6mm imaging lens
By designing a small number of lenses and rationally matching optical power, and using specific materials and lens combinations, the problems of large size and low imaging quality of existing security lenses have been solved, achieving lens miniaturization and high imaging quality, and adapting to all-weather usage environments.
Patent Information
- Application Number
- CN202520304802.5
- 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 security lenses have a large number of lenses, are difficult to manufacture, have large and heavy optical systems, have a small spectral range, and low image quality. They cannot meet the needs of all-weather use environments and are not suitable for the lightweight and miniaturized consumer-grade requirements.
Design a 6mm imaging lens that uses a small number of lenses and controls the positive and negative combinations of the optical power of the lenses. It uses a negative optical power meniscus glass spherical lens and a positive optical power meniscus plastic aspherical lens, combined with a fourth and fifth lens made of high and low dispersion materials, to form an edge-contact positive and negative dual-lens combination, thereby achieving lens miniaturization and high imaging quality.
It effectively balances low-order aberrations of the lens, reduces tolerance sensitivity, ensures clear imaging at different temperatures, adapts to all-weather usage environments, improves image quality, and meets consumer-grade needs.
Smart Images
Figure CN223624472U_ABST
Abstract
Description
Technical Field ,
[0009]
[0001] The utility model relates to the field of optical equipment, and specifically relates to a 6mm imaging lens. Background Art
[0002] In the existing security lenses, the number of optical lenses in the lens is large, the manufacturing difficulty is high, the optical assembly yield is low, and there are also problems such as large volume and large weight. In addition, the spectral range of the lens is small, the imaging quality is low, the use environment is single, and it cannot meet the requirements of all-weather use environments, and it cannot adapt to the large-volume consumer-level requirements of the market for light weight and miniaturization. Summary of the Invention
[0003] The purpose of the utility model is to provide a 6mm 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: [[ID=十七]]
[0005] A 6mm imaging lens includes, in order from the object side to the image side, a first lens, a second lens, an aperture stop, a third lens, a fourth lens, and a fifth lens; the first lens has a negative refractive power, the object side surface of the first lens is convex, and the image side surface is concave; the second lens has a positive refractive power, the object side surface of the second lens is concave, and the image side surface is convex; the third lens has a positive refractive power, the object side surface of the third lens is convex, and the image side surface is convex; the fourth lens has a negative refractive power, the object side surface of the fourth lens is convex, and the image side surface is concave; the fifth lens has a positive refractive power, the object side surface of the fifth lens is convex, and the image side surface is convex.
[0006] The small number of lenses miniaturizes the lens, and at the same time, by controlling the positive and negative combination of the optical powers of each lens of the lens, the low-order aberrations of the lens are effectively balanced, the sensitivity of the lens to tolerances is reduced, and the imaging quality of the lens is guaranteed.
[0007] Further, the first lens is a negative-power meniscus glass spherical lens, which can ensure that the wide-angle optical system has a large aperture ratio, is beneficial to compressing the aperture of the optical system, and realizes the miniaturization of the lens.
[0008] Furthermore, the first lens satisfies the following conditions: 1.4 < Nd1 < 1.5, 65 < Vd1 < 75, f1 = -13.62, f1 / f = -2.27; where Nd1 is the refractive index of the first lens, Vd1 is the Abbe number of the first lens, f1 is the focal length of the first lens, and f1 / f is the ratio of the focal length of the first lens to the focal length of the lens. It can ensure a wide viewing angle of the lens while reducing the volume and chromatic aberration.
[0009] Furthermore, the second lens is a positive-powered meniscus plastic aspherical lens and satisfies the following conditions: 1.6 < Nd2 < 1.65, 20 < Vd2 < 30; where Nd2 is the refractive index of the second lens and Vd2 is the Abbe number of the second lens.
