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

Abstract

The present application relates to a kind of small day and night confocal security zoom lens and its imaging method;The zoom lens is composed of compensation group and zoom group arranged in order along the direction of light incidence, the compensation group is composed of first lens, second lens, third lens arranged in order along the direction of light incidence, the zoom group is composed of fourth lens, fifth lens, sixth lens, seventh lens, eighth lens, ninth lens arranged in order along the direction of light incidence, the sixth lens and seventh lens are glued into glued lens group, the present application is by reasonable lens collocation, so that optical system realizes wide spectrum, large relative aperture, miniaturization and high image quality, day and night confocal monitoring and other optical characteristics, while on-axis, off-axis aberration is well corrected, with good imaging quality.

Description

Technical Field

[0001] This invention relates to a small day / night confocal security zoom lens and its imaging method. Background Technology

[0002] Depending on the application environment, security lenses come in fixed-focus, zoom, floating-aperture, fixed-aperture, and wavelength-specific types. For example, short-focus fixed-focus lenses are suitable for monitoring confined spaces or homes; zoom lenses are used for large-area monitoring such as forest fire prevention and border surveillance; and visible-infrared confocal lenses are used in nighttime or low-light environments. A zoom lens can be considered as a combination of multiple fixed-focus lenses with different focal lengths, enabling both short-range, large-area monitoring and long-range, small-area monitoring. Therefore, lens selection should consider the usage environment and cost, ensuring that requirements are met while keeping costs to a minimum. Expanding the system's operating wavelength and field of view allows for the acquisition of more information about monitored targets; therefore, wide-spectrum, wide-field-of-view security zoom lenses have become a key research and development focus for security companies. Among these, the development of wide-spectrum, large relative aperture, miniaturized, and high-quality day-and-night zoom monitoring lenses is a core objective for security companies and a goal pursued by designers. Summary of the Invention

[0003] In view of the shortcomings of the prior art, the present invention provides a small day-night confocal security zoom lens and its imaging method. It simultaneously takes into account optical characteristics such as wide spectrum, large relative aperture, miniaturization, high image quality, and day-night confocal monitoring.

[0004] The solution adopted by this invention to solve the technical problem is a small day and night confocal security zoom lens: the zoom lens consists of a compensation group and a zoom group arranged sequentially along the incident direction of light. The compensation group consists of a first lens, a second lens, and a third lens arranged sequentially along the incident direction of light. The zoom group consists of a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens, and a ninth lens arranged sequentially along the incident direction of light. The seventh lens and the eighth lens are cemented together to form an achromatic cemented doublet lens.

[0005] Furthermore, 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 biconcave negative lens with a concave object-side surface and a concave image-side surface; the third lens is a biconvex positive lens with a convex object-side surface and a convex 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 biconvex positive lens with a convex object-side surface and a convex image-side surface; the sixth lens is a meniscus convex negative lens with a convex object-side surface and a concave image-side surface; the seventh lens is a meniscus concave negative lens with a convex object-side surface and a concave image-side surface; the eighth lens is a biconvex positive lens with a convex object-side surface and a convex image-side surface; and the ninth lens is a meniscus concave negative lens with a convex object-side surface and a concave image-side surface.

[0006] Furthermore, the air gap between the first lens and the second lens is 4.5~5.0mm; the air gap between the second lens and the third lens is 0.1~0.5mm; the air gap between the fourth lens and the fifth lens is 0.1~0.5mm; the air gap between the fifth lens and the sixth lens is 0.1~0.5mm; the air gap between the sixth lens and the seventh lens is 0.1~0.5mm; and the air gap between the eighth lens and the ninth lens is 0.5~1.0mm.

[0007] Furthermore, the first lens satisfies the following relationship: 1.5 ≤ ≤1.8, ≤50.0; The second lens satisfies the relationship: 1.5≤ ≤1.8, ≥50.0; The third lens satisfies the relationship: 1.5≤ ≤1.8, ≤50.0; The fourth lens satisfies the relation: 1.2≤ ≤1.5, ≥50.0; The fifth lens satisfies the relationship: 1.5≤ ≤1.8, ≤50.0; The sixth lens satisfies the relationship: 1.5≤ ≤1.8, ≤50.0; The seventh lens satisfies the relationship: 1.5≤ ≤1.8, ≤50.0; The eighth lens satisfies the relationship: 1.5≤ ≤1.8, ≥50.0; The ninth lens satisfies the relationship: 1.5≤ ≤1.8, ≥50.0; of which For refractive index, Let be Abbe's constant.

