Day and night confocal small zoom monitoring lens and imaging method thereof

Abstract

The invention relates to a day and night confocal small zoom monitoring lens, an optical system of the zoom monitoring lens is composed of a compensation group and a zoom group which are sequentially arranged from left to right along a light incident light path, the compensation group has negative focal power, and the zoom group has positive focal power; the compensation group is composed of a first lens, a second lens and a third lens which are sequentially arranged from left to right along a light incident light path; the zoom group is composed of a fourth lens, a fifth lens, a sixth lens, a seventh lens and an eighth lens which are sequentially arranged from left to right along a light incident light path. The first lens and the fourth lens are glass spherical lenses, and the second lens, the third lens, the fifth lens, the sixth lens, the seventh lens and the eighth lens are plastic aspheric lenses. Through reasonable lens matching, the zoom lens has the advantages of large aperture, wide spectrum, miniaturization, low temperature drift, high image quality and day and night confocal monitoring, and meanwhile, a plurality of plastic aspheric lenses are adopted, so that the cost is lower compared with the similar zoom lens in the prior art.

Description

Technical Field

[0001] This invention relates to a small zoom surveillance lens with day and night confocal focus and its imaging method, and relates to the field of lens technology. Background Technology

[0002] The "Skynet" network, comprised of surveillance cameras, is a crucial weapon for safeguarding people's lives and property. In recent years, the government and an increasing number of enterprises and institutions have placed greater emphasis on building all-weather, blind-spot-free, high-quality surveillance camera networks. Simultaneously, as people's lives become more affluent, more and more people desire multifunctional surveillance equipment for security. The emergence of zoom lenses has brought revolutionary development to the field of security monitoring. With its unique advantages such as adjustable focus, high definition, autofocus, remote control, and multi-functionality, zoom lenses are gradually leading a new trend in security monitoring.

[0003] However, current market products generally fail to achieve optical characteristics such as high image quality, wide field of view, day and night operation, miniaturization, and low temperature drift, making it difficult to meet the security needs of the general public. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the technical problem to be solved by the present invention is to provide a small zoom surveillance lens with day and night confocal focus and its imaging method, while taking into account the optical characteristics such as large field of view, large aperture, low temperature drift, miniaturization, high image quality, and day and night confocal monitoring.

[0005] To solve the above-mentioned technical problems, the technical solution of the present invention is: a small zoom surveillance lens with day and night confocal focusing, wherein the optical system of the zoom surveillance lens consists of a compensation group and a zoom group arranged sequentially from left to right along the incident light path, wherein the compensation group has negative optical power and the zoom group has positive optical power; the compensation group consists of a first lens, a second lens, and a third lens arranged sequentially from left to right along the incident light path; the zoom group consists of a fourth lens, a fifth lens, a sixth lens, a seventh lens, and an eighth lens arranged sequentially from left to right along the incident light path; an aperture stop is provided between the compensation group and the zoom group; wherein the first lens is a meniscus lens with negative optical power, and its object-side surface... The first lens is convex, and the image-side surface is concave; the second lens is a meniscus lens with negative optical power, with both its object-side and image-side surfaces being convex; the third lens is a biconvex lens with positive optical power, with both its object-side and image-side surfaces being convex; the fourth lens is a biconvex lens with positive optical power, with both its object-side and image-side surfaces being convex; the fifth lens is a meniscus lens with negative optical power, with both its object-side and image-side surfaces being concave; the sixth lens is a biconvex lens with positive optical power, with both its object-side and image-side surfaces being convex; the seventh lens is a biconcave lens with negative optical power, with both its object-side and image-side surfaces being concave; and the eighth lens is a meniscus lens with positive optical power, with both its object-side and image-side surfaces being convex.

[0006] Preferably, the focal length of the optical system is set to f, and the focal lengths of the first lens, second lens, third lens, fourth lens, fifth lens, sixth lens, seventh lens, and eighth lens are f1, f2, f3, f4, f5, f6, f7, and f8, respectively, wherein f1, f2, f3, f4, f5, f6, f7, and f8 satisfy the following ratio with f: -3.0 <f1 / f<-2.0,-4.0<f2 / f<-3.0,4.0<f3 / f<5.0,2.0<f4 / f<3.0,-27.0<f5 / f<-26.0,1.0<f6 / f<2.0,-1.0<f7 / f<0.0,2.0<f8 / f<3.0。

[0007] Preferably, the first lens satisfies the relationship: 1.5 ≤ N d ≤1.8, V d ≥50.0; The second lens satisfies the relationship: 1.5≤N d ≤1.8, V d ≥50.0; The third lens satisfies the relationship: 1.5≤N d ≤1.8, V d ≤50.0; The fourth lens satisfies the relationship: 1.5≤N d ≤1.8, V d ≥50.0; The fifth lens satisfies the relationship: 1.5≤N d ≤1.8, V d ≤50.0; The sixth lens satisfies the relationship: 1.5≤N d ≤1.8, V d ≥50.0; The seventh lens satisfies the relationship: 1.5≤N d ≤1.8, V d ≤50.0; The eighth lens satisfies the relationship: 1.5≤N d ≤1.8, V d ≤50.0; where N d V is the refractive index. d Let be Abbe's constant.

