Day and night confocal lens

Abstract

The application discloses a day and night confocal lens, which comprises a first lens, a second lens, a third lens, a diaphragm, a fourth lens, a fifth lens and a sixth lens arranged in sequence along an optical axis from an object side to an image side, wherein the first lens has a negative refractive power, the second lens has a negative refractive power, the third lens has a positive refractive power, the fourth lens has a positive refractive power, the fifth lens has a negative refractive power, and the sixth lens has a positive refractive power; the lens satisfies the condition: 6.5 < f123 / f456 < 8.5, wherein f123 is the combined focal length value of the first lens, the second lens and the third lens, and f456 is the combined focal length value of the fourth lens, the fifth lens and the sixth lens. The day and night confocal lens adopts a 2G4P glass-plastic hybrid design, has the advantages of light weight, small size, low cost, flexible installation and use, a large field of view, high lens resolution and good imaging quality, and can ensure day and night confocal and has high imaging quality for visible light and infrared light.

Description

Technical Field

[0001] This invention relates to the field of optical lens technology, and more specifically, to a day-night confocal lens. Background Technology

[0002] With the continuous advancement of science and technology and the ongoing development of society, optical imaging lenses have also experienced rapid development in recent years. People's demands for optical imaging lenses are also increasing, with day-night confocal focusing becoming a fundamental characteristic required for most lenses. Existing day-night confocal lenses generally suffer from the following drawbacks: the use of multiple glass or cemented lens elements to improve resolution and correct chromatic aberration results in a large number of lens elements, excessively high TTL values, heavy and bulky lenses, limiting installation and use. Furthermore, existing day-night confocal lenses have excessively large incident angles, leading to poor edge field-of-view imaging quality. In addition, existing day-night confocal lenses have significant center defocus, resulting in poor night vision imaging performance.

[0003] In view of this, the inventors of this application have invented a day-night confocal lens. Summary of the Invention

[0004] The purpose of this invention is to provide a day and night confocal lens that is small in size, light in weight, and has good imaging quality in both visible and infrared light.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: a day and night confocal lens, comprising a first lens, a second lens, a third lens, an aperture stop, a fourth lens, a fifth lens, and a sixth lens arranged sequentially along an optical axis from the object side to the image side. Each of the first lens to the sixth lens includes an object side facing the object side and allowing imaging light to pass through, and an image side facing the image side and allowing imaging light to pass through.

[0006] The first lens has negative refractive power, and the object side of the first lens is convex, while the image side is concave.

[0007] The second lens has negative refractive power, and the object side of the second lens is convex, while the image side is concave.

[0008] The third lens has positive refractive power, and the object side and the image side of the third lens are both convex.

[0009] The fourth lens has positive refractive power, and the object side and the image side of the fourth lens are both convex.

[0010] The fifth lens has negative refractive power, and the object side and image side of the fifth lens are concave.

[0011] The sixth lens has positive refractive power, and the object side and the image side of the sixth lens are both convex.

[0012] The lens satisfies: 6.5 < f123 / f456 < 8.5, where f123 is the combined focal length value of the first lens, the second lens, and the third lens, and f456 is the combined focal length value of the fourth lens, the fifth lens, and the sixth lens.

[0013] Furthermore, the first lens and the third lens are both glass spherical lenses, and the second lens, the fourth lens, the fifth lens, and the sixth lens are all plastic aspherical lenses.

[0014] Furthermore, the lens satisfies: 4 < |f1 / f| < 5.5, 1.5 < |f2 / f| < 2, 2.5 < |f3 / f| < 3, 3 < |f4 / f| < 4.5, 1.5 < |f5 / f| < 2.5, 1.5 < |f6 / f| < 2, where f is the overall focal length value of the lens, and f1, f2, f3, f4, f5, and f6 are the focal length values of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, and the sixth lens, respectively.

