An imaging lens for a drone

Abstract

The present invention discloses an imaging lens for a drone, which includes a first lens to a ninth lens. The first lens to the ninth lens each include an object side and an image side; the first lens has a positive refractive power; the second lens has a negative refractive power; the third lens has a negative refractive power; the fourth lens has a positive refractive power; the fifth lens has a negative refractive power; the sixth lens has a positive refractive power; the seventh lens has a positive refractive power; the eighth lens has a positive refractive power; the ninth lens has a negative refractive power; the first lens, the third lens, the fourth lens, the fifth lens, and the seventh lens are glass spherical lenses, and the second lens, the sixth lens, the eighth lens, and the ninth lens are glass aspherical lenses; there are only the above nine lenses with refractive power in this optical imaging lens. The present invention uses nine lenses along the object side to the image side direction, and through corresponding designs for each lens, the lateral chromatic aberration and axial chromatic aberration of the lens are small, the color reducibility is good, and the blue-violet edge phenomenon is eliminated.

Description

Technical Field

[0001] The present invention relates to the technical field of lenses, and particularly to an imaging lens for an unmanned aerial vehicle (UAV). Background Art

[0002] With the continuous progress of science and technology and the continuous development of society, in recent years, optical imaging lenses have also developed rapidly and have been widely used in various fields such as smart phones, vehicle-mounted monitoring, security monitoring, and unmanned aerial vehicles. At present, the camera lenses mounted on professional UAVs play an important role in aerial photography, detection, surveillance, communication, electronic interference and other occasions, and have become an important tool in civil and military industries. However, the lenses mounted on existing UAVs have at least the following deficiencies: (1) The imaging lenses of existing professional UAVs are prone to purple fringing; (2) The imaging lenses of existing professional UAVs generally have ghost images in a strong light source environment, which affects the imaging effect; (3) The imaging lenses of existing professional UAVs have a large temperature drift. When the temperature disturbance is too large, the imaging quality is affected; (4) The imaging lenses of existing professional UAVs have a long structure and a large weight. Summary of the Invention

[0003] The purpose of the present invention is to provide an imaging lens for an unmanned aerial vehicle to at least solve one of the above problems.

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

[0005] An imaging lens for an unmanned aerial vehicle sequentially includes a first lens to a ninth lens along an optical axis from the object side to the image side. The first lens to the ninth lens each include 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;

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

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

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

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

[0010] The fifth lens has a negative refractive power. The object side of the fifth lens is a concave surface, and the image side is a convex surface;

[0011] The sixth lens has a positive refractive power. The object side of the sixth lens is a convex surface, and the image side is a convex surface;

[0012] The seventh lens has a positive refractive power, the object side surface of the seventh lens is convex, and the image side surface is concave;

[0013] The eighth lens has a positive refractive power, the object side surface of the eighth lens is concave, and the image side surface is convex;

[0014] The ninth lens has a negative refractive power, the object side surface of the ninth lens is concave, and the image side surface is convex;

[0015] The first lens, the third lens, the fourth lens, the fifth lens, and the seventh lens are glass spherical lenses, and the second lens, the sixth lens, the eighth lens, and the ninth lens are glass aspherical lenses;

[0016] There are only the above nine lenses with refractive power in this optical imaging lens.

[0017] Preferably, the image side surface of the fourth lens and the object side surface of the fifth lens are adhesively bonded to each other and satisfy Vd4 - Vd5 > 20, where Vd4 is the dispersion coefficient of the fourth lens and Vd5 is the dispersion coefficient of the fifth lens.

[0018] Preferably, the refractive index temperature coefficient dn / dt of the sixth lens is negative.

[0019] Preferably, this lens satisfies the following conditional formula: TTL ≤ 31 mm, where TTL is the distance from the object side surface of the first lens to the imaging surface on the optical axis.

[0020] Preferably, this lens further includes a diaphragm, and the diaphragm is disposed between the fifth lens and the sixth lens.

[0021] Preferably, this lens satisfies the following conditional formula: |R9| > 52 mm, R11 > 13 mm, R14 > 11.5 mm, |R18| > 45 mm, and antireflection films are coated on the lens surfaces of the first lens to the ninth lens, where R9 is the radius of curvature of the image side surface of the fifth lens, R11 is the radius of curvature of the object side surface of the sixth lens, R14 is the radius of curvature of the image side surface of the seventh lens, and R18 is the radius of curvature of the image side surface of the ninth lens.

