Low-light lenses and low-light cameras

Abstract

The present invention discloses a low-light lens and a low-light camera. The low-light lens has an object side and an image side disposed opposite to each other along the optical axis direction. The low-light lens includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens, a ninth lens and an image sensor sequentially arranged from the object side to the image side. The low-light lens satisfies the following conditions: 2<f1 / f<3; 1<f2 / f<2; -1<f3 / f<-0.5; 1<f4 / f<2; 1<f5 / f<2; 0<f6 / f<1; -1<f7 / f<0; 0<f8 / f<1; -1<f9 / f<0. The maximum designed image plane of the low-light lens is Φ29mm, the maximum aperture is 36mm, and F / #≤1.4. Through the constraints of the above nine lenses within the above focal length ratio ranges and the matching of performance index parameters between the respective lenses, the ratio of the distance from the first lens to the image sensor to the focal length is made less than 1.74, so as to realize the small volume of the low-light lens, which can be applied to a low-light camera chip of up to 1.7 inches, with a wider observable range, so as to provide a low-light lens with a large aperture and a large target surface.

Description

Technical Field

[0001] This invention relates to the field of optical technology, and more particularly to low-light lenses and low-light cameras. Background Technology

[0002] Low-light night vision lenses are increasingly widely used in various fields such as seabed exploration, satellite remote sensing, and biological research. Because low-light lenses cover the visible and near-infrared wavelengths, and their design incorporates a large aperture, they possess strong observation capabilities even at night. This is an advantage that ordinary visible light lenses cannot match. The smaller target area also limits the lens's field of view. At the same focal length and recognition distance, a larger target area lens offers a wider field of view, resulting in clearer monitoring images and meeting users' demands for high-definition surveillance. High-performance low-light lenses that balance aperture and target area are currently a market trend, but this also presents a design challenge. Summary of the Invention

[0003] The main objective of this invention is to provide a low-light lens and a low-light camera, with the aim of providing a low-light lens with a large aperture and a large target area.

[0004] To achieve the above objectives, the present invention proposes a low-light lens, which has an object side and an image side arranged opposite to each other along the optical axis. The low-light lens includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens, a ninth lens, and a photosensitive chip arranged sequentially from the object side to the image side. The low-light lens satisfies the following conditions:

[0005] 2 <f1 / f<3;1<f2 / f<2;-1<f3 / f<-0.5;1<f4 / f<2;1<f5 / f<2;0<f6 / f<1;-1<f7 / f<0;0<f8 / f<1;-1<f9 / f<0;

[0006] Wherein, the total focal length of the low-light lens is f, the focal length of the first lens is f1, the focal length of the second lens is f2, the focal length of the third lens is f3, the focal length of the fourth lens is f4, the focal length of the fifth lens is f5, the focal length of the sixth lens is f6, the focal length of the seventh lens is f7, the focal length of the eighth lens is f8, and the focal length of the ninth lens is f9.

[0007] Optionally, the first lens has positive optical power, the second lens has positive optical power, the third lens has negative optical power, the fourth lens has positive optical power, the fifth lens has positive optical power, the sixth lens has positive optical power, the seventh lens has negative optical power, the eighth lens has positive optical power, and the ninth lens has negative optical power.

[0008] Optionally, the first lens is a meniscus lens, with its concave surface facing the image side;

[0009] The second lens is a meniscus lens, with its concave surface facing the image side;

[0010] The third lens is a biconcave lens;

[0011] The fourth lens is a meniscus lens, with its concave surface facing the image side;

[0012] The fifth lens is a biconvex lens;

[0013] The sixth lens is a biconvex lens;

[0014] The seventh lens is a biconcave lens;

[0015] The eighth lens is a biconvex lens;

[0016] The ninth lens is a meniscus lens, with its concave surface facing the object side.

[0017] Optionally, 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 are all spherical lenses.

[0018] Optionally, 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 are all glass lenses.

[0019] Optionally, the low-light lens also satisfies the following conditions:

[0020] 40.0<vd1<60.0; 70.0<vd2<85.0; 15.0<vd3<35.0; 15.0<vd4<30.0; 35.0<vd 5<55.0; 60.0<vd6<80.0; 15.0<vd7<35.0; 30.0<vd8<50.0; 30.0<vd9<50.0;

[0021] Wherein, the dispersion coefficient of the first lens is vd1, the dispersion coefficient of the second lens is vd2, the dispersion coefficient of the third lens is vd3, the dispersion coefficient of the fourth lens is vd4, the dispersion coefficient of the fifth lens is vd5, the dispersion coefficient of the sixth lens is vd6, the dispersion coefficient of the seventh lens is vd7, the dispersion coefficient of the eighth lens is vd8, and the dispersion coefficient of the ninth lens is vd9.

