An ultra-wide-angle and ultra-large aperture optical lens

Abstract

The present invention relates to the field of optical imaging technology, and in particular to an ultra-wide-angle ultra-large aperture optical lens, which includes, from the object side to the image side along the optical axis direction: a first meniscus lens with negative optical power, a first biconcave lens with negative optical power, a first cemented lens group with positive optical power, a first biconvex lens with positive optical power, a second cemented lens group with negative optical power, a third cemented lens group with positive optical power, a fourth biconvex lens with positive optical power, a fifth meniscus lens with positive optical power, a filter, and an image plane. By adopting an ultra-wide-angle ultra-large aperture optical lens composed of lenses with a specific structural shape and reasonable optical power distribution, an ultra-wide angle and 4K pixel-level resolution can be achieved while achieving an ultra-large aperture.

Description

Technical Field

[0001] The present invention relates to the field of optical imaging technology, and in particular to an ultra-wide-angle and ultra-large-aperture optical lens. Background Art

[0002] In the field of security, network cameras are commonly used equipment in security systems, and lenses are the main components of network cameras. Lens performance directly affects image quality and imaging field of view. As the technical indicators of security systems continue to increase, how to improve the imaging field of view at night and under low light conditions has become a major issue in the security industry. The aperture of the ultra-wide-angle lens of the existing solution is generally around 2.0, and the field of view of the ultra-large aperture lens of the existing solution is generally below 100 degrees. Due to the larger light transmission than ordinary lenses, large aperture lenses have higher image brightness than ordinary lenses in the same environment, and can also present better effects in dim environments. Therefore, they are very popular in the security monitoring industry. However, large aperture and ultra-wide angle bring a larger imaging field of view and more difficult to correct aberrations, making it difficult for large aperture lenses designed and manufactured with traditional structures to take into account a large field of view and generally have low resolution. Summary of the invention

[0003] The purpose of the present invention is to overcome the deficiencies of the above-mentioned technologies and to provide an ultra-wide-angle and ultra-large aperture optical lens.

[0004] In order to achieve the above-mentioned object, the present invention adopts the following technical scheme: an ultra-wide-angle ultra-large aperture optical lens, characterized in that: it comprises, from the object side to the image side along the optical axis direction: a first meniscus lens with negative optical power, a first biconcave lens with negative optical power, a first cemented lens group with positive optical power, a first biconvex lens with positive optical power, a second cemented lens group with negative optical power, a third cemented lens group with positive optical power, a fourth biconvex lens with positive optical power, a fifth meniscus lens with positive optical power, a filter and an image plane;

[0005] The effective focal length of the second cemented lens group and the effective focal length of the ultra-wide-angle and ultra-large-aperture optical lens satisfy a first set relationship, and the effective focal length of the third cemented lens group and the effective focal length of the ultra-wide-angle and ultra-large-aperture optical lens satisfy a second set relationship;

[0006] Wherein, the first setting relationship is: 6.75<|fB / f|<7.25,

[0007] The second setting relationship is: 16.8<|fC / f|<17.8,

[0008] The ultra-wide-angle and ultra-large-aperture optical lens meets the following condition: L / h<4.3

[0009] Wherein: L represents the total length of the ultra-wide-angle and ultra-large aperture optical lens, and h represents the size of the image plane;

[0010] fB represents the effective focal length of the second cemented lens group, fC represents the effective focal length of the third cemented lens group, and f represents the effective focal length of the ultra-wide-angle and ultra-large aperture optical lens.

[0011] Preferably, a surface of the first meniscus lens facing the object side is a convex surface.

[0012] Preferably, the second meniscus lens with positive optical power has a convex surface facing the image side, and the third meniscus lens with negative optical power has a convex surface facing the image side; the second meniscus lens and the third meniscus lens are seamlessly glued to form a first glued lens group.

[0013] Preferably, the second biconvex lens has a positive optical power and the second biconvex lens has a negative optical power; the second biconvex lens and the second biconcave lens are seamlessly glued together to form a second glued lens group.

