An ultra-wide-angle large-aperture aspherical lens

Abstract

The present invention relates to an ultra-wide-angle large-aperture aspherical lens, which comprises a first lens group, a variable aperture and a second lens group arranged in sequence along the light incident direction; wherein, the first lens group has a non-moving positive optical power position; the second lens group has a moving positive optical power position; and the focal length value f1 of the first lens group and the focal length value f2 of the second lens group satisfy 1.5 < f1 / f2 < 2. In this way, this lens can have a large aperture and a small overall length, small distortion and high resolution, and can focus at a short distance.

Description

Technical Field

[0001] The present invention belongs to the technical field of lenses, and particularly relates to an ultra-wide-angle large-aperture aspherical lens. Background Art

[0002] With the development of society, people's demand for video shooting is increasing, and the requirements for video lenses are also getting higher and higher. For example, for common short-focus video lenses, their important indicators are high definition, large light transmission of large apertures, good chromatic aberration performance, and small distortion. However, the applicant has found that the existing short-focus video lenses on the market at present have the disadvantages of insufficient resolution, large distortion, small aperture, and long close-focusing distance during shooting, seriously affecting the shooting quality and simply unable to meet the requirements for high-quality short-focus video shooting. Summary of the Invention

[0003] To solve the above problems existing in the prior art, the present invention provides an ultra-wide-angle large-aperture aspherical lens with a large aperture and a small overall length, small distortion and high resolution, and capable of focusing at a short distance.

[0004] To solve the above technical problems, the present invention adopts the following technical solutions:

[0005] An ultra-wide-angle large-aperture aspherical lens, comprising a first lens group, a variable aperture stop, and a second lens group sequentially arranged along the light incident direction; wherein,

[0006] The first lens group has a non-movable positive optical power position;

[0007] The second lens group has a movable positive optical power position;

[0008] Moreover, the first lens group and the second lens group satisfy the following formula:

[0009] 1.5 < f1 / f2 < 2

[0010] In the formula, f1 is the focal length value of the first lens group, and f2 is the focal length value of the second lens group.

[0011] Furthermore, both the first lens group and the second lens group are composed of 7 lenses. Among them, at least one lens in the first lens group has a refractive index greater than 1.4 and less than 1.6, and at least five lenses have a refractive index greater than 1.8 and less than 2. At least three lenses in the second lens group G2 have a refractive index greater than 1.8 and less than 1.9.

[0012] Furthermore, at least four lenses in the second lens group have an Abbe number greater than 30 and less than 50.

[0013] Further, the first lens group includes two meniscus lenses with relatively large curvatures, and in the optical system composed of the first lens group and the second lens group, the second lens and the fourteenth lens counted from the light incident direction are both glass aspherical lenses.

[0014] Further, the second lens group includes a triplet lens.

[0015] Further, the overall optical length of the lens is greater than 89.5 mm and less than 91.5 mm.

[0016] Advantages of the present invention:

[0017] 1. Through the above technical solutions, the present invention can achieve a large aperture and a small overall length, small distortion and high resolution, and can also perform close focusing.

[0018] 2. By adopting two meniscus lenses with relatively large curvatures in the first lens group, and making the second lens and the fourteenth lens counted from the light incident direction in the optical system both glass aspherical lenses. In this way, on the one hand, it can optimize and increase the field of view angle (both L11 and L12 are meniscus lenses with relatively large curvatures, and the convex surfaces are both facing the object side, increasing the incident angle of the object-side light on the optical system), and on the other hand, the added aspherical surface can effectively optimize and improve the MTF.

[0019] In a possible implementation manner, the second lens group includes a triplet lens (that is, a lens composed of three lenses), which can effectively optimize apochromatism, thereby improving the imaging clarity of the lens and making the image quality more vivid. Description of the Drawings

[0020] Figure 1 is a schematic structural diagram of an embodiment of an ultra-wide-angle large-aperture aspherical lens according to the present invention;

[0021] Figure 2 is a longitudinal chromatic aberration diagram of an embodiment of an ultra-wide-angle large-aperture aspherical lens according to the present invention;

[0022] Figure 3 is a lateral chromatic aberration diagram of an embodiment of an ultra-wide-angle large-aperture aspherical lens according to the present invention;

[0023] Figure 4 is a field curvature and distortion diagram of an embodiment of an ultra-wide-angle large-aperture aspherical lens according to the present invention;

[0024] Figure 5 is a spot diagram of an embodiment of an ultra-wide-angle large-aperture aspherical lens according to the present invention;

