Large-aperture day and night confocal wide-angle monitoring lens and imaging method thereof

Abstract

The invention relates to a large-aperture day and night confocal wide-angle monitoring lens and an imaging method thereof, an optical system of the lens has six lenses with focal power, the six lenses are a first lens, a second lens, a third lens, a fourth lens, a fifth lens and a sixth lens in sequence along the incident direction of an optical path, and a diaphragm is arranged between the third lens and the fourth lens; the first lens is a meniscus negative lens, the object side surface is a convex surface, and the image side surface is a concave surface; the object side surface of the second lens is a convex surface, and the image side surface of the second lens is a concave surface; the third lens is a meniscus positive lens, the object side surface is a convex surface, and the image side surface is a concave surface; the fourth lens is a biconvex positive lens; the fifth lens is a meniscus negative lens, the object side surface is a convex surface, and the image side surface is a concave surface; the sixth lens is a biconvex positive lens; wherein the first lens and the fourth lens are glass spherical lenses, and the second lens, the third lens, the fifth lens and the sixth lens are plastic aspheric lenses.

Description

Technical Field

[0001] This invention relates to the field of optical imaging technology, and in particular to a large-aperture, day-night confocal wide-angle surveillance lens and its imaging method. Background Technology

[0002] In the field of security monitoring, traditional surveillance lenses struggle to meet today's complex and ever-changing monitoring needs. While many ordinary security surveillance lenses operate across both visible and near-infrared wavelengths, they only consider and correct for chromatic aberration in the visible light band, neglecting to correct for chromatic aberration in both visible and infrared light. This results in significant misalignment between the visible and infrared image planes. Current surveillance lenses primarily rely on filter switching to achieve all-weather monitoring, acquiring color images during the day and black-and-white images at night. Images captured in low-light conditions suffer from poor clarity, making it difficult to obtain detailed, color images. Furthermore, aperture size directly affects the amount of light entering the system; a larger aperture results in a larger imaging beam and a greater amount of light entering the system. To improve image clarity in low-light and nighttime environments, large aperture technology is crucial, but existing lenses fall short in balancing large aperture with performance and cost. Summary of the Invention

[0003] In view of this, the purpose of this invention is to provide a large-aperture, day-night confocal wide-angle surveillance lens and its imaging method, which meets the monitoring requirements of large aperture, high resolution, day-night confocal focus and low temperature drift while ensuring low cost.

[0004] This invention is implemented using the following scheme: a large-aperture day and night confocal wide-angle surveillance lens, wherein the optical system of the lens has 6 lenses with optical power, arranged sequentially along the incident direction of the light path as a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens, with an aperture stop between the third lens and the fourth lens; the first lens is a meniscus negative lens with a convex object side and a concave image side; the second lens is a meniscus negative lens with a convex object side and a concave image side; the third lens is a meniscus positive lens with a convex object side and a concave image side; the fourth lens is a biconvex positive lens; the fifth lens is a meniscus negative lens with a convex object side and a concave image side; and the sixth lens is a biconvex positive lens; wherein the first and fourth lenses are glass spherical lenses, and the second, third, fifth, and sixth lenses are plastic aspherical lenses.

[0005] Furthermore, the focal length of the optical system is f, and the focal lengths of the first lens, second lens, third lens, fourth lens, fifth lens, and sixth lens are f1, f2, f3, f4, f5, and f6, respectively, wherein f1, f2, f3, f4, f5, and f6 satisfy the following ratio with f: -3.0 <f1 / f<-2.0,-6.0<f2 / f<-4.0,8.0<f3 / f<10.0,2.0<f4 / f<3.0,-3.0<f5 / f<-2.0,1.0<f6 / f<2.0。

[0006] Furthermore, 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; where N d V is the refractive index. d Let be Abbe's constant.

