Zoom optical system

Abstract

The invention discloses a zoom optical system, and relates to the technical field of zoom optical systems.The zoom optical system is provided with an object side and an image side which are oppositely arranged in the optical axis direction, and the zoom optical system comprises a first lens group, a second lens group and an image plane which are sequentially arranged from the object side to the image side; the first lens group and the second lens group are movably arranged along the direction of an optical axis, the second lens group is used for zooming, the first lens group is used for focusing, the maximum optical total length of the zoom optical system is within 51mm, the focal length of the zoom optical system at a wide-angle end is fw, the focal length of the first lens group is f1, the focal length of the second lens group is f2, and the zoom optical system meets the following conditions: fw, f1, f2 and fw respectively. -0.55 < = fw / f1 < =-0.1; and 0.2323 < = fw / f2 < = 0.75. By means of the arrangement, the zoom optical system has the field angle of 140 degrees or above when located at the wide-angle end, and the zoom optical system is wide in view field, small in size, low in cost, high in resolution ratio and capable of meeting the requirement for face recognition in the high-low-temperature environment.

Description

Technical Field

[0001] The present invention relates to the technical field of zoom optical systems, and particularly to a zoom optical system. Background Art

[0002] Zoom optical systems can be applied to a variety of monitoring scenarios due to their variable focal lengths. For example, in the security market, they can simultaneously meet the requirements for image acquisition in long-distance monitoring scenarios and the requirements for face recognition at close range.

[0003] However, existing lenses have a small aperture, cannot meet the requirements for image brightness in low-light environments, and cannot balance a large image plane and a small volume, thus not meeting the spatial requirements of the lens. They also have a low pixel count and cannot balance infrared performance and high and low temperature performance, resulting in the inability to meet the real-time requirements for face recognition in high and low temperature environments. Summary of the Invention

[0004] The main objective of the present invention is to propose a zoom optical system, aiming to improve the problems that existing zoom optical systems cannot meet the requirements for image brightness in low-light environments, cannot balance a large image plane and a small volume, do not meet the spatial requirements of the lens, have a low pixel count, and cannot balance infrared performance and high and low temperature performance, resulting in the inability to meet the real-time requirements for face recognition in high and low temperature environments.

[0005] To achieve the above objective, the zoom optical system proposed by the present invention has an object side and an image side arranged oppositely along the optical axis direction. The zoom optical system includes a first lens group, a second lens group, and an image plane arranged in sequence from the object side to the image side. Both the first lens group and the second lens group are movably arranged along the optical axis direction. The second lens group is used for zooming, the first lens group is used for focusing, and the maximum optical total length of the zoom optical system is within 51 mm.

[0006] Among them, the focal length of the zoom optical system at the wide-angle end is fw, the focal length of the first lens group is f1, the focal length of the second lens group is f2, and the zoom optical system satisfies the following conditions:

[0007] -0.55 ≤ fw / f1 ≤ -0.1; and 0.2323 ≤ fw / f2 ≤ 0.75.

[0008] In one embodiment, the optical power of the first lens group is negative;

[0009] The optical power of the second lens group is positive.

[0010] In one embodiment, the first lens group includes a first lens, a second lens, and a third lens arranged in sequence from the object side to the image side;

[0011] The focal length of the first lens is f11, the focal length of the second lens is f12, and the focal length of the third lens is f13, where 0.67 ≤ f1 / f11 ≤ 0.90; and 0.44 ≤ f1 / f12 ≤ 0.60; and -0.41 ≤ f1 / f13 ≤ -0.30.

[0012] In one embodiment, the object side surface of the first lens is convex, and the image side surface is concave;

[0013] The object side surface of the second lens is concave, and the image side surface is concave;

[0014] The object side surface of the third lens is convex, and the image side surface is convex.

[0015] In one embodiment, the second lens group includes a fourth lens, a fifth lens, a sixth lens, a seventh lens, and an eighth lens sequentially arranged from the object side to the image side;

[0016] The focal length of the fourth lens is f21, the focal length of the fifth lens is f22, the focal length of the sixth lens is f23, the focal length of the seventh lens is f24, and the focal length of the eighth lens is f25, where 0.68 ≤ f2 / f21 ≤ 0.91, and 1.34 ≤ f2 / f22 ≤ 1.81, and 1.95 ≤ f2 / f23 ≤ 2.64, and -0.66 ≤ f2 / f24 ≤ -0.49, and 1.08 ≤ f2 / f25 ≤ 1.46.

