Imaging lens
By designing a multi-lens combination and selecting materials, the problems of small field of view and focus drift at high and low temperatures in automotive imaging lenses have been solved, achieving imaging effects with a large field of view, low distortion, and stable temperature, making them suitable for automotive environments.
Patent Information
- Application Number
- CN202520304801.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-25
- Publication Date
- 2025-12-02
- Estimated Expiration
- 2035-02-25
AI Technical Summary
Existing vehicle-mounted imaging lenses have a small field of view, excessive F-Tan distortion, and are prone to focus loss at high and low temperatures, failing to meet the wide-angle monitoring and clear imaging requirements of vehicle-mounted lenses in high-temperature environments.
An imaging lens composed of multiple lenses was designed. By rationally controlling the optical power and material selection of the lenses, including the combination of negative refractive index, positive refractive index, refractive index and Abbe coefficient, high refractive index and low dispersion materials, especially high dispersion glass materials, are used to form a cemented lens to correct aberrations and chromatic aberrations. Special refractive index temperature coefficient materials are selected to reduce the effects of thermal expansion and contraction, thereby achieving miniaturization of the lens and stable imaging under high temperature environments.
It achieves imaging effects with a large field of view, low distortion and temperature stability. The lens is miniaturized and has high image quality, making it suitable for a variety of applications in the automotive environment.
Smart Images
Figure CN223624471U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the field of optical devices, and specifically relates to an imaging lens. Background Art
[0002] The vehicle-mounted imaging lens is a core component of the vehicle vision system and is widely used in fields such as autonomous driving, driving assistance, vehicle safety, and in-vehicle entertainment. There are at least one of the following defects in existing vehicle-mounted lenses: (1) The lens field angle is small and cannot meet the wide-angle monitoring requirements of vehicle-mounted lenses on the market; (2) The F-Tan(Theta) distortion of the vehicle-mounted lens with a field angle is too large, and the distortion is serious, affecting the observation of drivers or other personnel; (3) It is easy to defocus at high and low temperatures and cannot meet the requirement that the lens still maintains clear imaging under the actual use temperature environment of the vehicle-mounted lens. Summary of the Invention
[0003] The purpose of the utility model is to provide an imaging lens, aiming to overcome the problems existing in the prior art.
[0004] To achieve the purpose, the utility model provides the following technical solutions:
[0005] An imaging lens, which sequentially includes a first lens, a second lens, a third lens, an aperture stop, a fourth lens, a fifth lens, and a sixth lens from the object side to the image side;
[0006] The above-mentioned first lens has a negative refractive power, the object side is a convex surface, and the image side is a concave surface;
[0007] The above-mentioned second lens has a negative refractive power, the object side is a convex surface, and the image side is a concave surface;
[0008] The above-mentioned third lens has a positive refractive power, the object side is a convex surface, and the image side is a flat surface or a convex surface;
[0009] The above-mentioned fourth lens has a negative refractive power, the object side is a concave surface, and the image side is a concave surface;
[0010] The above-mentioned fifth lens has a positive refractive power, the object side is a convex surface, and the image side is a convex surface;
[0011] The above-mentioned sixth lens has a positive refractive power, the object side is a convex surface, and the image side is a convex surface.
[0012] Furthermore, the above-mentioned first lens is a negative-power meniscus hat-shaped lens and satisfies the following conditions: 1.5 < Nd1 < 1.6, 50 < Vd1 < 60; where Nd1 is the refractive index of the first lens and Vd1 is the Abbe number of the first lens.
[0013] The first lens can ensure a large optical aperture ratio, which is beneficial to compressing the front aperture of the optical system to achieve the miniaturization of the lens.
[0014] Furthermore, the second lens satisfies the following conditions: 1.55 < Nd2 < 1.65, 35 < Vd2 < 45; where Nd2 is the refractive index of the second lens and Vd2 is the Abbe number of the second lens.
[0015] The second lens has a light diverging effect, making the incident angle of the marginal field light on the subsequent optical elements smaller, achieving a large field of view imaging range, making the optical system structure compact and having a small volume, which is extremely beneficial to reducing the space occupied by the entire optical system.