[0014] Preferably, a third biconvex lens with positive optical power and a fourth meniscus lens with negative optical power, with the convex surface facing the image side, are seamlessly glued together to form a third glued lens group.

[0015] Preferably, the Abbe coefficients of the second biconvex lens, the third biconvex lens and the fourth biconvex lens are all greater than 65.

[0016] Preferably, the refractive index of the third meniscus lens is greater than 1.9.

[0017] Preferably, the refractive index of the first biconvex lens and the refractive index of the fourth meniscus lens are both greater than 2.0.

[0018] The beneficial effects of the present invention are as follows: relative to the prior art, by adopting an ultra-wide-angle and ultra-large aperture optical lens composed of a lens with a specific structural shape and reasonable optical focal length distribution, it is possible to achieve ultra-wide angle and 4K pixel-level resolution while achieving ultra-wide aperture. The ultra-wide angle and ultra-large aperture are taken into consideration, and the maximum field of view angle reaches 150°-160°. The aperture is larger, and the F NO. reaches 0.9, which can clearly image at night without fill light, and the low-light effect is better. The total length is short, less than 30mm. The resolution is higher and can match 4K chips (more than eight million pixels). In addition, the ultra-wide-angle and ultra-large aperture optical lens of the present invention also has a lower cost. The structural shape of the optical lens system provided by the present invention is adopted, and the parameters such as the Abbe coefficient of the optical glass material are better matched with the imaging conditions, so that the spherical aberration, coma, astigmatism, field curvature, magnification chromatic aberration, and position chromatic aberration of the lens system are well corrected, meeting the use requirements of 4K cameras and having a compact structure and small size. In addition, all optical lenses adopt a spherical design, the lens cold processing technology has good performance, the glass material cost is low and the price of the finished lens is also low, and the mass production yield is high; it can be widely used in the field of security monitoring. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the structure of the present invention;

[0020] Figure 2 This is a 300lp / mm MTF analysis diagram of an embodiment of the present invention;

[0021] Figure 3 This is a 160lp / mm MTF analysis diagram of an embodiment of the present invention. DETAILED DESCRIPTION

[0022] The specific implementation of the present invention is described in detail below in conjunction with the accompanying drawings and preferred embodiments. Figure 1 As shown, an ultra-wide-angle and ultra-large aperture optical lens comprises, in order from the object side to the image side along the optical axis direction: a first meniscus lens 1 with negative optical focal length, a first biconcave lens 2 with negative optical focal length, a first cemented lens group A with positive optical focal length, a first biconvex lens 5 with positive optical focal length, a second cemented lens group B with negative optical focal length, a third cemented lens group C with positive optical focal length, a fourth biconvex lens 10 with positive optical focal length, a fifth meniscus lens 11 with positive optical focal length, a filter and an image plane; wherein the surface of the first meniscus lens facing the object side is a convex surface.

[0023] In the ultra-wide-angle and ultra-large-aperture optical lens provided in the embodiment of the present invention, Figure 1As shown, the first cemented lens group A includes: a second meniscus lens 3 with positive focal power, with a convex surface facing the image side; a third meniscus lens 4 with negative focal power, with a convex surface facing the image side; the second meniscus lens and the third meniscus lens are seamlessly glued together to form the first cemented lens group A. Since the second meniscus lens 3 with positive focal power has negative chromatic aberration, and the third meniscus lens 4 with negative focal power has positive chromatic aberration, the second meniscus lens 3 with positive focal power and the third meniscus lens 4 with negative focal power are seamlessly glued together to form the first cemented lens group to achieve mutual compensation of chromatic aberration, eliminate chromatic aberration, optimize imaging clarity, improve the image quality of the optical system, and increase resolution.