[0017] In one embodiment, the object side surface of the fourth lens is convex, and the image side surface is convex;

[0018] The object side surface of the fifth lens is convex, and the image side surface is convex;

[0019] The object side surface of the sixth lens is concave, and the image side surface is convex;

[0020] The object side surface of the seventh lens is concave, and the image side surface is concave;

[0021] The object side surface of the eighth lens is convex, and the image side surface is concave.

[0022] In one embodiment, the target surface size of the zoom optical system is φ, φ ≤ 6.6 mm.

[0023] In one embodiment, the aperture of the zoom optical system is Fno, 1.57 ≤ Fno ≤ 2.64.

[0024] In one embodiment, the focal length of the zoom optical system is f, 3.46 mm ≤ f ≤ 10.48 mm.

[0025] In one embodiment, the zoom optical system further includes a diaphragm and a filter. The diaphragm is disposed between the first lens group and the second lens group, and the filter is disposed on the image side of the second lens group.

[0026] In the technical solution of the present invention, the first lens group and the second lens group are both movably disposed along the optical axis direction. The second lens group moves along the optical axis direction to zoom the zoom optical system. At the same time, the first lens group moves cooperatively along the optical axis direction to focus the zoom optical system, so that the imaging of the image plane remains clear during the zooming process of the zoom optical system. Thus, by restricting the ratio of the focal length of the first lens group to the focal length of the zoom optical system at the wide-angle end within the range of -0.55 ≤ fw / f1 ≤ -0.1, and restricting the ratio of the focal length of the second lens group to the focal length of the zoom optical system at the wide-angle end within the range of 0.2323 ≤ fw / f2 ≤ 0.75, and the maximum optical total length of the zoom optical system is within 51 mm, so that the zoom optical system has a field of view angle of more than 140° at the wide-angle end, to provide a zoom optical system with a wide field of view, small volume, low cost, high resolution and capable of meeting the requirements of face recognition in high and low temperature environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on the structures shown in these drawings.

[0028] Figure 1 It is a schematic structural diagram of an embodiment of the zoom optical system provided by the present invention;

[0029] Figure 2 It is a LON schematic diagram of the zoom optical system provided by the present invention at the wide-angle end;

[0030] Figure 3 It is a LON schematic diagram of the zoom optical system provided by the present invention at the telephoto end.

[0031] Explanation of the reference numerals in the drawings:

[0032] 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; 3, diaphragm; 4, filter.

[0033] The implementation, functional features and advantages of the present invention will be further described with reference to the embodiments and the accompanying drawings. Detailed implementation manners

[0034] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0035] It should be noted that if there are directional indications (such as up, down, left, right, front, back...) involved in the embodiments of the present invention, the directional indications are only used to explain the relative position relationship and movement conditions between components in a specific posture. If the specific posture changes, the directional indications will also change accordingly.

[0036] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of the features. In addition, if "and / or" or "and / or" appears throughout the text, its meaning includes three parallel solutions. Taking "A and / or B" as an example, it includes solution A, solution B, or a solution where A and B are satisfied simultaneously. In addition, the technical solutions between the embodiments can be combined with each other, but it must be based on the ability of those of ordinary skill in the art to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the protection scope required by the present invention.

[0037] The present invention provides a zoom optical system, aiming to solve the problems that the existing zoom optical systems cannot meet the requirements of image brightness in low-light environments, cannot balance a large image plane and a small volume, cannot meet the space requirements of the lens, have low pixels, and cannot balance infrared performance and high and low temperature performance, resulting in the inability to meet the real-time requirements of face recognition in high and low temperature environments.

[0038] Please refer to Figure 1, in an embodiment of the present invention, the zoom optical system 100 has an object side and an image side that are oppositely arranged along the optical axis direction. The zoom optical system 100 includes a first lens group 1, a second lens group 2, and an image plane arranged in sequence from the object side to the image side. Both the first lens group 1 and the second lens group 2 are movably arranged along the optical axis direction. The second lens group 2 is used for zooming, and the first lens group 1 is used for focusing. Moreover, the maximum optical total length of the zoom optical system 100 is within 51 mm. The focal length of the zoom optical system 100 at the wide-angle end is fw, the focal length of the first lens group 1 is f1, and the focal length of the second lens group 2 is f2. The zoom optical system 100 satisfies the following conditions: -0.55 ≤ fw / f1 ≤ -0.1; and 0.2323 ≤ fw / f2 ≤ 0.75.