[0007] Furthermore, the air gap between the first lens and the second lens is 0.5~1.0mm; the air gap between the second lens and the third lens is 2.5~3.0mm; the air gap between the third lens and the fourth lens is 0~0.5mm; the air gap between the fourth lens and the fifth lens is 0~0.5mm; and the air gap between the fifth lens and the sixth lens is 0~0.5mm.

[0008] Furthermore, the total optical length TTL of the optical system and the focal length f of the optical system satisfy the following condition: 7.0 ≤ TTL / f ≤ 7.5.

[0009] Furthermore, the F-number of the optical system is ≤1.6.

[0010] Furthermore, the image height H of the optical system and the focal length f of the optical system satisfy the following condition: H / f ≥ 2.3.

[0011] Furthermore, a filter is provided on the rear side of the sixth lens.

[0012] An imaging method for a large-aperture day and night confocal wide-angle surveillance lens as described above, wherein light passes sequentially through a first lens, a second lens, a third lens, an aperture stop, a fourth lens, a fifth lens, a sixth lens, and a filter before forming an image.

[0013] Compared with the prior art, the present invention has the following advantages: The lens adopts a glass-plastic hybrid optical system, which consists of two glass spherical lenses and four plastic aspherical lenses. It has the advantages of high resolution, large aperture, and all-weather high-definition monitoring. In addition, the image plane shift is small under high and low temperature conditions, which can meet the clear imaging requirements from -30℃ to 80℃. At the same time, it ensures low cost and meets the monitoring requirements of large aperture, high resolution, day and night confocal focus and low temperature drift.

[0014] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below through specific embodiments and related drawings. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the optical system structure according to Embodiment 1 of the present invention; Figure 2 This is the transverse chromatic aberration diagram of the entire working band of Embodiment 1 of the present invention; Figure 3 This is the axial chromatic aberration diagram of the entire working band of Embodiment 1 of the present invention; Figure 4 This is a field curvature distortion diagram of the entire working band of Embodiment 1 of the present invention; Figure 5 This is the MTF curve of the entire working band of Embodiment 1 of the present invention; Figure 6 This is an infrared operating band MTF curve diagram of Embodiment 1 of the present invention; Figure 7 This is a schematic diagram of the optical system structure according to Embodiment 2 of the present invention; Figure 8 This is the transverse chromatic aberration diagram of the entire working band of Embodiment 2 of the present invention; Figure 9 This is the axial chromatic aberration diagram of the entire working band of Embodiment 2 of the present invention; Figure 10 This is the field curvature distortion diagram of the entire working band of Embodiment 2 of the present invention; Figure 11 This is the MTF curve of the entire working band of Embodiment 2 of the present invention; Figure 12 This is the MTF curve of the infrared working band of Embodiment 2 of the present invention; Figure 13 This is a relative illumination diagram of Embodiment 2 of the present invention; Explanation of the labels 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 - equivalent glass plate; IMA - imaging plane. Detailed Implementation

[0016] 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.

[0017] 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.

[0018] Example 1: like Figure 1 As shown, a large-aperture day / night confocal wide-angle surveillance lens is disclosed. The lens's optical system comprises six lenses with optical power, arranged sequentially along the incident light path as a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens. An aperture stop is provided between the third and fourth lenses. The first lens is a meniscus negative lens with a convex object-side surface and a concave image-side surface; the second lens is a meniscus negative lens with a convex object-side surface and a concave image-side surface; the third lens is a meniscus positive lens with a convex object-side surface and a concave image-side surface; the fourth lens is a biconvex positive lens with a convex object-side surface and a convex image-side surface; the fifth lens is a meniscus negative lens with a convex object-side surface and a concave image-side surface; and the sixth lens is a biconvex positive lens with a convex object-side surface and a convex image-side surface. The positive and negative signs of the lenses refer to their optical power. The first and fourth lenses are glass spherical lenses, while the second, third, fifth, and sixth lenses are plastic aspherical lenses.