[0025] Figure 6 is an MTF diagram of an embodiment of an ultra-wide-angle large-aperture aspherical lens according to the present invention;

[0026] Figure 7 It is the MTF defocus curve graph of an embodiment of the ultra-wide-angle large-aperture aspherical lens described in the present invention. Detailed implementation manners

[0027] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0028] An ultra-wide-angle large-aperture aspherical lens described in the present invention includes a first lens group, a variable aperture and a second lens group arranged in sequence along the light incident direction. Among them,

[0029] The first lens group has a non-moving positive focal length position;

[0030] The second lens group has a moving positive focal length position;

[0031] Moreover, the first lens group and the second lens group satisfy the following formula:

[0032] 1.5 < f1 / f2 < 2

[0033] In the formula, f1 is the focal length value of the first lens group, and f2 is the focal length value of the second lens group.

[0034] In a possible implementation manner, at least one lens of the first lens group has a refractive index greater than 1.4 and less than 1.6, and at least five lenses have a refractive index greater than 1.8 and less than 2. At least three lenses of the second lens group have a refractive index greater than 1.8 and less than 1.9.

[0035] At least four lenses of the second lens group have an Abbe number greater than 30 and less than 50.

[0036] By adopting the above structure, the ultra-wide-angle large-aperture aspherical lens described in the present invention can, on the one hand, achieve a large aperture and a small total length, on the other hand, achieve a small distortion and a high resolution, and can focus at a short distance. Thus, the problems of optimizing small distortion and good chromatic aberration while meeting the shooting requirements of high resolution and large aperture throughout the entire working distance of the optical system, and meeting the shooting requirements at the near end are solved. At the same time, the present invention takes into account high resolution, small distortion, large aperture, meets a short close-up distance, and can be matched with shooting of more than 20 million pixels.

[0037] In a possible implementation, the first lens group includes two meniscus lenses with a relatively large curvature, and in the optical system composed of the first lens group and the second lens group, the second lens and the fourteenth lens counted from the light incident direction are both glass aspherical lenses. In this way, on the one hand, it can be optimized to achieve a larger field angle (L11 and L12 are both meniscus lenses with a relatively large curvature, and the convex surfaces are both facing the object side, increasing the incident angle of the light from the object side to the optical system), and on the other hand, the added aspherical surface can effectively optimize and improve the MTF.

[0038] In a possible implementation, the second lens group includes a triplet lens (i.e., a lens composed of three lenses), which can effectively optimize apochromatism, thereby improving the imaging clarity of the lens and making the image quality more vivid.

[0039] In a possible implementation, the overall optical length of the lens is greater than 89.5 mm and less than 91.5 mm.

[0040] The following further illustrates the ultra-wide-angle large-aperture aspherical lens of the present invention through specific embodiments.

[0041] See Figure 1, the ultra-wide-angle large-aperture aspherical lens according to the embodiment of the present invention is a lens with a focal length of 9 mm, including a first lens group G1 and a second lens group G2 arranged in sequence along the light incident direction. The first lens group G1 is a lens group with a positive optical power that is fixed and immovable, composed of 7 lenses, and the second lens group G2 is a lens group with a positive optical power and serves as a moving focusing group, composed of 7 lenses. Moreover, the second lens from the light incident direction in the first lens group G1 is a glass aspherical lens, and the seventh lens from the light incident direction in the second lens group G2 is a glass aspherical lens. Specifically: The first lens group G1 is composed of lens L11, lens L12, lens L13, lens L14, lens L15, lens L16, and lens L17, and the second lens group G2 is composed of lens L21, lens L22, lens L23, lens L24, lens L25, lens L26, and lens L27; where the lens L11 is a meniscus lens with a negative optical power and a convex surface facing the object side, the lens L12 is a meniscus lens with a negative optical power and a convex surface facing the object side, the lens L13 is a biconcave lens with a negative optical power, the lens L14 is a biconvex lens with a positive optical power, the lens L15 is a biconcave lens with a negative optical power, the lens L16 is a plano-convex lens with a positive optical power and a convex surface facing the object side, the lens L17 is a biconvex lens with a positive optical power, the lens L21 is a meniscus lens with a positive optical power and a convex surface facing the image side, the lens L22 is a plano-concave lens with a negative optical power and a concave surface facing the object side, the lens L23 is a meniscus lens with a negative optical power and a convex surface facing the object side, the lens L24 is a biconvex lens with a positive optical power, the lens L25 is a meniscus lens with a negative optical power and a convex surface facing the image side, the lens L26 is a biconvex lens with a positive optical power, and the lens L27 is a meniscus lens with a negative optical power and a convex surface facing the image side. Moreover, the lens L12 and the lens L27 are glass aspherical lenses, and the lens L23, the lens L24, and the lens L25 form a three-piece cemented lens. The specific parameters of each lens in this embodiment of the present invention are as shown in Table 1 below.

