Zoom optical system and security lens

Abstract

The utility model discloses a zoom optical system and a security lens, and relates to the technical field of optics, the zoom optical system is provided with an object side and an image side which are oppositely arranged along the optical axis direction, and the zoom optical system comprises a first lens group, a diaphragm, a second lens group and an image surface which are sequentially arranged from the object side to the image side; wherein the focal power of the first lens group is negative, the focal power of the second lens group is positive, and at least one of the first lens group and the second lens group can move along the direction of the optical axis, so that the zoom optical system is zoomed. Through reasonable arrangement of structures and positions of the first lens group with negative focal power and the second lens group with positive focal power, the zoom optical system has the effects of large target surface, large aperture and small size.

Description

Technical Field

[0001] This utility model relates to the field of optical technology, and in particular to a zoom optical system and a security lens. Background Technology

[0002] With the development of the security industry, the requirements for zoom lens performance are becoming increasingly stringent. As security monitoring systems move towards higher definition, greater intelligence, and greater concealment, zoom lenses, as core optical components, must simultaneously meet the performance requirements of large aperture, large target surface, and small size.

[0003] However, existing technologies face multiple contradictions in this direction. To improve imaging quality in low-light environments (such as night surveillance), existing security lenses typically adopt a design that increases the aperture (F-number ≤ 1.8). However, a large aperture requires a complex optical structure (such as increasing the number of lenses or aspherical lenses), resulting in a significant increase in lens size, making it difficult to achieve a balance between a large aperture and a small size. In addition, to adapt to high-resolution sensors, existing technologies need to expand the image plane coverage area, but a large target surface design will exacerbate astigmatism and field curvature problems at the edge of the field of view, which cannot meet market demands. Utility Model Content

[0004] The main purpose of this invention is to propose a zoom optical system and a security lens, aiming to provide a zoom optical system with a large target area, large aperture, and small size.

[0005] To achieve the above objectives, this utility model proposes a zoom optical system, which has an object side and an image side arranged opposite to each other along the optical axis. The zoom optical system includes a first lens group, an aperture stop, a second lens group, and an image plane arranged sequentially from the object side to the image side.

[0006] In this system, at least one of the first lens group and the second lens group is movable along the optical axis to enable the zoom optical system to zoom.

[0007] In one embodiment, the focal length at the wide-angle end of the zoom optical system is F. W The focal length F of the first lens group 100 The value is negative, and the focal length F of the second lens group is negative. 200 It is positive; the focal length satisfies:

[0008] 0.1<|F W / F 100 |<0.55, 0.1<|F W / F 200 |<1.2.

[0009] In one embodiment, the first lens group includes a first lens, a second lens, and a third lens arranged sequentially from the object side to the image side along the optical axis.

[0010] The first lens has a negative optical power, the second lens has a negative optical power, and the third lens has a positive optical power.

[0011] In one embodiment, the focal length of the first lens group is F. 100 The focal length of the first lens is F1, the focal length of the second lens is F2, and the focal length of the third lens is F3. The focal lengths satisfy the following:

[0012] 0.82<|F 100 / F1|<1.11, 0.59<|F 100 / F2|<0.80, 0.56<|F 100 / F3|<0.76.

[0013] In one embodiment, the second lens group includes a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens, a ninth lens, a tenth lens, and an eleventh lens arranged sequentially from the object side to the image side along the optical axis.

[0014] The fourth lens has a positive optical power, the fifth lens has a negative optical power, the sixth lens has a positive optical power, the seventh lens has a negative optical power, the eighth lens has a positive optical power, the ninth lens has a negative optical power, the tenth lens has a positive optical power, and the eleventh lens has a negative optical power.