[0022] Preferably, the focal lengths of the first lens to the ninth lens and the focal length of the entire lens satisfy the following conditions:

[0023] 5.4 < |(f1 / f)| < 5.6, 1.5 < |(f2 / f)| < 1.7, 2.1 < |(f3 / f)| < 2.3,

[0024] 0.8 < |(f4 / f)| < 0.9, 1.8 < |(f5 / f)| < 2.0, 1.7 < |(f6 / f)| < 1.8,

[0025] 4.9 < |(f7 / f)| < 5.1, 1.0 < |(f8 / f)| < 1.2, 0.6 < |(f9 / f)| < 0.8,

[0026] where f is the focal length of the lens, and f1, f2, f3, f4, f5, f6, f7, f8, and f9 are the focal length values of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the eighth lens, and the ninth lens, respectively.

[0027] Preferably, the focal lengths of the first lens to the ninth lens satisfy the following conditions:

[0028] 51.739 ≤ f1 ≤ 52.451, -15.663 ≤ f2 ≤ -15.608, -21.325 ≤ f3 ≤ -21.210, 8.303 ≤ f4 ≤ 8.314, -18.059 ≤ f5 ≤ -17.997, 16.504 ≤ f6 ≤ 16.666,

[0029] 46.938 ≤ f7 ≤ 48.511, 10.665 ≤ f8 ≤ 10.787, -6.806 ≤ f9 ≤ -6.665.

[0030] After adopting the above technical solutions, compared with the background technology, the present invention has the following advantages:

[0031] 1. The present invention uses nine lenses along the object side to the image side direction, and through corresponding designs of each lens, the lateral chromatic aberration and axial chromatic aberration of the lens are small, the chromatic aberration is well optimized, the color reducibility is good, and the blue-violet edge phenomenon is eliminated.

[0032] 2. The present invention disperses the energy of ghost images by coating an antireflection film on the mirror surfaces of each lens and controlling the R value of the lens, and can well weaken the energy of ghost images in a strong light source environment, ensuring the imaging effect of the lens.

[0033] 3. The refractive index temperature coefficient dn / dt of the sixth lens in the present invention is negative, and the optical power of the sixth lens is positive. Through the optimization of the optical structure design, the athermalization effect of the lens is achieved, the temperature drift is small, and when the lens is used in the high and low temperature ranges, the picture can be ensured to be clear and not out of focus, meeting the requirements of most usage environments.

[0034] 4. The overall optical length of the present invention is 31 mm, and the weight is about 24 g, making the lens light in weight, compact in structure, and strong in practicability. Description of the Drawings

[0035] Figure 1 It is the optical path diagram of Embodiment 1;

[0036] Figure 2 MTF curve graph of the lens in Example 1 under visible light of 434nm - 656nm;

[0037] Figure 3 Defocus curve graph of the lens in Example 1 under visible light of 434nm - 656nm;

[0038] Figure 4 Lateral chromatic aberration curve graph of the lens in Example 1 under visible light of 546nm;

[0039] Figure 5 Axial chromatic aberration curve graph of the lens in Example 1 under visible light of 434nm - 656nm;

[0040] Figure 6 Field curvature and distortion graph of the lens in Example 1 under visible light of 434nm - 656nm;

[0041] Figure 7 Optical path diagram of Example 2;

[0042] Figure 8 MTF curve graph of the lens in Example 2 under visible light of 434nm - 656nm;

[0043] Figure 9 Defocus curve graph of the lens in Example 2 under visible light of 434nm - 656nm;

[0044] Figure 10 Lateral chromatic aberration curve graph of the lens in Example 2 under visible light of 546nm;

[0045] Figure 11 Axial chromatic aberration curve graph of the lens in Example 2 under visible light of 434nm - 656nm;

[0046] Figure 12 Field curvature and distortion graph of the lens in Example 2 under visible light of 434nm - 656nm;

[0047] Figure 13 Optical path diagram of Example 3;