[0008] Preferably, the first and fourth lenses are glass spherical lenses, and the second, third, fifth, sixth, seventh, and eighth lenses are plastic aspherical lenses.

[0009] Preferably, the air gap between the first lens and the second lens in the compensation group is 2.5–3.0 mm; the air gap between the second lens and the third lens is 0.5–1.0 mm; the air gap between the fourth lens and the fifth lens in the zoom group is 0.0–0.1 mm; the air gap between the fifth lens and the sixth lens is 0.0–0.1 mm; the air gap between the sixth lens and the seventh lens is 0.1–0.5 mm; and the air gap between the seventh lens and the eighth lens is 0.5–1.0 mm.

[0010] Preferably, the equations for the aspherical curves of the second, third, fifth, sixth, seventh, and eighth lenses are as follows:

[0011]

[0012] Where z is the distance from the vertex of the aspherical surface to the optical axis at a height of h; c is the paraxial curvature of the aspherical surface, r = 1 / c; k is the conic constant; α1, α2, α3, α4, α5, α6, α7, and α8 are all higher-order coefficients.

[0013] Preferably, a filter is provided on the rear side of the zoom group.

[0014] An imaging method for a small zoom surveillance lens with day and night confocal focus is performed according to the following steps: light passes through a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, and an eighth lens in sequence before forming an image.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] 1. The lens has an imaging angle of more than 130 degrees at the wide-angle end, and both the wide-angle and telephoto ends have a large light-gathering aperture, good light transmission performance, high resolution, and take into account the imaging quality of ultraviolet and short-wave infrared bands, which can provide all-weather high-definition monitoring and more comprehensive monitoring details.

[0017] 2. By rationally matching the various optical lenses, the system structure becomes compact and reasonable, the overall length of the lens is shorter, which is conducive to miniaturization. At the same time, it has low tolerance sensitivity, is easy to assemble, and is more suitable for large-scale high-yield production.

[0018] 3. This optical system uses two glass lenses and six plastic lenses. Compared with an all-glass system, it is lighter and has stronger optical performance stability compared with an all-plastic system. It can better compensate for focal plane displacement at high and low temperatures, better adapt to complex outdoor environments and climates, and is also cheaper.

[0019] 4. Various aberrations are corrected by using multiple plastic aspherical surfaces, ensuring that the imaging system can maintain high imaging quality even at large angles.

[0020] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the optical structure at the wide-angle end of the present invention;

[0022] Figure 2 This is the axial color difference diagram at the wide-angle end of the present invention;

[0023] Figure 3 This is the chromatic aberration diagram of the wide-angle end of the present invention;

[0024] Figure 4 This is the field curvature distortion diagram at the wide-angle end of the present invention;

[0025] Figure 5 This is the axial chromatic aberration diagram of the telescope end of the present invention;

[0026] Figure 6 This is the vertical axis chromatic aberration diagram of the telescope end of the present invention;

[0027] Figure 7 This is a field curvature distortion diagram of the telescope end of the present invention;

[0028] In the diagram: STO - aperture stop; 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 - equivalent glass plate; IMA - imaging plane. Detailed Implementation

[0029] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0030] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0031] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0032] like Figures 1-7As shown, this embodiment provides a small zoom surveillance lens with day and night confocal focusing. The optical system of the zoom surveillance lens consists of a compensation group and a zoom group arranged sequentially from left to right along the incident light path. The compensation group has negative optical power, and the zoom group has positive optical power. The compensation group consists of a first lens, a second lens, and a third lens arranged sequentially from left to right along the incident light path. The zoom group consists of a fourth lens, a fifth lens, a sixth lens, a seventh lens, and an eighth lens arranged sequentially from left to right along the incident light path. An aperture stop is provided between the compensation group and the zoom group. The first lens is a meniscus lens with negative optical power, its object side is convex, and its image side... The first lens is concave; the second lens is a meniscus lens with negative power, its object-side surface is convex and its image-side surface is concave; the third lens is a biconvex lens with positive power, both its object-side and image-side surfaces are convex; the fourth lens is a biconvex lens with positive power, both its object-side and image-side surfaces are convex; the fifth lens is a meniscus lens with negative power, its object-side surface is concave and its image-side surface is convex; the sixth lens is a biconvex lens with positive power, both its object-side and image-side surfaces are convex; the seventh lens is a biconcave lens with negative power, its object-side and image-side surfaces are concave; the eighth lens is a meniscus lens with positive power, its object-side surface is convex and its image-side surface is concave.