[0010] Furthermore, the third lens satisfies the following conditions: 1.55 < Nd3 < 1.65, 65 < Vd3 < 75, f3 = 7.81, f3 / f = 1.3; where Nd3 is the refractive index of the third lens, Vd3 is the Abbe number of the third lens, f3 is the focal length of the third lens, and f3 / f is the ratio of the focal length of the third lens to the focal length of the lens.
[0011] Preferably, the third lens satisfies the following condition: dn / dT < -5.4 * 10E-6 in the temperature range of -40°C to 105°C, where dn / dT is the refractive index temperature coefficient of the third lens; using a material with a special refractive index temperature coefficient can effectively reduce the image plane shift caused by the thermal expansion and contraction of the lens structural parts, so as to achieve the purpose that the lens can be clearly imaged without additional focusing at different temperatures, increase the imaging performance clarity consistency of the imaging lens at different temperatures, balance the temperature drift, and achieve the purpose of lens athermalization.
[0012] Furthermore, the fourth lens satisfies the following conditions: Nd4 > 1.6, Vd4 < 25; where Nd4 is the refractive index of the fourth lens and Vd4 is the Abbe number of the fourth lens. Preferably, the fourth lens uses a glass material with high dispersion and low Abbe number, which is beneficial to correcting secondary chromatic aberration and can improve the imaging quality.
[0013] Furthermore, the following condition is satisfied: Vd3 - Vd4 > 40; where Vd3 is the Abbe number of the third lens and Vd4 is the Abbe number of the fourth lens. The difference in dispersion ability (usually represented by the Abbe number), the larger the Abbe number, the smaller the dispersion ability of the material, that is, the smaller the refractive index difference of light with different wavelengths in the material. The fourth lens and the third lens are selected with high and low dispersion materials, and the combined use is beneficial to correcting secondary chromatic aberration, reducing the chromatic aberration and astigmatism of the image, and improving the imaging quality of the lens. Moreover, the third lens with positive optical power has lower dispersion, that is, a higher Abbe number, and the fourth lens with negative optical power has higher dispersion, that is, a lower Abbe number. Such a combination can play a role in correcting primary chromatic aberration, making the red light with a long cut-off wavelength and the blue light with a short wavelength coincide at the focus on the optical axis. Such an idea is extremely beneficial to the design of wide wavelength lenses.
[0014] Further, the fifth lens is a plastic aspherical lens and satisfies the following conditions: 1.5 < Nd5 < 1.6, 50 < Vd5 < 60; where Nd5 is the refractive index of the fifth lens and Vd5 is the Abbe number of the fifth lens. It can effectively control the light deflection angle on the lens and improve the imaging quality.
[0015] In addition, the fourth lens and the fifth lens play an achromatic role in the optical system. At the same time, in terms of shape, they form an edge-contact positive and negative doublet lens combination. There is an appropriate air gap between the positive and negative doublets, and the refractive indices form a "high - low - high" layout. When light passes through this area, strong refraction occurs in the air gap. However, since the radii of the two lens surfaces are relatively close and one is positive and the other is negative, most of the spherical aberration will be cancelled out. At the same time, due to the different light height differences, the spherical aberration will not be completely cancelled out. It is this part of the spherical aberration difference that has a good compensation effect on the higher-order spherical aberration and can reduce the higher-order spherical aberration.
[0016] The utility model has the following beneficial effects compared with the prior art:
[0017] By reasonably selecting materials and controlling the positive and negative combinations of the optical powers of each lens of the lens, the utility model can effectively balance the low-order aberrations of the lens, and at the same time reduce the sensitivity of the lens to tolerances, maintain the miniaturization of the lens while ensuring the imaging quality of the lens, and is especially suitable for security lenses. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] Figure 1 is the optical path schematic diagram of the utility model.
[0019] Figure 2 is the MTF graph of the first embodiment of the utility model at 435 - 650 nm.
[0020] Figure 3 is the MTF graph of the first embodiment of the utility model at 850 - 940 nm.
[0021] Figure 4 is the distortion graph of the first embodiment of the utility model at 435 - 650 nm. In the figure, the left side is the field curvature of the thin beam, and the right side is the distortion curve.