[0024] In the ultra-wide-angle and ultra-large-aperture optical lens provided in the embodiment of the present invention, Figure 1 As shown, the second cemented lens group B includes: a second biconvex lens 6 with positive optical power; a second biconcave lens 7 with negative optical power; the second biconvex lens 6 and the second biconcave lens 7 are seamlessly glued to form the second cemented lens group B. The second cemented lens group has a similar function to the first cemented lens group, which is used to compensate for chromatic aberration, eliminate chromatic aberration, optimize imaging clarity, improve the image quality of the optical system, and increase resolution.

[0025] In a specific implementation, in the ultra-wide-angle and ultra-large-aperture optical lens provided in the embodiment of the present invention, Figure 1 As shown, the third cemented lens group C includes: a third biconvex lens 8 with positive focal power; a fourth meniscus lens 9 with negative focal power, with the convex surface facing the image side; the third biconvex lens 8 and the fourth meniscus lens 9 are seamlessly glued to form the third cemented lens group C. The third cemented lens group has a similar function to the first cemented lens group, which is used to compensate for chromatic aberration, eliminate chromatic aberration, optimize the clarity of imaging, improve the image quality of the optical system, and increase the resolution.

[0026] Furthermore, in a specific implementation, in the ultra-wide-angle and ultra-large aperture optical lens provided in an embodiment of the present invention, the Abbe coefficients of the second biconvex lens 6, the third biconvex lens 8, and the fourth biconvex lens 10 are all greater than 65.

[0027] Furthermore, in the above-mentioned ultra-wide-angle and ultra-large aperture optical lens provided by an embodiment of the present invention, the relative aperture of the ultra-wide-angle and ultra-large aperture optical lens is F0.9.

[0028] Further, in the above-mentioned ultra-wide-angle and ultra-large-aperture optical lens provided in an embodiment of the present invention, the effective focal length of the second cemented lens group and the effective focal length of the ultra-wide-angle and ultra-large-aperture optical lens satisfy a first set relationship, and the effective focal length of the third cemented lens group and the effective focal length of the optical lens satisfy a second set relationship;

[0029] Wherein, the first setting relationship is: 6.75<|fB / f|<7.25,

[0030] The second setting relationship is: 16.8<|fC / f|<17.8, fB represents the effective focal length of the second cemented lens group, fC represents the effective focal length of the third cemented lens group, and f represents the effective focal length of the ultra-wide-angle ultra-large aperture optical lens. When the value of |fB / f| exceeds the upper limit of 7.25, fB becomes relatively large, that is, the optical focal length becomes relatively small, so that the optical back focus is insufficient, and it is difficult to arrange parts such as the automatic switching device of the red filter in the structural space; when the value of |fB / f| is lower than the lower limit of 6.75, fB becomes relatively small, that is, the optical focal length becomes relatively large, which will cause the increase of high-order aberrations. Therefore, the ultra-wide-angle ultra-large aperture optical lens in the embodiment of the present invention can achieve better imaging quality and a reasonable structural space form when the condition 6.75<|fB / f|<7.25 is met.

[0031] Further, in the specific implementation, in the above-mentioned ultra-wide-angle ultra-large aperture optical lens provided in the embodiment of the present invention, the effective focal length of the second cemented lens group and the effective focal length of the ultra-wide-angle ultra-large aperture optical lens satisfy the second setting relationship, and the second setting relationship is: 16.8<|fC / f|<17.8, fC represents the effective focal length of the second cemented lens group, and f represents the effective focal length of the ultra-wide-angle ultra-large aperture optical lens. When the value of |fC / f| exceeds the upper limit of 17.8, fC becomes relatively large, that is, the focal length becomes relatively small, making the total length of the optical system too long, destroying the miniaturization of the lens; when the value of |fC / f| is lower than the lower limit of 16.8, fC becomes relatively small, that is, the focal length becomes relatively large, which will cause the increase of high-order aberrations, thereby requiring a large number of lenses, making it difficult to achieve an optical system with good imaging performance with fewer lens structures. Therefore, when the ultra-wide-angle and ultra-large-aperture optical lens in the embodiment of the present invention satisfies the condition 16.8<|fC / f|<17.8, it has better imaging quality while achieving a reasonable structural spatial form.

