Long-focal-length low-light night vision optical lens and electronic equipment

Abstract

The invention discloses a long-focal-length low-light night vision optical lens and electronic equipment. The lens sequentially comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens and a seventh lens from the object side to the image side. The second lens and the third lens are mutually glued to form a first doublet lens, and the fourth lens and the fifth lens are mutually glued to form a second doublet lens; the first lens has positive diopter, and the object side surface is a convex surface; the second lens has positive diopter, the object side surface is a convex surface, and the image side surface is a convex surface; the third lens has negative diopter, the object side surface is a concave surface, and the image side surface is a concave surface; the fourth lens has positive diopter; the fifth lens has negative diopter, the object side surface is a concave surface, and the image side surface is a concave surface; the sixth lens has positive diopter, the object side surface is a convex surface, and the image side surface is a convex surface; the seventh lens has negative diopter, the object side surface is a concave surface, and the image side surface is a convex surface. According to the scheme, the positive and negative diopter lenses are reasonably matched, and the doublet lens is arranged, so that chromatic aberration is effectively corrected, and confocal of visible light and infrared light is realized.

Description

Technical Field

[0001] The invention relates to the technical field of night vision optical lenses, and in particular to a long-focal-length low-light-level night vision optical lens and electronic equipment. Background Art

[0002] A long focal length low light level night vision optical lens is an optical lens specially designed for long-distance observation in low light conditions (such as at night or in low light environments). This lens usually has a longer focal length and a larger relative aperture to ensure that it can capture enough light in low light environments to provide a clear image. Existing long focal length low light level night vision optical lenses have at least one of the following disadvantages:

[0003] 1) Chromatic aberration of long focal length lenses is difficult to control, and the focus shift of visible light and infrared light is large;

[0004] 2) Long focal length lenses have low light transmission, low energy utilization, and poor reflection effect;

[0005] 3) Conventional lenses are prone to losing focus when using telephoto lenses in high and low temperature environments;

[0006] 4) The resolution of telephoto lenses is uneven, with a large gap between the center and the edges. Summary of the invention

[0007] In view of this, the purpose of the present invention is to provide a long focal length low light level night vision optical lens and electronic equipment. The lens can solve at least one technical disadvantage mentioned in the background technology.

[0008] According to one aspect of the present invention, there is provided a long focal length low light level night vision optical lens, wherein the lens comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, and a seventh lens in order from the object side to the image side; the second lens and the third lens are glued together to form a first double glued lens, and the fourth lens and the fifth lens are glued together to form a second double glued lens;

[0009] The first lens has positive refractive power, and the object side surface is convex; the second lens has positive refractive power, the object side surface is convex, and the image side surface is convex; the third lens has negative refractive power, the object side surface is concave, and the image side surface is concave; the fourth lens has positive refractive power; the fifth lens has negative refractive power, the object side surface is concave, and the image side surface is concave; the sixth lens has positive refractive power, the object side surface is convex, and the image side surface is convex; the seventh lens has negative refractive power, the object side surface is concave, and the image side surface is convex.

[0010] In the above technical scheme, this scheme adopts the reasonable combination of positive and negative refractive lenses and the setting of double glued lenses to effectively correct chromatic aberration and achieve confocality of visible light and infrared light. In the optical system, chromatic aberration is one of the important factors affecting the imaging quality, especially in wide-spectrum imaging. The design of the lens enables light of different wavelengths to be focused on the same plane, so that clear and accurate imaging can be obtained in the entire spectrum range, meeting the needs of special application scenarios such as low-light night vision for wide-spectrum imaging, and maintaining good imaging effects regardless of the visible light environment during the day or the infrared light environment at night. The lens group design of the lens of this scheme is conducive to achieving a large amount of light. The reasonable layout and convex shape of the positive refractive lens can enable more light to enter the lens and converge on the imaging plane, thereby improving the brightness of the image. In addition, the reasonable combination of lenses and the optimization of optical focal length reduce the loss of light during propagation, improve the light transmittance, and further enhance the brightness and uniformity of the image. The lens can capture more light information in a low-light environment, making the image clearer and brighter, which helps to observe the target object at night or in a dimly lit environment and improve the night vision effect. The lens of this solution can maintain stable imaging performance in an environment of -40℃ to 85℃, thanks to its athermal design. By reasonably selecting lens materials, optimizing lens shape and focal power distribution, the lens can automatically compensate for the impact of temperature changes in different temperature environments and maintain a stable focus state and imaging quality. The reasonable design of the lens group and the precise control of the focal power of this solution enable the lens to achieve high-resolution and high-pixel imaging effects. The mutual cooperation of positive and negative refractive power lenses and the correction effect of double-cemented lenses effectively reduce aberrations and improve the clarity and detail expression of imaging. At the same time, the lens focuses on the uniformity of image quality in the central field of view and the edge field of view during the design process. By optimizing the lens shape, focal power distribution, and the convergence and divergence characteristics of light, the imaging quality in the entire field of view is kept consistent. This makes the lens not only have a clear image in the central area when observing the target object, but also have a high resolution and clarity in the edge area, providing users with more complete and accurate visual information.

[0011] In some embodiments, the lens satisfies the following relationship:

[0012] -1.3<f2 / f3<-0.8

[0013] Where f2 is the focal length of the second lens, and f3 is the focal length of the third lens.