[0039] In the technical solution of the present invention, both the first lens group 1 and the second lens group 2 are movably arranged along the optical axis direction. The second lens group 2 moves along the optical axis to zoom the zoom optical system 100. At the same time, the first lens group 1 moves cooperatively along the optical axis to focus the zoom optical system 100, so that the imaging of the image plane remains clear during the zooming process of the zoom optical system 100. Thus, by restricting the ratio of the focal length of the first lens group 1 to the focal length of the zoom optical system 100 at the wide-angle end within the range of -0.55 ≤ fw / f1 ≤ -0.1, and restricting the ratio of the focal length of the second lens group 2 to the focal length of the zoom optical system 100 at the wide-angle end within the range of 0.2323 ≤ fw / f2 ≤ 0.75, and keeping the maximum optical total length of the zoom optical system 100 within 51 mm, the zoom optical system 100 has a field of view angle of more than 140° when at the wide-angle end, so as to provide a zoom optical system 100 with a wide field of view, small volume, low cost, high resolution, and capable of meeting the requirements of face recognition in high and low temperature environments.

[0040] It should be noted that the present invention does not limit the specific driving forms of the first lens group 1 and the second lens group 2 moving along the optical axis. In an embodiment of the present invention, the driving force for the first lens group 1 and the second lens group 2 to move along the optical axis can be driven by a driving motor; in another embodiment of the present invention, the driving force for the first lens group 1 and the second lens group 2 to move along the optical axis can also be manually adjusted; in yet another embodiment of the present invention, the driving force for one of the first lens group 1 and the second lens group 2 to move along the optical axis is driven by a driving motor, and the driving force for the other to move along the optical axis is manually adjusted. In actual settings, it can be selected according to requirements, and the present invention does not limit this here.

[0041] It is understandable that in the present invention, the optical power of the first lens group 1 is negative, and the optical power of the second lens group 2 is positive. With such a setting, through the cooperation of multiple lens groups with reasonable optical powers, the imaging quality of the zoom optical system 100 is ensured.

[0042] In addition, in the present invention, the focal length of the zoom optical system 100 is f, and 3.46 mm ≤ f ≤ 10.48 mm.

[0043] Specifically, in an embodiment of the present invention, the first lens group 1 includes a first lens 11 with a negative optical power, a second lens 12 with a negative optical power, and a third lens 13 with a positive optical power arranged in sequence along the optical axis direction.

[0044] In a specific embodiment of the present invention, the focal length of the first lens 11 is f11, the focal length of the second lens 12 is f12, and the focal length of the third lens 13 is f13.

[0045] It is understandable that the present invention does not limit the specific values of the focal lengths of the first lens 11, the second lens 12, and the third lens 13. In the embodiments of the present invention, the first lens 11, the second lens 12, and the third lens 13 can be set to any value within the range.

[0046] Moreover, in this embodiment, the first lens 11 is a glass spherical lens. With such a setting, using a lens made of glass can reduce the influence of temperature on the optical performance of the lens. The glass lens is not easily affected by thermal expansion and contraction and does not have a focus shift phenomenon. Therefore, the glass lens can well resist the problem of lens thermal deformation and maintain the high precision of the lens for a long time. The second lens 12 and the third lens 13 are plastic aspherical lenses. With such a setting, the aspherical lens has better curvature radius characteristics and has the advantages of improving distortion aberration and astigmatism aberration. After using the aspherical lens, the aberration that appears during imaging can be eliminated as much as possible, thereby improving the imaging quality of the lens. At the same time, using plastic aspherical lenses can also reduce the manufacturing cost of the projection optical system.

[0047] Meanwhile, setting the second lens 12 and the third lens 13 as plastic aspherical lenses is also beneficial for the zoom optical system 100 to collect light, can effectively increase the field of view range, correct distortion, and reduce the volume.

[0048] Specifically, in an embodiment of the present invention, the object side of the first lens 11 is convex, the image side is concave, the object side of the second lens 12 is concave, the image side is concave, the object side of the third lens 13 is convex, and the image side is convex.

[0049] In addition, in another embodiment of the present invention, the second lens group 2 includes a fourth lens 21, a fifth lens 22, a sixth lens 23, a seventh lens 24, and an eighth lens 25 arranged in sequence from the object side to the image side.

[0050] In a further specific embodiment of the present invention, the focal length of the fourth lens 21 is f21, the focal length of the fifth lens 22 is f22, the focal length of the sixth lens 23 is f23, the focal length of the seventh lens 24 is f24, and the focal length of the eighth lens 25 is f25. Among them, 0.68 ≤ f2 / f21 ≤ 0.91, 1.34 ≤ f2 / f22 ≤ 1.81, 1.95 ≤ f2 / f23 ≤ 2.64, -0.66 ≤ f2 / f24 ≤ -0.49, and 1.08 ≤ f2 / f25 ≤ 1.46.