[0048] Figure 14 MTF curve graph of the lens in Example 3 under visible light of 434nm - 656nm;

[0049] Figure 15 Defocus curve graph of the lens in Example 3 under visible light of 434nm - 656nm;

[0050] Figure 16 Lateral chromatic aberration curve graph of the lens in Example 3 under visible light of 546nm;

[0051] Figure 17 It is the axial chromatic aberration curve graph of the lens in Example 3 under visible light of 434nm - 656nm;

[0052] Figure 18 It is the field curvature and distortion graph of the lens in Example 3 under visible light of 434nm - 656nm;

[0053] Figure 19 It is the optical path diagram of Example 4;

[0054] Figure 20 It is the MTF curve graph of the lens in Example 4 under visible light of 434nm - 656nm;

[0055] Figure 21 It is the defocus curve graph of the lens in Example 4 under visible light of 434nm - 656nm;

[0056] Figure 22 It is the lateral chromatic aberration curve graph of the lens in Example 4 under visible light of 546nm;

[0057] Figure 23 It is the axial chromatic aberration curve graph of the lens in Example 4 under visible light of 434nm - 656nm;

[0058] Figure 24 It is the field curvature and distortion graph of the lens in Example 4 under visible light of 434nm - 656nm.

[0059] Explanation of reference numerals:

[0060] The first lens 1, the second lens 2, the third lens 3, the fourth lens 4, the fifth lens 5, the sixth lens 6, the seventh lens 7, the eighth lens 8, the ninth lens 9, the aperture 10, the protective glass 11. Detailed implementation manners

[0061] To further illustrate each embodiment, the present invention provides accompanying drawings. These accompanying drawings are part of the disclosure of the present invention, which are mainly used to illustrate the embodiments and can be combined with the relevant descriptions in the specification to explain the operating principles of the embodiments. With reference to these contents, those of ordinary skill in the art should be able to understand other possible implementation manners and the advantages of the present invention. The components in the figures are not drawn to scale, and similar component symbols are usually used to represent similar components.

[0062] Now, the present invention will be further described in combination with the accompanying drawings and specific implementation manners.

[0063] As used in this specification, "a lens has a positive refractive power (or negative refractive power)" means that the paraxial refractive power of the lens calculated by Gaussian optical theory is positive (or negative). The "object side (or image side) of the lens" is defined as a specific range through which imaging light passes through the lens surface. The determination of the convexity or concavity of the lens surface can be made in the same way as that of an ordinary person in this field, that is, by the positive or negative sign of the radius of curvature (abbreviated as R value) to determine the convexity or concavity 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.

[0064] The present invention discloses an imaging lens for a drone, which sequentially includes a first lens to a ninth lens along an optical axis from the object side to the image side. Each of the first lens to the ninth 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.

[0065] The first lens has a positive refractive power, the object side of the first lens is a convex surface, and the image side is a concave surface.

[0066] The second lens has a negative refractive power, the object side of the second lens is a convex surface, and the image side is a concave surface.

[0067] The third lens has a negative refractive power, the object side of the third lens is a concave surface, and the image side is a convex surface.

[0068] The fourth lens has a positive refractive power, the object side of the fourth lens is a convex surface, and the image side is a convex surface.

[0069] The fifth lens has a negative refractive power, the object side of the fifth lens is a concave surface, and the image side is a convex surface.

[0070] The sixth lens has a positive refractive power, the object side of the sixth lens is a convex surface, and the image side is a convex surface.

[0071] The seventh lens has a positive refractive power, the object side of the seventh lens is a convex surface, and the image side is a concave surface.

[0072] The eighth lens has a positive refractive power, the object side of the eighth lens is a concave surface, and the image side is a convex surface.

[0073] The ninth lens has a negative refractive power, the object side of the ninth lens is a concave surface, and the image side is a convex surface.

[0074] The first lens, the third lens, the fourth lens, the fifth lens, and the seventh lens are glass spherical lenses, and the second lens, the sixth lens, the eighth lens, and the ninth lens are glass aspherical lenses, which can well correct chromatic aberration and eliminate the blue-violet edge phenomenon that is prone to occur in lens imaging;

[0075] There are only the above nine lenses with refractive power in this optical imaging lens.

