1.2, 0.01<|(D42 / R42)|≤0.5, wherein D11, D12, D21, D22, D31, D32, D41 and D42 are the object side surfaces of the first lens respectively. , the image side surface of the first lens, the object side surface of the second lens, the image side surface of the second lens, the object side surface of the third lens, the image side surface of the third lens, the object side surface of the fourth lens and the image side surface of the fourth lens, R11, R12, R21, R22, R31, R32, R41 and R42 are the curvature radii of the object side surface of the first lens, the image side surface of the first lens, the object side surface of the second lens, the image side surface of the second lens, the object side surface of the third lens, the image side surface of the third lens, the object side surface of the fourth lens and the image side surface of the fourth lens respectively, so that the lenses are easy to process and shape.

[0069] The optical imaging lens of the present invention will be described in detail below with reference to specific embodiments.

[0070] Embodiment 1

[0071] like Figure 1 As shown, an optical imaging lens comprises a first lens 1, a second lens 2, an aperture 5, a third lens 3, a fourth lens 4 and an imaging surface 6 in sequence from an object side A1 to an image side A2 along an optical axis I; the first lens 1 to the fourth lens 4 each comprise an object-side surface facing the object side A1 and allowing imaging light to pass through, and an image-side surface facing the image side A2 and allowing imaging light to pass through.

[0072] The first lens 1 has a positive refractive power, an object-side surface 11 of the first lens 1 is a convex surface, and an image-side surface 12 of the first lens 1 is a concave surface.

[0073] The second lens element 2 has a negative refractive power, an object-side surface 21 of the second lens element 2 is a concave surface, and an image-side surface 22 of the second lens element 2 is a concave surface.

[0074] The third lens element 3 has a positive refractive power, an object-side surface 31 of the third lens element 3 is a flat surface, and an image-side surface 32 of the third lens element 3 is a convex surface.

[0075] The fourth lens element 4 has a positive refractive power. The object-side surface 41 of the fourth lens element 4 is a convex surface, and the image-side surface 42 of the fourth lens element 4 is a concave surface.

[0076] In this specific embodiment, the first lens 1 to the fourth lens 4 are all glass spherical lenses.

[0077] In this specific embodiment, the object-side surfaces 11 , 21 , 31 , 41 and the image-side surfaces 12 , 22 , 32 , 42 are all coated with an anti-reflection film with a wavelength of 900 nm.

[0078] The detailed optical data of this specific embodiment are shown in Table 1-1.

[0079] Table 1-1 Detailed optical data of Example 1

[0080]

[0081] Please refer to Table 6 for the numerical values ​​of the relevant conditional expressions of this specific embodiment.

[0082] The MTF curve diagram of this specific embodiment is shown in Figure 2 , focal shift curve diagram, see Figure 3 It can be seen that the MTF value of the spatial frequency 20lp / mm is greater than 0.3, which meets the requirements of picture clarity and has good uniformity; please refer to the field curvature and distortion diagram Figure 4 (A) and (B) show that the field curvature and distortion are small, and the image quality is good. For relative illumination, please refer to Figure 5 , it can be seen that the entire field of view is greater than 98%, and the overall brightness uniformity of the picture is high; please refer to the spot diagram Figure 6 , it can be seen that the aberration is small and the imaging quality is good.

[0083] In this specific embodiment, the focal length of the optical imaging lens is f=7.6 mm; the aperture value FNO=1.2; the field of view angle FOV=25°; the image plane size is 1 / 2.8 inch; and the distance TTL from the object side surface 11 of the first lens 1 to the imaging plane 6 on the optical axis I is 15.13 mm.

[0084] Embodiment 2

[0085] like Figure 7 As shown, the surface profile and refractive power of each lens in this embodiment are the same as those in the first embodiment, and only the optical parameters such as the curvature radius of each lens surface and the lens thickness are different.

[0086] The detailed optical data of this specific embodiment are shown in Table 2-1.

[0087] Table 2-1 Detailed optical data of Example 2

[0088]

[0089] Please refer to Table 6 for the numerical values ​​of the relevant conditional expressions of this specific embodiment.

[0090] The MTF curve diagram of this specific embodiment is shown in Figure 8 , see the focal shift curve for details Fig. 9It can be seen that the MTF value of the spatial frequency 20lp / mm is greater than 0.6, which meets the requirements of picture clarity and has good uniformity; please refer to the field curvature and distortion diagram Fig.10 (A) and (B) show that the field curvature and distortion are small, and the image quality is good. For relative illumination, please refer to Fig.11 , it can be seen that the entire field of view is greater than 98%, and the overall brightness uniformity of the picture is high; please refer to the spot diagram Fig.12 , it can be seen that the aberration is small and the imaging quality is good.