[0016] Furthermore, the third lens satisfies the following conditions: 1.95 < Nd3 < 2.05, 25 < Vd3 < 30; where Nd3 is the refractive index of the third lens and Vd3 is the Abbe number of the third lens.
[0017] The third lens is made of a glass material with a high refractive index and high dispersion (i.e., low Abbe number), which helps to distribute the positive optical power of the third lens, reduce the sensitivity of the wide-angle optical lens, and improve the lens optical assembly yield.
[0018] Furthermore, the second lens and the third lens form a first cemented lens.
[0019] Furthermore, the fourth lens satisfies the following conditions: 1.8 < Nd4 < 1.9, 15 <vd4>25; where, Nd4 is the refractive index of the fourth lens, and Vd4 is the Abbe number of the fourth lens.
[0020] The fourth lens is made of a glass material with a high refractive index and low dispersion, which is beneficial for correcting secondary chromatic aberration and can improve the imaging quality.
[0021] Furthermore, the above-mentioned fifth lens satisfies the following conditions: 1.55 < Nd5 < 1.65, 65 < Vd5 < 70, and in the temperature range of -40°C to 105°C, dn / dT < -6*10E-6; where, Nd5 is the refractive index of the fifth lens, Vd5 is the Abbe number of the fifth lens, and dn / dT is the refractive index temperature coefficient.
[0022] The fifth lens is made of a material with a special refractive index temperature coefficient, which can effectively reduce the imaging surface shift caused by the thermal expansion and contraction of the lens structural parts, enabling the lens to not require additional focusing at different temperatures, increasing the consistency of the imaging performance clarity of the lens at different temperatures, balancing the temperature drift, and achieving the purpose of lens athermalization.
[0023] Furthermore, the fourth lens and the fifth lens form a second cemented lens, and Vd5 - Vd4 > 50. Using high- and low-dispersion materials in combination is beneficial for correcting secondary chromatic aberration, making the focal points of the cut-off long wavelength of 650nm and short wavelength of 435nm coincide on the optical axis, reducing the chromatic aberration and astigmatism of the imaging, and improving the imaging quality of the lens. Such an idea is extremely beneficial for the design of a wide-spectrum composite light lens.
[0024] Furthermore, the above-mentioned sixth lens satisfies the following conditions: 1.75 < Nd6 < 1.85, 40 < Vd6 < 50; where, Nd6 is the refractive index of the sixth lens, and Vd6 is the Abbe number of the sixth lens.
[0025] The sixth lens is made of a material with a high refractive index and high dispersion, which not only optimizes the optical performance of the lens, improves the imaging resolution, but also effectively reduces the outer diameter size at the rear end of the lens.
[0026] Through this design, the lens can meet the specification requirements of the M12 thread interface, thereby enhancing its application versatility in various imaging systems. The application of high-refractive-index materials enables the lens to achieve a more compact size design while maintaining high optical performance, which is of great significance for improving the integration and portability of the system.
[0027] The utility model has the following beneficial effects compared with the prior art:
[0028] This invention is particularly suitable for automotive applications. By rationally controlling the positive and negative combinations of the optical power of each lens, it can effectively balance the low-order aberrations of the lens. At the same time, it can reduce the lens's sensitivity to tolerances, maintaining the lens's miniaturization while ensuring image quality. Attached Figure Description
[0029] Figure 1 This is a schematic diagram of the optical path in the first embodiment of this utility model.
[0030] Figure 2 This is the MTF pattern of the first embodiment of the present invention at 435-650nm.
[0031] Figure 3 This is a distortion diagram of the first embodiment of this invention in the 435-650nm range. In the diagram, the left side shows the field curvature of the narrow beam, and the right side shows the distortion curve.
[0032] Figure 4 This is a relative illumination diagram at 555nm for the first embodiment of this utility model.
[0033] Figure 5 This is a schematic diagram of the optical path in the second embodiment of this utility model.
[0034] Figure 6 This is the MTF pattern of the second embodiment of the present invention at 435-650nm.