[0019] By rationally combining the optical power and surface shape of the six lenses and using multiple plastic aspherical surfaces, the optical system possesses excellent aberration correction and resolving capabilities, such as... Figures 2 to 6 As shown.

[0020] In this embodiment, the on-axis distances of the optical system satisfy the following relationships: the air gap between the first lens and the second lens is 0.5~1.0mm; the air gap between the second lens and the third lens is 2.5~3.0mm; the air gap between the third lens and the fourth lens is 0~0.5mm; the air gap between the fourth lens and the fifth lens is 0~0.5mm; and the air gap between the fifth lens and the sixth lens is 0~0.5mm.

[0021] In this embodiment, the focal length of the optical system is f, and the focal lengths of the first lens, second lens, third lens, fourth lens, fifth lens, and sixth lens are f1, f2, f3, f4, f5, and f6, respectively, wherein f1, f2, f3, f4, f5, and f6 satisfy the following ratio with f: -3.0 <f1 / f<-2.0,-6.0<f2 / f<-5.0,9.0<f3 / f<10.0,2.0<f4 / f<3.0,-3.0<f5 / f<-2.0,1.0<f6 / f<2.0。

[0022] In this embodiment, 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; where N d V is the refractive index. d Let be Abbe's constant.

[0023] In this embodiment, the second, third, fifth, and sixth lenses are plastic aspherical lenses. The equation for the aspherical curve is:

[0024] Where Z is the distance from the vertex of the aspherical surface to the optical axis at a position of height r; c is the paraxial curvature of the aspherical surface; and k is the conic constant. All are coefficients of higher-order terms.

[0025] The aspherical coefficients of the aspherical lenses in the optical system of this embodiment are shown in the table below:

[0026] In this embodiment, the total optical length (TTL) of the optical system and the focal length (f) of the optical system satisfy the following condition: 7.0 ≤ TTL / f ≤ 7.5.

[0027] In this embodiment, the F-number of the optical system is ≤1.6.

[0028] In this embodiment, the image height H of the optical system and the focal length f of the optical system satisfy the following condition: H / f≥2.3.

[0029] In this embodiment, a filter is provided on the rear side of the sixth lens.

[0030] The technical specifications achieved by the optical system in this embodiment are as follows: (1) Focal length: 3.0≤EFFL≤4.0mm; (2) Aperture F≤1.6; (3) Field of view: 2w ≥ 140°; (4) Operating bands: visible light and short-wave infrared bands.

[0031] To achieve the above design parameters, the specific design of the optical system adopted in this embodiment is shown in the table below:

[0032] This embodiment's optical system achieves a wide-angle surveillance lens with a large aperture, high resolution, day and night confocal focus, and no obvious purple fringing by rationally allocating the optical power, surface shape, center thickness of each lens, and on-axis distance between each lens. The design adopts a 6-element structure, which, while ensuring low cost, provides high-definition image quality, a field of view of up to 140 degrees, and ensures that the lens will not lose focus in environments ranging from -30℃ to 80℃.

[0033] An imaging method for a large-aperture day and night confocal wide-angle surveillance lens as described above, wherein light passes sequentially through a first lens, a second lens, a third lens, an aperture stop, a fourth lens, a fifth lens, a sixth lens, and a filter before forming an image.

[0034] Example 2: like Figure 7As shown, a large-aperture day / night confocal wide-angle surveillance lens is disclosed. The lens's optical system comprises six lenses with optical power, arranged sequentially along the incident light path as a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens. An aperture stop is located behind the third lens. The first lens is a meniscus negative lens with a convex object-side surface and a concave image-side surface; the second lens is a meniscus negative lens with a convex object-side surface and a concave image-side surface; the third lens is a meniscus positive lens with a convex object-side surface and a concave image-side surface; the fourth lens is a biconvex positive lens with a convex object-side surface and a convex image-side surface; the fifth lens is a meniscus negative lens with a convex object-side surface and a concave image-side surface; and the sixth lens is a biconvex positive lens with a convex object-side surface and a convex image-side surface. The positive and negative signs of the lenses refer to their optical power. The first and fourth lenses are glass spherical lenses, while the second, third, fifth, and sixth lenses are plastic aspherical lenses.