[0015] In one embodiment, the focal length of the second lens group is F. 200 The fourth lens has a focal length of F4, the fifth lens has a focal length of F5, the sixth lens has a focal length of F6, the seventh lens has a focal length of F7, the eighth lens has a focal length of F8, the ninth lens has a focal length of F9, and the tenth lens has a focal length of F... 10 The focal length of the eleventh lens is F. 11 The focal length satisfies:

[0016] 0.57<|F 200 / F4|<0.77, 3.00<|F 200 / F5|<4.06, 0.97<|F 200 / F6|<1.31, 0.76<|F 200 / F7|<1.03, 0.95<|F 200 / F8|<1.28, 1.87<|F 200 / F9|<2.52, 17.75<|F 200 / F 10 |<24.01, 31.06<|F 200 / F 11 |<42.03.

[0017] In one embodiment, the first lens group includes a first lens, a second lens, and a third lens arranged sequentially from the object side to the image side along the optical axis, wherein the second lens and the third lens are cemented together; and / or,

[0018] The second lens group includes a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens, a ninth lens, a tenth lens, and an eleventh lens arranged sequentially from the object side to the image side along the optical axis. The fifth and sixth lenses are cemented together, and the seventh, eighth, and ninth lenses are cemented together.

[0019] In one embodiment, the fourth lens, the tenth lens, and the eleventh lens are aspherical lenses.

[0020] In one embodiment, the zoom optical system further includes a filter disposed along the optical axis between the second lens group and the image plane, and close to the image plane.

[0021] This utility model also proposes a security lens, including a zoom optical system. The zoom optical system has an object side and an image side that are arranged opposite to each other along the optical axis. The zoom optical system includes a first lens group, an aperture stop, a second lens group, and an image plane arranged sequentially from the object side to the image side.

[0022] In this system, at least one of the first lens group and the second lens group is movable along the optical axis to enable the zoom optical system to zoom.

[0023] In the technical solution of this utility model, at least one of the first lens group and the second lens group moves along the optical axis toward the image side. The focal length of the two lens groups is different at different positions, so that the zoom optical system can continuously change from the wide-angle end to the telephoto end to achieve zoom. The aperture is set between the first lens group and the second lens group, which can adjust the field of view, block off-axis light rays, avoid the off-axis light rays from affecting the image quality, improve image quality, and enable the lens to have a large light transmission capacity, thereby having night vision function. Through the reasonable setting of the structure and position of the first lens group with negative optical power and the second lens group with positive optical power, the zoom optical system has the effect of large target surface, large aperture and small volume. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0025] Figure 1 A schematic diagram of a structure of an embodiment of the zoom optical system provided by this utility model;

[0026] Figure 2 for Figure 1 A schematic diagram of the field curvature / distortion curve of a medium zoom optical system at the wide-angle end;

[0027] Figure 3 for Figure 1 A schematic diagram of the field curvature / distortion curve of a medium zoom optical system at the telephoto end;

[0028] Figure 4 for Figure 1 A transverse chromatic aberration diagram of a medium zoom optical system at the wide-angle end;

[0029] Figure 5 for Figure 1 A transverse chromatic aberration diagram of a medium zoom optical system at the telephoto end.

[0030] Explanation of icon numbers:

[0031] 100. Zoom optical system; 1. First lens group; 11. First lens; 12. Second lens; 13. Third lens; 2. Second lens group; 21. Fourth lens; 22. Fifth lens; 23. Sixth lens; 24. Seventh lens; 25. Eighth lens; 26. Ninth lens; 27. Tenth lens; 28. Eleventh lens; 3. Aperture stop; 4. Filter; 5. Image plane.

[0032] The realization of the purpose, functional features and advantages of this utility model will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0033] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present utility model.

[0034] It should be noted that if the embodiments of this utility model involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indicators will also change accordingly.

[0035] Furthermore, if the embodiments of this utility model involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the use of "and / or" or "and / or" throughout the text includes three parallel solutions. For example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this utility model.

[0036] This utility model proposes a zoom optical system 100.