[0091] In this specific embodiment, the focal length of the optical imaging lens is f=7.6 mm; the aperture value FNO=1.2; the field of view angle FOV=25°; the image plane size is 1 / 2.8 inch; and the distance TTL from the object side surface 11 of the first lens 1 to the imaging plane 6 on the optical axis I is 14.29 mm.

[0092] Embodiment 3

[0093] like Fig.13 As shown, the surface profile and refractive power of each lens in this embodiment are the same as those in the first embodiment, and only the optical parameters such as the curvature radius of each lens surface and the lens thickness are different.

[0094] The detailed optical data of this specific embodiment are shown in Table 3-1.

[0095] Table 3-1 Detailed optical data of Example 3

[0096]

[0097]

[0098] Please refer to Table 6 for the numerical values ​​of the relevant conditional expressions of this specific embodiment.

[0099] The MTF curve diagram of this specific embodiment is shown in Fig.14 , see the focal shift curve for details Fig.15 It can be seen that the MTF value of the spatial frequency 20lp / mm is greater than 0.5, which meets the requirements of picture clarity and has good uniformity; please refer to the field curvature and distortion diagram Fig.16 (A) and (B) show that the field curvature and distortion are small, and the image quality is good. For relative illumination, please refer to Fig.17 , it can be seen that the entire field of view is greater than 98%, and the overall brightness uniformity of the picture is high; please refer to the spot diagram Fig.18 , it can be seen that the aberration is small and the imaging quality is good.

[0100] In this specific embodiment, the focal length of the optical imaging lens is f=7.6 mm; the aperture value FNO=1.2; the field of view angle FOV=25°; the image plane size is 1 / 2.8 inch; and the distance TTL from the object side surface 11 of the first lens 1 to the imaging plane 6 on the optical axis I is 18.30 mm.

[0101] Embodiment 4

[0102] like Fig.19 As shown, the surface profile and refractive power of each lens in this embodiment are the same as those in the first embodiment, and only the optical parameters such as the curvature radius of each lens surface and the lens thickness are different.

[0103] The detailed optical data of this specific embodiment are shown in Table 4-1.

[0104] Table 4-1 Detailed optical data of Example 4

[0105]

[0106]

[0107] Please refer to Table 6 for the numerical values ​​of the relevant conditional expressions of this specific embodiment.

[0108] The MTF curve diagram of this specific embodiment is shown in Fig. 20 , see the focal shift curve for details Fig.21 It can be seen that the MTF value of the spatial frequency 20lp / mm is greater than 0.5, which meets the requirements of picture clarity and has good uniformity; please refer to the field curvature and distortion diagram Fig. 22 (A) and (B) show that the field curvature and distortion are small, and the image quality is good. For relative illumination, please refer to Fig.23 , it can be seen that the entire field of view is greater than 98%, and the overall brightness uniformity of the picture is high; please refer to the spot diagram Fig.24 , it can be seen that the aberration is small and the imaging quality is good.

[0109] In this specific embodiment, the focal length of the optical imaging lens is f=7.6 mm; the aperture value FNO=1.2; the field of view angle FOV=25°; the image plane size is 1 / 2.8 inch; and the distance TTL from the object side surface 11 of the first lens 1 to the imaging plane 6 on the optical axis I is 19.53 mm.

[0110] Embodiment 5

[0111] like Fig.25 As shown, the surface concave-convex and refractive power of each lens in this embodiment and the first embodiment are substantially the same, and only the image side surface 42 of the fourth lens 4 is a convex surface. In addition, the optical parameters such as the curvature radius of each lens surface and the lens thickness are also different.

[0112] The detailed optical data of this specific embodiment are shown in Table 5-1.

[0113] Table 5-1 Detailed optical data of Example 5

[0114]

[0115] Please refer to Table 6 for the numerical values ​​of the relevant conditional expressions of this specific embodiment.

[0116] The MTF curve diagram of this specific embodiment is shown in Fig.26 , see the focal shift curve for details Fig. 27 It can be seen that the MTF value of the spatial frequency 20lp / mm is greater than 0.5, which meets the requirements of picture clarity and has good uniformity; please refer to the field curvature and distortion diagram Fig.28 (A) and (B) show that the field curvature and distortion are small, and the image quality is good. For relative illumination, please refer to Fig.29 , it can be seen that the entire field of view is greater than 98%, and the overall brightness uniformity of the picture is high; please refer to the spot diagram Fig.30 , it can be seen that the aberration is small and the imaging quality is good.

[0117] In this specific embodiment, the focal length of the optical imaging lens is f=7.6 mm; the aperture value FNO=1.2; the field of view angle FOV=25°; the image plane size is 1 / 2.8 inch; and the distance TTL from the object side surface 11 of the first lens 1 to the imaging plane 6 on the optical axis I is 18.46 mm.