[0032] Furthermore, in the above-mentioned ultra-wide-angle ultra-large aperture optical lens provided in the embodiment of the present invention, the ultra-wide-angle ultra-large aperture optical lens satisfies the following conditional formula: L / h<4.3

[0033] Wherein: L represents the total length of the ultra-wide-angle and ultra-large aperture optical lens, and h represents the size of the image plane.

[0034] Furthermore, in the above-mentioned ultra-wide-angle and ultra-large aperture optical lens provided by an embodiment of the present invention, the refractive index of the second meniscus lens and the refractive index of the third meniscus lens are both greater than 1.9.

[0035] Furthermore, in the above-mentioned ultra-wide-angle and ultra-large aperture optical lens provided by an embodiment of the present invention, the refractive index of the first biconvex lens and the refractive index of the fourth meniscus lens are both greater than 2.0.

[0036] The following will cite two embodiments of the ultra-wide-angle ultra-large aperture optical lens of the present invention. It should be noted that the data listed in Table 1 below are preferred data of the present invention and are not used to limit the present invention. Any person skilled in the art can make appropriate changes to the parameters or settings after referring to the present invention, which should still fall within the scope of the present invention.

[0037]

[0038] Among them, the effective focal length of the optical system provided in Table 1 is 3.12mm, the clear aperture is F / 0.9, and the total length of the optical system is 30mm. In Table 1, mirror numbers 1 and 2 represent the two mirrors of lens 1 along the incident direction of light, mirror numbers 3 and 4 represent the two mirrors of lens 2 along the incident direction of light, mirror number 5 represents the mirror of lens 3 facing the object side, mirror number 6 represents the bonding surface of lens 3 and lens 4, mirror number 7 represents the mirror of lens 4 facing the image side, mirror numbers 8 and 9 represent the two mirrors of lens 5 along the incident direction of light, and mirror number 10 represents the mirror of lens 6 facing the object side. Mirror number 11 represents the bonding surface of lens 6 and lens 7, mirror number 12 represents the mirror surface of lens 7 facing the image side, mirror number 13 represents the mirror surface of lens 8 facing the object side, mirror number 14 represents the bonding surface of lens 8 and lens 9, mirror number 15 represents the mirror surface of lens 9 facing the image side, mirror numbers 16 and 17 represent the two mirror surfaces of lens 10 along the incident direction of light, mirror numbers 18 and 19 represent the two mirror surfaces of lens 11 along the incident direction of light,

[0039] 6.75<|fB / f|<7.25,

[0040] The second setting relationship is: 16.8<|fC / f|<17.8

[0041] In specific implementation, in the above embodiment, the thickness of the filter is 0.700 mm, the refractive index is 1.517, and the Abbe constant is 64.212; in the embodiment of the present invention, |fB / f|=|-21.646746 / 3.12|=6.938, satisfying 6.75<|fB / f|<7.25. In the first embodiment of the present invention, |fC / f|=54.241873 / 3.12=17.385, satisfying 16.8<|fC / f|<17.8.

[0042] In the embodiment of the present invention, the Abbe coefficient of the second biconvex lens is 68.624378, the Abbe coefficient of the third biconvex lens is 68.624378, and the Abbe coefficient of the fourth biconvex lens is 81.608379, all of which are greater than 65.

[0043] In the embodiment of the present invention, the refractive index of the second meniscus lens is 1.921189, the refractive index of the third meniscus lens is 1.945945, and both are greater than 1.9. The refractive index of the first biconvex lens is 2.000694, and the refractive index of the fourth meniscus lens is 2.000694, and both are greater than 2.0.