[0008] Furthermore, the focal lengths of the first lens, second lens, third lens, fourth lens, fifth lens, sixth lens, seventh lens, eighth lens, and ninth lens are: , , , , , , , , ,in , , , , , , , , , , , and Meets the following ratio: 1.0 < / <2.0, -3.0< / <-2.0, -2.0< / <-1.0, -6.0< / <-5.0, 7.0< / <8.0, 0.1< / <1.0, -1.0< / <-0.1, 11.0< / <12.0.

[0009] Furthermore, the first, fourth, seventh, and eighth lenses are glass spherical lenses, while the second, third, fifth, sixth, and ninth lenses are plastic aspherical lenses.

[0010] Furthermore, the equations for the aspherical curves of the second, third, fifth, sixth, and ninth 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; , , , , , , , All are coefficients of higher-order terms.

[0013] Furthermore, the compensation group has negative optical power, the zoom group has positive optical power, and both the first lens and the second lens are lenses with negative optical power.

[0014] Furthermore, the field of view of the zoom lens is 2w ≥ 120°.

[0015] An imaging method for a small day-night confocal security zoom lens: When light is incident, the light path sequentially enters the first lens, the second lens, the third lens, the aperture stop, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the eighth lens, and the ninth lens, and finally forms an image on the image plane.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] 1. The wide-angle end of this lens has an imaging angle of more than 120 degrees. Both the wide-angle and telephoto ends have the advantages of high imaging clarity, large light aperture, low tolerance sensitivity and good high and low temperature stability, which can enable more comprehensive monitoring.

[0018] 2. By rationally matching the various optical lenses, the system structure is compact and reasonable, easy to assemble, has low tolerance sensitivity, and is more suitable for large-scale high-yield production;

[0019] 3. It uses four glass lenses in combination with five plastic lenses, which results in a lighter system weight compared to an all-glass system and stronger optical performance stability compared to an all-plastic system, while reducing costs while adapting to different environments.

[0020] 4. It adopts a zoom design, which combines long-distance and close-range wide-angle high-quality monitoring capabilities;

[0021] 5. The wide-angle end has a smaller F-number and a larger aperture, ensuring sufficient light intake for the system and enabling it to adapt to various complex environments;

[0022] 6. It can provide good compensation for focal plane displacement at high and low temperatures and has adaptability to complex environments;

[0023] 7. Corrected chromatic aberration along each axis, lateral chromatic aberration, and higher-order chromatic aberrations to ensure high imaging quality even at large angles. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the optical structure at the wide-angle end of the present invention;

[0025] Figure 2 This is the axial color difference diagram at the wide-angle end of the present invention;

[0026] Figure 3 This is the lateral chromatic aberration diagram at the wide-angle end of the present invention;

[0027] Figure 4 This is the field curvature distortion diagram at the wide-angle end of the present invention;

[0028] Figure 5 This is the axial chromatic aberration diagram of the telescope end of the present invention;

[0029] Figure 6 This is the vertical axis chromatic aberration diagram of the telescope end of the present invention;

[0030] Figure 7 This is a field distortion diagram of the telescope end of the present invention.

[0031] In the diagram: STO - aperture stop; L1 - first lens; L2 - second lens; L3 - third lens; L4 - equivalent glass plate; L5 - fourth lens; L6 - fifth lens; L7 - sixth lens; L8 - seventh lens; L9 - eighth lens; L10 - ninth lens; L11 - equivalent glass plate; IMA - imaging plane. Detailed Implementation

[0032] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0033] like Figure 1 As shown, a small day / night confocal security zoom lens is provided: the zoom lens consists of a compensation group and a zoom group arranged sequentially along the incident direction of light. The compensation group consists of a first lens, a second lens, and a third lens arranged sequentially along the incident direction of light. The zoom group consists of a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens, and a ninth lens arranged sequentially along the incident direction of light. The seventh lens and the eighth lens are cemented together to form an achromatic cemented doublet lens.

[0034] In this embodiment, 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 biconcave negative lens with a concave object-side surface and a concave image-side surface; the third lens is a biconvex positive lens with a convex object-side surface and a convex 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 biconvex positive lens with a convex object-side surface and a convex image-side surface; the sixth lens is a meniscus convex negative lens with a convex object-side surface and a concave image-side surface; the seventh lens is a meniscus concave negative lens with a convex object-side surface and a concave image-side surface; the eighth lens is a biconvex positive lens with a convex object-side surface and a convex image-side surface; and the ninth lens is a meniscus concave negative lens with a convex object-side surface and a concave image-side surface.