[0076] The equations of the object side and image side curves of the aspherical lens are expressed as follows:

[0077]

[0078] Where:

[0079] z: The depth of the aspheric surface (the vertical distance between a point on the aspheric surface with a distance of y from the optical axis and the tangent plane at the vertex of the aspheric surface on the optical axis);

[0080] c: The curvature of the aspheric vertex (the vertex curvature);

[0081] K: The conic constant (Conic Constant);

[0082] , the radial distance (radial distance);

[0083] r n : The normalization radius (normalization radius (NRADIUS));

[0084] u: r / r n ;

[0085] a m : The m-th order Q con coefficient (is the m th Q con coefficient);

[0086] Q m con : The m-th order Q con polynomial (the m th Q con polynomial).

[0087] Preferably, the image side of the fourth lens and the object side of the fifth lens are adhesively bonded to each other and satisfy Vd4 - Vd5 > 20, where Vd4 is the dispersion coefficient of the fourth lens and Vd5 is the dispersion coefficient of the fifth lens. The combination of the two lenses with high and low dispersion materials is beneficial to correcting chromatic aberration, optimizing image quality, improving system performance, and eliminating the blue-violet edge phenomenon that easily occurs in lens imaging.

[0088] Preferably, the refractive index temperature coefficient dn / dt of the sixth lens is negative, that is, the refractive index of the lens decreases as the temperature increases, and the optical power of the sixth lens is positive. When the external temperature changes, using a material with a negative dn / dt for the sixth lens can well offset the influence of temperature change on the back focal length of the lens, enabling the lens to compensate for temperature drift. It can ensure that the picture is clear and in focus when the lens is used in the temperature range of -20°C to 70°C, meeting the requirements of most usage environments.

[0089] Preferably, the lens meets the following conditional formula: TTL ≤ 31 mm, where TTL is the distance from the object side of the first lens to the imaging plane on the optical axis, making the lens have a short overall length, a compact structure, and strong practicality.

[0090] Preferably, the lens further includes a diaphragm, and the diaphragm is disposed between the fifth lens and the sixth lens.

[0091] Preferably, the lens meets the following conditional formulas: |R9| > 52 mm, R11 > 13 mm, R14 > 11.5 mm, |R18| > 45 mm, and the surfaces of the first lens to the ninth lens are all coated with an anti-reflection film. Among them, R9 is the radius of curvature of the image side of the fifth lens, R11 is the radius of curvature of the object side of the sixth lens, R14 is the radius of curvature of the image side of the seventh lens, and R18 is the radius of curvature of the image side of the ninth lens. By coating the anti-reflection film on the surfaces of each lens and controlling the R values of the fifth lens, sixth lens, seventh lens, and ninth lens, the energy of ghost images can be dispersed, and the energy of ghost images can be well weakened in a strong light source environment, ensuring the imaging effect of the lens.

[0092] Preferably, the focal lengths of the first lens to the ninth lens and the focal length of the entire lens satisfy the following conditions:

[0093] 5.4 < |(f1 / f)| < 5.6, 1.5 < |(f2 / f)| < 1.7, 2.1 < |(f3 / f)| < 2.3,

[0094] 0.8 < |(f4 / f)| < 0.9, 1.8 < |(f5 / f)| < 2.0, 1.7 < |(f6 / f)| < 1.8,

[0095] 4.9 < |(f7 / f)| < 5.1, 1.0 < |(f8 / f)| < 1.2, 0.6 < |(f9 / f)| < 0.8,

[0096] wherein, f is the focal length of the lens, and f1, f2, f3, f4, f5, f6, f7, f8, and f9 are the focal length values of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the eighth lens, and the ninth lens, respectively.

[0097] Preferably, the focal lengths of the first lens to the ninth lens satisfy the following conditions:

[0098] 51.739 ≤ f1 ≤ 52.451, -15.663 ≤ f2 ≤ -15.608, -21.325 ≤ f3 ≤ -21.210, 8.303 ≤ f4 ≤ 8.314, -18.059 ≤ f5 ≤ -17.997, 16.504 ≤ f6 ≤ 16.666, 46.938 ≤ f7 ≤ 48.511, 10.665 ≤ f8 ≤ 10.787, -6.806 ≤ f9 ≤ -6.665,

[0099] By reasonably distributing the optical power, it is more beneficial to improve the optical system performance of the lens.