[0035] Figure 7 This is a distortion diagram of the second embodiment of this invention in the 435-650nm range. In the diagram, the left side shows the field curvature of the narrow beam, and the right side shows the distortion curve.
[0036] Figure 8 This is a relative illumination diagram at 555nm for the second embodiment of this utility model.
[0037] Figure 9 This is a schematic diagram of the optical path in the third embodiment of this utility model.
[0038] Figure 10 This is the MTF diagram of the third embodiment of the present invention at 435-650nm.
[0039] Figure 11 This is a distortion diagram of the third embodiment of this invention in the 435-650nm range. In the diagram, the left side shows the field curvature of the narrow beam, and the right side shows the distortion curve.
[0040] Figure 12 This is a relative illumination diagram at 555nm for the third embodiment of this utility model. Detailed Implementation
[0041] The following describes the specific embodiments of the present invention with reference to the accompanying drawings. To fully understand the present invention, many details are described below. However, for those skilled in the art, the present invention can be implemented without these details.
[0042] As Figure 1 , Figure 5 and Figure 9 shown, an imaging lens includes, in order from the object side to the image side, a first lens 1, a second lens 2, a third lens 3, an aperture stop 4, a fourth lens 5, a fifth lens 6, and a sixth lens 7. In addition, like existing imaging lenses, a filter 8 and a protective sheet 9 are provided after the sixth lens 7.
[0043] As Figure 1 , Figure 5 and Figure 9 shown, the first lens has a negative refractive power, with a convex object side surface and a concave image side surface.
[0044] Specifically, the first lens 1 is a negative meniscus lens with a hat shape and satisfies the following conditions: 1.5 < Nd1 < 1.6, 50 < Vd1 < 60; where Nd1 is the refractive index of the first lens and Vd1 is the Abbe number of the first lens.
[0045] The first lens 1 can ensure a large optical aperture ratio, which is beneficial for compressing the front aperture of the optical system to achieve miniaturization of the lens.
[0046] Of course, as the first glass lens of this imaging lens, since it needs to be exposed to the air, during the optical design stage, it is also necessary to consider improving the automotive-grade reliability and reliability of the system, and it needs to meet reliability tests such as automotive-grade ball drop and gravel drop. Therefore, during the design stage, it is also necessary to consider glass materials with excellent mechanical properties and chemical stability for the first lens 1.
[0047] As Figure 1 , Figure 5 and Figure 9 shown, the second lens 2 has a negative refractive power, with a convex object side surface and a concave image side surface.
[0048] Specifically, the second lens 2 is a negative doublet lens and satisfies the following conditions: 1.55 < Nd2 < 1.65, 35 < Vd2 < 45; where Nd2 is the refractive index of the second lens and Vd2 is the Abbe number of the second lens.
[0049] The second lens 2 has a light diverging effect, making the incident angle of the marginal field light on the subsequent optical elements smaller, achieving a large field of view imaging range, making the optical system structure compact and the volume smaller, which is extremely beneficial for reducing the space occupied by the entire optical system.
[0050] As Figure 1 , Figure 5 and Figure 9 As shown in Figure 1 , Figure 5 , and Figure 9 , the third lens 3 has a positive refractive power, with a convex object side and a flat or convex image side.
[0051] Specifically, the third lens 3 satisfies the following conditions: 1.95 < Nd3 < 2.05, 25 < Vd3 < 30; where Nd3 is the refractive index of the third lens and Vd3 is the Abbe number of the third lens. In the first and second embodiments, the image side of the third lens 3 is flat, and in the third embodiment, the image side of the third lens 3 is convex.
[0052] The third lens 3 is made of a high-refractive-index and high-dispersion (i.e., low Abbe number) glass material, which helps to distribute the positive optical power of the third lens, reduce the sensitivity of the wide-angle optical lens, and improve the lens assembly yield.
[0053] Preferably, the second lens 2 and the third lens 3 form a first cemented lens to correct aberration.
[0054] As Figure 1 , Figure 5 and Figure 9 As shown in Figure 1 , Figure 5 , and Figure 9 , the fourth lens 5 has a negative refractive power, with a concave object side and a concave image side.
