A small day and night confocal security zoom lens and imaging method thereof

Abstract

The present invention relates to a small day and night confocal security zoom lens and an imaging method thereof. The lens comprises a compensation group and a magnification group which are arranged in sequence along the incident direction of light within a lens structure. The compensation group comprises a first lens, a second lens, and a third lens which are arranged in sequence from left to right along the incident light path of the light. The magnification group comprises a fourth lens, a fifth lens, a sixth lens, and a seventh lens which are arranged in sequence from left to right along the incident light path of the light. The compensation group has a negative optical focal length, and the magnification group has a positive optical focal length. The imaging angle of the wide-angle end of the lens of the present invention to an object is greater than 130 degrees. Both the wide-angle end and the telephoto end have the advantages of high imaging clarity, large light clearance, low tolerance sensitivity, and good high and low temperature stability, and can also perform more comprehensive monitoring.

Description

Technical Field

[0001] The invention relates to a small day and night confocal security zoom lens and an imaging method thereof. Background Art

[0002] Modern society places increasing emphasis on security, and people are increasingly concerned about the safety of their lives and property caused by external factors, driving rapid development in the security and surveillance sector. Amidst the rapid growth of the global security industry, China has established the world's largest security and surveillance network, the "China Skynet," which ranks first globally in terms of the total number of security cameras and its monitoring capabilities. In recent years, with the continued growth of my country's economic strength and the comprehensive advancement of security initiatives such as Safe Cities, Smart Cities, and Intelligent Transportation, demand for domestic security and surveillance equipment has rapidly increased, resulting in the largest overall market size globally.

[0003] Broadening the system's operating wavelength and field of view allows for more information about the monitored target. Therefore, security zoom lenses with wide spectrum and large field of view have become a key R&D focus for security companies. Specifically, the development of day / night zoom lenses with wide spectrum, large relative aperture, miniaturization, and high image quality is a core goal for security companies and a goal pursued by designers. Summary of the Invention

[0004] The present invention proposes a small day-and-night confocal security zoom lens and an imaging method thereof, which simultaneously take into account optical characteristics such as a wide spectrum, a large relative aperture, miniaturization, high image quality, and day-and-night confocal monitoring.

[0005] The solution adopted by the present invention to solve the technical problem is a small day and night confocal security zoom lens: it includes a compensation group and a magnification group arranged in sequence along the incident direction of light in the lens structure, the compensation group is composed of a first lens, a second lens and a third lens arranged in sequence from left to right along the incident light path of the light, and the magnification group is composed of a fourth lens, a fifth lens, a sixth lens and a seventh lens arranged in sequence from left to right along the incident light path of the light, wherein the compensation group has a negative optical focal length and the magnification group has a positive optical focal length.

[0006] Furthermore, the first lens is a meniscus concave negative lens with a convex object side and a concave image side; the second lens is a double concave negative lens with a concave object side and a concave image side; the third lens is a meniscus convex positive lens with a convex object side and a concave image side; the fourth lens is a double convex positive lens with a convex object side and a convex image side; the fifth lens is a meniscus concave negative lens with a convex object side and a concave image side; the sixth lens is a double convex positive lens with a convex object side and a convex image side; the seventh lens is a double concave negative lens with a concave object side and a concave image side.

[0007] Furthermore, the first lens and the fourth lens are glass spherical lenses, the second lens, the third lens, the fifth lens, the sixth lens and the seventh lens are plastic aspherical lenses, the sixth lens and the seventh lens are cemented into a lens group, and an aperture is provided between the compensation group and the zoom group.

[0008] Furthermore, the focal lengths of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, and the seventh lens are f1, f2, f3, f4, f5, f6, and f7, wherein f2, f3, f4, f5, f6, and f7 satisfy the following ratio with respect to f1: 1.0 <f2 / f1<2.0,-3.0<f3 / f1<-2.0,-2.0<f4 / f1<-1.0,0.0<f5 / f1<1.0,-1.0<f6 / f1<0.0,1.0<f7 / f1<2.0。

[0009] 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: 1.2≤N d ≤1.5, 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; where N d is the refractive index, V d is the Abbe constant.

[0010] Furthermore, the air gap between the first lens and the second lens is 4.1 to 4.5 mm; the air gap between the second lens and the third lens is 0.5 to 1.0 mm; the air gap between the fourth lens and the fifth lens is 0.1 to 0.5 mm; the air gap between the fifth lens and the sixth lens is 0.5 to 1.0 mm; the sixth lens and the seventh lens are a cemented lens group, and the air gap is 0.0 mm.

