Zoom optical system and monitoring lens

Abstract

The invention discloses a zoom optical system and a monitoring 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 direction of an optical axis, and the zoom optical system comprises a first lens group, a diaphragm, a second lens group and a photosensitive chip which are sequentially arranged from the object side to the image side; wherein the first lens group has negative focal power, and the second lens group has positive focal power; 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 can zoom, and the zoom optical system has the effects of ultra-high definition, large magnification and small zoom.

Description

Technical Field

[0001] The present invention relates to the field of optical technology, and in particular to a zoom optical system and a monitoring lens. Background Art

[0002] The zoom optical systems currently used for surveillance generally have the following shortcomings: low pixels, small magnification for the same total length, and failure to ensure complete confocality of each focal length infrared during the zoom process.

[0003] Currently, there is no lens on the market that fully takes into account the above characteristics. There are only a few lenses that improve one aspect at the expense of other aspects. For example, in order to achieve ultra-high definition, the magnification is designed to be very small, and the infrared at each focal length is not guaranteed to be completely confocal, etc., which affects the popularity of the lens. Summary of the invention

[0004] The main purpose of the present invention is to propose a zoom optical system and a monitoring lens, aiming to provide an ultra-high-definition, large-magnification, small-zoom zoom optical system.

[0005] To achieve the above object, the present invention provides a zoom optical system, wherein the zoom optical system has an object side and an image side that are arranged opposite to each other along an optical axis direction, and the zoom optical system comprises a first lens group, an aperture, a second lens group, and a photosensitive chip that are sequentially arranged from the object side to the image side;

[0006] Wherein, the first lens group has negative optical power; the second lens group has positive optical power;

[0007] At least one of the first lens group and the second lens group is movable along the optical axis direction to enable the zoom optical system to zoom.

[0008] In one embodiment, the interval between the first lens group and the aperture is L1, the interval between the second lens group and the aperture is L2, and each of the intervals satisfies the following relationship: 0.8 mm ≤ L1 ≤ 8.483 mm, 0.73 mm ≤ L2 ≤ 10.594 mm.

[0009] 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 along the optical axis;

[0010] Among them, the optical focal power of the first lens is negative, the optical focal power of the second lens is negative, and the optical focal power of the third lens is positive.

[0011] 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 in sequence from the object side to the image side along the optical axis;

[0012] Among them, the optical power of the fourth lens is positive, the optical power of the fifth lens is negative, the optical power of the sixth lens is positive, the optical power of the ninth lens is positive, the optical power of the tenth lens is negative, and the optical power of the eleventh lens is negative.

[0013] 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 along the optical axis, and the second lens and the third lens are cemented together; and / or,

[0014] 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 in sequence from the object side to the image side along the optical axis, the fifth lens and the sixth lens are cemented together, and the ninth lens and the tenth lens are cemented together.

[0015] In one implementation, the fourth lens is a glass aspheric lens, and the seventh lens, the eighth lens, and the eleventh lens are plastic aspheric lenses.

[0016] In one embodiment, the eleventh lens has a mirror surface edge vignetting arrangement.

[0017] In one implementation, the seventh lens and the eighth lens are cemented lenses.

[0018] In one embodiment, the zoom optical system further includes a filter, and the filter is disposed between the second lens group and the photosensitive chip along the optical axis and is disposed close to the photosensitive chip.

[0019] The present invention further provides a monitoring lens, comprising a zoom optical system, wherein the zoom optical system has an object side and an image side arranged opposite to each other along an optical axis direction, and the zoom optical system comprises a first lens group, an aperture, a second lens group and a photosensitive chip arranged in sequence from the object side to the image side;

[0020] Wherein, the first lens group has negative optical power, and the second lens group has positive optical power;

[0021] At least one of the first lens group and the second lens group is movable along the optical axis direction to enable the zoom optical system to zoom.

[0022] In the technical solution of the present invention, at least one of the first lens group and the second lens group moves along the optical axis toward the image side, and different positions of the two lens groups correspond to different overall focal lengths, so that the zoom optical system changes continuously from the wide-angle end to the telephoto end to achieve zooming; the aperture stop is arranged between the first lens group and the second lens group, which can adjust the field of view, block the far-axis light, avoid the far-axis light from affecting the imaging quality, improve the image quality, and make the lens have a large light throughput; through the reasonable arrangement of the structure and position of the first lens group with negative optical focal power and the second lens group with positive optical focal power, the zoom optical system has the effects of ultra-high definition, large magnification, small zoom, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0024] Figure 1 This is a schematic structural diagram of an embodiment of the wide-angle end of the zoom optical system provided by the present invention.