[0035] By rationally combining the optical power and surface shape of the six lenses and using multiple plastic aspherical surfaces, the optical system possesses excellent aberration correction and resolving capabilities, such as... Figures 8 to 13 As shown.

[0036] In this embodiment, the on-axis distances of the optical system satisfy the following relationships: the air gap between the first lens and the second lens is 0.5~1.0mm; the air gap between the second lens and the third lens is 2.5~3.0mm; the air gap between the third lens and the fourth lens is 0~0.5mm; the air gap between the fourth lens and the fifth lens is 0~0.5mm; and the air gap between the fifth lens and the sixth lens is 0~0.5mm.

[0037] In this embodiment, the focal length of the optical system is f, and the focal lengths of the first lens, second lens, third lens, fourth lens, fifth lens, and sixth lens are f1, f2, f3, f4, f5, and f6, respectively, wherein f1, f2, f3, f4, f5, and f6 satisfy the following ratio with f: -3.0 <f1 / f<-2.0,-5.0<f2 / f<-4.0,8.0<f3 / f<9.0,2.0<f4 / f<3.0,-3.0<f5 / f<-2.0,1.0<f6 / f<2.0。

[0038] In this embodiment, 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≤Nd ≤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; where N d V is the refractive index. d Let be Abbe's constant.

[0039] In this embodiment, the second, third, fifth, and sixth lenses are plastic aspherical lenses. The equation for the aspherical curve is:

[0040] Where Z is the distance from the vertex of the aspherical surface to the optical axis at a position of height r; c is the paraxial curvature of the aspherical surface; and k is the conic constant. All are coefficients of higher-order terms.

[0041] The aspherical coefficients of the aspherical lenses in the optical system of this embodiment are shown in the table below:

[0042] In this embodiment, the total optical length (TTL) of the optical system and the focal length (f) of the optical system satisfy the following condition: 7.0 ≤ TTL / f ≤ 7.5.

[0043] In this embodiment, the F-number of the optical system is ≤2.0.

[0044] In this embodiment, the image height H of the optical system and the focal length f of the optical system satisfy the following condition: H / f≥2.3.

[0045] In this embodiment, a filter is provided on the rear side of the sixth lens.

[0046] The technical specifications achieved by the optical system in this embodiment are as follows: (5) Focal length: 3.0 ≤ EFFL ≤ 4.0 mm; (6) Aperture F≤2.0; (7) Field of view: 2w ≥ 150°; (8) Operating bands: visible light and short-wave infrared bands.

[0047] To achieve the above design parameters, the specific design of the optical system adopted in this embodiment is shown in the table below:

[0048] This embodiment's optical system achieves a wide-angle surveillance lens with a large aperture, high resolution, day and night confocal focus, and no obvious purple fringing by rationally allocating the optical power, surface shape, center thickness of each lens, and on-axis distance between each lens. The design employs a 6-element structure, ensuring high-definition image quality, a 150-degree field of view, high relative illumination, and bright and clear imaging even in low-light environments, while also guaranteeing that the lens will not lose focus in environments ranging from -30℃ to 80℃.

[0049] An imaging method for a large-aperture day and night confocal wide-angle surveillance lens as described above, wherein light passes sequentially through a first lens, a second lens, a third lens, an aperture stop, a fourth lens, a fifth lens, a sixth lens, and a filter before forming an image.