[0022] Optionally, the sixth lens and the seventh lens are cemented together to form a cemented lens.

[0023] Optionally, the low-light lens further comprises a diaphragm, and the diaphragm is arranged between the third lens and the fourth lens.

[0024] Optionally, the distance between the first lens and the photosensitive chip is T, and the focal length from the first lens to the ninth lens is F, where T / F<1.74.

[0025] The present invention further provides a low-light camera, and the low-light camera comprises the low-light lens described above.

[0026] In the technical solution provided by the present invention, the low-light lens satisfies the following conditions: 2<f1 / f<3; 1<f2 / f<2; -1<f3 / f<-0.5; 1<f4 / f<2; 1<f5 / f<2; 0<f6 / f<1; -1<f7 / f<0; 0<f8 / f<1; -1<f9 / f<0. Through the constraints of the nine lenses within the above focal length ratio ranges and the matching of performance index parameters between the lenses, the ratio of the distance from the first lens to the photosensitive chip to the focal length is made less than 1.74, so as to realize the small volume of the low-light lens, which is applicable to low-light camera chips up to 1.7 inches, with a wider observable range. Compared with similar products, the lens not only has a long recognition distance and a larger field of view, but also can realize monitoring and imaging without additional artificial light sources, so as to provide a low-light lens with a large aperture and a large target surface. Brief Description of the Drawings

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required in the description of the embodiments or the prior art. Obviously, the drawings described below are only some embodiments of the present invention, and for those of ordinary skill in the art, other drawings can also be obtained according to the structures shown in these drawings without creative efforts.

[0028] Figure 1 is a schematic structural diagram of the low-light lens provided by the present invention;

[0029] Figure 2 is a schematic diagram of the MTF curve of the low-light lens at normal temperature;

[0030] Figure 3 is a schematic diagram of the MTF curve of the low-light lens at a low temperature of -40°C;

[0031] Figure 4 is a schematic diagram of the MTF curve of the low-light lens at a low temperature of +80°C.

[0032] Description of Reference Numerals in the Drawings:

[0033]

[0034]

[0035] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0036] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0037] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicators will also change accordingly.

[0038] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the meaning of "and / or" throughout the text includes three parallel solutions; for example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0039] Low-light night vision lenses are increasingly widely used in various fields such as seabed exploration, satellite remote sensing, and biological research. Because low-light lenses cover the visible and near-infrared wavelengths, and their design incorporates a large aperture, they possess strong observation capabilities even at night. This is an advantage that ordinary visible light lenses cannot match. The smaller target area also limits the lens's field of view. At the same focal length and recognition distance, a larger target area lens offers a wider field of view, resulting in clearer monitoring images and meeting users' demands for high-definition surveillance. High-performance low-light lenses that balance aperture and target area are currently a market trend, but this also presents a design challenge.

[0040] To address the above problems, the present invention provides a low-light lens. Figure 1 is a schematic structural diagram of a low-light lens provided by the present invention; Figure 2 is a schematic diagram of the normal-temperature MTF curve of the low-light lens; Figure 3 is a schematic diagram of the MTF curve of the low-light lens at a low temperature of -40°C; Figure 4 is a schematic diagram of the MTF curve of the low-light lens at a low temperature of +80°C.

[0041] Please refer to Figure 1 , the low-light lens has an object side and an image side arranged opposite to each other along the optical axis direction, and the low-light lens includes a first lens 1, a second lens 2, a third lens 3, a fourth lens 4, a fifth lens 5, a sixth lens 6, a seventh lens 7, an eighth lens 8, a ninth lens 9 and an imaging chip 11 which are sequentially arranged from the object side to the image side. The low-light lens satisfies the following conditions: 2<f1 / f<3; 1<f2 / f<2; -1<f3 / f<-0.5; 1<f4 / f<2; 1<f5 / f<2; 0<f6 / f<1; -1<f7 / f<0; 0<f8 / f<1; -1<f9 / f<0; where the total focal length of the low-light lens is f, the focal length of the first lens 1 is f1, the focal length of the second lens 2 is f2, the focal length of the third lens 3 is f3, the focal length of the fourth lens 4 is f4, the focal length of the fifth lens 5 is f5, the focal length of the sixth lens 6 is f6, the focal length of the seventh lens 7 is f7, the focal length of the eighth lens 8 is f8, and the focal length of the ninth lens 9 is f9.

