An imaging lens

Abstract

The utility model discloses an imaging lens, include: along the optical axis from object side to image side arrange in proper order with the first lens group of negative focal length, with the second lens group of positive focal length, diaphragm, with the third lens group of positive focal length, fourth lens group, with the fifth lens group of positive focal length, wherein, fourth lens group is focusing group, and fourth lens group includes fourteenth lens and fifteenth lens, and fourteenth lens and fifteenth lens constitute the cemented lens group. Fourth lens group only includes fourteenth lens and fifteenth lens, and fourteenth lens and fifteenth lens constitute cemented lens, and the stroke of focusing movement is reduced to two cemented lenses, is favorable to the length of imaging system's reduction, and the weight of the focus group and the load of push motor are alleviated, and it is favorable to the quick focus of imaging lens and imaging equipment.

Description

Technical Field

[0001] This utility model relates to the field of photographic lenses, and more particularly to an imaging lens. Background Technology

[0002] A wide-angle lens, also known as a short-focus lens, simply means that from the same position, a wide-angle lens can capture a larger area. Because a wide-angle lens is very short, the scene projected onto the film appears smaller. In addition to capturing more scenery, it can also capture wide-angle images in narrow environments.

[0003] Currently, traditional wide-angle lenses have a large number of elements in the fourth lens group, resulting in excessive weight of the lens group, heavy focusing load, difficulty in ensuring focusing speed, and large lens size and high cost due to the large number of elements. Utility Model Content

[0004] To overcome the shortcomings of existing wide-angle lenses, such as excessive weight, high focusing load, and unreliable focusing speed due to the large number of lenses in the fourth lens group, as well as the large size and high cost of the lens due to the excessive number of lenses, this utility model provides an imaging lens, comprising: Along the optical axis from the object side to the image side, the following lenses are arranged in sequence: a first lens group with negative optical power, a second lens group with positive optical power, an aperture stop, a third lens group with positive optical power, a fourth lens group, and a fifth lens group with positive optical power; wherein, the fourth lens group is a focusing group, which includes a fourteenth lens and a fifteenth lens, and the fourteenth and fifteenth lenses form a cemented lens group.

[0005] Optionally, in the first lens group, there is at least one meniscus aspherical lens ASP, the focal length of which is Fasp, and it is an ultra-wide-angle lens that satisfies the following condition: (1) -6≤|F1 / F|≤-8.6; (2)-1.8≤|FASP / EFL|≤-1; Wherein, F1: focal length of the first lens group G1; Fasp: focal length of the meniscus aspherical surface ASP in the first lens group; F: focal length of the entire optical system at infinity; EFL: focal length of the entire optical system at infinity.

[0006] Optionally, the first lens group includes a first lens with negative optical power, a second lens with negative optical power, a third lens with negative optical power, and a fourth lens with positive optical power.

[0007] Optionally, the second lens group includes a fifth lens with positive optical power, a sixth lens with negative optical power, a seventh lens with positive optical power, an eighth lens with positive optical power, and a ninth lens with positive optical power.

[0008] Optionally, the fifth, sixth, and seventh lenses form a cemented lens group, and the eighth and ninth lenses form a cemented lens group.

[0009] Optionally, the third lens group includes a tenth lens with positive optical power, an eleventh lens with negative optical power, a twelfth lens with positive optical power, and a thirteenth lens with negative optical power.

[0010] Optionally, the tenth and eleventh lenses form a cemented lens group, and the twelfth and thirteenth lenses form a cemented lens group. Optionally, the fifth lens group includes a sixteenth lens with orthogonal angles.

[0011] Optionally, the fourteenth lens is a concave lens and the fifteenth lens is a convex lens.

[0012] Optionally, the sixteenth lens is a concave-convex lens.

[0013] The beneficial effects of this utility model are as follows: The focusing assembly of the imaging lens involved in this utility model is completed only by the fourth lens group, which includes only the fourteenth and fifteenth lenses. The fourteenth and fifteenth lenses form a cemented lens. The two cemented lenses reduce the focusing movement stroke, which helps to shorten the length of the imaging system, reduce the weight of the focusing assembly and the load on the drive motor, and facilitates the rapid focusing of the imaging lens and imaging device. Compared with the prior art, the overall weight of the lens assembly of this application is not large, the focusing load is small, and the focusing speed is fast. Since the number of focusing lenses is small, the overall size of the lens can also be reduced accordingly, and the cost is reduced accordingly. Attached Figure Description

[0014] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0015] Figure 1 These are schematic diagrams of lens configurations in some embodiments; Figure 2 These are schematic diagrams of lens configurations and optical paths in some embodiments; Figure 3 These are schematic diagrams illustrating spherical aberration at infinity in some embodiments: Figure 4 These are schematic diagrams of field curvature at infinity in some embodiments; Figure 5 These are schematic diagrams illustrating distortion at infinity in some embodiments: Figure 6 These are schematic diagrams illustrating chromatic aberration at infinity focus in some embodiments. Figure 7 Here are some schematic diagrams illustrating spherical aberration when focusing at a distance of 1m in some embodiments: Figure 8 These are schematic diagrams of field curvature in some embodiments when focusing at a distance of 1m; Figure 9 These are schematic diagrams illustrating distortion when focusing at a distance of 1m in some embodiments: Figure 10 This diagram illustrates the magnification chromatic aberration when focusing at a distance of 1m according to Embodiment 1 of the present invention.