[0022] Figure 5 is the relative illumination graph of the first embodiment of the utility model at 550 nm.
[0023] Figure 6 is the MTF graph of the second embodiment of the utility model at 435 - 650 nm.
[0024] Figure 7 is the MTF graph of the second embodiment of the utility model at 850 - 940 nm.
[0025] Figure 8 In the present utility model, this is the distortion diagram of the second embodiment at 435 - 650 nm. In the figure, the left side is the fine beam field curvature, and the right side is the distortion curve.
[0026] Figure 9 In the present utility model, this is the relative illumination diagram of the second embodiment at 550 nm.
[0027] Figure 10 In the present utility model, this is the MTF diagram of the third embodiment at 435 - 650 nm.
[0028] Figure 11 In the present utility model, this is the MTF diagram of the third embodiment at 850 - 940 nm.
[0029] Figure 12 In the present utility model, this is the distortion diagram of the third embodiment at 435 - 650 nm. In the figure, the left side is the fine beam field curvature, and the right side is the distortion curve.
[0030] Figure 13
[0035] As shown in Figure 1 FIG. [X], the second lens 2 has a positive refractive power. The object side surface of the second lens 2 is concave, and the image side surface is convex.
[0036] Specifically, the second lens 2 is a positive meniscus plastic aspherical lens and satisfies the following conditions: 1.6 < Nd2 < 1.65, 20 < Vd2 < 30; where Nd2 is the refractive index of the second lens, and Vd2 is the Abbe number of the second lens.
[0037] As shown in Figure 1 FIG. [X], the third lens 4 has a positive refractive power. The object side surface of the third lens 4 is convex, and the image side surface is convex.
[0038] Specifically, the third lens 4 is a positive biconvex spherical lens and satisfies the following conditions: 1.55 < Nd3 < 1.65, 65 < Vd3 < 75, f3 = 7.81, f3 / f = 1.3; where Nd3 is the refractive index of the third lens, Vd3 is the Abbe number of the third lens, f3 is the focal length of the third lens, and f3 / f is the ratio of the focal length of the third lens to the focal length of the lens. The third lens has a low refractive index, low dispersion, and a high Abbe number, and can correct chromatic aberration of different wavelengths and the abnormal refractive index temperature coefficient, achieving the purpose of balancing temperature drift.
[0039] Preferably, the third lens 4 satisfies the following condition: dn / dT < -5.4 * 10E-6 in the temperature range of -40°C to 105°C, where dn / dT is the refractive index temperature coefficient of the third lens; using a material with a special refractive index temperature coefficient can effectively reduce the imaging surface shift caused by the thermal expansion and contraction of the lens structural parts, so as to achieve the purpose that the lens can be clearly imaged without additional focusing at different temperatures, increasing the consistency of the imaging performance of the imaging lens at different temperatures, balancing the temperature drift, and achieving the purpose of lens athermalization.
[0040] As shown in Figure 1 FIG. [X], the fourth lens 5 has a negative refractive power. The object side surface of the fourth lens 5 is convex, and the image side surface is concave.
[0041] Specifically, the fourth lens 5 satisfies the following conditions: Nd4 > 1.6, Vd4 < 25; where Nd4 is the refractive index of the fourth lens, and Vd4 is the Abbe number of the fourth lens. Preferably, the fourth lens uses a glass material with high dispersion and low Abbe number, which is beneficial to correcting secondary chromatic aberration and can improve the imaging quality.