[0100] Next, the imaging lens of the present invention will be described in detail with specific embodiments.

[0101] Embodiment 1

[0102] Refer to Figure 1 As shown, this embodiment discloses an imaging lens for a drone, which sequentially includes a first lens 1 to a ninth lens 9 along an optical axis from the object side A1 to the image side A2. The first lens 1 to the ninth lens 9 each include an object side facing the object side A1 and allowing imaging light to pass through, and an image side facing the image side A2 and allowing imaging light to pass through;

[0103] The first lens 1 has a positive refractive power, the object side of the first lens 1 is a convex surface, and the image side is a concave surface;

[0104] The second lens 2 has a negative refractive power, the object side of the second lens 2 is a convex surface, and the image side is a concave surface;

[0105] The third lens 3 has a negative refractive power, the object side of the third lens 3 is a concave surface, and the image side is a convex surface;

[0106] The fourth lens 4 has a positive refractive power, the object side of the fourth lens 4 is a convex surface, and the image side is a convex surface;

[0107] The fifth lens 5 has a negative refractive power, the object side of the fifth lens 5 is a concave surface, and the image side is a convex surface;

[0108] The sixth lens 6 has a positive refractive power, the object side surface of the sixth lens 6 is convex, and the image side surface is convex;

[0109] The seventh lens 7 has a positive refractive power, the object side surface of the seventh lens 7 is convex, and the image side surface is concave;

[0110] The eighth lens 8 has a positive refractive power, the object side surface of the eighth lens 8 is concave, and the image side surface is convex;

[0111] The ninth lens 9 has a negative refractive power, the object side surface of the ninth lens 9 is concave, and the image side surface is convex;

[0112] The first lens 1, the third lens 3, the fourth lens 4, the fifth lens 5, and the seventh lens 7 are glass spherical lenses, and the second lens 2, the sixth lens 6, the eighth lens 8, and the ninth lens 9 are glass aspherical lenses, so that chromatic aberration is well corrected, and the phenomenon of blue-violet edges that easily appears in lens imaging is eliminated;

[0113] There are only the above nine lenses with refractive power in this optical imaging lens.

[0114] The image side surface of the fourth lens 4 and the object side surface of the fifth lens 4 are adhesively bonded to each other. The refractive index temperature coefficient dn / dt of the sixth lens 6 is negative. The diaphragm 10 is disposed between the fifth lens 5 and the sixth lens 6. Of course, in other embodiments, the diaphragm 10 can also be disposed at other suitable positions.

[0115] The detailed optical data of this specific embodiment are shown in Table 1.

[0116] Table 1 Detailed optical data of Embodiment 1

[0117]

[0118] For the detailed data of the aspherical parameters of the second lens 2, the sixth lens 6, the eighth lens 8, and the ninth lens 9, please refer to the following table:

[0119]

[0120] In this specific embodiment, the focal length f of the optical imaging lens is 9.442 mm; the aperture value FNO is 2.33; the CRA (chief ray angle) is 29.3°, which is matched with the sensor. The size of the imaging surface is 1 / 1 inch, and the imaging surface size is ∅15.8 mm. The distance TTL from the object side surface of the first lens to the imaging surface on the optical axis is 31 mm; (f1 / f) = 5.42, (f2 / f) = -1.63, (f3 / f) = -2.22, (f4 / f) = 0.87, (f5 / f) = -1.89, (f6 / f) = 1.73, (f7 / f) = 5.08, (f8 / f) = 1.12, (f9 / f) = -0.70.