[0014] In the above technical solution, in the optical system, when light of different wavelengths passes through the lens, different focal lengths will be generated due to the difference in refractive index, which will lead to chromatic aberration. By accurately selecting the ratio of positive and negative focal lengths, the focal length difference of light of different wavelengths can be compensated after passing through the second and third lenses, thereby effectively reducing chromatic aberration. When the focal length ratio is in the range of -1.3<f2 / f3<-0.8, it can be ensured that in the combination of the second and third lenses, light of different wavelengths is properly converged and diverged, so that chromatic aberration is effectively corrected. If the ratio exceeds this range, the chromatic aberration correction effect may be reduced, thereby affecting the image quality. Under the condition that the focal length ratio satisfies -1.3<f2 / f3<-0.8, the light can be more accurately focused on the imaging plane after passing through the second and third lenses, thereby improving the clarity and resolution of the image. In addition to chromatic aberration, other types of aberrations, such as spherical aberration, coma, etc., will also affect the resolution of the image. By reasonably selecting the focal length ratio, these aberrations can be controlled to a certain extent, making the image clearer.

[0015] In some embodiments, the lens satisfies the following relationship:

[0016] |Vd2-Vd3|>40

[0017] Wherein, Vd2 is the dispersion coefficient of the second lens, and Vd3 is the dispersion coefficient of the third lens.

[0018] In the above technical solution, in the design of day and night confocal lens, the imaging quality of visible light and infrared light must be taken into account. Visible light and infrared light have different wavelength ranges and their dispersion characteristics are also different. By selecting materials with significantly different dispersion coefficients, it can be ensured that light can be accurately focused in the visible light and infrared light bands, thereby achieving day and night confocal.

[0019] In some embodiments, the lens satisfies the following relationship:

[0020] Vd1>50

[0021] Wherein, Vd1 is the dispersion coefficient of the first lens.

[0022] In the above technical solution, in the day and night confocal lens design, the first lens uses low-dispersion material. Low-dispersion materials, that is, materials with high Abbe numbers, can effectively reduce chromatic aberration, allowing light of different wavelengths to focus more accurately on the same plane after passing through the lens, thereby improving the clarity and quality of imaging. In the visible light and infrared light bands, the application of low-dispersion materials can ensure that light is accurately focused and achieve day and night confocality. In this way, the lens can maintain clear imaging effects both during the day (visible light) and at night (infrared light), without the need to adjust the focal length when switching between day and night.

[0023] In some embodiments, the lens satisfies the following relationship:

[0024] nd4>1.8, 0.5<f4 / f<1.2, -0.8<f5 / f<-0.2

[0025] In the formula, nd4 is the refractive index of the fourth lens, f4 is the focal length of the fourth lens, f5 is the focal length of the fifth lens, and f is the focal length of the lens.

[0026] In the above technical solution, in the design of this lens, the fourth lens is made of high refractive index material. High refractive index materials can significantly improve the optical power of the lens. Under the same curvature radius, the lens has a stronger ability to converge or diverge light. This is conducive to designing a lens with a smaller aperture while ensuring the required focal length and imaging quality. The fourth lens assumes the key convergence function in the lens, and the ratio of its focal length to the focal length of the entire lens is set to 0.5 to 1.2. This ratio range ensures that the fourth lens converges the light just right, and will not cause the increase of aberrations due to excessive convergence, nor will it affect the brightness and clarity of the image due to too weak convergence, which is conducive to achieving day and night confocality. The ratio of the focal length of the fifth lens to the focal length of the entire lens is set to -0.8 to -0.2. This ratio range ensures that the fifth lens can effectively correct aberrations while avoiding excessive influence on the convergence position of light, which is conducive to achieving day and night confocality. In the above design, the reasonable combination of the fourth lens and the fifth lens can effectively correct aberrations. The high refractive index fourth lens enhances the convergence of light, while the negative focal length fifth lens moderately diverges the light. The two work together to reduce aberrations and improve the clarity and quality of imaging. The focal length ratio range of the fourth lens and the fifth lens ensures that the convergence and divergence of light in the lens are moderate, which helps to achieve focal length control and image quality optimization of the entire lens. The parameter relationship between the fourth lens and the fifth lens ensures that clear imaging effects can be maintained under different lighting conditions (visible light and infrared light). By optimizing the refractive index and focal length ratio of the lens, confocality can be achieved day and night, thereby improving the applicability and reliability of the lens.

[0027] In some embodiments, the lens satisfies the following relationship:

[0028] 0.3<f6 / f<0.7

[0029] Wherein, f6 is the focal length of the sixth lens, and f is the focal length of the lens.

[0030] In the above technical solution, by reasonably allocating the refractive power of the sixth lens, the focusing point of visible light and infrared light can be effectively controlled. When light of different wavelengths passes through the lens, different focusing positions will be produced due to the difference in refractive index. By reasonably selecting the focal length ratio of the sixth lens, it can be ensured that visible light and infrared light can be better focused on the same plane after passing through the sixth lens, thereby achieving day and night confocality. Specifically, the focal length ratio of the sixth lens should be within the above range to ensure that its convergence ability is moderate. The lower limit of the range ensures that the sixth lens has sufficient convergence ability to avoid excessive divergence of light, affecting the brightness and clarity of the image; the upper limit ensures that the sixth lens does not converge light too strongly, preventing the increase of aberrations and affecting the image quality.