[0035] In this embodiment, the air gap between the first lens and the second lens is 4.5~5.0mm; the air gap between the second lens and the third lens is 0.1~0.5mm; the air gap between the fourth lens and the fifth lens is 0.1~0.5mm; the air gap between the fifth lens and the sixth lens is 0.1~0.5mm; the air gap between the sixth lens and the seventh lens is 0.1~0.5mm; and the air gap between the eighth lens and the ninth lens is 0.5~1.0mm. Reducing the distance between the lenses while meeting imaging requirements is beneficial to the overall optical length of the lens.

[0036] In this embodiment, the first lens satisfies the relationship: 1.5 ≤ ≤1.8, ≤50.0; The second lens satisfies the relationship: 1.5≤ ≤1.8, ≥50.0; The third lens satisfies the relationship: 1.5≤ ≤1.8, ≤50.0; The fourth lens satisfies the relation: 1.2≤ ≤1.5, ≥50.0; The fifth lens satisfies the relationship: 1.5≤ ≤1.8, ≤50.0; The sixth lens satisfies the relationship: 1.5≤ ≤1.8, ≤50.0; The seventh lens satisfies the relationship: 1.5≤ ≤1.8, ≤50.0; The eighth lens satisfies the relationship: 1.5≤ ≤1.8, ≥50.0; The ninth lens satisfies the relationship: 1.5≤ ≤1.8, ≥50.0; of which For refractive index, Let be Abbe's constant.

[0037] In this embodiment, the focal lengths of the first lens, second lens, third lens, fourth lens, fifth lens, sixth lens, seventh lens, eighth lens, and ninth lens are: , , , , , , , , ,in , , , , , , , , , , , and Meets the following ratio: 1.0 < / <2.0, -3.0< / <-2.0, -2.0< / <-1.0, -6.0< / <-5.0, 7.0< / <8.0, 0.1< / <1.0, -1.0< / <-0.1, 11.0< / <12.0.

[0038] In this embodiment, the first lens, the fourth lens, the seventh lens, and the eighth lens are glass spherical lenses, and the second lens, the third lens, the fifth lens, the sixth lens, and the ninth lens are plastic aspherical lenses.

[0039] In this embodiment, the equations for the aspherical curves of the second lens, third lens, fifth lens, sixth lens, and ninth lens are as follows:

[0040]

[0041] 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; , , , , , , , All are coefficients of higher-order terms.

[0042] In this embodiment, an aperture is provided between the compensation group and the zoom group.

[0043] In this embodiment, a filter is provided between the compensation group and the zoom group.

[0044] In this embodiment, the compensation group has negative optical power, the zoom group has positive optical power, and both the first lens and the second lens are lenses with negative optical power.

[0045] In this embodiment, the field of view of the zoom lens is: 2w ≥ 120°.

[0046] An imaging method for a small day-night confocal security zoom lens: When light is incident, the light path sequentially enters the first lens, the second lens, the third lens, the aperture stop, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the eighth lens, and the ninth lens, and finally forms an image on the image plane.

[0047] The technical specifications achieved by the optical system in this embodiment are as follows:

[0048] (1) Focal length: 3.0≤EFFL≤4.0mm;

[0049] (2) Aperture F≤1.6;

[0050] (3) Field of view: 2w ≥ 120°;

[0051] (4) Operating bands: visible light and short-wave infrared bands.

[0052] To achieve the above design parameters, the specific design of the optical system adopted in this embodiment is shown in the table below:

[0053]

[0054] The aspherical coefficients of the aspherical lenses in the optical system of this embodiment are shown in the table below:

[0055]

[0056] 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:

[0057]

[0058] This embodiment, through a reasonable lens combination, enables the optical system to achieve zoom, ultra-wide-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.

[0059] 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.

[0060] If the terms "first" or "second" are used in this document to specify components, those skilled in the art should know that the use of "first" or "second" is merely for the purpose of distinguishing components in description, and unless otherwise stated, the above terms have no special meaning.

[0061] 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).

[0062] Furthermore, the orientations or positional relationships used in any of the technical solutions disclosed in this invention above to indicate positional relationships, such as "longitudinal," "lateral," "up," "down," "front," "back," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," are based on the orientations or positional relationships shown in the accompanying drawings and are only for the convenience of describing this patent. They are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this patent. In addition, unless otherwise stated, the terms used to indicate shape in any of the technical solutions disclosed in this invention above include shapes that are similar to, close to, or approximate with it.