[0050] Unless otherwise stated, if any of the technical solutions disclosed in this invention specify a numerical range, then the disclosed numerical range is a preferred numerical range. Anyone skilled in the art should understand that the preferred numerical range is merely one among many feasible numerical values ​​that has a more obvious or representative technical effect. Because there are many numerical values, it is impossible to list them all. Therefore, this invention discloses only some numerical values ​​to illustrate the technical solutions of this invention. Furthermore, the numerical values ​​listed above should not constitute a limitation on the scope of protection of this invention.

[0051] If this invention discloses or relates to mutually fixedly connected components or structural parts, then, unless otherwise stated, a fixed connection can be understood as: a detachable fixed connection (e.g., using bolts or screws), or a non-detachable fixed connection (e.g., riveting, welding). Of course, mutually fixed connections can also be replaced by an integral structure (e.g., manufactured in one piece using a casting process) (except where it is obviously impossible to use an integral molding process).

[0052] In addition, unless otherwise stated, the terms used in any of the technical solutions disclosed in this invention to indicate positional relationships or shapes include states or shapes that are similar to, close to, or approximate with those states or shapes.

[0053] Any component provided by this invention can be assembled from multiple individual components or can be a single component manufactured by a one-piece molding process.

[0054] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present 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 large-aperture, day-night confocal wide-angle surveillance lens, characterized in that: The optical system of the lens has six lenses with optical power, arranged sequentially along the incident light path as a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens. An aperture stop is provided between the third and fourth lenses. The first lens is a meniscus negative lens with a convex object-side surface and a concave image-side surface; the second lens is a meniscus negative lens with a convex object-side surface and a concave image-side surface; the third lens is a meniscus positive lens with a convex object-side surface and a concave image-side surface; the fourth lens is a biconvex positive lens; the fifth lens is a meniscus negative lens with a convex object-side surface and a concave image-side surface; and the sixth lens is a biconvex positive lens. Among these, the first and fourth lenses are glass spherical lenses, while the second, third, fifth, and sixth lenses are plastic aspherical lenses.

2. The large-aperture day and night confocal wide-angle surveillance lens according to claim 1, characterized in that: The optical system has a focal length of f, and the focal lengths of the first, second, third, fourth, fifth, and sixth lenses are f1, f2, f3, f4, f5, and f6, respectively. The ratios of f1, f2, f3, f4, f5, and f6 to f satisfy the following proportions: -3.0 < f1 / f < -2.0, -6.

0. <f2 / f<-4.0,8.0<f3 / f<10.0,2.0< f4 / f<3.0,-3.0< f5 / f<-2.0,1.0< f6 / f<2.0。 3. The large-aperture day and night confocal wide-angle surveillance lens 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; where N d V is the refractive index. d Let be Abbe's constant.

4. The large-aperture day and night confocal wide-angle surveillance lens according to claim 1, characterized in that: The air gap between the first lens and the second lens is 0.5~1.0mm; the air gap between the second lens and the third lens is 2.5~3.0mm; the air gap between the third lens and the fourth lens is 0~0.5mm; the air gap between the fourth lens and the fifth lens is 0~0.5mm; and the air gap between the fifth lens and the sixth lens is 0~0.5mm.

5. The large-aperture day and night confocal wide-angle surveillance lens according to claim 1, characterized in that: The total optical length (TTL) of the optical system and the focal length (f) of the optical system satisfy the following condition: 7.0 ≤ TTL / f ≤ 7.

5.

6. The large-aperture day and night confocal wide-angle surveillance lens according to claim 1, characterized in that: The image height H of the optical system and the focal length f of the optical system satisfy the following condition: H / f≥2.

3.

7. The large-aperture day and night confocal wide-angle surveillance lens according to claim 1, characterized in that: A filter is provided on the rear side of the sixth lens.

8. An imaging method for a large-aperture day-night confocal wide-angle surveillance lens as described in claim 7, characterized in that: The light rays pass through the first lens, the second lens, the third lens, the aperture, the fourth lens, the fifth lens, the sixth lens, and the filter in sequence to form an image.

Images