[0015] Furthermore, the lens satisfies: -6 < f1 < -4.5, -2.5 < f2 < -1.5, 2 < f3 < 3, 3 < f4 < 4.5, -2.5 < f5 < -1.5, 1.5 < f6 < 2.5, where f1, f2, f3, f4, f5, and f6 are the focal length values of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, and the sixth lens, respectively.

[0016] Furthermore, the lens satisfies: 0.95 < (f12 / f) < 1.2, where f12 is the combined focal length value of the first lens and the second lens, and f is the overall focal length value of the lens.

[0017] Furthermore, the lens satisfies: 1.9 < ALT / AAG < 2.2, where ALT is the sum of the central thicknesses of the first to sixth lenses on the optical axis, and AAG is the sum of the air gaps of the first to sixth lenses on the optical axis.

[0018] Furthermore, the lens satisfies: TTL ≤ 13.4 mm, where TTL is the overall optical length of the lens.

[0019] Furthermore, the field angle of the lens satisfies; FOV ≤ 170°.

[0020] Furthermore, the lens satisfies: 1.0 < f < 1.1, where f is the overall focal length value of the lens.

[0021] Furthermore, the maximum aperture of the lens is F / NO = 2.0.

[0022] After adopting the above technical solutions, compared with the prior art, the present invention has the following advantages:

[0023] The day and night confocal lens of this invention adopts a 2G4P glass-plastic hybrid design, which makes the lens lightweight, small in size, and low in cost. It is also flexible in installation and use. In addition, it has a large field of view, high lens resolution, and good imaging quality. While ensuring day and night confocality, it also has high imaging quality in both visible and infrared fields. Attached Figure Description

[0024] Figure 1 This is the optical path diagram of Embodiment 1 of the present invention;

[0025] Figure 2 This is the MTF curve of the lens in Embodiment 1 of the present invention under visible light 435nm-650nm;

[0026] Figure 3 This is a defocus curve of the lens in Embodiment 1 of the present invention in the visible light range of 435nm-650nm;

[0027] Figure 4 This is a defocus curve of the lens in Embodiment 1 of the present invention under infrared light at 850nm;

[0028] Figure 5 This is a lateral chromatic aberration curve of the lens in Embodiment 1 of the present invention under visible light 435nm-650nm.

[0029] Figure 6 This is a longitudinal chromatic aberration curve of the lens in Embodiment 1 of the present invention under visible light 435nm-650nm.

[0030] Figure 7 The image shows the field curvature and distortion of the lens in Embodiment 1 of the present invention under visible light (435nm-650nm).

[0031] Figure 8 This is the optical path diagram of Embodiment 2 of the present invention;

[0032] Figure 9 This is the MTF curve of the lens in Embodiment 2 of the present invention under visible light 435nm-650nm;

[0033] Figure 10 This is a defocus curve of the lens in Embodiment 2 of the present invention under visible light 435nm-650nm;

[0034] Figure 11 This is a defocus curve of the lens in Embodiment 2 of the present invention under infrared light at 850nm;

[0035] Figure 12 This is a lateral chromatic aberration curve of the lens in Embodiment 2 of the present invention under visible light 435nm-650nm.

[0036] Figure 13This is a longitudinal chromatic aberration curve of the lens in Embodiment 2 of the present invention under visible light 435nm-650nm.

[0037] Figure 14 The image shows the field curvature and distortion of the lens in Embodiment 2 of the present invention under visible light (435nm-650nm).

[0038] Figure 15 This is the optical path diagram of Embodiment 3 of the present invention;

[0039] Figure 16 This is the MTF curve of the lens in Embodiment 3 of the present invention under visible light 435nm-650nm;

[0040] Figure 17 This is a defocus curve of the lens in Embodiment 3 of the present invention in the visible light range of 435nm-650nm;

[0041] Figure 18 This is a defocus curve of the lens in Embodiment 3 of the present invention under infrared light at 850nm;

[0042] Figure 19 This is a lateral chromatic aberration curve of the lens in Embodiment 3 of the present invention under visible light 435nm-650nm.