[0042] It can be understood that f1 / f can be set to 2.1, 2.3, 2.5, 2.7, 2.9, etc., f2 / f can be set to 1.1, 1.3, 1.5, 1.7, 1.9, etc., f3 / f can be set to -0.6, -0.7, -0.8, -0.9, etc., f4 / f can be set to 1.1, 1.3, 1.5, 1.7, 1.9, etc., f5 / f can be set to 1.1, 1.3, 1.5, 1.7, 1.9, etc., f6 / f can be set to 0.1, 0.3, 0.5, 0.7, 0.9, etc., f7 / f can be set to -0.1, -0.3, -0.5, -0.7, -0.9, etc., f8 / f can be set to 0.1, 0.3, 0.5, 0.7, 0.9, etc., and f9 / f can be set to -0.1, -0.3, -0.5, -0.7, -0.9, etc.

[0043] In the technical solution provided by the present invention, the low-light lens satisfies the following conditions: 2<f1 / f<3; 1<f2 / f<2; -1<f3 / f<-0.5; 1<f4 / f<2; 1<f5 / f<2; 0<f6 / f<1; -1<f7 / f<0; 0<f8 / f<1; -1<f9 / f<0. Through the constraints of the above nine lenses within the above focal length ratio ranges and the matching of performance index parameters between the respective lenses, the ratio of the distance from the first lens 1 to the photosensitive chip 11 to the focal length is made less than 1.74, so as to realize the small volume of the low-light lens, which is applicable to low-light camera chips up to 1.7 inches, with a wider observable range. Compared with similar products, the lens not only has a long recognition distance and a larger field of view range, but also can realize monitoring imaging without an additional artificial light source, so as to provide a low-light lens with a large aperture and a large target surface.

[0044] In this embodiment, the first lens 1 has positive refractive power, the second lens 2 has positive refractive power, the third lens 3 has negative refractive power, the fourth lens 4 has positive refractive power, the fifth lens 5 has positive refractive power, the sixth lens 6 has positive refractive power, the seventh lens 7 has negative refractive power, the eighth lens 8 has positive refractive power, and the ninth lens 9 has negative refractive power.

[0045] Specifically, in this embodiment, the first lens 1 is a meniscus lens with its concave surface facing the image side; the second lens 2 is a meniscus lens with its concave surface facing the image side; the third lens 3 is a biconcave lens; the fourth lens 4 is a meniscus lens with its concave surface facing the image side; the fifth lens 5 is a biconvex lens; the sixth lens 6 is a biconvex lens; the seventh lens 7 is a biconcave lens; the eighth lens 8 is a biconvex lens; the ninth lens 9 is a meniscus lens with its concave surface facing the object side.

[0046] It should be noted that, different from spherical lenses which have a constant radius of curvature, the radius of curvature of an aspheric lens changes continuously from the center to the edge along with the change of the main optical axis, which can better correct spherical aberration and chromatic aberration, thereby improving the spot quality of the lens. By adjusting the conic constant and aspheric coefficients, the lens is optimized to minimize aberrations to the greatest extent. However, different from spherical lenses, aspheric lenses cannot be mass-produced by traditional grinding methods, and can only be processed by diamond turning or mold opening, which greatly increases processing time and cost.

[0047] In this embodiment, 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, and the ninth lens 9 are all glass spherical lenses. Spherical lenses have a simple spherical shape, are easier to manufacture and process, and have relatively low costs.

[0048] It should be noted that glass, being a material with excellent optical transparency, can effectively transmit light without causing significant absorption and scattering. Therefore, it can provide high-quality imaging and accurate optical performance in the aforementioned low-light lens. The refractive index of the glass can be adjusted as needed; by selecting glass materials with different refractive indices, the refraction and focusing of light can be controlled. Glass has high mechanical strength and hardness, allowing the low-light lens to withstand high pressure and temperature changes. Simultaneously, glass exhibits good stability under various environmental conditions, maintaining its optical performance over long periods. Furthermore, glass has high corrosion resistance to most chemicals, remaining stable under diverse environmental conditions. This allows the glass lens to operate stably for extended periods in various applications. Therefore, this design makes the low-light lens less susceptible to focus deviation due to thermal expansion and contraction, effectively resisting lens deformation caused by heat and maintaining high lens precision over extended periods.