[0016] Explanation of reference numerals in the attached diagram: L1, first lens; L2, second lens; L3, third lens; L4, fourth lens; L5, fifth lens; L6, sixth lens; L7, seventh lens; L8, eighth lens; L9, ninth lens; L10, tenth lens; L11, eleventh lens; L12, twelfth lens; L13, thirteenth lens; L14, fourteenth lens; L15, fifteenth lens; L16, sixteenth lens; G1, first lens group; G2, second lens group; G3, third lens group; G4, fourth lens group; G5, fourth lens group; CG, protective glass; IAMG, image plane. Detailed Implementation

[0017] The following will clearly and completely describe the concept, specific structure, and technical effects of this utility model in conjunction with embodiments and accompanying drawings, so as to fully understand the purpose, features, and effects of this utility model. Obviously, the described embodiments are only a part of the embodiments of this utility model, not all of them. Other embodiments obtained by those skilled in the art based on the embodiments of this utility model without creative effort are all within the scope of protection of this utility model. Furthermore, all connections / linkages involved in the patent do not simply refer to direct contact between components, but rather to the ability to form a better connection structure by adding or reducing connecting accessories according to specific implementation conditions. The various technical features in this utility model can be combined interactively without contradicting each other.

[0018] This utility model provides an imaging lens, comprising: a first lens group G1 with negative optical power, a second lens group G2 with positive optical power, an aperture, a third lens group G3 with positive optical power, a fourth lens group G5G4, and a fifth lens group with positive optical power arranged sequentially from the object side to the image side along the optical axis; wherein, the fourth lens group G5G4 includes a fourteenth lens L14 and a fifteenth lens L15, and the fourteenth lens L14 and the fifteenth lens L15 form a cemented lens group.

[0019] In implementation, the first lens group G1, the second lens group G2, the third lens group G3, the fourth lens group G5G4, and the fifth lens group are arranged sequentially along the optical axis from the object side to the image side. The focusing group includes a fourteenth lens L14 and a fifteenth lens L15, which together form a cemented lens group. During focusing, the fourteenth / fifteenth cemented lens moves along the optical axis towards the image side. The positions of the first lens group G1, the second lens group G2, the third lens group, and the fifth lens group relative to the image plane remain unchanged. The focusing assembly of the imaging lens involved in this invention consists only of the first lens group G1, the second lens group G2, the third lens group G3, the fifth lens group G4, and the fifth lens group G5G4. The four-lens group G5G4 is completed, and the fourth lens group G5G4 only includes the fourteenth lens L14 and the fifteenth lens L15. The fourteenth lens L14 and the fifteenth lens L15 form a cemented lens. The two cemented lenses reduce the focus movement stroke, which helps to reduce the length of the imaging system, reduce the weight of the focusing group and the load on the drive motor, and facilitate the rapid focusing of the imaging lens and imaging device. Compared with the prior art, the overall weight of the lens group in this application is not large, the focusing load is small, and the focusing speed is fast. Since there are fewer focusing lenses, the overall size of the lens can also be reduced accordingly, and the cost is reduced accordingly.

[0020] Furthermore, the fourteenth lens L14 is a concave lens, and the fifteenth lens L15 is a convex lens.

[0021] In some embodiments, the first lens group G1 includes at least one meniscus aspherical lens ASP, the focal length of which is Fasp, and is an ultra-wide-angle lens that satisfies the following condition: (1) -6≤|F1 / F|≤-8.6 (2) -1.8≤|FASP / EFL|≤-1 Wherein, F1: focal length of the first lens group G1G1; Fasp: focal length of the meniscus aspherical surface ASP in the first lens group G1; F: focal length of the entire optical system at infinity; EFL: focal length of the entire optical system at infinity.

[0022] In practice, under the condition that conditions (1) and (2) are met, the first lens group G1 can have a suitable refractive power to control the volume of the first lens group G1, while achieving the effect of ultra-wide angle.

[0023] It should be noted that if the upper limit of condition (1) is exceeded, the refractive power of the first lens group G1 will be too strong. Although this is very beneficial for the ultra-wide viewing angle and miniaturization, the excessive refractive power will cause various image fields to be unable to be well corrected, making it difficult to achieve high performance. If the lower limit of condition (1) is exceeded, although the performance is easy to achieve, the ultra-wide viewing angle and small size cannot be achieved. If the lower limit of condition (2) is exceeded, the refractive power of the aspherical lens ASP in the first lens group G1 will be too strong. Although this is very beneficial for the miniaturization of the entire optical system, the excessive strength will cause the aspherical lens ASP to be too sensitive in the system. Because the refractive power is very strong, the center and edge thickness ratio is too high, making production extremely difficult with current technology, resulting in high yield and high cost. If the upper limit of condition (2) is exceeded, the refractive power of the aspherical ASP will be very weak. Although the sensitivity in the system is very low and the processing is relatively easy, it is difficult to achieve the design goal of ultra-wide angle.