[0121] For the optical path diagram of the optical imaging lens in this specific embodiment, please refer to Figure 1 . For the MTF curve diagram of the lens under the light of 434 nm - 656 nm, please refer to Figure 2 . It can be seen from the figure that when the spatial frequency of the lens reaches 190 lp / mm, the full field transfer function image is still greater than 0.2, and the resolution can reach the level of 20 million pixels, ensuring the imaging quality. At the same time, the static resolution and video resolution of the overall solution are greatly improved, which greatly facilitates the development of the later image optimization algorithm. For the defocus curve diagram of the lens under the light of 434 nm - 656 nm, please refer to Figure 3 . It can be seen from the figure that the defocus amount of the lens under visible light is small. For the lateral chromatic aberration curve diagram of the lens under the light of 546 nm, please refer to Figure 4 , and for the longitudinal chromatic aberration curve diagram of the lens under the light of 434 nm - 656 nm, please refer to Figure 5 . It can be seen from the figure that the field chromatic aberration is small, the color reproducibility is good, and the blue-violet edge phenomenon is not obvious. For the field curvature and distortion diagram of the lens under the light of 434 nm - 656 nm, please refer to Figure 6 . The optical distortion is controlled within 1.2%. It can be seen that the distortion is small and the imaging quality is high, and there is no need to correct the distortion by the later image algorithm.

[0122] Embodiment 2

[0123] Cooperate with Figures 7 to 12 As shown, the surface concavity and convexity and refractive index of each lens in this embodiment are roughly the same as those in Embodiment 1, but the optical parameters such as the curvature radius of each lens surface and the lens thickness are different.

[0124] The detailed optical data of this specific embodiment are shown in Table 2.

[0125] Table 2 Detailed optical data of Embodiment 2

[0126]

[0127] Please refer to the following table for detailed parameter data of the aspheric surfaces of the second lens 2, the sixth lens 6, the eighth lens 8, and the ninth lens 9:

[0128]

[0129] In this specific embodiment, the focal length of the optical imaging lens is f=9.449 mm; the aperture value FNO=2.33; the CRA (chief ray angle) is 29.3°, which matches the sensor, the imaging surface size is 1 / 1 inch, and the imaging surface size is ∅15.8 mm; the distance TTL from the object side of the first lens 1 to the imaging surface on the optical axis is 31 mm; (f1 / f)=5.55, (f2 / f)=-1.66, (f3 / f)=-2.26, (f4 / f)=0.88, (f5 / f)=-1.90, (f6 / f)=1.76, (f7 / f)=5.00, (f8 / f)=1.14, (f9 / f)=-0.72.

[0130] For the optical path diagram of the optical imaging lens in this specific embodiment, please refer to Figure 7 Please refer to the MTF curve of the lens under 434nm-656nm light Figure 8 From the figure, we can see that when the spatial frequency of the lens reaches 190lp / mm, the full field transfer function image is still greater than 0.2, and the resolution can reach 20 million pixels, which ensures the imaging quality and greatly improves the overall static resolution and video resolution of the solution, greatly facilitating the development of later image optimization algorithms. For the defocus curve of the lens under 434nm-656nm light, please refer to Figure 9 , it can be seen from the figure that the lens has a small defocus under visible light. For the vertical axis chromatic aberration curve of the lens under 546nm light, please refer to Figure 10 、For the axial chromatic aberration curve of the lens under 434nm-656nm light, please refer to Figure 11 As can be seen from the figure, the field of view has small chromatic aberration, good color reproduction, and no obvious blue-purple fringing. Please refer to the field curvature and distortion diagram of the lens under 434nm-656nm light. Figure 12 , the optical distortion is controlled within 1.0%. It can be seen that the distortion is small and the imaging quality is high, and there is no need for post-processing image algorithms to correct the distortion.

[0131] Embodiment 3

[0132] Cooperate Figures 13 to 18 As shown, the surface profile and refractive power of each lens in this embodiment and the first embodiment are substantially the same, but the optical parameters such as the curvature radius of each lens surface and lens thickness are different.

[0133] The detailed optical data of this specific embodiment are shown in Table 3.

[0134] Table 3 Detailed Optical Data of Embodiment Three

[0135]

[0136] For the detailed parameter data of the aspheres of the second lens 2, sixth lens 6, eighth lens 8, and ninth lens 9, please refer to the following table:

[0137]

[0138] In this specific embodiment, the focal length f of the optical imaging lens is 9.460 mm; the aperture value FNO is 2.33; the CRA (chief ray angle) is 29.3°, which is matched with the sensor. The imaging surface size is 1 / 1 inch, and the imaging surface dimension is ∅15.8 mm. The distance TTL from the object side of the first lens 1 to the imaging surface on the optical axis is 31 mm; (f1 / f) = 5.55, (f2 / f) = -1.65, (f3 / f) = -2.25, (f4 / f) = 0.88, (f5 / f) = -1.91, (f6 / f) = 1.76, (f7 / f) = 4.96, (f8 / f) = 1.14, (f9 / f) = -0.72.