[0063] 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.

[0064] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them; although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications can still be made to the specific implementation of the present invention or equivalent substitutions can be made to some technical features without departing from the spirit of the technical solutions of the present invention, and all such modifications and substitutions should be covered within the scope of the technical solutions claimed in the present invention.

Claims

1. A small day / night confocal security zoom lens, characterized in that: The zoom lens consists of a compensation group and a zoom group arranged sequentially along the incident direction of light. The compensation group consists of a first lens, a second lens, and a third lens arranged sequentially along the incident direction of light. The zoom group consists of a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens, and a ninth lens arranged sequentially along the incident direction of light. The seventh lens and the eighth lens are cemented together to form an achromatic cemented doublet lens. The first lens is a meniscus negative lens with a convex object side and a concave image side; the second lens is a biconcave negative lens with a concave object side and a concave image side; the third lens is a biconvex positive lens with a convex object side and a convex image side; the fourth lens is a biconvex positive lens with a convex object side and a convex image side; the fifth lens is a biconvex positive lens with a convex object side and a convex image side; the sixth lens is a meniscus negative lens with a convex object side and a concave image side; the seventh lens is a meniscus negative lens with a convex object side and a concave image side; the eighth lens is a biconvex positive lens with a convex object side and a convex image side; and the ninth lens is a meniscus negative lens with a convex object side and a concave image side.

2. The zoom lens according to claim 1, characterized in that: The air gap between the first lens and the second lens is 4.5~5.0mm; the air gap between the second lens and the third lens is 0.1~0.5mm; the air gap between the fourth lens and the fifth lens is 0.1~0.5mm; the air gap between the fifth lens and the sixth lens is 0.1~0.5mm; the air gap between the sixth lens and the seventh lens is 0.1~0.5mm; and the air gap between the eighth lens and the ninth lens is 0.5~1.0mm.

3. The zoom lens according to claim 1, characterized in that: The first lens satisfies the following relationship: 1.5 ≤ ≤1.8, ≤50.0; The second lens satisfies the relationship: 1.5≤ ≤1.8, ≥50.0; The third lens satisfies the relationship: 1.5≤ ≤1.8, ≤50.0; The fourth lens satisfies the relation: 1.2≤ ≤1.5, ≥50.0; The fifth lens satisfies the relationship: 1.5≤ ≤1.8, ≤50.0; The sixth lens satisfies the relationship: 1.5≤ ≤1.8, ≤50.0; The seventh lens satisfies the relationship: 1.5≤ ≤1.8, ≤50.0; The eighth lens satisfies the relationship: 1.5≤ ≤1.8, ≥50.0; The ninth lens satisfies the relationship: 1.5≤ ≤1.8, ≥50.0; of which For refractive index, Let be Abbe's constant.

4. The zoom lens according to claim 1, characterized in that: The focal lengths of the first, second, third, fourth, fifth, sixth, seventh, eighth, and ninth lenses are: , , , , , , , , ,in , , , , , , , , , , , and Meets the following ratio: 1.0 < / <2.0, -3.0< / <-2.0, -2.0< / <-1.0, -6.0< / <-5.0, 7.0< / <8.0, 0.1< / <1.0, -1.0< / <-0.1, 11.0< / <12.

0.

5. The zoom lens according to claim 1, characterized in that: The first, fourth, seventh, and eighth lenses are glass spherical lenses, while the second, third, fifth, sixth, and ninth lenses are plastic aspherical lenses.

6. The zoom lens according to claim 5, characterized in that: The equations for the aspherical curves of the second, third, fifth, sixth, and ninth 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; , , , , , , , All are coefficients of higher-order terms.

7. The zoom lens according to claim 1, characterized in that: The compensation group has negative optical power, the zoom group has positive optical power, and the first lens and the second lens are both lenses with negative optical power.

8. The zoom lens according to claim 1, characterized in that: The field of view of the zoom lens is 2w ≥ 120°.

9. An imaging method for a small day / night confocal security zoom lens, employing the lens as described in any one of claims 1-8, characterized in that: When light is incident, the light path sequentially enters the first lens, the second lens, the third lens, the aperture stop, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the eighth lens, and the ninth lens, and finally forms an image on the image plane.

Images