[0024] In some embodiments, the first lens group G1 includes a first lens L1 having negative optical power, a second lens L2 having negative optical power, a third lens L3 having negative optical power, and a fourth lens L4 having positive optical power.

[0025] Furthermore, the first lens L1 is a concave-convex lens, the second lens L2 is a concave-convex lens, the third lens L3 is a concave-convex lens, and the fourth lens L4 is a concave-convex lens.

[0026] In some embodiments, the second lens group G2 includes a fifth lens L5 having positive optical power, a sixth lens L6 having negative optical power, a seventh lens L7 having positive optical power, an eighth lens L8 having positive optical power, and a ninth lens L9 having positive optical power.

[0027] Furthermore, the fifth lens L5 is a convex lens, the sixth lens L6 is a concave lens, the seventh lens L7 is a concave-convex lens, the eighth lens L8 is a concave-convex lens, and the ninth lens is a convex lens. The fifth lens L5, the sixth lens L6, and the seventh lens L7 form a cemented lens group, and the eighth lens L8 and the ninth lens L9 form a cemented lens group.

[0028] In some embodiments, the third lens group G3 includes a tenth lens L10 with positive optical power, an eleventh lens L11 with negative optical power, a twelfth lens L12 with positive optical power, and a thirteenth lens L13 with negative optical power.

[0029] Furthermore, the tenth lens L10 is a convex lens, the eleventh lens L11 is a concave-convex lens, the twelfth lens L12 is a concave-convex lens, and the thirteenth lens L13 is a concave-convex lens. The tenth lens L10 and the eleventh lens L11 form a cemented lens group, and the twelfth lens L12 and the thirteenth lens L13 form a cemented lens group. In some embodiments, the fifth lens group includes a sixteenth lens L16 having an orthogonal angle.

[0030] Furthermore, the sixteenth lens, L16, is a concave-convex lens.

[0031] Table 1 below lists the relevant parameters of each lens in this embodiment, including surface type, radius of curvature, thickness, refractive index of the material, and Abbe number:

[0032] Table 2 below lists the focusing data for this embodiment, including object distance, focal length, thickness of mirror 16 in Table 1, and thickness of mirror 18 in Table 1:

[0033] The aspherical coefficients of this embodiment are listed in Table 3 below:

[0034] The above is a detailed description of the preferred embodiments of the present utility model. However, the present utility model is not limited to the described embodiments. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present utility model. All such equivalent modifications or substitutions are included within the scope defined by the claims of this application.

Claims

1. An imaging lens, characterized in that, include: Along the optical axis from the object side to the image side, the following lenses are arranged in sequence: a first lens group with negative optical power, a second lens group with positive optical power, an aperture stop, a third lens group with positive optical power, a fourth lens group, and a fifth lens group with positive optical power; wherein, the fourth lens group is a focusing group, which includes a fourteenth lens and a fifteenth lens, and the fourteenth and fifteenth lenses form a cemented lens group.

2. The imaging lens according to claim 1, characterized in that, In the first lens group, there is at least one meniscus aspherical lens ASP, the focal length of which is Fasp, and it is an ultra-wide-angle lens that satisfies the following condition: (1) -6≤|F1 / F|≤-8.6; (2)-1.8≤|FASP / EFL|≤-1; Wherein, F1: focal length of the first lens group G1; Fasp: focal length of the meniscus aspherical surface ASP in the first lens group; F: focal length of the entire optical system at infinity; EFL: focal length of the entire optical system at infinity.

3. The imaging lens according to claim 1, characterized in that, The first lens group includes a first lens with negative optical power, a second lens with negative optical power, a third lens with negative optical power, and a fourth lens with positive optical power.

4. The imaging lens according to claim 1, characterized in that, The second lens group includes a fifth lens with positive optical power, a sixth lens with negative optical power, a seventh lens with positive optical power, an eighth lens with positive optical power, and a ninth lens with positive optical power.

5. The imaging lens according to claim 4, characterized in that, The fifth, sixth, and seventh lenses form a cemented lens group, and the eighth and ninth lenses form a cemented lens group.

6. The imaging lens according to claim 1, characterized in that, The third lens group includes a tenth lens with positive optical power, an eleventh lens with negative optical power, a twelfth lens with positive optical power, and a thirteenth lens with negative optical power.

7. The imaging lens according to claim 6, characterized in that, The tenth and eleventh lenses form a cemented lens group, and the twelfth and thirteenth lenses form a cemented lens group.

8. The imaging lens according to claim 1, characterized in that, The fifth lens group includes a sixteenth lens with orthogonal angles.

9. The imaging lens according to claim 1, characterized in that, The fourteenth lens is a concave lens, and the fifteenth lens is a convex lens.

10. The imaging lens according to claim 8, characterized in that, The sixteenth lens is a concave-convex lens.

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