[0051] It can be understood that the present invention also does not limit the specific values of the focal lengths of the fourth lens 21, the fifth lens 22, the sixth lens 23, the seventh lens 24, and the eighth lens 25. In the embodiments of the present invention, the focal lengths of the fourth lens 21, the fifth lens 22, the sixth lens 23, the seventh lens 24, and the eighth lens 25 can be set to any value within the range.

[0052] It should also be noted that, in this embodiment, the fourth lens 21 is a glass spherical lens, and the fifth lens 22, the sixth lens 23, the seventh lens 24, and the eighth lens 25 are plastic aspherical lenses.

[0053] In a further specific embodiment of the present invention, the object side surface of the fourth lens 21 is convex, the image side surface is convex, the object side surface of the fifth lens 22 is convex, the image side surface is convex, the object side surface of the sixth lens 23 is concave, the image side surface is convex, the object side surface of the seventh lens 24 is concave, the image side surface is concave, and the object side surface of the eighth lens 25 is convex, the image side surface is concave.

[0054] It should be noted that, in the present invention, the target surface size of the zoom optical system 100 is φ, and φ ≤ 6.6 mm.

[0055] It should be further noted that, in the present invention, the aperture of the zoom optical system 100 is Fno, and 1.57 ≤ Fno ≤ 2.64. In this way, the zoom optical system 100 has the characteristic of a large aperture, enabling the zoom optical system 100 to still have excellent imaging effects in a low-illumination environment, meeting the imaging requirements in bright and dark environments, and realizing the night vision function.

[0056] In addition, in the embodiments of the present invention, the zoom optical system 100 further includes a diaphragm 3 and a filter 4. The diaphragm 3 is disposed between the first lens group 1 and the second lens group 2, and the filter 4 is disposed on the image side of the second lens group 2. The diaphragm 3 is used to adjust the light flux according to actual conditions to improve the imaging quality. The setting of the filter 4 can effectively filter out stray light in non-working bands to reduce light noise, making it easier for the subsequent optoelectronic module processing part and thus improving the imaging quality.

[0057] Specifically, in a specific embodiment of the present invention, the object side surface of the first lens 11 is S1, the image side surface is S2, the object side surface of the second lens 12 is S3, the image side surface is S4, the object side surface of the third lens 13 is S5, the image side surface is S6, the diaphragm 3 is S7, the object side surface of the fourth lens 21 is S8, the image side surface is S9, the object side surface of the fifth lens 22 is S10, the image side surface is S11, the object side surface of the sixth lens 23 is S12, the image side surface is S13, the object side surface of the seventh lens 24 is S14, the image side surface is S15, the object side surface of the eighth lens 25 is S16, the image side surface is S17, the object side surface of the filter 4 is S18, the image side surface is S19, and the image plane is S20.

[0058] It should be noted that in this embodiment, the surface types, curvature radii, thicknesses, material refractive indices, and material Abbe numbers of the lenses of the zoom optical system 100 are shown in Table 1 below:

[0059] Table 1

[0060]

[0061]

[0062] It can be understood that in this embodiment, the second lens 12, the third lens 13, the fifth lens 22, the sixth lens 23, the seventh lens 24, and the eighth lens 25 are all aspherical lenses. The characteristics of aspherical lenses are that the curvature changes continuously from the center to the periphery of the lens. Different from spherical lenses with a constant curvature from the center to the periphery of the lens, aspherical lenses have better curvature radius characteristics and have the advantages of improving distortion aberration and astigmatism aberration. After using aspherical lenses, it is possible to eliminate the aberration that appears during imaging as much as possible, thereby improving the imaging quality of the lens.

[0063] Correspondingly, in this embodiment, the first lens 11 and the fourth lens 21 are set as spherical lenses. Using spherical lenses can reduce costs, have a lower assembly sensitivity, and improve the yield rate of finished products while ensuring image quality and reliability.