[0025] Description of Figure Numbers:

[0026] 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; 4. Filter; 5. Photosensitive chip.

[0027] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components in a certain specific posture. If the specific posture changes, the directional indication will also change accordingly.

[0030] 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 used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features limited to "first" and "second" may explicitly or implicitly include at least one of the features. In addition, if "and / or" or "and / or" appears in the full text, its meaning includes three parallel solutions. Taking "A and / or B" as an example, it includes solution A, solution B, or solutions that satisfy both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0031] The present invention provides a zoom optical system 100 .

[0032] First of all, it can be understood that the focal length is equal to the difference between the convergence of the image-side light beam and the convergence of the object-side light beam, and it characterizes the ability of the optical system to deflect light. The larger the absolute value of the focal length, the stronger the ability to bend light, and the smaller the absolute value of the focal length, the weaker the ability to bend light. When the focal length is a positive number, the refraction of light is convergent; when the focal length is a negative number, the refraction of light is divergent. The focal length can be used to characterize a certain refractive surface of a lens (i.e., a surface of a lens), can be used to characterize a certain lens, and can also be used to characterize a system formed by multiple lenses (i.e., a lens group).

[0033] See also Figure 1 In one embodiment of the present invention, the zoom optical system 100 has an object side and an image side that are arranged opposite to each other along the optical axis direction, and the zoom optical system 100 includes a first lens group 1, an aperture 3, a second lens group 2 and a photosensitive chip 5 arranged in sequence from the object side to the image side; wherein 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 direction to enable the zoom optical system 100 to zoom.

[0034] In the technical solution of the present invention, at least one of the first lens group 1 and the second lens group 2 moves along the optical axis toward the image side, and different positions of the two lens groups correspond to different overall focal lengths, so that the zoom optical system 100 changes continuously from the wide-angle end to the telephoto end to achieve zooming; the aperture 3 is arranged between the first lens group 1 and the second lens group 2, and can adjust the field of view, block the far-axis light, avoid the far-axis light from affecting the imaging quality, improve the image quality, and make the lens have a large light throughput; through the reasonable arrangement of the structure and position of the first lens group 1 with negative optical focal power and the second lens group 2 with positive optical focal power, the zoom optical system 100 has the effects of ultra-high definition, large magnification, and small zoom.

[0035] Specifically, in one embodiment of the present invention, it should be understood that when the optical projection system is at the wide-angle end, the focal length is the shortest, and the distance between the lens groups is the smallest. When the optical projection system is at the telephoto end, the focal length is the longest, and the distance between the lens groups is also the largest. At the wide-angle end and the telephoto end, the optical projection system has different focal lengths and optical powers, and also has different lengths or shapes. When the optical projection system zooms from the wide-angle end to the telephoto end, in order to further improve the imaging effect, the first lens group 1 is linked with the second lens group 2, and the first lens group 2 is connected to the second lens group 2. The interval between the lens group 1 and the aperture 3 is L1, the interval between the second lens group 2 and the aperture 3 is L2, and each of the intervals satisfies the following relationship: 0.8mm≤L1≤8.483mm, 0.73mm≤L2≤10.594mm. By limiting the zoom distance of the first lens group 1 and the second lens group 2, the focal plane position is ensured to remain unchanged during the zooming process, and real zooming is achieved, that is, the imaging quality from the wide-angle end to the telephoto end during the zooming process does not change substantially, and according to the actual use needs, the zoom ratio is achieved to 3.5 times.

[0036] Furthermore, in one embodiment of the present invention, the first lens group 1 comprises a first lens 11, a second lens 12, and a third lens 13 arranged in sequence from the object side to the image side along the optical axis; wherein the first lens 11 has a positive optical power and a convex object side surface and a concave image side surface, which can introduce more light; the second lens 12 has a concave object side surface and a concave image side surface, and the third lens 13 has a convex object side surface and a convex image side surface, and by such an arrangement, the concave and convex sides of the second lens 12 and the third lens 13 complement each other, fit more closely, and have a more compact structure; in addition, it is also ensured that the optical power of the second lens 12 is negative and the optical power of the third lens 13 is positive, so that the light trend is controlled and the resolution is improved. By limiting the positive and negative optical powers of the first lens 11, the second lens 12, and the third lens 13 in the first lens group 1, the height of the light entering the rear group is reduced, and the aberration of the off-axis system is reduced.