[0037] First, it's important to clarify that optical power is equal to the difference between the image-side convergence and the object-side convergence of the light beam; it characterizes the ability of an optical system to deflect light rays. The larger the absolute value of the optical power, the stronger the bending ability of light rays; the smaller the absolute value, the weaker the bending ability. When the optical power is positive, the refraction of light rays is converging; when the optical power is negative, the refraction of light rays is diverging. Optical power can be used to characterize a single refractive surface of a lens (i.e., one surface of the lens), a single lens, or a system formed by multiple lenses (i.e., a lens group).

[0038] Please see Figure 1 In one embodiment of the present invention, the zoom optical system 100 has an object side and an image side arranged opposite to each other along the optical axis. The zoom optical system 100 includes a first lens group 1, an aperture stop 3, a second lens group 2, and an image plane 5 arranged sequentially from the object side to the image side. The first lens group 1 has a negative optical power, and the second lens group 2 has a positive optical power. At least one of the first lens group 1 and the second lens group 2 can move along the optical axis to zoom the zoom optical system 100.

[0039] In the technical solution of this utility model, at least one of the first lens group 1 and the second lens group 2 moves along the optical axis toward the image side. The focal length of the two lens groups is different at different positions, so that the zoom optical system 100 can continuously change from the wide-angle end to the telephoto end to achieve zoom. The aperture 3 is located between the first lens group 1 and the second lens group 2, which can adjust the field of view, block the far-axis light rays, avoid the far-axis light rays from affecting the image quality, improve the image quality, and make the lens have a large light transmission. Through the reasonable setting of the structure and position of the first lens group 1 with negative optical power and the second lens group 2 with positive optical power, the zoom optical system 100 has the effect of large target surface, large aperture, and small volume.

[0040] In one embodiment of the present invention, the zoom optical system 100 further includes a filter 4, which is disposed between the second lens group 2 and the image plane 5 along the optical axis and close to the image plane 5. By disposing of the filter 4, the filter 4 can filter out stray light and prevent stray light from reaching the image plane 5 and interfering with normal visible light imaging, thereby improving the imaging quality.

[0041] Specifically, in one embodiment of this utility model, the focal length at the wide-angle end of the zoom optical system is FW, and the focal length of the first lens group 1 is F. 100 The value is negative, and the focal length F of the second lens group 2 is negative. 200 The value is positive; the focal length satisfies: 0.1 < |F W / F 100 |<0.55, 0.1<|FW / F 200 |<1.2; By conditionally limiting the focal length at the wide-angle end of the optical system and the focal length ratio of each lens group, the optical system can achieve a small size and a larger zoom range, adapting to the requirements of shooting in different scenarios.

[0042] In one embodiment of this utility model, the first lens group 1 includes a first lens, a second lens 12, and a third lens 13 arranged sequentially from the object side to the image side along the optical axis. The object side of the first lens is convex, allowing more light to enter. The object side and image side of the second lens 12 are concave, and both the object side and image side of the third lens 13 are convex. This arrangement ensures that the second lens 12 and the third lens 13 complement each other, resulting in a closer fit and a more compact structure. Furthermore, it ensures that the optical power of the second lens 12 is negative and the optical power of the third lens 13 is positive, controlling the light path and improving resolution. By limiting the positive and negative optical powers of the first lens, the second lens 12, and the third lens 13 in the first lens group 1, the height of light entering the subsequent group is reduced, thus reducing off-axis aberrations.

[0043] Furthermore, in one embodiment of this utility model, the focal length of the first lens group 1 is F100, the focal length of the first lens is F1, the focal length of the second lens 12 is F2, and the focal length of the third lens 13 is F3. The focal length satisfies: 0.82 < |F100||F2||F3||F3||F4||F5||F6||F7 ...6||F7|| 100 / F1|<1.11, 0.59<|F 100 / F2|<0.80, 0.56<|F 100 / F3|<0.76. Lens resolution is improved by conditionally limiting the focal length ratios of each lens and the first lens group 1.