[0031] In some embodiments, the lens satisfies the following relationship:

[0032] -1.2<f7 / f<-0.5

[0033] Wherein, f7 is the focal length of the seventh lens, and f is the focal length of the lens.

[0034] In the above technical solution, the seventh lens is a negative focal length lens, that is, it has a divergent effect. This ratio range ensures that the divergence of the light by the seventh lens is moderate. Specifically, the lower limit of the ratio range ensures that the seventh lens has sufficient divergence ability to prevent excessive convergence of light, thereby affecting the brightness and clarity of the image; while the upper limit limits the divergence intensity of the seventh lens to avoid increased aberrations due to excessive divergence, thereby damaging the image quality. By reasonably allocating the refractive power of the seventh lens, the focusing points of visible light and infrared light can be effectively regulated. Since light of different wavelengths produces different focusing positions due to differences in refractive index when passing through the lens, the focal length ratio of the seventh lens is within the above range, which can ensure that visible light and infrared light can be more accurately focused on the same plane after passing through the seventh lens, thereby achieving day and night confocality.

[0035] In some embodiments, the second lens and the sixth lens are made of a material having a negative relative refractive index temperature coefficient.

[0036] In the above technical solution, in the design of this lens, the second lens and the sixth lens are selected to use materials with negative relative refractive index temperature coefficients, which can ensure that the lens can maintain stable imaging quality under different temperature conditions. This design can significantly reduce the impact of temperature changes on imaging quality and improve the applicability and reliability of the lens.

[0037] In some embodiments, the lens satisfies the following relationship:

[0038] -20<R 71 <0

[0039] In the formula, R 71is the radius of curvature of the object side of the seventh lens.

[0040] In the above technical solution, in the present lens design, the object side surface of the seventh lens is designed to be concave (negative curvature radius), and this design can effectively optimize the field curvature. Field curvature is one of the common aberrations in optical systems, which manifests itself as the imaging plane is not an ideal plane, but curved. By designing the object side surface of the seventh lens to be concave, the field curvature can be corrected, so that the imaging plane is closer to the ideal plane, thereby improving the imaging quality. When the field curvature is corrected, the imaging quality in the entire field of view is more uniform, and the imaging clarity in the edge area is also improved. In the design of day and night confocal lenses, optimizing the field curvature can ensure clear imaging under different lighting conditions (visible light and infrared light). By optimizing the radius of curvature of the lens, day and night confocality can be achieved, improving the applicability and reliability of the lens. The above range is to find a balance between correcting field curvature and controlling other aberrations. If R 71 If R is too small, other aberrations such as spherical aberration and coma may be introduced, affecting the image quality. 71 If it is too large, the field curvature correction effect is not obvious. The curvature radius within this range can ensure the processing accuracy and quality of the lens. A curvature radius that is too small may increase the processing difficulty and affect the manufacturing cost and quality of the lens. Specifically, in the above range, the lower limit ensures that the object side of the seventh lens has moderate concavity and is not too curved. If it is too small (that is, the concavity is too large), it may cause excessive divergence of light, increase aberrations, and affect imaging quality. The upper limit ensures that the object side of the seventh lens is concave and has the ability to diverge light, thereby effectively correcting field curvature.

[0041] According to another aspect of the present invention, there is provided an electronic device, comprising: a long focal length low-light-level night vision optical lens as described above; and an image sensor configured to receive an image formed by the long focal length low-light-level night vision optical lens.

[0042] In the above technical solution, the advantages of the electronic device rely on the long focal length low light level night vision optical lens, which will not be elaborated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art 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.

[0044] Figure 1 It is a structural schematic diagram of Example 1 of a long focal length low light level night vision optical lens of the present invention;

[0045] Figure 2 This is a visible light MTF diagram of Example 1 of a long focal length low light level night vision optical lens of the present invention;

[0046] Figure 3 It is an infrared light MTF diagram of Example 1 of a long focal length low light level night vision optical lens of the present invention;

[0047] Figure 4 is a relative illumination diagram of Example 1 of a long focal length low light level night vision optical lens of the present invention;

[0048] Figure 5 is a chromatic aberration curve diagram of Example 1 of a long focal length low light level night vision optical lens of the present invention;

[0049] Figure 6 It is a structural schematic diagram of Example 2 of a long focal length low light level night vision optical lens of the present invention;

[0050] Figure 7 is a visible light MTF diagram of Example 2 of a long focal length low light level night vision optical lens of the present invention;

[0051] Figure 8 It is an infrared light MTF diagram of Example 2 of a long focal length low light level night vision optical lens of the present invention;

[0052] Fig. 9 is a relative illumination diagram of Example 2 of a long focal length low light level night vision optical lens of the present invention;

[0053] Fig.10 is a chromatic aberration curve diagram of Example 2 of a long focal length low light level night vision optical lens of the present invention;

[0054] Fig.11 It is a structural schematic diagram of Example 3 of a long focal length low light level night vision optical lens of the present invention;

[0055] Fig.12 is a visible light MTF diagram of Example 3 of a long focal length low light level night vision optical lens of the present invention;

[0056] Fig.13 It is an infrared light MTF diagram of Example 3 of a long focal length low light level night vision optical lens of the present invention;

[0057] Fig.14 is a relative illumination diagram of Example 3 of a long focal length low light level night vision optical lens of the present invention;