[0037] In addition, in an 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, an eighth lens 25, a ninth lens 26, a tenth lens 27, and an eleventh lens 28, which are arranged in sequence from the object side to the image side along the optical axis; wherein 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 ninth lens 26 has a positive optical power, the tenth lens 27 has a negative optical power, and the eleventh lens 28 has a negative optical power. By limiting the positive and negative optical powers of the lenses, the residual spherical aberration of the system can be corrected, and at the same time, the light height of the off-axis field of view can be increased, so that the system has a larger target surface.

[0038] In one embodiment of the present invention, the first lens group 1 includes a first lens 11, a second lens 12, and a third lens 13 arranged in sequence from the object side to the image side along the optical axis, and the second lens 12 and the third lens 13 are glued together; the first lens group 1 uses a single lens and two spherical lenses glued together for use, which can not only correct the chromatic aberration of the zoom optical system 100 well, but also reduce the surface sensitivity, thereby ensuring the high resolution of the system.

[0039] In addition, in another embodiment of the 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 in sequence from the object side to the image side along the optical axis direction. The fifth lens 22 and the sixth lens 23 are glued together, and the ninth lens 26 and the tenth lens 27 are glued together. By arranging the fifth lens 22 and the sixth lens 23 to be glued together, chromatic aberration is reduced while correcting light, and then the ninth lens 26 and the tenth lens 27 are glued together, so that aberration and chromatic aberration are further reduced, thereby improving imaging quality.

[0040] Specifically, the fourth lens 21 is a glass aspheric lens, the seventh lens 24, the eighth lens 25, and the eleventh lens 28 are plastic aspheric lenses;

[0041] It is understandable that the characteristics of aspherical lenses are: the curvature changes continuously from the center of the lens to the periphery of the lens. Unlike spherical lenses with constant curvature from the center of the lens to the periphery of the lens, aspherical lenses have better curvature radius characteristics and have the advantages of improving distortion aberration and improving astigmatism aberration. After using aspherical lenses, aberrations that occur during imaging can be eliminated as much as possible, thereby improving the imaging quality of the lens. In addition, setting the last eleventh lens 28 as a plastic aspherical lens can also optimize and adjust the angle and direction of the light entering the image plane, making the image clearer.

[0042] Specifically, in one embodiment of the present invention, the surface shape of the aspheric lens in the projection optical system should satisfy the following equation:

[0043]

[0044] Among them, 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 curve coefficient, and A, B, C, D, E, F, G... represent the fourth-order, sixth-order, eighth-order, tenth-order, twelfth-order, fourteenth-order, sixteenth-order... aspheric coefficients respectively.

[0045] More specifically, in one embodiment of the present invention, the even-order coefficients of each aspherical surface are shown in Table 1 below.

[0046] Table 1

[0047]

[0048]

[0049] The above parameters can be used to accurately set the shape and size of the aspheric surfaces of the front and back surfaces of the lens. At the same time, the use of plastic lenses greatly reduces costs.

[0050] In one embodiment of the present invention, the 11th lens 28 is provided with vignetting at the edge of the mirror surface. It should be noted that vignetting refers to the phenomenon that when light enters the optical system from the edge, the light beam is partially blocked due to the physical limitations of the optical elements (such as the edge of the lens, the aperture 3, the frame, etc.). This phenomenon will cause the light intensity at the edge of the image to weaken, thereby producing a dark corner effect. By providing vignetting at the edge of the mirror surface of the 11th lens 28, the peripheral stray light can be blocked without affecting the brightness of the image plane, so that the center and edge of the image plane can maintain the same resolution.

[0051] In addition, in one embodiment of the present invention, the seventh lens 24 and the eighth lens 25 are quasi-cemented lenses. It should be noted that quasi-cemented refers to the combination and optimized design of multiple plastic lenses in an optical system to achieve functions and performance similar to those of traditional cemented lenses. Traditional cemented lenses are made by gluing lenses of different materials together to reduce chromatic aberration and other aberrations. Quasi-cemented design achieves similar effects by combining multiple plastic lenses without gluing, and compared to the gluing design, the combination of multiple plastic lenses achieves functions similar to those of traditional cemented lenses, including reducing chromatic aberration, spherical aberration and other aberrations, while maintaining a low cost and lightweight design.