[0033] In this embodiment of the invention, the first and fourth lenses are glass spherical lenses, and the second, third, fifth, sixth, seventh, and eighth lenses are plastic aspherical lenses.

[0034] Both the first and second lenses are lenses with negative optical power, which can adjust light at large angles; the plastic aspherical surface has the function of reducing optical system distortion.

[0035] In this embodiment of the invention, the focal length of the optical system is set to f, and the focal lengths of the first lens, second lens, third lens, fourth lens, fifth lens, sixth lens, seventh lens, and eighth lens are f1, f2, f3, f4, f5, f6, f7, and f8, respectively, wherein f1, f2, f3, f4, f5, f6, f7, and f8 satisfy the following ratio with f: -3.0 <f1 / f<-2.0,-4.0<f2 / f<-3.0,4.0<f3 / f<5.0,2.0<f4 / f<3.0,-27.0<f5 / f<-26.0,1.0<f6 / f<2.0,-1.0<f7 / f<0.0,2.0<f8 / f<3.0。

[0036] In this embodiment of the invention, the first lens satisfies the relationship: 1.5 ≤ N d ≤1.8, V d ≥50.0; The second lens satisfies the relationship: 1.5≤N d ≤1.8, Vd ≥50.0; The third lens satisfies the relationship: 1.5≤N d ≤1.8, V d ≤50.0; The fourth lens satisfies the relationship: 1.5≤N d ≤1.8, V d ≥50.0; The fifth lens satisfies the relationship: 1.5≤N d ≤1.8, V d ≤50.0; The sixth lens satisfies the relationship: 1.5≤N d ≤1.8, V d ≥50.0; The seventh lens satisfies the relationship: 1.5≤N d ≤1.8, V d ≤50.0; The eighth lens satisfies the relationship: 1.5≤N d ≤1.8, V d ≤50.0; where N d V is the refractive index. d Let be Abbe's constant.

[0037] In this embodiment of the invention, the air gap between the first and second lenses in the compensation group is 2.5–3.0 mm; the air gap between the second and third lenses is 0.5–1.0 mm; the air gap between the fourth and fifth lenses in the zoom group is 0.0–0.1 mm; the air gap between the fifth and sixth lenses is 0.0–0.1 mm; the air gap between the sixth and seventh lenses is 0.1–0.5 mm; and the air gap between the seventh and eighth lenses is 0.5–1.0 mm. Reducing the distance between the lenses, while meeting imaging requirements, helps to shorten the overall optical length of the lens.

[0038] In this embodiment of the invention, the aspherical curve equations of the second, third, fifth, sixth, seventh, and eighth lenses are expressed as follows:

[0039]

[0040] Where z is the distance from the vertex of the aspherical surface to the optical axis at a height of h; c is the paraxial curvature of the aspherical surface, r = 1 / c; k is the conic constant; α1, α2, α3, α4, α5, α6, α7, and α8 are all higher-order coefficients.

[0041] In this embodiment of the invention, a filter is provided on the rear side of the zoom group.

[0042] An imaging method for a small zoom surveillance lens with day and night confocal focus is performed according to the following steps: light passes through a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, and an eighth lens in sequence before forming an image.

[0043] In this embodiment of the invention, the technical specifications achieved by the optical system are as follows:

[0044] (1) Focal length EFFL: 4.5~8.2mm;

[0045] (2) Aperture F: 1.8~2.6;

[0046] (3) Field of view: 2w ≥ 130°;

[0047] (4) Total optical length: TTL≦36mm;

[0048] (5) Operating bands: visible light and short-wave infrared bands;

[0049] (6) Operating temperature: -30℃~80℃.

[0050] To achieve the above design parameters, the specific design of the optical system adopted in this embodiment is shown in the table below:

[0051]

[0052] The aspherical coefficients of the aspherical lenses in the optical system of this embodiment are shown in the table below:

[0053]

[0054] The values ​​of air layer thickness between the compensation group and the zoom group when switching from the wide-angle end to the telephoto end in this embodiment are shown in the table below:

[0055] Air gap (mm) between compensation group and variable magnification group Wide-angle end 8.09 Observation Depth 1.21

[0056] This embodiment employs two lens groups for zooming. By rationally allocating the optical power and on-axis distance of each lens, the optical system achieves a wide spectrum, large angle, large aperture, day and night confocal focus, and low temperature drift design. Simultaneously, it effectively corrects on-axis and off-axis aberrations, resulting in good image quality. Figures 2 to 7 As shown.