[0139] For the optical path diagram of the optical imaging lens in this specific embodiment, please refer to Figure 13 .. For the MTF curve diagram of the lens under the light of 434 nm - 656 nm, please refer to Figure 14 .. It can be seen from the figure that when the spatial frequency of the lens reaches 190 lp / mm, the full-field transfer function image is still greater than 0.2, and the resolution can reach the level of 20 million pixels, ensuring the imaging quality. At the same time, the static resolution and video resolution of the overall solution are greatly improved, which is extremely convenient for the development of subsequent image optimization algorithms. For the defocus curve diagram of the lens under the light of 434 nm - 656 nm, please refer to Figure 15 .. It can be seen from the figure that the defocus amount of the lens under visible light is small. For the lateral chromatic aberration curve diagram of the lens under the light of 546 nm, please refer to Figure 16 .. For the longitudinal chromatic aberration curve diagram of the lens under the light of 434 nm - 656 nm, please refer to Figure 17 .. It can be seen from the figure that the field chromatic aberration is small, the color reducibility is good, and the blue-violet edge phenomenon is not obvious. For the field curvature and distortion diagram of the lens under the light of 434 nm - 656 nm, please refer to Figure 18 .. The optical distortion is controlled within 1.0%. It can be seen that the distortion is small and the imaging quality is high, and there is no need for subsequent image algorithm to correct the distortion.

[0140] Embodiment Four

[0141] Cooperate with Figures 19 to 24As shown, the surface concavity and convexity and refractive index of each lens in this embodiment are approximately the same as those in Embodiment 1, and the optical parameters such as the curvature radius of each lens surface and the lens thickness are different.

[0142] The detailed optical data of this specific embodiment are shown in Table 4.

[0143] Table 4 Detailed Optical Data of Embodiment 4

[0144]

[0145] For the detailed parameter data of the aspherical surfaces of the second lens 2, the sixth lens 6, the eighth lens 8, and the ninth lens 9, please refer to the following table:

[0146]

[0147] In this specific embodiment, the focal length f of the optical imaging lens is 9.556 mm; the aperture value FNO is 2.33; the CRA (chief ray angle) is 29.3°, which is matched with the sensor. The imaging surface size is 1 / 1 inch, and the imaging surface dimension is ∅15.8 mm. The distance TTL from the object side surface of the first lens 1 to the imaging surface on the optical axis is 31 mm; (f1 / f) = 5.41, (f2 / f) = -1.63, (f3 / f) = -2.22, (f4 / f) = 0.87, (f5 / f) = -1.89, (f6 / f) = 1.73, (f7 / f) = 5.08, (f8 / f) = 1.12, (f9 / f) = -0.70.

[0148] For the optical path diagram of the optical imaging lens in this specific embodiment, please refer to Figure 19 ... For the MTF curve diagram of the lens under the light of 434 nm - 656 nm, please refer to Figure 20 ... It can be seen from the figure that when the spatial frequency of the lens reaches 200 lp / mm, the full-field transfer function image is still greater than 0.2, and the resolution can reach the level of 20 million pixels, ensuring the imaging quality. At the same time, the static resolution and video resolution of the overall solution are greatly improved, which greatly facilitates the development of the later image optimization algorithm. For the defocus curve diagram of the lens under the light of 434 nm - 656 nm, please refer to Figure 21 ... It can be seen from the figure that the defocus amount of the lens under visible light is small. For the lateral chromatic aberration curve diagram of the lens under the light of 546 nm, please refer to Figure 22 ... For the longitudinal chromatic aberration curve diagram of the lens under the light of 434 nm - 656 nm, please refer to Figure 23 ... It can be seen from the figure that the field chromatic aberration is small, the color reducibility is good, and the blue-violet edge phenomenon is not obvious. For the field curvature and distortion diagram of the lens under the light of 434 nm - 656 nm, please refer to Figure 24, the optical distortion control is within 1.4%. It can be seen that the distortion is small, the imaging quality is high, and there is no need for post-image algorithm to correct the distortion.