[0049] Specifically, in optical lenses, light dispersion leads to undesirable chromatic aberration, resulting in blurring or a blurred effect or "color fringing" around the observed object. To ensure good image quality, in this embodiment, the low-light lens also satisfies the following conditions: 40.0 < vd1 < 60.0; 70.0 < vd2 < 85.0; 15.0 < vd3 < 35.0; 15.0 < vd4 < 30.0; 35.0 < vd5 < 55.0; 60.0 < vd6 < 80.0; 15.0 < vd7 < 35.0. 0; 30.0 < vd8 < 50.0; 30.0 < vd9 < 50.0; where the dispersion coefficient of the first lens 1 is vd1, the dispersion coefficient of the second lens 2 is vd2, the dispersion coefficient of the third lens 3 is vd3, the dispersion coefficient of the fourth lens 4 is vd4, the dispersion coefficient of the fifth lens 5 is vd5, the dispersion coefficient of the sixth lens 6 is vd6, the dispersion coefficient of the seventh lens 7 is vd7, the dispersion coefficient of the eighth lens 8 is vd8, and the dispersion coefficient of the ninth lens 9 is vd9. The dispersion coefficient is used to measure the degree of light dispersion in a transparent medium. The Abbe number is an index used to represent the dispersion ability of a transparent medium. The larger the dispersion coefficient (Abbe number), the less obvious the dispersion, and the better the image quality of the lens. In this embodiment, the dispersion coefficients of each lens are controlled at a high value, so that the dispersion of the fixed-focus lens is not obvious and the image quality of the lens is good.

[0050] Understandably, vd1 can be set to 41, 43, 45, 47, 49, 51, 53, 55, 57, etc.; vd2 can be set to 72, 74, 76, 78, 80, 82, 84, etc.; vd3 can be set to 16, 19, 22, 25, 28, 31, 33, etc.; vd4 can be set to 16, 18, 20, 22, 24, 26, 2, etc.; and vd5 can be set to 36, 3, etc. 9, 42, 45, 48, 51, 54, etc.; vd6 can be set to 62, 64, 66, 68, 70, 72, 74, 76, 78, etc.; vd7 can be set to 16, 19, 22, 25, 28, 31, 33, etc.; vd8 can be set to 31, 33, 36, 39, 42, 45, 48, etc.; vd9 can be set to 31, 33, 36, 39, 42, 45, 48, etc.

[0051] Specifically, to improve the image quality of the optical system, reduce light energy loss, and increase imaging clarity by optimizing the manufacturing process to meet design requirements, in this embodiment, the sixth lens 6 and the seventh lens 7 are cemented together to form a cemented lens. By rationally using the cemented component, appropriately allocating the optical power, and combining it with the thermal parameters of the glass material, aberrations are effectively corrected and a thermal effect at both high and low temperatures is achieved, while maintaining a clear image. The low-light lens uses a glass combination of a cemented lens and positive and negative lenses to eliminate aberrations, and selects materials with suitable coefficients of thermal expansion to achieve a thermal effect at both room temperature and high and low temperatures.

[0052] In this embodiment, the low-light lens further includes an aperture stop 10, which is disposed between the third lens 3 and the fourth lens 4. The aperture stop 10 limits the beam aperture on the imaging axis, blocking part of the light during the imaging process, reducing light spots, improving the image contrast of the low-light lens, and helping to improve image quality.

[0053] In this embodiment, the distance between the first lens 1 and the photosensitive chip 11 is T, and the focal length from the first lens 1 to the ninth lens 9 is F, wherein T / F < 1.74, so as to achieve a small volume of the low-light lens.

[0054] Specifically, the surface of the photosensitive chip 11 facing the object forms an image plane, which can be the surface of a camera element such as a CCD or CMOS. It is understood that the light carrying the information of the photographed object can pass through 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, and the ninth lens 9 in sequence, and finally form an image on the image plane.

[0055] Specifically, the refractive index, radius of curvature, and thickness interval of each lens in a specific embodiment of the low-light lens are shown in Table 1 below:

[0056] Table 1

[0057]

[0058]

[0059] Figure 2 This is a schematic diagram of the room temperature MTF curve of the low-light lens; Figure 3 A schematic diagram of the MTF curve of the low-light lens at -40℃; Figure 4 A schematic diagram of the MTF curve of the low-light lens at a temperature of +80℃.

[0060] As shown in the above figure, the low-light lens in this embodiment has a field-of-view MTF ≥ 0.5 at room temperature (40 lp) and a field-of-view MTF ≥ 0.3 at 0.8, resulting in high imaging quality. Moreover, the performance difference under various temperature conditions is not significant, and the consistency is good. It can achieve clear imaging at both high and low temperatures without focusing.