[0044] Furthermore, in one embodiment of this invention, the second lens group 2 includes a fourth lens 21, a fifth lens 22, a sixth lens 23, a seventh lens 24, an eighth lens 25, a ninth lens 26, a tenth lens 27, and an eleventh lens 28 arranged sequentially from the object side to the image side along the optical axis. The fourth lens 21 has a positive optical power, the fifth lens 22 has a negative optical power, the sixth lens 23 has a positive optical power, the seventh lens 24 has a negative optical power, the eighth lens 25 has a positive optical power, the ninth lens 26 has a negative optical power, the tenth lens 27 has a positive optical power, and the eleventh lens 28 has a negative optical power. By limiting the positive and negative values ​​of the optical powers of each lens, residual spherical aberration of the system is corrected, and the ray height of the off-axis field of view is increased, giving the system a larger target surface. In one embodiment, the target surface of the zoom optical system can reach φ10.6mm.

[0045] Furthermore, the focal length of the second lens group 2 is F. 200 The fourth lens 21 has a focal length of F4, the fifth lens 22 has a focal length of F5, the sixth lens 23 has a focal length of F6, the seventh lens 24 has a focal length of F7, the eighth lens 25 has a focal length of F8, the ninth lens 26 has a focal length of F9, and the tenth lens 27 has a focal length of F... 10 The eleventh lens 28 has a focal length of F. 11 The focal length satisfies: 0.57 < |F 200 / F4|<0.77, 3.00<|F 200 / F5|<4.06, 0.97<|F 200 / F6|<1.31, 0.76<|F 200 / F7|<1.03, 0.95<|F 200 / F8|<1.28, 1.87<|F 200 / F9|<2.52, 17.75<|F 200 / F 10 |<24.01, 31.06<|F 200 / F11 |<42.03; By conditionally restricting the focal length ratio of each lens and the second lens group 2, the lens resolution is improved.

[0046] Specifically, in one embodiment of this utility model, the specific relationship between the focal length of the zoom optical system, the focal length of each lens group, and the focal length of each lens is shown in Table 1 below.

[0047] Table 1

[0048]

[0049] Furthermore, in one embodiment of this utility model, the first lens group 1 includes a first lens, a second lens 12, and a third lens 13 arranged sequentially from the object side to the image side along the optical axis direction. The second lens 12 and the third lens 13 are cemented together. The first lens group 1 uses a single lens and two spherical lenses cemented together, which can not only effectively correct the chromatic aberration of the zoom optical system 100, but also reduce the surface sensitivity and ensure the high resolution of the system.

[0050] Furthermore, in one embodiment of the utility model, the second lens group 2 includes a fourth lens 21, a fifth lens 22, a sixth lens 23, a seventh lens 24, an eighth lens 25, a ninth lens 26, a tenth lens 27, and an eleventh lens 28 arranged sequentially from the object side to the image side along the optical axis. The fifth lens 22 and the sixth lens 23 are cemented together, and the seventh lens 24, the eighth lens 25, and the ninth lens 26 are cemented together. By cementing the fifth lens 22 and the sixth lens 23 together, chromatic aberration is reduced while correcting the light. Furthermore, cementing the seventh lens 24, the eighth lens 25, and the ninth lens 26 further reduces aberration and chromatic aberration, thereby improving the image quality.

[0051] It is understandable that either of the cemented lenses in the two lens groups can be selected, or both can be used in both lens groups to further improve image quality.

[0052] Specifically, in one embodiment of this utility model, the fourth lens 21, the tenth lens 27, and the eleventh lens 28 are aspherical lenses.

[0053] Understandably, aspherical lenses are characterized by a continuous change in curvature from the center to the periphery. Unlike spherical lenses, which have a constant curvature from the center to the periphery, aspherical lenses have better curvature radius characteristics. They have the advantage of improving distortion aberrations and astigmatism. By using aspherical lenses, aberrations that occur during imaging can be eliminated as much as possible, thereby improving the image quality of the lens.