[0057] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A small zoom surveillance lens with day and night confocal focus, characterized in that: The optical system of the zoom monitoring lens consists of a compensation group and a zoom group arranged sequentially from left to right along the incident light path. The compensation group has negative optical power, and the zoom group has positive optical power. The compensation group consists of a first lens, a second lens, and a third lens arranged sequentially from left to right along the incident light path. The zoom group consists of a fourth lens, a fifth lens, a sixth lens, a seventh lens, and an eighth lens arranged sequentially from left to right along the incident light path. An aperture stop is provided between the compensation group and the zoom group. The first lens is a meniscus lens with negative optical power, its object side is convex and its image side is concave. The second lens is a meniscus lens with negative optical power, its object side is convex and its image side is concave. The third lens is a biconvex lens with positive optical power, and both its object-side and image-side surfaces are convex. The fourth lens is a biconvex lens with positive optical power, and both its object-side and image-side surfaces are convex. The fifth lens is a meniscus lens with negative optical power, and its object-side and image-side surfaces are concave. The sixth lens is a biconvex lens with positive optical power, and both its object-side and image-side surfaces are convex. The seventh lens is a biconcave lens with negative optical power, and both its object-side and image-side surfaces are concave. The eighth lens is a meniscus lens with positive optical power, and its object-side and image-side surfaces are convex.

2. The small zoom surveillance lens with day and night confocal focus according to claim 1, characterized in that: Let the focal length of the optical system be f, and the focal lengths of the first lens, second lens, third lens, fourth lens, fifth lens, sixth lens, seventh lens, and eighth lens be f1, f2, f3, f4, f5, f6, f7, and f8, respectively. Where f1, f2, f3, f4, f5, f6, f7, and f8 satisfy the following ratio with f: -3.0 <f1 / f<-2.0,-4.0<f2 / f<-3.0,4.0<f3 / f<5.0,2.0<f4 / f<3.0, -27.0 <f5 / f<-26.0,1.0<f6 / f<2.0,-1.0<f7 / f<0.0,2.0<f8 / f<3.0。 3. The small zoom surveillance lens with day and night confocal focus according to claim 1, characterized in that: The first lens satisfies the relationship: 1.5 ≤ N d ≤1.8, V d ≥50.0; The second lens satisfies the relationship: 1.5≤N d ≤1.8, V d ≥50.0; The third lens satisfies the relationship: 1.5≤N d ≤1.8, V d ≤50.0; The fourth lens satisfies the relationship: 1.5≤N d ≤1.8, V d ≥50.0; The fifth lens satisfies the relationship: 1.5≤N d ≤1.8, V d ≤50.0; The sixth lens satisfies the relationship: 1.5≤N d ≤1.8, V d ≥50.0; The seventh lens satisfies the relationship: 1.5≤N d ≤1.8, V d ≤50.0; The eighth lens satisfies the relationship: 1.5≤N d ≤1.8, V d ≤50.0; Where N d V is the refractive index. d Let be Abbe's constant.

4. The small zoom surveillance lens with day and night confocal focus according to claim 1, characterized in that: The first and fourth lenses are glass spherical lenses, while the second, third, fifth, sixth, seventh, and eighth lenses are plastic aspherical lenses.

5. The small zoom surveillance lens with day and night confocal focus according to claim 1, characterized in that: The air gap between the first and second lenses in the compensation group is 2.5–3.0 mm; the air gap between the second and third lenses is 0.5–1.0 mm; the air gap between the fourth and fifth lenses in the zoom group is 0.0–0.1 mm; the air gap between the fifth and sixth lenses is 0.0–0.1 mm; the air gap between the sixth and seventh lenses is 0.1–0.5 mm; and the air gap between the seventh and eighth lenses is 0.5–1.0 mm.

6. The small zoom surveillance lens with day and night confocal focus according to claim 1, characterized in that: The equations for the aspherical curves of the second, third, fifth, sixth, seventh, and eighth lenses are as follows: Where z is the distance from the vertex of the aspherical surface to the optical axis at a height of h; c is the paraxial curvature of the aspherical surface, r = 1 / c; k is the conic constant; α1, α2, α3, α4, α5, α6, α7, and α8 are all higher-order coefficients.

7. The small zoom surveillance lens with day and night confocal focus according to claim 1, characterized in that: A filter is provided on the rear side of the zoom group.

8. An imaging method for a small zoom surveillance lens with day and night confocal focusing as described in any one of claims 1-7, characterized in that, The following steps are performed: light rays pass through the first lens, second lens, third lens, fourth lens, fifth lens, sixth lens, seventh lens, and eighth lens in sequence to form an image.

Images