[0058] Fig.15 is a chromatic aberration curve diagram of Example 3 of a long focal length low light level night vision optical lens of the present invention;

[0059] Fig.16 It is a structural schematic diagram of Example 4 of a long focal length low light level night vision optical lens of the present invention;

[0060] Fig.17 is a visible light MTF diagram of Example 4 of a long focal length low light level night vision optical lens of the present invention;

[0061] Fig.18 It is an infrared light MTF diagram of Example 4 of a long focal length low light level night vision optical lens of the present invention;

[0062] Fig.19 is a relative illumination diagram of Example 4 of a long focal length low light level night vision optical lens of the present invention;

[0063] Fig. 20 is a chromatic aberration curve diagram of Example 4 of a long focal length low light level night vision optical lens of the present invention;

[0064] Fig.21 It is a structural schematic diagram of an electronic device of the present invention. DETAILED DESCRIPTION

[0065] The present invention will be further described in detail below in conjunction with the accompanying drawings and examples. It is particularly noted that the following examples are only used to illustrate the present invention, but are not intended to limit the scope of the present invention. Similarly, the following examples are only partial embodiments of the present invention rather than all embodiments, and all other embodiments obtained by those of ordinary skill in the art without creative work are within the scope of protection of the present invention.

[0066] The purpose of the present invention is to provide a long focal length low light level night vision optical lens and electronic equipment with high optical performance. The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0067] Figure 1 , Figure 6 , Fig.11 , Fig.16 They are cross-sectional views of long focal length micro-light systems (optical systems) according to Examples 1 to 4, respectively. The long focal length micro-light systems according to each example are used for optical devices including imaging devices such as digital cameras, digital still cameras, broadcast cameras, surveillance cameras, and interchangeable lenses. In each cross-sectional view, the left side is the object side OBJ and the right side is the image side IMA. In each cross-sectional view, Gi represents the i-th group of cemented lenses, and Lj represents the j-th lens. ST represents an aperture (fixed aperture or visible aperture). IMA represents an image plane, and when the long focal length micro-light systems 1 to 4 according to each example are used for imaging optical systems of digital cameras or digital still cameras, a solid-state imaging element (photoelectric conversion element) such as a CMOS image sensor or a CCD image sensor is arranged on the imaging plane IMA.

[0068] According to each example, the long focal length low light night vision optical lens includes, in order from the object side to the image side: from the object side to the image side, the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, the aperture ST, and the seventh lens L7; the second lens L2 and the third lens L3 are glued to each other as the first double glued lens G1, and the fourth lens L4 and the fifth lens L5 are glued to each other as the second double glued lens G2; the second lens L2 and the sixth lens L6 are made of materials with negative relative refractive index temperature coefficients. In the design of this lens, the second lens and the sixth lens are selected to use materials with negative relative refractive index temperature coefficients, which can ensure that the lens can maintain stable imaging quality under different temperature conditions. This design can significantly reduce the impact of temperature changes on imaging quality and improve the applicability and reliability of the lens. The specific details of each lens are as follows: the first lens L1 has positive refractive power, and the object side surface is convex; the second lens L2 has positive refractive power, the object side surface is convex, and the image side surface is convex; the third lens L3 has negative refractive power, the object side surface is concave, and the image side surface is concave; the fourth lens L4 has positive refractive power; the fifth lens L5 has negative refractive power, the object side surface is concave, and the image side surface is concave; the sixth lens L6 has positive refractive power, the object side surface is convex, and the image side surface is convex; the seventh lens L7 has negative refractive power, the object side surface is concave, and the image side surface is convex. The long focal length low light level night vision optical lens according to each example can meet at least one of the following setting conditions 1) to 7):

[0069] 1)-1.3<f2 / f3<-0.8

[0070] 2)|Vd2-Vd3|>40

[0071] 3) Vd1>50

[0072] 4)nd4>1.8, 0.5<f4 / f<1.2, -0.8<f5 / f<-0.2

[0073] 5)0.3<f6 / f<0.7

[0074] 6)-1.2<f7 / f<-0.5

[0075] 7) -20<R 71 <0

[0076] In the above conditional formula, f2 is the focal length of the second lens, f3 is the focal length of the third lens, Vd2 is the dispersion coefficient of the second lens, Vd3 is the dispersion coefficient of the third lens, Vd1 is the dispersion coefficient of the first lens, nd4 is the refractive index of the fourth lens, f4 is the focal length of the fourth lens, f5 is the focal length of the fifth lens, f is the focal length of the lens, f6 is the focal length of the sixth lens, f is the focal length of the lens, f7 is the focal length of the seventh lens, f is the focal length of the lens, R 71is the radius of curvature of the object side of the seventh lens.

[0077] Conditional equation 1) defines the focal length ratio of the second and third lenses. In an optical system, when light of different wavelengths passes through a lens, different focal lengths will be generated due to differences in refractive index, which will lead to chromatic aberration. By accurately selecting the ratio of positive and negative focal lengths, the focal length differences of light of different wavelengths can be compensated after passing through the second and third lenses, thereby effectively reducing chromatic aberration. When the focal length ratio is within the range of -1.3<f2 / f3<-0.8, it can be ensured that in the combination of the second and third lenses, light of different wavelengths is properly converged and diverged, so that chromatic aberration is effectively corrected. If the ratio exceeds this range, the chromatic aberration correction effect may be reduced, thereby affecting the image quality. Under the condition that the focal length ratio satisfies -1.3<f2 / f3<-0.8, the light can be more accurately focused on the imaging plane after passing through the second and third lenses, thereby improving the clarity and resolution of the image. In addition to chromatic aberration, other types of aberrations, such as spherical aberration, coma, etc., will also affect the resolution of the image. By properly selecting the focal length ratio, these aberrations can be controlled to a certain extent, making the image clearer.