[0054] Specifically, in one embodiment of this utility model, the surface shape of the aspherical lens in the optical system should satisfy the following equation:

[0055]

[0056] Where c is the curvature corresponding to the radius; y is the radial coordinate (its unit is the same as the lens length unit); k is the conic quadratic coefficient, and A, B, C, D, E, F, G... represent the second, fourth, sixth, eighth, tenth, twelfth, fourteenth, sixteenth... aspherical coefficients, respectively.

[0057] More specifically, in one embodiment of this utility model, the coefficients of even-order terms for each aspherical surface are shown in Table 2 below, where A = 0.

[0058] Table 2

[0059]

[0060] The above parameters allow for precise setting of the shape and size of the aspherical surfaces on the front and back of the lens, effectively correcting symmetrical aberrations such as spherical aberration and field curvature.

[0061] Furthermore, in one embodiment of this invention, the eleventh lens 28 features a vignetting effect at its edge. It should be noted that vignetting refers to the phenomenon where light entering the optical system from the edge is partially blocked due to physical limitations of optical elements (such as lens edges, apertures, and frames). This phenomenon leads to reduced light intensity at the image edges, resulting in a vignetting effect. By setting a vignetting effect at the edge of the eleventh lens 28, stray light from the periphery can be blocked without affecting the image brightness, ensuring the same resolution at the center and edges of the image.

[0062] Specifically, in one embodiment of this utility model, the parameters of the zoom optical system are shown in Table 3 below.

[0063] Table 3

[0064]

[0065]

[0066] It should be noted that the thickness in Table 2 refers to the distance from the center of the surface to the next surface along the optical axis. Taking the first lens 11 as an example, the thickness of the object side of the first lens 11 refers to the distance from the center of the first lens 11, that is, the thickness of the first lens 11; the thickness of the image side of the first lens 11 refers to the distance from the center of the image side of the first lens 11 to the center of the object side of the second lens 12, that is, the air gap between the first lens 11 and the second lens 12.

[0067] In addition, the zoom magnification data of the zoom optical system at the wide-angle end and the telephoto end during the zoom process are shown in Table 3 below.

[0068] Table 3

[0069]

[0070] It should be noted that the data in Table 3 represents the distance of the surface from the next surface during the zoom process, in millimeters (mm). Specifically, the data for the image side of the eleventh lens refers to the distance between the image side of the eleventh lens and the object side of the filter 4 during the zoom process.

[0071] Figure 2 The figure shown is a schematic diagram of the field curvature / distortion curve at the wide-angle end of an embodiment of this utility model. Figure 3 The figure shown is a schematic diagram of the field curvature / distortion curve at the telescope end according to an embodiment of the present invention. Figure 4 This is a chromatic aberration diagram of the wide-angle end according to an embodiment of the present invention. Figure 5 This is a chromatic aberration diagram of the telescope end according to an embodiment of the present invention.

[0072] Depend on Figure 2-5 It can be seen that the fixed-focus optical system provided in this embodiment has good imaging capabilities.

[0073] In one embodiment of this utility model, the total optical length (TTL) of the optical system satisfies: TTL≤51.4mm, where the total optical length refers to the distance from one side of the first lens to the image plane, thus enabling the zoom optical system to achieve a small size.

[0074] It is understandable that the light carrying information about the subject can pass sequentially through the first lens 11, the second lens 12, the third lens 13, the aperture 3, the fourth lens 21, the fifth lens 22, the sixth lens 23, the seventh lens 24, the eighth lens 25, the ninth lens 26, the tenth lens 27, the eleventh lens 28, and the filter 4, and finally be imaged on the image plane 5.

[0075] This utility model also proposes a security lens, which includes a zoom optical system. The specific structure of the zoom optical system is as described in the above embodiments. Since the security lens adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be described in detail here.