[0044] In the embodiment of the present invention, it can be calculated from Table 1 that the field angle 2w of the ultra-wide-angle ultra-large aperture optical lens is 154 degrees, and the relative aperture is 0.9. In the embodiment of the present invention, the total length of the lens is 30 mm, and the structure is relatively compact. Figure 2 and Figure 3 They are the modulation transfer function (MTF) curves of the visible light band, representing the comprehensive resolution capability of the optical system. The horizontal axis represents the spatial frequency, in cycles / mm, and the vertical axis represents the value of the modulation transfer function (MTF). The value of MTF is used to evaluate the imaging quality of the lens, ranging from 0 to 1. It is particularly pointed out that the optical transfer function is a relatively accurate, intuitive and common way to evaluate the imaging quality of an optical system. The higher and smoother the curve is, the better the imaging quality of the system is and the stronger the ability to restore the real image is. Figure 2 It can be seen that when the spatial frequency of the visible light band is 300lp / mm, the MTF of the imaging area near the center is > 0.6, and the imaging quality is very good. Figure 3 It can be seen that when the spatial frequency of the visible light band is 160lp / mm, the MTF of the full field of view is greater than 0.4. The ultra-wide-angle and ultra-large aperture optical lens provided by this specific implementation corrects various aberrations, such as spherical aberration, coma, astigmatism, field curvature, magnification chromatic aberration, position chromatic aberration, etc., thereby improving the resolution and achieving a 4K 8-megapixel resolution under white light. Figure 2 and Figure 3 It can be seen that the ultra-wide-angle and ultra-large aperture optical lens of the embodiment of the present invention has corrected and balanced various aberrations to a good level.

[0045] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. An ultra-wide-angle ultra-large aperture optical lens, having eleven lenses in total: from the object side to the image side along the optical axis, in order: a first meniscus lens with negative optical power, a first biconcave lens with negative optical power, a first cemented lens group with positive optical power, a first biconvex lens with positive optical power, a second cemented lens group with negative optical power, a third cemented lens group with positive optical power, a fourth biconvex lens with positive optical power, a fifth meniscus lens with positive optical power, a filter and an image plane; The effective focal length of the second cemented lens group and the effective focal length of the ultra-wide-angle and ultra-large-aperture optical lens satisfy a first set relationship, and the effective focal length of the third cemented lens group and the effective focal length of the ultra-wide-angle and ultra-large-aperture optical lens satisfy a second set relationship; in, The first setting relationship is: 6.75<|fB / f|<7.25, The second setting relationship is: 16.8<|fC / f|<17.8, The ultra-wide-angle and ultra-large-aperture optical lens meets the following condition: L / h<4.3, Wherein: L represents the total length of the ultra-wide-angle and ultra-large aperture optical lens, and h represents the size of the image plane; fB represents the effective focal length of the second cemented lens group, fC represents the effective focal length of the third cemented lens group, and f represents the effective focal length of the ultra-wide-angle and ultra-large aperture optical lens; The first cemented lens group comprises: a second meniscus lens with positive optical power, with a convex surface facing the image side, and a third meniscus lens with negative optical power, with a convex surface facing the image side, and the second meniscus lens and the third meniscus lens are seamlessly glued to form a first cemented lens group; The second cemented lens group includes: a second biconvex lens with positive optical power, and a second biconcave lens with negative optical power; the second biconvex lens and the second biconcave lens are seamlessly glued to form a second cemented lens group; The third cemented lens group includes: a third biconvex lens with positive optical power, and a fourth meniscus lens with negative optical power, with the convex surface facing the image side; the third biconvex lens and the fourth meniscus lens are seamlessly glued to form the third cemented lens group.

2. The ultra-wide-angle and ultra-large-aperture optical lens according to claim 1, characterized in that: A surface of the first meniscus lens facing the object side is a convex surface.

3. The ultra-wide-angle and ultra-large-aperture optical lens according to claim 1, characterized in that: The Abbe coefficients of the second biconvex lens, the third biconvex lens and the fourth biconvex lens are all greater than 65.

4. The ultra-wide-angle and ultra-large-aperture optical lens according to claim 1, characterized in that: The refractive index of the third meniscus lens is greater than 1.

9.

5. The ultra-wide-angle and ultra-large-aperture optical lens according to claim 1, characterized in that: The refractive index of the first biconvex lens and the refractive index of the fourth meniscus lens are both greater than 2.0.

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