[0042] As shown in Figure 1As shown, the imaging lens also satisfies the following conditions: Vd3 - Vd4 > 40; where Vd3 is the Abbe number of the third lens and Vd4 is the Abbe number of the fourth lens. The difference in dispersion ability (usually represented by the Abbe number), the larger the Abbe number, the smaller the dispersion ability of the material, that is, the smaller the refractive index difference of light with different wavelengths in the material. The fourth lens and the third lens are made of high- and low-dispersion materials, and their combined use is beneficial to correcting secondary chromatic aberration, reducing chromatic aberration and astigmatism in imaging, and improving the imaging quality of the lens. Moreover, the third lens with positive focal length has lower dispersion, that is, a higher Abbe number, and the fourth lens with negative focal length has higher dispersion, that is, a lower Abbe number. Such a combination can play a role in correcting primary chromatic aberration, making the foci of the long-wavelength red light and the short-wavelength blue light that are cut off coincide on the optical axis. Such an idea is extremely beneficial to the design of a wide-wavelength lens.
[0043] As Figure 1 shown, the fifth lens 6 has a positive refractive power, the object side surface of the fifth lens 6 is convex, and the image side surface is convex.
[0044] Specifically, the fifth lens 6 is a plastic aspherical lens and satisfies the following conditions: 1.5 < Nd5 < 1.6, 50 < Vd5 < 60; where Nd5 is the refractive index of the fifth lens and Vd5 is the Abbe number of the fifth lens. It can effectively control the light deflection angle on the lens and improve the imaging quality.
[0045] [[ID=eleven]]In addition, the fourth lens and the fifth lens play a role in achromatism in the optical system. At the same time, in terms of shape, they form an edge-contact type positive and negative doublet lens combination. There is an appropriate air gap between the positive and negative doublets, and the refractive indices form a "high-low-high" layout. When light passes through this area, strong refraction occurs in the air gap. However, since the radii of the two lens surfaces are relatively close and one is positive and the other is negative, most of the spherical aberration will be cancelled out. At the same time, due to the different light height differences, the spherical aberration will not be completely cancelled out. It is this part of the spherical aberration difference that has a good compensation effect on the higher-order spherical aberration and can reduce the higher-order spherical aberration.
[0046] Provide the detailed optical data of three embodiments of the present invention. Among them, the lens parameters of the three embodiments are as follows:
[0047]
[0048] The first embodiment
[0049] Table 1. Detailed optical data of the first embodiment
[0050]
[0051] In the first embodiment, the optical system has a focal length f=6mm, a light transmission FNO=1.6, a field of view FOV=60.4°, a target surface size IMH=6.18mm, and a total optical length TTL=22mm.
[0052] like Figure 2 and Figure 3 As shown, it can be seen that the MTF value of the first embodiment is greater than 0.8 at 60 LP / mm in the 435-650nm (visible light) range and greater than 0.6 at 65 LP / mm in the 850-940nm (near-infrared light) range. This indicates that the embodiment has high resolution and good imaging quality in both visible and near-infrared light.
[0053] like Figure 4 As shown, it can be seen that in the first embodiment, the edge field distortion values are all less than ±12% in the 435-650nm (visible light) range, the optical distortion is small, the imaging effect is good, and the imaging fidelity is high.
[0054] like Figure 5 As shown, it can be seen that in the first embodiment, at 550nm, the relative illumination of the lens at a half-image height of 3.09 is greater than 65%, and the imaging quality is good.
[0055] Second Embodiment
[0056] Table 2. Detailed optical data for the second embodiment
[0057]
[0058] In the second embodiment, the optical system has a focal length f=6mm, a light transmission FNO=1.6, a field of view FOV=60.66°, a target surface size IMH=6.18mm, and a total optical length TTL=22mm.
[0059] like Figure 6 and Figure 7 As shown, it can be seen that the MTF value of the second embodiment at 65 LP / mm is greater than 0.75 in the 435-650nm (visible light) range and greater than 0.6 in the 850-940nm (near-infrared light) range, indicating that this embodiment has high resolution and good imaging quality in visible and near-infrared light.
[0060] like Figure 8 As shown, it can be seen that in the second embodiment, under 435-650nm (visible light) and with a half-image height of 3.09, the edge field distortion values are all less than ±12%, the optical distortion is small, the imaging effect is good, and the image reproduction is high.
[0061] like Figure 9As shown, it can be seen that the second embodiment has a relative illuminance of more than 65% at 550nm and good imaging quality.