[0078] Conditional equation 2) defines the difference in dispersion coefficient between the second and third lenses. In the design of day-night confocal lenses, the imaging quality of visible light and infrared light must be taken into account. Visible light and infrared light have different wavelength ranges and their dispersion characteristics are also different. By selecting materials with significantly different dispersion coefficients, it can be ensured that light can be accurately focused in the visible light and infrared light bands, thereby achieving day-night confocality.

[0079] Conditional equation 2) defines the difference in dispersion coefficient between the second and third lenses. In the design of day-night confocal lenses, the imaging quality of visible light and infrared light must be taken into account. Visible light and infrared light have different wavelength ranges and their dispersion characteristics are also different. By selecting materials with significantly different dispersion coefficients, it can be ensured that light can be accurately focused in the visible light and infrared light bands, thereby achieving day-night confocality.

[0080] Conditional equation 3) defines the dispersion coefficient of the first lens. In the design of the day-night confocal lens, the first lens uses low-dispersion material. Low-dispersion materials, that is, materials with high Abbe numbers, can effectively reduce chromatic aberration, allowing light of different wavelengths to focus more accurately on the same plane after passing through the lens, thereby improving the clarity and quality of imaging. In the visible and infrared light bands, the application of low-dispersion materials can ensure that light is accurately focused and achieve day-night confocality. In this way, the lens can maintain clear imaging effects both during the day (visible light) and at night (infrared light), without the need to adjust the focal length when switching between day and night.

[0081] Conditional formula 4) defines the refractive index of the fourth lens, the ratio of the focal length of the fourth lens to the focal length of the entire lens, and the ratio of the focal length of the fifth lens to the focal length of the entire lens. In the design of this lens, the fourth lens is made of high refractive index material. High refractive index materials can significantly improve the optical power of the lens. Under the same curvature radius, the lens has a stronger ability to converge or diverge light. This is conducive to designing a lens with a smaller aperture while ensuring the required focal length and imaging quality. The ratio range of the focal length of the fourth lens to the focal length of the entire lens ensures that the fourth lens converges the light to the right degree, and neither the aberration increases due to excessive convergence nor the brightness and clarity of the image is affected due to weak convergence, which is conducive to achieving day and night confocality. The ratio range of the focal length of the fifth lens to the focal length of the entire lens ensures that the fifth lens can effectively correct aberrations while avoiding excessive influence on the convergence position of light, which is conducive to achieving day and night confocality. The reasonable combination of the fourth lens and the fifth lens can effectively correct aberrations. The high refractive index fourth lens enhances the convergence of light, while the negative focal length fifth lens moderately diverges the light. The two work together to reduce aberrations and improve the clarity and quality of imaging. The focal length ratio range of the fourth lens and the fifth lens ensures that the convergence and divergence of light in the lens are moderate, which helps to achieve focal length control and image quality optimization of the entire lens. The parameter relationship between the fourth lens and the fifth lens ensures that clear imaging effects can be maintained under different lighting conditions (visible light and infrared light). By optimizing the refractive index and focal length ratio of the lens, confocality can be achieved day and night, thereby improving the applicability and reliability of the lens.

[0082] Conditional formula 5) defines the ratio of the focal length of the sixth lens to the focal length of the entire lens. By reasonably allocating the refractive power of the sixth lens, the focusing points of visible light and infrared light can be effectively controlled. When light of different wavelengths passes through the lens, different focal positions will be produced due to the difference in refractive index. By reasonably selecting the focal length ratio of the sixth lens, it can be ensured that visible light and infrared light can be better focused on the same plane after passing through the sixth lens, thereby achieving day and night confocality. Specifically, the focal length ratio of the sixth lens should be within the above range to ensure that its convergence ability is moderate. The lower limit of the range ensures that the sixth lens has sufficient convergence ability to avoid excessive divergence of light, affecting the brightness and clarity of the image; the upper limit ensures that the sixth lens does not converge light too strongly, preventing the increase of aberrations and affecting the image quality.

[0083] Conditional formula 6) defines the ratio of the focal length of the seventh lens to the focal length of the entire lens. The seventh lens is a negative focal length lens, that is, it has a divergent effect. This ratio range ensures that the divergence of the light by the seventh lens is moderate. Specifically, the lower limit of the ratio range ensures that the seventh lens has sufficient divergence ability to prevent excessive convergence of light, thereby affecting the brightness and clarity of the image; while the upper limit limits the divergence intensity of the seventh lens to avoid increased aberrations due to excessive divergence, thereby damaging the image quality. By reasonably allocating the refractive power of the seventh lens, the focusing points of visible light and infrared light can be effectively regulated. Since light of different wavelengths produces different focusing positions due to differences in refractive index when passing through the lens, the focal length ratio of the seventh lens is within the above range, which can ensure that visible light and infrared light can be more accurately focused on the same plane after passing through the seventh lens, thereby achieving day and night confocality.