[0149] As mentioned above, it is only the preferred specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. An imaging lens for a drone, characterized in that, From the object side to the image side along an optical axis, it successively includes a first lens to a ninth lens. Each of the first lens to the ninth lens includes an object side face facing the object side and allowing imaging light rays to pass through, and an image side face facing the image side and allowing imaging light rays to pass through; The first lens has a positive refractive power. The object side face of the first lens is convex, and the image side face is concave; The second lens has a negative refractive power. The object side face of the second lens is convex, and the image side face is concave; The third lens has a negative refractive power. The object side face of the third lens is concave, and the image side face is convex; The fourth lens has a positive refractive power. The object side face of the fourth lens is convex, and the image side face is convex; The fifth lens has a negative refractive power. The object side face of the fifth lens is concave, and the image side face is convex; The sixth lens has a positive refractive power. The object side face of the sixth lens is convex, and the image side face is convex; The seventh lens has a positive refractive power. The object side face of the seventh lens is convex, and the image side face is concave; The eighth lens has a positive refractive power. The object side face of the eighth lens is concave, and the image side face is convex; The ninth lens has a negative refractive power. The object side face of the ninth lens is concave, and the image side face is convex; The first lens, the third lens, the fourth lens, the fifth lens, and the seventh lens are glass spherical lenses, and the second lens, the sixth lens, the eighth lens, and the ninth lens are glass aspherical lenses; The focal lengths of the first lens to the ninth lens and the focal length of the entire lens satisfy the following conditions: 5.4 < |(f1 / f)| < 5.6, 1.5 < |(f2 / f)| < 1.7, 2.1 < |(f3 / f)| < 2.3, 0.8 < |(f4 / f)| < 0.9, 1.8 < |(f5 / f)| < 2.0, 1.7 < |(f6 / f)| < 1.8, 4.9 < |(f7 / f)| < 5.1, 1.0 < |(f8 / f)| < 1.2, 0.6 < |(f9 / f)| < 0.8, where f is the focal length of the lens, and f1, f2, f3, f4, f5, f6, f7, f8, f9 are the focal length values of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the eighth lens, and the ninth lens respectively; The imaging lens of this drone has only the above nine lenses with refractive power.

2. The imaging lens for a drone according to claim 1, characterized in that, The image side face of the fourth lens and the object side face of the fifth lens are adhesively bonded to each other and satisfy Vd4 - Vd5 > 20, where Vd4 is the dispersion coefficient of the fourth lens and Vd5 is the dispersion coefficient of the fifth lens.

3. The imaging lens for a drone according to claim 1, characterized in that, The refractive index temperature coefficient dn / dt of the sixth lens is negative.

4. The imaging lens for a drone according to claim 1, characterized in that, It conforms to the following conditional formula: TTL ≤ 31 mm, where TTL is the distance from the object side face of the first lens to the imaging surface on the optical axis.

5. The imaging lens for a drone according to claim 1, characterized in that, It further includes a diaphragm, and the diaphragm is arranged between the fifth lens and the sixth lens.

6. The imaging lens for a drone according to claim 1, characterized in that, Meet the following conditional expressions: |R9| > 52 mm, R11 > 13 mm, R14 > 11.5 mm, |R18| > 45 mm, and the mirror surfaces of the first to ninth lenses are all coated with an antireflection film, where R9 is the radius of curvature of the image side of the fifth lens, R11 is the radius of curvature of the object side of the sixth lens, R14 is the radius of curvature of the image side of the seventh lens, and R18 is the radius of curvature of the image side of the ninth lens.

7. The imaging lens for a drone according to claim 1, characterized in that, The focal lengths of the first to ninth lenses satisfy the following conditions: 51.739 ≤ f1 ≤ 52.451, -15.663 ≤ f2 ≤ -15.608, -21.325 ≤ f3 ≤ -21.210, 8.303 ≤ f4 ≤ 8.314, -18.059 ≤ f5 ≤ -17.997, 16.504 ≤ f6 ≤ 16.666, 46.938 ≤ f7 ≤ 48.511, 10.665 ≤ f8 ≤ 10.787, -6.806 ≤ f9 ≤ -6.665.

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