[0011] Furthermore, the second lens, the third lens, the fifth lens, the sixth lens, and the seventh lens are plastic aspheric lenses, and the aspheric curve equation is expressed as:

[0012]

[0013] Among them, Z is the height of the aspheric surface from the vertex of the aspheric surface when it is at a height of h along the optical axis; r is the height in the vertical direction relative to the optical axis; c is the paraxial curvature of the aspheric surface; k is the cone constant; α1, α2, α3, α4, α5, α6, α7, and α8 are all high-order coefficients.

[0014] Furthermore, the system focal length EFFL of the overall optical lens satisfies: 3.0≤EFFL≤4.0mm.

[0015] Furthermore, the F number of the overall optical lens is ≤1.6, and the field of view angle is: 2w≥130°.

[0016] A small day and night confocal security zoom lens and an imaging method thereof: when light is incident, the light path sequentially enters a first lens, a second lens, a third lens, an aperture, a fourth lens, a fifth lens, a sixth lens, and a seventh lens, and finally forms an image on an image plane.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] 1. The imaging angle of the lens at the wide-angle end is greater than 130 degrees. Both the wide-angle and telephoto ends have the advantages of high imaging clarity, large aperture, low tolerance sensitivity and good high and low temperature stability, which can provide more comprehensive monitoring.

[0019] 2. Through the reasonable matching of optical lenses, the system structure is compact and reasonable, easy to assemble, with low tolerance sensitivity, and more suitable for large-scale high-yield production;

[0020] 3. It uses two glass lenses with five plastic lenses. Compared with the all-glass system, it has a lighter system mass and stronger optical performance stability than the all-plastic system. At the same time, it can adapt to the environment and reduce costs.

[0021] 4. The zoom design provides both long-distance and close-range wide-angle and high-quality image monitoring capabilities;

[0022] 5. The F number at the wide-angle end is smaller and the aperture is larger, ensuring sufficient light entering the system and being able to adapt to a variety of complex environments;

[0023] 6. Able to make good compensation for focal plane displacement at high and low temperatures, and have adaptability to complex environments;

[0024] 7. The axial chromatic aberration, vertical chromatic aberration and high-order chromatic aberration are corrected to ensure that the imaging system can have high imaging quality even at large angles. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematic diagram of the optical structure of the wide-angle end of the present invention;

[0026] Figure 2 is an axial chromatic aberration diagram at the wide-angle end of the present invention;

[0027] Figure 3 This is a vertical axial chromatic aberration diagram at the wide-angle end of the present invention;

[0028] Figure 4 This is a field curvature distortion diagram at the wide-angle end of the present invention;

[0029] Figure 5 is an axial chromatic aberration diagram at the telephoto end of the present invention;

[0030] Figure 6 is a diagram of vertical axial chromatic aberration at the telephoto end of the present invention;

[0031] Figure 7 This is a field curvature distortion diagram at the telephoto end of the present invention;

[0032] In the figure: STO - aperture; L1 - first lens; L2 - second lens; L3 - third lens; L4 - fourth lens; L5 - fifth lens; L6 - sixth lens; L7 - seventh lens; L8 - equivalent glass plate; IMA - imaging surface. DETAILED DESCRIPTION

[0033] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0034] like Figure 1-7 A small day / night confocal security zoom lens is shown. It includes a compensation group and a zoom group, arranged sequentially along the incident light path within the lens structure. The compensation group consists of the first, second, and third lenses, arranged sequentially from left to right along the incident light path. The zoom group consists of the fourth, fifth, sixth, and seventh lenses, arranged sequentially along the incident light path. The compensation group has negative optical power, while the zoom group has positive optical power. Both the first and second lenses have negative optical power to adjust for wide-angle light. The plastic aspheric surface also reduces optical distortion. The sixth and seventh lenses form an achromatic doublet, and a filter is located behind the zoom group.

[0035] In this embodiment, the first lens is a meniscus concave negative lens with a convex object-side surface and a concave image-side surface; the second lens is a biconcave negative lens with a concave object-side surface and a concave image-side surface; the third lens is a meniscus convex 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 concave negative lens with a convex object-side surface and a concave image-side surface; the sixth lens is a biconvex positive lens with a convex object-side surface and a convex image-side surface; and the seventh lens is a biconcave negative lens with a concave object-side surface and a concave image-side surface.