[0062] Third Embodiment
[0063] Table 3. Detailed optical data for the third embodiment
[0064]
[0065] In the third embodiment, the optical system has a focal length f=6mm, a light transmission FNO=1.6, a field of view FOV=60.72°, a target surface size IMH=6.18mm, and a total optical length TTL=22mm.
[0066] like Figure 10 and Figure 11 As shown, it can be seen that the MTF value of the second embodiment at 65 LP / mm is greater than 0.6 in the 435-650nm (visible light) range and greater than 0.5 in the 850-940nm (near-infrared light) range, indicating that this embodiment has high resolution and good imaging quality in visible and near-infrared light.
[0067] like Figure 12 As shown, it can be seen that in the second embodiment, the edge field distortion values are all less than ±12% in the 435-650nm (visible light) range, the optical distortion is small, the imaging effect is good, and the imaging fidelity is high.
[0068] like Figure 13 As shown, it can be seen that in the second embodiment, at 550nm, the lens has a relative illumination of more than 65% at a half-image height of 3.09, resulting in good image quality.
[0069] 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. A 6mm imaging lens, characterized in that: From the object side to the image side, there are a first lens, a second lens, an aperture stop, a third lens, a fourth lens, and a fifth 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 positive refractive power, the object side is concave, and the image side is convex; The third lens has a positive refractive power, the object side is convex, and the image side is convex; The fourth lens has a negative refractive power, the object side is convex, 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.
2. The 6mm imaging lens according to claim 1, characterized in that: The first lens is a negative meniscus glass spherical lens.
3. A 6mm imaging lens according to claim 2, characterized in that: The first lens satisfies the following conditions: 1.4 < Nd1 < 1.5, 65 < Vd1 < 75, f1 = -13.62, f1 / f = -2.27; where Nd1 is the refractive index of the first lens, Vd1 is the Abbe number of the first lens, f1 is the focal length of the first lens, and f1 / f is the ratio of the focal length of the first lens to the focal length of the lens.
4. A 6mm imaging lens according to claim 3, characterized in that: The second lens is a positive meniscus plastic aspherical lens and satisfies the following conditions: 1.6 < Nd2 < 1.65, 20 < Vd2 < 30; where Nd2 is the refractive index of the second lens and Vd2 is the Abbe number of the second lens.
5. A 6mm imaging lens according to claim 3 or 4, characterized in that: The third lens satisfies the following conditions: 1.55 < Nd3 < 1.65, 65 < Vd3 < 75, f3 = 7.81, f3 / f = 1.3; where Nd3 is the refractive index of the third lens, Vd3 is the Abbe number of the third lens, f1 is the focal length of the third lens, and f3 / f is the ratio of the focal length of the third lens to the focal length of the lens.
6. A 6mm imaging lens according to claim 5, characterized in that: The third lens satisfies the following conditions: dn / dT < -5.4 * 10E-6 in the temperature range of -40°C to 105°C, where dn / dT is the refractive index temperature coefficient of the third lens.
7. A 6mm imaging lens according to claim 5, characterized in that: The fourth lens satisfies the following conditions: Nd4 > 1.6, Vd4 < 25; where Nd4 is the refractive index of the fourth lens and Vd4 is the Abbe number of the fourth lens.
8. A 6mm imaging lens according to claim 7, characterized in that: Satisfies the following conditions: Vd3 - Vd4 > 40; where Vd3 is the Abbe number of the third lens and Vd4 is the Abbe number of the fourth lens.
9. A 6mm imaging lens according to claim 7, characterized in that: The fifth lens is a plastic aspherical lens and satisfies the following conditions: 1.5 < Nd5 < 1.6, 50 < Vd5 < 60; where Nd5 is the refractive index of the fifth lens and Vd5 is the Abbe number of the fifth lens.
10. A 6mm imaging lens according to claim 9, characterized in that: The fourth lens and the fifth lens form an edge-contact type positive-negative doublet combination.