[0118] Table 6 Numerical values ​​of relevant important parameters of five embodiments of the present invention

[0119]

[0120]

[0121] Among them, T 1比 is the ratio of the edge thickness of the first lens 1 to the center thickness of the lens; T 2比 is the ratio of the edge thickness of the second lens 2 to the center thickness of the lens; T 3比 is the ratio of the edge thickness of the third lens 3 to the center thickness of the lens; T 4比 is the ratio of the edge thickness of the fourth lens 4 to the center thickness of the lens.

[0122] Although the present invention has been specifically shown and described in conjunction with the preferred embodiments, it should be understood by those skilled in the art that various changes may be made to the present invention in form and details without departing from the spirit and scope of the present invention as defined by the appended claims, all of which are within the scope of protection of the present invention.

Claims

1. An optical imaging lens, characterized in that: It sequentially includes a first lens, a second lens, a diaphragm, a third lens, and a fourth lens along an optical axis from the object side to the image side; each of the first lens to the fourth lens includes an object side facing the object side and allowing imaging light to pass through and an image side facing the image side and allowing imaging light to pass through. The first lens has a positive refractive power, the object side of the first lens is convex, and the image side of the first lens is concave. The second lens has a negative refractive power, the object side of the second lens is concave, and the image side of the second lens is concave. The third lens has a positive refractive power, the object side of the third lens is flat, and the image side of the third lens is convex. The fourth lens has a positive refractive power, and the object side of the fourth lens is convex. The first lens to the fourth lens are all glass lenses. The ratio of the edge thickness to the center thickness of the lenses of the first lens, the third lens, and the fourth lens is between 0.4 and 0.

8. The ratio of the edge thickness to the center thickness of the second lens is between 2.2 and 2.9, and it satisfies: 1.67 < nd1, 1.75 < nd3, 1.7 < nd4, 1 < |f1 / f| < 3, 0 < |f2 / f| < 3, 1 < |f3 / f| < 3, and 1 < |f4 / f| < 3, 10 mm < f1 < 22 mm, -8 mm < f2 < -5 mm, 7 mm < f3 < 11 mm, and 10 mm < f4 < 15 mm, 7 mm < R11 < 15 mm, 30 mm < R12 < 62 mm, -8 mm < R21 < -5 mm, 13 mm < R22 < 17 mm, -10 mm < R32 < -7 mm, 7 mm < R41 < 10 mm, where nd1 is the refractive index of the first lens, nd3 is the refractive index of the third lens, nd4 is the refractive index of the fourth lens, f1 is the focal length of the first lens, f2 is the focal length of the second lens, f3 is the focal length of the third lens, f4 is the focal length of the fourth lens, f is the focal length of this optical imaging lens, R11, R21, and R41 are the curvature radii of the object sides of the first lens, the second lens, and the fourth lens, and R12, R22, and R32 are the curvature radii of the image sides of the first lens, the second lens, and the third lens respectively. The only lenses with refractive power in this optical imaging lens are the above-mentioned first lens to the fourth lens.

2. The optical imaging lens according to claim 1, wherein: The object sides and image sides of the first lens to the fourth lens are all coated with an anti-reflection film with a wavelength of 900 nm.

3. The optical imaging lens according to claim 1, wherein: This optical imaging lens further satisfies: 1.67 < nd1 < 1.9, 20 < vd1 < 56; 1.5 < nd2 < 1.76, 35 < vd2 < 57, 1.75 < nd3 < 2.0, 20 < vd3 < 48, 1.7 < nd4 < 1.93, 20 < vd4 < 40, where nd2 is the refractive index of the second lens, and vd1, vd2, vd3, and vd4 are the dispersion coefficients of the first lens to the fourth lens respectively.

4. The optical imaging lens according to claim 1, wherein: The optical imaging lens further satisfies the following requirements: 0.6<(D11 / R11)<1.2, 0.1<(D12 / R12)<0.7, 0.7<|(D21 / R21)|<1.1, 0.1<(D22 / R22)<0.7, 1<|(D32 / R32)|<1.3, 0.8<(D41 / R41)≤1.2, 0.01<|(D42 / R42)|≤0.5, wherein D11, D12, D21, D22, D31, D32, D41 and D42 are the first lens elements, respectively. The clear aperture of the object side surface of the first lens, the image side surface of the second lens, the image side surface of the second lens, the object side surface of the third lens, the image side surface of the third lens, the object side surface of the fourth lens and the image side surface of the fourth lens, R11, R12, R21, R22, R31, R32, R41 and R42 are the curvature radii of the object side surface of the first lens, the image side surface of the first lens, the object side surface of the second lens, the image side surface of the second lens, the object side surface of the third lens, the image side surface of the third lens, the object side surface of the fourth lens and the image side surface of the fourth lens respectively.

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