[0064] Further, in this embodiment, the aspherical surface shape of the aspherical lens satisfies the following conditions:

[0065]

[0066] Wherein, c is the curvature corresponding to the radius, y is the radial coordinate (with the same unit as the lens length unit), k is the conic quadratic curve coefficient (when the k coefficient is less than -1, the surface curve is a hyperbola; when the k coefficient is equal to -1, it is a parabola; when the k coefficient is between -1 and 0, it is an ellipse; when the k coefficient is equal to 0, it is a circle; when the k coefficient is greater than 0, it is an oblate circle), A, B, C, D, E, F, G, H are the high-order aspherical coefficients (please refer to Table 2 below). Through the above parameters, the shape dimensions of the aspherical surfaces on the object side and image side of the lens can be set. Please refer to Table 2 below:

[0067] Table 2 Conic Coefficients and Aspherical Coefficients Corresponding to the Aspherical Lens

[0068]

[0069]

[0070] With such settings, by reasonably distributing the lens optical power, adjusting the glass shape and material combination, chromatic aberration and secondary spectrum are effectively eliminated, and spherical aberration, coma, astigmatism, etc. on each lens are compensated and offset from each other to achieve a clear imaging effect and realize the optimal correction of higher-order aberrations and chromatic aberration.

[0071] In addition, the intervals that change between the lens groups of the zoom optical system 100 in this embodiment from the Wide end (wide-angle end) to the Tele end (telephoto end) are as follows in Table 3:

[0072] Table 3

[0073] Surface number Wide angle Telephoto 6 13.4 1.1 7 7.7 1.7 17 0.26 6.2

[0074] The above description is only an exemplary embodiment of the present invention, and does not limit the patent scope of the present invention. Any equivalent structural transformation made under the technical concept of the present invention by using the content of the specification and drawings of the present invention, or directly / indirectly applied in other related technical fields, is included in the patent protection scope of the present invention.

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 direction. The zoom optical system includes a first lens group, a second lens group, and an image plane that are arranged in sequence from the object side to the image side. The first lens group and the second lens group are both movably arranged along the optical axis direction. The second lens group is used for zooming, and the first lens group is used for focusing. The maximum optical total length of the zoom optical system is within 51 mm. The focal length of the zoom optical system at the wide-angle end is fw, the focal length of the first lens group is f1, the focal length of the second lens group is f2, and the zoom optical system meets the following conditions: -0.55≤fw / f1≤-0.1; and 0.2323≤fw / f2≤0.

75.

2. The zoom optical system according to claim 1, wherein: The optical power of the first lens group is negative; The optical power of the second lens group is positive.

3. The zoom optical system according to claim 1, wherein: The first lens group includes a first lens, a second lens and a third lens arranged in sequence from the object side to the image side; The focal length of the first lens is f11, the focal length of the second lens is f12, and the focal length of the third lens is f13, wherein 0.67≤f1 / f11≤0.90; and 0.44≤f1 / f12≤0,60; and -0.41≤f1 / f13≤-0.

30.

4. The zoom optical system according to claim 3, wherein: The object side surface of the first lens is convex, and the image side surface is concave; The object side surface of the second lens is concave, and the image side surface is concave; The object side surface of the third lens is convex, and the image side surface is convex.

5. The zoom optical system according to claim 1, wherein: The second lens group includes a fourth lens, a fifth lens, a sixth lens, a seventh lens and an eighth lens arranged in sequence from the object side to the image side; The focal length of the fourth lens is f21, the focal length of the fifth lens is f22, the focal length of the sixth lens is f23, the focal length of the seventh lens is f24, and the focal length of the eighth lens is f25, wherein 0.68≤f2 / f21≤0.91, and 1.34≤f2 / f22≤1.81, and 1.95≤f2 / f23≤2.64, and -0.66≤f2 / f24≤-0.49, and 1.08≤f2 / f25≤1.

46.

6. The zoom optical system according to claim 5, wherein: The object side surface of the fourth lens is convex, and the image side surface is convex; The object side surface of the fifth lens is convex, and the image side surface is convex; The object side surface of the sixth lens is concave, and the image side surface is convex; The object side surface of the seventh lens is concave, and the image side surface is concave; The object side surface of the eighth lens is convex, and the image side surface is concave.

7. The zoom optical system according to claim 1, wherein: The target surface size of the zoom optical system is φ, φ≤6.6mm.

8. The zoom optical system according to claim 1, wherein: The aperture of the zoom optical system is Fno, 1.57≤Fno≤2.

64.

9. The subject matter 1 according to claim 1, characterized in that: The focal length of the zoom optical system is f, 3.46mm≤f≤10.48mm.

10. The subject matter 1 according to claim 1, characterized in that: The zoom optical system further includes an aperture and a filter. The aperture is arranged between the first lens group and the second lens group. The filter is arranged on a side of the second lens group facing the image side.

Images