[0042] Table 1

[0043]

[0044]

[0045] The parameters of the two glass aspherical lenses (lens L12 and lens L27) are specifically as shown in Table 2 below.

[0046] Table 2

[0047]

[0048]

[0049] The ultra-wide-angle large-aperture aspherical lens described in the embodiments of the present invention is subjected to longitudinal chromatic aberration, lateral chromatic aberration, field curvature distortion, circle of confusion, MTF, and MTF defocus tests, and the test results are as follows Figures 2 - 7 shown. From Figures 2 - 7 it can be known that the aberration correction of the optical system of the lens in this embodiment is good (where the longitudinal chromatic aberration is controlled within 0.055 mm from a wavelength of 435 mm to a wavelength of 656 mm, and the lateral chromatic aberration is controlled within 5 μm), the distortion is small (the optical distortion is less than -1.6%), and the resolution is high (it can be seen from the MTF curve graph that it can match a chip with more than 20 million pixels).

[0050] It can be seen that the lens of the embodiment of the present invention can achieve a short focal length, a large aperture, a short overall length, small distortion, and high resolution. Moreover, the lenses L22 to L27 of the second lens group G2 all use a short overall length and compact structure with the lens interval compressed to the extreme (see Table 1 for details), which greatly reduces the sensitivity of the tolerance to the subsequent manufacturing process assembly, improves the mass production yield, and thus reduces the production cost.

[0051] The above is the preferred embodiment of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements are also regarded as the protection scope of the present invention.

Claims

1. An ultra-wide-angle large-aperture aspherical lens, characterized in that It includes a first lens group, a variable aperture, and a second lens group that are sequentially arranged along the light incident direction; wherein, The first lens group has a non-moving positive focal power position; The second lens group has a moving positive focal power position; Moreover, the first lens group and the second lens group satisfy the following formula: 1.5 < f1 / f2 < 2 In the formula, f1 is the focal length value of the first lens group, and f2 is the focal length value of the second lens group; The first lens group is composed of lens L11, lens L12, lens L13, lens L14, lens L15, lens L16, and lens L17, and the second lens group is composed of lens L21, lens L22, lens L23, lens L24, lens L25, lens L26, and lens L27; wherein, lens L11 is a meniscus lens with a negative focal power and a convex surface facing the object side, lens L12 is a meniscus lens with a negative focal power and a convex surface facing the object side, lens L13 is a double concave lens with a negative focal power, lens L14 is a double convex lens with a positive focal power, lens L15 is a double concave lens with a negative focal power, lens L16 is a plano-convex lens with a positive focal power and a convex surface facing the object side, lens L17 is a double convex lens with a positive focal power, lens L21 is a meniscus lens with a positive focal power and a convex surface facing the image side, lens L22 is a plano-concave lens with a negative focal power and a concave surface facing the object side, lens L23 is a meniscus lens with a negative focal power and a convex surface facing the object side, lens L24 is a double convex lens with a positive focal power, lens L25 is a meniscus lens with a negative focal power and a convex surface facing the image side, lens L26 is a double convex lens with a positive focal power, and lens L27 is a meniscus lens with a negative focal power and a convex surface facing the image side.

2. The ultra-wide-angle large-aperture aspherical lens according to claim 1, characterized in that, At least one lens in the first lens group has a refractive index greater than 1.4 and less than 1.6, and at least five lenses have a refractive index greater than 1.8 and less than 2. At least three lenses in the second lens group have a refractive index greater than 1.8 and less than 1.

9.

3. The ultra-wide-angle large-aperture aspherical lens according to claim 2, wherein, At least four lenses in the second lens group have an Abbe number greater than 30 and less than 50.

4. The ultra-wide-angle large-aperture aspherical lens according to claim 2 or 3, characterized in that, In the optical system composed of the first lens group and the second lens group, the second lens and the fourteenth lens counted from the light incident direction are both glass aspherical lenses.

5. The ultra-wide-angle large-aperture aspherical lens according to claim 2 or 3, characterized in that, The second lens group includes a triplet lens.

6. The ultra-wide-angle large-aperture aspherical lens according to claim 1 or 2 or 3, characterized in that, The overall optical length of the lens is greater than 89.5 mm and less than 91.5 mm.

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