[0036] In this embodiment, the first lens and the fourth lens are glass spherical lenses, the second lens, the third lens, the fifth lens, the sixth lens, and the seventh lens are plastic aspherical lenses, the sixth lens and the seventh lens are cemented together to form a lens group, and an aperture is provided between the compensation group and the zoom group.

[0037] In this embodiment, the focal lengths of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, and the seventh lens are f1, f2, f3, f4, f5, f6, and f7, wherein f2, f3, f4, f5, f6, and f7 satisfy the following ratio with respect to f1: 1.0 <f2 / f1<2.0,-3.0<f3 / f1<-2.0,-2.0<f4 / f1<-1.0,0.0<f5 / f1<1.0,-1.0<f6 / f1<0.0,1.0<f7 / f1<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: 1.2≤N d ≤1.5, 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; where N d is the refractive index, V d is the Abbe constant.

[0039] In this embodiment, the air gap between the first lens and the second lens is 4.1-4.5 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 is 0.1-0.5 mm; and the air gap between the fifth lens and the sixth lens is 0.5-1.0 mm.

[0040] In this embodiment, the second lens, the third lens, the fifth lens, the sixth lens, and the seventh lens are plastic aspheric lenses, and the aspheric curve equation is expressed as:

[0041]

[0042] Among them, Z is the height of the aspheric surface from the vertex of the aspheric surface when it is at a height of h along the optical axis; r is the height in the vertical direction relative to the optical axis; c is the paraxial curvature of the aspheric surface; k is the cone constant; α1, α2, α3, α4, α5, α6, α7, and α8 are all high-order coefficients.

[0043] In this embodiment, the overall optical lens meets the focal length requirement of 3.0≤EFFL≤4.0 mm.

[0044] In this embodiment, the F number of the overall optical lens is ≤1.6, and the field of view angle is: 2w ≥130°.

[0045] A small day and night confocal security zoom lens and an imaging method thereof: when light is incident, the light path sequentially enters a first lens, a second lens, a third lens, an aperture, a fourth lens, a fifth lens, a sixth lens, and a seventh lens, and finally forms an image on an image plane.

[0046] The technical indicators achieved by the optical system of this embodiment are as follows:

[0047] The system focal length EFFL satisfies: 3.0≤EFFL≤4.0mm;

[0048] Aperture F≤1.6;

[0049] Field of view: 2w ≥ 130°;

[0050] Working band: visible light and shortwave infrared band.

[0051] To achieve the above design parameters, the specific design adopted by the optical system of this embodiment is shown in the following table:

[0052]

[0053]

[0054] The aspheric coefficients of the aspheric lenses of the optical system of this embodiment are as follows:

[0055]

[0056] When this embodiment is moved from the wide-angle end to the telephoto end, the values ​​of the thickness of the air layer between the compensation group and the zoom group are as follows:

[0057] Air layer distance between compensation group and zoom group / mm Wide-angle end 21.581 Telephoto end 1.641

[0058] This embodiment uses a reasonable lens combination to enable the optical system to achieve zoom, ultra-wide angle, large aperture, day and night confocal, and low temperature drift design, while also performing good correction for on-axis and off-axis aberrations, and having good imaging quality. Figures 2 to 4 shown.

[0059] Unless otherwise stated, for any of the technical solutions disclosed in the present invention, if a numerical range is disclosed, the disclosed numerical range is a preferred numerical range. Any person skilled in the art should understand that the preferred numerical range is merely a numerical range that is representative or has a more obvious technical effect among many feasible numerical values. Due to the large number of numerical values, it is impossible to enumerate them exhaustively. Therefore, the present invention discloses some numerical values ​​to illustrate the technical solutions of the present invention. Moreover, the numerical values ​​listed above should not be construed as limiting the scope of protection of the present invention.

[0060] If words such as "first" and "second" are used in this document to limit components, those skilled in the art should know that the use of "first" and "second" is only for the convenience of description to distinguish between components. Unless otherwise stated, the above words have no special meaning.

[0061] If the present invention discloses or involves components or structural parts that are fixedly connected to each other, then, unless otherwise stated, the fixed connection can be understood as: a detachable fixed connection (for example, connection using bolts or screws), and can also be understood as: a non-detachable fixed connection (for example, riveting, welding). Of course, the mutual fixed connection can also be replaced by an integrated structure (for example, manufactured by integrated molding using a casting process) (except where it is obviously impossible to use an integrated molding process).