[0052] In addition, in one embodiment of the present invention, the first lens 11, the second lens 12, the third lens 13, the fifth lens 22, the sixth lens 23, the ninth lens 26, and the tenth lens 27 are glass spherical lenses. In order to improve the imaging quality of the lens at various magnifications, the present invention combines high-refractive-index glass with ultra-low-dispersion glass materials to reduce various optical aberrations while effectively suppressing the chromatic aberration of the system. At the same time, because the glass lens is not easily affected by thermal expansion and contraction and has a focus shift phenomenon, the glass lens can well resist the problem of lens deformation due to heat and maintain the high precision of the lens for a long time. In addition, the aberrations that occur during imaging can be eliminated as much as possible, and the positive and negative matching of the changes in the high and low temperature elements is achieved, ensuring the synchronization and clarity of the image plane at high and low temperatures, thereby improving the imaging quality of the lens and reducing the influence of temperature on the optical performance of the system.

[0053] Specifically, in an embodiment of the present invention, the parameters of the zoom optical system 100 are shown in Table 2 below.

[0054] Table 2

[0055]

[0056]

[0057] In one embodiment of the present invention, the zoom optical system 100 also includes a filter 4, which is arranged between the second lens group 2 and the photosensitive chip 5 along the optical axis and is arranged close to the photosensitive chip 5. By setting the filter 4, the filter 4 can filter out stray light and prevent the stray light from reaching the photosensitive chip 5 and interfering with normal visible light imaging, thereby improving the imaging quality.

[0058] It can be understood that the light carrying the information of the subject can pass 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, the filter 4 in sequence and finally form an image on the photosensitive chip 5.

[0059] The present invention further proposes a monitoring lens, which includes a zoom optical system. The specific structure of the zoom optical system refers to the above embodiment. Since the monitoring lens adopts all the technical solutions of all the above embodiments, it at least has all the beneficial effects brought by the technical solutions of the above embodiments, which will not be described one by one here.

[0060] The above description is only an exemplary embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification and drawings under the technical concept of the present invention, or directly / indirectly applied in other related technical fields are 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 which are arranged opposite to each other along the optical axis direction, and the zoom optical system comprises a first lens group, an aperture, a second lens group and a photosensitive chip which are arranged in sequence from the object side to the image side; Wherein, the first lens group has negative optical power, and the second lens group has positive optical power; At least one of the first lens group and the second lens group is movable along the optical axis direction so as to enable the zoom optical system to zoom.

2. The zoom optical system according to claim 1, wherein: The interval between the first lens group and the aperture is L1, the interval between the second lens group and the aperture is L2, and each of the intervals satisfies the following relationship: 0.8 mm ≤ L1 ≤ 8.483 mm, 0.73 mm ≤ L2 ≤ 10.594 mm.

3. The zoom optical system according to claim 1, wherein: The first lens group comprises a first lens, a second lens, and a third lens arranged in sequence from the object side to the image side along the optical axis direction; Among them, the optical focal power of the first lens is negative, the optical focal power of the second lens is negative, and the optical focal power of the third lens is positive.

4. 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, an eighth lens, a ninth lens, a tenth lens, and an eleventh lens, which are arranged in sequence from the object side to the image side along the optical axis; Among them, the optical power of the fourth lens is positive, the optical power of the fifth lens is negative, the optical power of the sixth lens is positive, the optical power of the ninth lens is positive, the optical power of the tenth lens is negative, and the optical power of the eleventh lens is negative.

5. The zoom optical system according to claim 1, wherein: The first lens group comprises a first lens, a second lens, and a third lens arranged in sequence from the object side to the image side along the optical axis, and 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 in sequence from the object side to the image side along the optical axis, the fifth lens and the sixth lens are cemented together, and the ninth lens and the tenth lens are cemented together.

6. The zoom optical system according to claim 5, wherein: The fourth lens is a glass aspheric lens, and the seventh lens, the eighth lens, and the eleventh lens are plastic aspheric lenses.

7. The zoom optical system according to claim 6, wherein: The eleventh lens has a mirror surface edge vignetting arrangement.

8. The zoom optical system according to claim 6, wherein: The seventh lens and the eighth lens are quasi-cemented lenses.

9. The zoom optical system according to claim 1, wherein: The zoom optical system also includes a filter, which is arranged between the second lens group and the photosensitive chip along the optical axis and is arranged close to the photosensitive chip.

10. A surveillance camera, characterized in that: Comprising the zoom optical system as claimed in any one of claims 1 to 9.

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