[0076] The above description is merely an exemplary embodiment of the present utility model and does not limit the patent scope of the present utility model. Any equivalent structural transformations made based on the technical concept of the present utility model and the contents of the present utility model specification and drawings, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present utility model.

Claims

1. A zoom optical system, characterized in that, The zoom optical system has an object side and an image side that are arranged opposite to each other along the optical axis. The zoom optical system includes a first lens group, an aperture stop, a second lens group, and an image plane arranged sequentially from the object side to the image side. Wherein, the first lens group has a negative optical power, the second lens group has a positive optical power, and at least one of the first lens group and the second lens group can move along the optical axis to enable the zoom optical system to zoom.

2. The zoom optical system as described in claim 1, characterized in that, The focal length at the wide-angle end of the zoom optical system is F. W The focal length F of the first lens group 100 The value is negative, and the focal length F of the second lens group is negative. 200 It is positive; the focal length satisfies: 0.1<|F W / F 100 |<0.55,0.1<|F W / F 200 |<1.2。 3. The zoom optical system as described in claim 1, characterized in that, The first lens group includes a first lens, a second lens, and a third lens arranged sequentially from the object side to the image side along the optical axis; The first lens has a negative optical power, the second lens has a negative optical power, and the third lens has a positive optical power.

4. The zoom optical system as described in claim 3, characterized in that, The focal length of the first lens group is F 100 The focal length of the first lens is F1, the focal length of the second lens is F2, and the focal length of the third lens is F3. The focal lengths satisfy the following: 0.82<|F 100 / F1|<1.11,0.59<|F 100 / F2|<0.80,0.56<|F 100 / F3|<0.76。 5. The zoom optical system as described in claim 1, characterized in that, The second lens group includes a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens, a ninth lens, a tenth lens, and an eleventh lens arranged sequentially from the object side to the image side along the optical axis. The fourth lens has a positive optical power, the fifth lens has a negative optical power, the sixth lens has a positive optical power, the seventh lens has a negative optical power, the eighth lens has a positive optical power, the ninth lens has a negative optical power, the tenth lens has a positive optical power, and the eleventh lens has a negative optical power.

6. The zoom optical system as described in claim 5, characterized in that, The focal length of the second lens group is F 200 The fourth lens has a focal length of F4, the fifth lens has a focal length of F5, the sixth lens has a focal length of F6, the seventh lens has a focal length of F7, the eighth lens has a focal length of F8, the ninth lens has a focal length of F9, and the tenth lens has a focal length of F... 10 The focal length of the eleventh lens is F. 11 The focal length satisfies: 0.57<|F 200 / F4|<0.77,3.00<|F 200 / F5|<4.06,0.97<|F 200 / F6|<1.31,0.76<|F 200 / F7|<1.03,0.95<|F 200 / F8|<1.28,1.87<|F 200 / F9|<2.52,17.75<|F 200 / F 10 |<24.01,31.06<|F 200 / F 11 |<42.03。 7. The zoom optical system as described in claim 1, characterized in that, The first lens group includes a first lens, a second lens, and a third lens arranged sequentially from the object side to the image side along the optical axis, wherein the second lens and the third lens are cemented together; and / or, The second lens group includes a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens, a ninth lens, a tenth lens, and an eleventh lens arranged sequentially from the object side to the image side along the optical axis. The fifth and sixth lenses are cemented together, and the seventh, eighth, and ninth lenses are cemented together.

8. The zoom optical system as described in claim 5, characterized in that, The fourth lens, the tenth lens, and the eleventh lens are aspherical lenses.

9. The zoom optical system as described in claim 1, characterized in that, The zoom optical system further includes a filter, which is disposed along the optical axis between the second lens group and the image plane, and is positioned close to the image plane.

10. A security camera lens, characterized in that, Includes the zoom optical system as described in any one of claims 1 to 9.

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