[0084] Conditional equation 7) defines the radius of curvature of the object side of the seventh lens. The object side of the seventh lens is designed to be concave (negative curvature radius). This design can effectively optimize the field curvature. Field curvature is one of the common aberrations in optical systems, which manifests itself as the imaging plane is not an ideal plane, but curved. By designing the object side of the seventh lens to be concave, the field curvature can be corrected, making the imaging plane closer to the ideal plane, thereby improving the imaging quality. When the field curvature is corrected, the imaging quality in the entire field of view is more uniform, and the imaging clarity in the edge area is also improved. In the design of day and night confocal lenses, optimizing the field curvature can ensure clear imaging under different lighting conditions (visible light and infrared light). By optimizing the radius of curvature of the lens, day and night confocality can be achieved, improving the applicability and reliability of the lens. The above range is to find a balance between correcting field curvature and controlling other aberrations. If R 71 If R is too small, other aberrations such as spherical aberration and coma may be introduced, affecting the image quality. 71 If it is too large, the field curvature correction effect is not obvious. The curvature radius within this range can ensure the processing accuracy and quality of the lens. A curvature radius that is too small may increase the processing difficulty and affect the manufacturing cost and quality of the lens. Specifically, in the above range, the lower limit ensures that the object side of the seventh lens has moderate concavity and is not too curved. If it is too small (that is, the concavity is too large), it may cause excessive divergence of light, increase aberrations, and affect imaging quality. The upper limit ensures that the object side of the seventh lens is concave and has the ability to diverge light, thereby effectively correcting field curvature.

[0085] A detailed description will now be given of lenses according to various examples.

[0086] For the optical structure of Example 1, please refer to Figure 1 Specific parameters of Example 1 are shown in Table 1 and Table 2. In Example 1, the focal length of the lens is f=65.

[0087] Table 1 Example 1 Parameters

[0088] Surface number surface Radius of curvature interval Material Refractive Index Dispersion coefficient focal length 1 First lens 67.039 4.98 Glass 1.61 56.67 110 2 Infinity 0.21 3 Second lens 29.884 9.80 Glass 1.50 81.59 42.8 4 The third lens -66.299 3.59 Glass 1.78 25.72 -41.5 5 66.299 5.81 6 The fourth lens Infinity 5.09 Glass 1.95 17.94 43.6 7 Fifth lens -41.661 3.74 Glass 1.60 38.01 -20.5 8 18.421 1.44 9 The sixth lens 18.966 8.42 Glass 1.59 68.35 30.2 10 -276.932 1.37 11 Aperture Infinity 19.04 12 Seventh lens -13.846 1.36 Glass 1.78 25.72 -61.1 13 -20.255 8.39 14 Optical Filters Infinity 0.65 Glass 1.52 64.21 15 Infinity 0.42 16 Image plane Infinity

[0089] Table 2 Example 1 Conditional Parameter Table

[0090] System focal length f FNO Field of view FOV Like high H Total length TTL 65 1.7 7.5 8.8 74.29 Back focus BFL Second lens focal length Third lens focal length f2 / f3 Fourth lens focal length 9.46 42.8 -41.5 -1.031325301 43.6 Fifth lens focal length Sixth lens focal length f4 / f f5 / f f6 / f -20.5 30.2 0.670769231 -0.315384615 0.464615385 Seventh lens focal length f7 / f R71 R72 -61.1 -0.94 -13.8456 -20.25458

[0091] See also Figure 2 , Example 1 lens MTF diagram under visible light 435-650nm, the MTF value is greater than 0.4 at 160lp / mm, indicating that this example has high resolution and good image quality. Figure 3 , Example 1 lens MTF diagram at night 850-940nm, the MTF value is greater than 0.3 at 160lp / mm, indicating that this example has high resolution and good image quality at night. Figure 4 , Example 1 lens relative illumination diagram, it can be seen that the lens relative illumination is greater than 90%. Please refer to Figure 5 , the chromatic aberration curve of the lens in Example 1 shows that the magnification chromatic aberration and coma at a wavelength of 435-650nm are well corrected, meeting the pixel requirements.

[0092] For the optical structure of Example 2, please refer to Figure 6 It should be noted that the image plane IMA is close to the protective sheet and is relatively close, which is not obvious in the figure. The specific parameters of Example 2 are shown in Tables 3 and 4. In Example 2, the focal length of the lens is f=67.

[0093] Table 3 Example 2 Parameters

[0094] Surface number surface Radius of curvature interval Material Refractive Index Dispersion coefficient focal length 1 First lens 58.166 5.51 Glass 1.61 56.67 103.1 2 757.835 0.19 3 Second lens 29.824 10.33 Glass 1.50 81.59 41.7 4 The third lens -60.572 1.02 Glass 1.78 25.72 -39.2 5 63.780 2.70 6 The fourth lens -751.552 8.23 Glass 1.95 17.94 45.2 7 Fifth lens -41.019 1.16 Glass 1.60 38.01 -23.2 8 21.650 2.70 9 The sixth lens 22.460 8.08 Glass 1.59 68.35 34.8 10 -230.568 0.16 11 Aperture Infinity 24.28 12 Seventh lens -13.780 1.79 Glass 1.78 25.72 -68.7 13 -19.525 9.64 14 Optical Filters Infinity 0.65 Glass 1.52 64.21 15 Infinity 0.00 16 Image plane Infinity