[0055] Specifically, the fourth lens 5 satisfies the following conditions: 1.8 < Nd4 < l.9, 15 <vd4>25; where, Nd4 is the refractive index of the fourth lens, and Vd4 is the Abbe number of the fourth lens.
[0056] The fourth lens 5 is made of a glass material with a high refractive index and low dispersion, which is beneficial to correcting secondary chromatic aberration and can improve the imaging quality.
[0057] As Figure 1 shown, the fifth lens 6 has a positive refractive power, the object side is convex, and the image side is convex.
[0058] Specifically, the fifth lens 6 is a biconvex lens with a positive optical power, and it satisfies the following conditions: 1.55 < Nd5 < 1.65, 65 < Vd5 < 70, and in the temperature range of -40°C to 105°C, dn / dT < -6×10E-6; where, Nd5 is the refractive index of the fifth lens, Vd5 is the Abbe number of the fifth lens, and dn / dT is the refractive index temperature coefficient.
[0059] The fifth lens 6 is made of a material with a special refractive index temperature coefficient, which can effectively reduce the imaging surface shift caused by the thermal expansion and contraction of the lens structural parts, so that the lens does not require additional focusing at different temperatures, increasing the consistency of the imaging performance of the lens at different temperatures, balancing the temperature drift, and achieving the purpose of athermalization of the lens.
[0060] Preferably, the fourth lens and the fifth lens form a second cemented lens, and Vd5 - Vd4 > 50. Using high- and low-dispersion materials in combination is beneficial to correcting secondary chromatic aberration, making the foci of the cut-off long wavelength of 650 nm and short wavelength of 435 nm coincide on the optical axis, reducing the chromatic aberration and astigmatism of the imaging, and improving the imaging quality of the lens. Such an idea is extremely beneficial to the design of a wide-spectrum composite light lens.
[0061] As Figure 1 、 Figure 5 and Figure 9 shown, the sixth lens 7 has a positive refractive power, the object side is convex, and the image side is convex.
[0062] Specifically, the sixth lens 7 is a biconvex lens with a positive optical power, and it satisfies the following conditions: 1.75 < Nd6 < 1.85, 40 < Vd6 < 50; where, Nd6 is the refractive index of the sixth lens, and Vd6 is the Abbe number of the sixth lens.
[0063] The sixth lens 7 is made of a material with a high refractive index and high dispersion, which not only optimizes the optical performance of the lens, improves the imaging resolution, but also effectively reduces the outer diameter size of the rear end of the lens.
[0064] The following provides the detailed optical data of three embodiments of the present invention. Among them, the lens parameters of the three embodiments are as follows:
[0065]
[0066] First Embodiment
[0067] Table 1. Detailed optical data of the first embodiment
[0068]
[0069] In the first embodiment, the optical system has a focal length of f=5.34mm, a light transmission FNO=2, a field of view FOV=77.22°, a target surface size IMH=5.76mm, and a total optical length TTL=22mm.
[0070] like Figure 2 As shown, it can be seen that in the first embodiment, the MTF value is greater than 0.6 at 125LP / mm in the 435-650nm range, indicating that this embodiment has high resolution and good imaging quality.
[0071] like Figure 3 As shown, it can be seen that in the first embodiment, the edge field distortion values are all less than ±20% in the range of 435-650nm, the optical distortion is small, the imaging effect is good, and the imaging fidelity is high.
[0072] like Figure 4 As shown, it can be seen that the first embodiment has a relative illumination of more than 80% at 555nm, and the imaging quality is good.
[0073] Second Embodiment
[0074] Table 2. Detailed optical data for the second embodiment
[0075]
[0076] In the second embodiment, the optical system has a focal length f=5.34mm, a light transmission FNO=2, a field of view FOV=77.22°, a target surface size IMH=5.76mm, and a total optical length TTL=22mm.
[0077] like Figure 6 As shown, it can be seen that the MTF value of the second embodiment at 435-650nm is greater than 0.6 at 125LP / mm, indicating that this embodiment has high resolution and good imaging quality.