[0062] In addition, the orientations or positional relationships indicated by terms such as "longitudinal", "transverse", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", and "outside" used in any of the technical solutions disclosed in the above invention are based on the orientations or positional relationships shown in the accompanying drawings and are only for the convenience of describing this patent, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limitations on this patent. Unless otherwise stated, the terms used to indicate shapes used in any of the technical solutions disclosed in the above invention include shapes that are approximate, similar, or close to them.

[0063] Any component provided by the present invention may be assembled from multiple separate components, or may be a separate component manufactured by an integral molding process.

[0064] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention and not to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or some technical features can be replaced by equivalents without departing from the spirit of the technical solution of the present invention. They should all be included in the scope of the technical solution for protection of the present invention.

Claims

1. A small day and night confocal security zoom lens, characterized by: The lens comprises a compensation group and a zoom group arranged in sequence along the incident direction of light within the lens structure, wherein the compensation group comprises a first lens, a second lens, and a third lens arranged in sequence from left to right along the incident light path, and the zoom group comprises a fourth lens, a fifth lens, a sixth lens, and a seventh lens arranged in sequence from left to right along the incident light path, wherein the compensation group has a negative optical power and the zoom group has a positive optical power; The first lens is a meniscus concave negative lens with a convex object-side surface and a concave image-side surface; the second lens is a biconcave negative lens with a concave object-side surface and a concave image-side surface; the third lens is a meniscus convex 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 concave negative lens with a convex object-side surface and a concave image-side surface; the sixth lens is a biconvex positive lens with a convex object-side surface and a convex image-side surface; the seventh lens is a biconcave negative lens with a concave object-side surface and a concave image-side surface; The focal lengths of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, and the seventh lens are f1, f2, f3, f4, f5, f6, and f7, wherein f2, f3, f4, f5, f6, and f7 satisfy the following ratio with respect to f1: 1.0 <f2 / f1<2.0,-3.0<f3 / f1<-2.0,-2.0<f4 / f1<-1.0,0.0<f5 / f1<1.0,-1.0<f6 / f1<0.0,1.0<f7 / f1<2.0。 2. The small day and night confocal security zoom lens according to claim 1, characterized in that: The first lens and the fourth lens are glass spherical lenses, the second lens, the third lens, the fifth lens, the sixth lens and the seventh lens are plastic aspherical lenses, the sixth lens and the seventh lens are cemented into a lens group, and an aperture is provided between the compensation group and the zoom group.

3. The small day and night confocal security zoom 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: 1.2≤N d ≤1.5, 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; where N d is the refractive index, V d is the Abbe constant.

4. The small day and night confocal security zoom lens according to claim 3, characterized in that: The air gap between the first lens and the second lens is 4.1 to 4.5 mm; the air gap between the second lens and the third lens is 0.5 to 1.0 mm; the air gap between the fourth lens and the fifth lens is 0.1 to 0.5 mm; the air gap between the fifth lens and the sixth lens is 0.5 to 1.0 mm; the sixth lens and the seventh lens are a cemented lens group, and the air gap is 0.0 mm.

5. The small day and night confocal security zoom lens according to claim 4, characterized in that: The second lens, the third lens, the fifth lens, the sixth lens, and the seventh lens are plastic aspheric lenses, and the aspheric curve equation is expressed as: Among them, Z is the height of the aspheric surface from the vertex of the aspheric surface when it is at a height of h along the optical axis; r is the height in the vertical direction relative to the optical axis; c is the paraxial curvature of the aspheric surface; k is the cone constant; α1, α2, α3, α4, α5, α6, α7, and α8 are all high-order coefficients.

6. The small day and night confocal security zoom lens according to claim 5, characterized in that: The system focal length EFFL of the overall optical lens satisfies: 3.0≤EFFL≤4.0mm.

7. The small day and night confocal security zoom lens according to claim 6, characterized in that: The F number of the overall optical lens is ≤1.6, and the field of view angle is: 2w≥130°.

8. A small day / night confocal security zoom lens and an imaging method thereof, using the small day / night confocal security zoom lens according to claim 7, characterized in that: When light is incident, the light path enters the first lens, second lens, third lens, aperture, fourth lens, fifth lens, sixth lens, and seventh lens in sequence, and finally forms an image on the image plane.

Images