[0095] Table 4 Example 2 Conditional Parameter Table

[0096] System focal length f FNO Field of view FOV Like high H Total length TTL 67 1.7 7.4 8.8 76.44 Back focus BFL Second lens focal length Third lens focal length f2 / f3 Fourth lens focal length 10.29 41.7 -39.2 -1.06377551 45.2 Fifth lens focal length Sixth lens focal length f4 / f f5 / f f6 / f -23.2 34.8 0.674626866 -0.346268657 0.519402985 Seventh lens focal length f7 / f R71 R72 -68.7 -1.025373134 -13.77987 -19.52537

[0097] See also Figure 7 , Example 2 lens MTF diagram under visible light 435-650nm, the MTF value is greater than 0.4 at 160lp / mm, indicating that this example has high resolution and good image quality. Figure 8 , Example 2 lens MTF diagram at night 850-940nm, the MTF value is greater than 0.4 at 160lp / mm, indicating that this example has high resolution and good image quality at night. Fig. 9 , Example 2 lens relative illumination diagram, it can be seen that the lens relative illumination is greater than 90%. Please refer to Fig.10 , the chromatic aberration curve of the lens in Example 2 shows that the magnification chromatic aberration and coma at a wavelength of 435-650nm are well corrected, meeting the pixel requirements.

[0098] For the optical structure of Example 3, please refer to Fig.11 Specific parameters of Example 3 are shown in Table 5 and Table 6. In Example 3, the focal length of the lens is f=66.

[0099] Table 5 Example 3 parameter table

[0100] Surface number surface Radius of curvature interval Material Refractive Index Dispersion coefficient focal length 1 First lens 40.862 8.50 Glass 1.50 81.59 66.1 2 -157.397 0.09 3 Second lens 30.726 9.49 Glass 1.50 81.59 39.4 4 The third lens -48.608 3.35 Glass 1.78 25.72 -35.5 5 68.221 1.85 6 The fourth lens -225.606 3.59 Glass 1.95 17.94 57.3 7 Fifth lens -44.384 8.50 Glass 1.70 55.53 -19.6 8 21.475 4.86 9 The sixth lens 24.508 6.18 Glass 1.52 64.21 29.1 10 -35.931 0.09 11 Aperture Infinity 16.45 12 Seventh lens -16.737 1.36 Glass 1.73 28.31 -41.5 13 -38.558 9.43 14 Optical Filters Infinity 0.65 Glass 1.52 64.21 15 Infinity 0.09 16 Image plane Infinity

[0101] Table 6 Example 3 Conditional Parameter Table

[0102] System focal length f FNO Field of view FOV Like high H Total length TTL 66 1.7 7.4 8.9 74.48 Back focus BFL Second lens focal length Third lens focal length f2 / f3 Fourth lens focal length 10.17 39.4 -35.5 -1.10986 57.3 Fifth lens focal length Sixth lens focal length f4 / f f5 / f f6 / f -19.6 29.1 0.868182 -0.29697 0.440909 Seventh lens focal length f7 / f R71 R72 -41.5 -0.62879 -16.737 -38.5583

[0103] See also Fig.12 , the MTF diagram of the lens in Example 3 under visible light 435-650nm, the MTF value is greater than 0.4 at 160lp / mm, indicating that this example has high resolution and good imaging quality. Fig.13 , Example 3 lens MTF diagram at night 850-940nm, the MTF value is greater than 0.4 at 160lp / mm, indicating that this example has high resolution and good image quality at night. Fig.14 , Example 3 lens relative illumination diagram, it can be seen that the lens relative illumination is greater than 90%. Please refer to Fig.15 , the chromatic aberration curve of the lens in Example 3 shows that the magnification chromatic aberration and coma at the wavelength of 435-650nm are well corrected, meeting the pixel requirements.

[0104] For the optical structure of Example 4, please refer to Fig.16 Specific parameters of Example 4 are shown in Tables 7 and 8. In Example 4, the focal length of the lens is f=64.

[0105] Table 7 Example 4 Parameters

[0106] Surface number surface Radius of curvature interval Material Refractive Index Dispersion coefficient focal length 1 First lens 46.751 6.17 Glass 1.59 68.62 80.2 2 2347.767 0.09 3 Second lens 28.972 9.14 Glass 1.44 95.10 47.7 4 The third lens -68.072 0.91 Glass 1.81 25.46 -47.8 5 90.331 2.56 6 The fourth lens Infinity 3.47 Glass 1.99 16.48 52.4 7 Fifth lens -52.278 9.14 Glass 1.67 32.18 -21.8 8 22.010 5.45 9 The sixth lens 22.506 5.44 Glass 1.52 58.96 32.9 10 -65.720 0.09 11 Aperture Infinity 18.97 12 Seventh lens -14.788 0.91 Glass 1.67 47.28 -44.8 13 -29.689 9.14 14 Optical Filters Infinity 0.64 Glass 1.52 64.21 15 Infinity 0.09 16 Image plane Infinity

[0107] Table 8 Example 4 Conditional Parameter Table

[0108] System focal length f FNO Field of view FOV Like high H Total length TTL 64 1.7 7.5 8.8 72.22 Back focus BFL Second lens focal length Third lens focal length f2 / f3 Fourth lens focal length 9.87 47.7 -47.8 -0.99791 52.4 Fifth lens focal length Sixth lens focal length f4 / f f5 / f f6 / f -21.8 32.9 0.81875 -0.34063 0.514063 Seventh lens focal length f7 / f R71 R72 -44.8 -0.7 -14.788 -29.6893