[0078] like Figure 7 As shown, it can be seen that in the second embodiment, the edge field distortion values are all less than ±20% in the range of 435-650nm, the optical distortion is small, the imaging effect is good, and the imaging fidelity is high.
[0079] like Figure 8 As shown, the second embodiment has a relative illumination of more than 80% at 555nm, resulting in good imaging quality.
[0080] Third Embodiment
[0081] Table 3. Detailed optical data for the third embodiment
[0082]
[0083] In the third embodiment, the optical system has a focal length of f=5.34mm, a light transmission FNO=2, a field of view FOV=77.72°, a target surface size IMH=5.76mm, and a total optical length TTL=22mm.
[0084] like Figure 10 As shown, it can be seen that the MTF value of the third embodiment at 435-650nm is greater than 0.6 at 125LP / mm, indicating that this embodiment has high resolution and good imaging quality.
[0085] like Figure 11 As shown, it can be seen that in the third embodiment, the edge field distortion values are all less than ±20% in the range of 435-650nm, the optical distortion is small, the imaging effect is good, and the imaging fidelity is high.
[0086] like Figure 12 As shown, the third embodiment has a relative illuminance of over 80% at 555nm, resulting in good imaging quality.
[0087] This is merely a specific embodiment of the present utility model, but the design concept of the present utility model is not limited thereto. Any non-substantial modifications made to the present utility model using this concept shall be considered as an infringement of the protection scope of the present utility model.
Claims
1. An imaging lens, characterized in that: From the object side to the image side, there are a first lens, a second lens, a third lens, an aperture stop, a fourth lens, a fifth lens, and a sixth lens in sequence; The first lens has a negative refractive power, the object side is convex, and the image side is concave; The second lens has a negative refractive power, the object side is convex, and the image side is concave; The third lens has a positive refractive power, the object side is convex, and the image side is flat or convex; The fourth lens has a negative refractive power, the object side is concave, and the image side is concave; The fifth lens has a positive refractive power, the object side is convex, and the image side is convex; The sixth lens has a positive refractive power, the object side is convex, and the image side is convex.
2. An imaging lens according to claim 1, characterized in that: The first lens is a negative meniscus lens with a meniscus shape like a hat and satisfies the following conditions: 1.5 < Nd1 < 1.6, 50 < Vd1 < 60; where, Nd1 is the refractive index of the first lens, and Vd1 is the Abbe number of the first lens.
3. An imaging lens according to claim 2, characterized in that: The second lens satisfies the following conditions: 1.55 < Nd2 < 1.65, 35 < Vd2 < 45; where, Nd2 is the refractive index of the second lens, and Vd2 is the Abbe number of the second lens.
4. An imaging lens according to claim 1, characterized in that: The third lens satisfies the following conditions: 1.95 < Nd3 < 2.05, 25 < Vd3 < 30; where, Nd3 is the refractive index of the third lens, and Vd3 is the Abbe number of the third lens.
5. An imaging lens according to claim 1, characterized in that: The fourth lens satisfies the following condition: 1.8 <Nd4<1.9,15 <vd4>25; where, Nd4 is the refractive index of the fourth lens, and Vd4 is the Abbe number of the fourth lens.< / vd4> 6. An imaging lens according to claim 5, characterized in that: The fifth lens satisfies the following conditions: 1.55 < Nd5 < 1.65, 65 < Vd5 < 70, and in the temperature range from -40°C to 105°C, dn / dT < -6 * 10E-6; where, Nd5 is the refractive index of the fifth lens, Vd5 is the Abbe number of the fifth lens, and dn / dT is the refractive index temperature coefficient.
7. An imaging lens according to claim 6, characterized in that: The fourth lens and the fifth lens form a first cemented lens, and Vd5 - Vd4 > 50.
8. An imaging lens according to claim 1, characterized in that: The sixth lens satisfies the following conditions: 1.75 < Nd6 < 1.85, 40 < Vd6 < 50; where, Nd6 is the refractive index of the sixth lens, and Vd6 is the Abbe number of the sixth lens.