[0061] In summary, the low-light lens uses a large 1.7-inch target surface, with a maximum image area of ​​29mm and a field of view of approximately 38°. It offers high resolution and a wider observation range. Furthermore, the lens has a large aperture (#F≤1.4), compared to other products with #F≥1.6, resulting in greater light transmission and clear imaging even in low light. 4. The use of laminated glass away from the aperture stop effectively reduces chromatic aberration, distortion, and astigmatism. By rationally allocating lens power, the lens achieves clear imaging in environments ranging from -40℃ to +60℃, meeting the needs of applications in various temperature conditions. 5. The use of all-glass lenses ensures excellent lens stability, meeting military standards compared to other products using plastic lenses. The use of global surface lenses reduces product cost.

[0062] The technical specifications achievable by the low-light lens are as follows: imaging circle diameter Ф29mm; focal length: EFFL=44mm; F / #=1.4; field of view: 2w≥37.5°; operating spectral range: 480nm~1000nm; total optical length TTL≤76.8mm; back focal length ≥9.5mm; F-Tan (Theta) distortion ≤2.8%.

[0063] The present invention also provides a low-light camera, which includes the low-light lens described in the above technical solution. The specific structure of the low-light lens is as described in the above embodiments. Since the low-light lens of this invention adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be described in detail here.

[0064] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention's specification and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A low-light lens, characterized in that, The low-light lens has an object side and an image side arranged opposite each other along the optical axis. The low-light lens includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens, a ninth lens, and a photosensitive chip, arranged sequentially from the object side to the image side. There are only nine lenses. The low-light lens satisfies the following conditions: 2 <f1 / f<3;1<f2 / f<2;-1<f3 / f<-0.5;1<f4 / f<2;1<f5 / f<2;0<f6 / f<1;-1<f7 / f<0;0<f8 / f<1;-1<f9 / f<0; Wherein, the total focal length of the low-light lens is f, the focal length of the first lens is f1, the focal length of the second lens is f2, the focal length of the third lens is f3, the focal length of the fourth lens is f4, the focal length of the fifth lens is f5, the focal length of the sixth lens is f6, the focal length of the seventh lens is f7, the focal length of the eighth lens is f8, and the focal length of the ninth lens is f9.

2. The low-light lens as described in claim 1, characterized in that, The first lens is a meniscus lens, with its concave surface facing the image side; The second lens is a meniscus lens, with its concave surface facing the image side; The third lens is a biconcave lens; The fourth lens is a meniscus lens, with its concave surface facing the image side; The fifth lens is a biconvex lens; The sixth lens is a biconvex lens; The seventh lens is a biconcave lens; The eighth lens is a biconvex lens; The ninth lens is a meniscus lens, with its concave surface facing the object side.

3. The low-light lens as described in claim 1, characterized in that, 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 are all spherical lenses.

4. The low-light lens as described in claim 1, characterized in that, 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 are all glass lenses.

5. The low-light lens as described in claim 1, characterized in that, The low-light lens also meets the following conditions: 40.0<vd1<60.0; 70.0<vd2<85.0; 15.0<vd3<35.0; 15.0<vd4<30.0; 35.0<vd 5<55.0; 60.0<vd6<80.0; 15.0<vd7<35.0; 30.0<vd8<50.0; 30.0<vd9<50.0; Wherein, the dispersion coefficient of the first lens is vd1, the dispersion coefficient of the second lens is vd2, the dispersion coefficient of the third lens is vd3, the dispersion coefficient of the fourth lens is vd4, the dispersion coefficient of the fifth lens is vd5, the dispersion coefficient of the sixth lens is vd6, the dispersion coefficient of the seventh lens is vd7, the dispersion coefficient of the eighth lens is vd8, and the dispersion coefficient of the ninth lens is vd9.

6. The low-light lens as described in claim 1, characterized in that, The sixth lens and the seventh lens are cemented together to form a cemented lens.

7. The low-light lens as described in claim 1, characterized in that, The low-light lens also includes an aperture stop, which is located between the third lens and the fourth lens.

8. The low-light lens as described in claim 1, characterized in that, The distance between the first lens and the photosensitive chip is T, and the focal length from the first lens to the ninth lens is F, where T / F < 1.

74.

9. A low-light camera, characterized in that, The low-light lens as described in any one of claims 1 to 8.

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