[0109] See also Fig.17 , the MTF diagram of the lens in Example 4 under visible light 435-650nm, the MTF value is greater than 0.4 at 160lp / mm, indicating that this example has high resolution and good imaging quality. Fig.18 , Example 4 lens MTF diagram at night 850-940nm, the MTF value is greater than 0.4 at 160lp / mm, indicating that this example has high resolution and good image quality at night. Fig.19 , Example 4 lens relative illumination diagram, it can be seen that the lens relative illumination is greater than 90%. Please refer to Fig. 20, the chromatic aberration curve of the lens in Example 4 shows that the magnification chromatic aberration and coma at a wavelength of 435-650nm are well corrected, meeting the pixel requirements.

[0110] Based on Examples 1 to 4, this case has the following specific advantages:

[0111] 1. The lens of this scheme has visible and infrared confocal, wide spectrum design and small chromatic aberration.

[0112] 2. The lens of this solution is designed with large light transmission, high relative illumination, sufficient and uniform brightness.

[0113] 3. The lens of this solution is designed to be non-thermal in an environment of -40℃ to 85℃.

[0114] 4. The lens of this solution has high resolution, high pixels, and uniform image quality in the center and edge fields of view.

[0115] Example 5

[0116] Reference Fig.21 , a description will be given of electronic device A according to Example 5 of the present invention. Fig.21 Schematic diagram of an electronic device (industrial line array camera) using any one of the long focal length low light level night vision optical lenses according to Examples 1 to 4 for an imaging optical system. Fig.21 , reference numeral A2 denotes an electronic device body, and reference numeral A1 denotes an imaging optical system (interchangeable lens) including any one of the long focal length low-light-level night vision optical lenses according to Examples 1 to 4. Reference numeral A3 denotes an image sensor (photoelectric conversion element) such as a CMOS image sensor or a CCD image sensor, which is built into the camera body A2 and receives light (optical image formed by the imaging optical system A1) from the imaging optical system A1 and performs photoelectric conversion. By using the long focal length low-light-level night vision optical lens according to any one of Examples 1 to 4 for an electronic device such as a digital still camera, an electronic device having a long focal length low-light-level night vision optical lens with high optical performance can be obtained. Each example can provide an electronic device with high optical performance.

[0117] While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments.The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

Claims

1. A long focal length low light level night vision optical lens, characterized in that: The lens comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens and a seventh lens in order from the object side to the image side; the second lens and the third lens are glued together to form a first double glued lens, and the fourth lens and the fifth lens are glued together to form a second double glued lens; The first lens has positive refractive power and a convex object side surface; The second lens has positive refractive power, an object side surface is convex, and an image side surface is convex; The third lens has negative refractive power, a concave object side surface and a concave image side surface; The fourth lens has positive refractive power; The fifth lens has negative refractive power, and its object side surface is concave and its image side surface is concave; The sixth lens has positive refractive power, an object side surface is convex, and an image side surface is convex; The seventh lens element has negative refractive power, a concave object-side surface, and a convex image-side surface.

2. The long focal length low light level night vision optical lens as claimed in claim 1, characterized in that: The lens satisfies the following relationship: -1.3<f2 / f3<-0.8 Where f2 is the focal length of the second lens, and f3 is the focal length of the third lens.

3. A long focal length low light level night vision optical lens as claimed in claim 1 or 2, characterized in that: The lens satisfies the following relationship: |Vd2-Vd3|>40 Wherein, Vd2 is the dispersion coefficient of the second lens, and Vd3 is the dispersion coefficient of the third lens.

4. The long focal length low light level night vision optical lens as claimed in claim 1, characterized in that: The lens satisfies the following relationship: Vd1>50 Wherein, Vd1 is the dispersion coefficient of the first lens.

5. The long focal length low light level night vision optical lens as claimed in claim 1, characterized in that: The lens satisfies the following relationship: nd4>1.8 0.5<f4 / f<1.2 -0.8<f5 / f<-0.2 In the formula, nd4 is the refractive index of the fourth lens, f4 is the focal length of the fourth lens, f5 is the focal length of the fifth lens, and f is the focal length of the lens.

6. The long focal length low light level night vision optical lens as claimed in claim 1, characterized in that: The lens satisfies the following relationship: 0.3<f6 / f<0.7 Wherein, f6 is the focal length of the sixth lens, and f is the focal length of the lens.

7. The long focal length low light level night vision optical lens as claimed in claim 1, characterized in that: The lens satisfies the following relationship: -1.2<f7 / f<-0.5 Wherein, f7 is the focal length of the seventh lens, and f is the focal length of the lens.

8. The long focal length low light level night vision optical lens as claimed in claim 1, characterized in that: The second lens and the sixth lens are made of a material with a negative relative refractive index temperature coefficient.

9. The long focal length low light level night vision optical lens as claimed in claim 1, characterized in that: The lens satisfies the following relationship: -20＜R 71 ＜0 In the formula, R 71 is the radius of curvature of the object side of the seventh lens.

10. An electronic device, characterized in that: A long focal length low light level night vision optical lens according to any one of claims 1 to 9; and The image sensor is configured to receive the image formed by the long-focal-length low-light-level night-vision optical lens.

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