[0043] Figure 20 This is a longitudinal chromatic aberration curve of the lens in Embodiment 3 of the present invention under visible light 435nm-650nm.

[0044] Figure 21 The image shows the field curvature and distortion of the lens in Embodiment 3 of the present invention under visible light (435nm-650nm).

[0045] Explanation of reference numerals in the attached figures:

[0046] 1. First lens; 2. Second lens; 3. Third lens; 4. Fourth lens; 5. Fifth lens; 6. Sixth lens; 7. Aperture stop; 8. Protective plate. Detailed Implementation

[0047] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0048] The phrase "a lens has a positive (or negative) refractive index" refers to the lens having a positive (or negative) paraxial refractive index calculated using Gaussian optics theory. The "object-side surface (or image-side surface)" is defined as the specific area through which imaging rays pass on the lens surface. The convexity or concavity of a lens surface can be determined using methods commonly employed in the field, namely by the sign of the radius of curvature (R-value). R-values ​​are commonly used in optical design software such as Zemax or CodeV. R-values ​​are also frequently found in lens data sheets within optical design software. For the object-side surface, a positive R-value indicates a convex surface, while a negative R-value indicates a concave surface. Conversely, for the image-side surface, a positive R-value indicates a concave surface, while a negative R-value indicates a convex surface.

[0049] The present invention discloses a day and night confocal lens, comprising a first lens 1, a second lens 2, a third lens 3, an aperture 7, a fourth lens 4, a fifth lens 5, and a sixth lens 6 arranged sequentially along an optical axis from the object side to the image side. Each of the first lens 1 to the sixth lens 6 includes an object side facing the object side and allowing imaging light to pass through, and an image side facing the image side and allowing imaging light to pass through.

[0050] The first lens 1 has negative refractive power, and the object side of the first lens 1 is convex, while the image side is concave.

[0051] The second lens 2 has negative refractive power, and the object side of the second lens 2 is convex, while the image side is concave.

[0052] The third lens 3 has positive refractive power, and the object side and the image side of the third lens 3 are convex.

[0053] The fourth lens 4 has positive refractive power, and the object side and the image side of the fourth lens 4 are convex.

[0054] The fifth lens 5 has negative refractive power, and the object side and the image side of the fifth lens 5 are concave.

[0055] The sixth lens 6 has positive diopter, and the object side and the image side of the sixth lens 6 are both convex.

[0056] The aperture 7 is located between the third lens 3 and the fourth lens 4. The first to third lenses 3 form the front group of the lens, and the fourth to sixth lenses 6 form the rear group of the lens.

[0057] In this lens, the first lens 1 and the third lens 3 are both glass spherical lenses, and the second lens 2, the fourth lens 4, the fifth lens 5, and the sixth lens 6 are all plastic aspherical lenses. The six-piece glass-plastic hybrid design has fewer lenses and a lighter lens weight. Its overall optical length TTL satisfies: TTL ≤ 13.4 mm. The overall volume of the lens is small, and it is flexible to install and use.

[0058] The lens of this application is designed with four plastic aspherical lenses plus one glass lens, which is beneficial for correcting secondary spectrum and higher-order aberrations. At the same time, the glass lens uses a high-refractive-index material, which can better optimize the optical structure and is beneficial for the lens structure design, reducing the lens cost. Specifically, the refractive index of the first lens 1 satisfies: nd1 > 1.8, and the refractive index of the third lens 3 satisfies: nd3 > 1.73. The refractive indices of the plastic aspherical lenses are correspondingly lower.

[0059] In addition, the lens of this application adopts a glass-plastic hybrid structure design. The plastic lenses can better correct chromatic aberration and higher-order aberrations, and can also well control the cost and reduce the lens weight. At the same time, due to the poor temperature drift performance of the plastic lenses, adding two glass lenses can well correct the temperature drift of the lens and can well ensure the working state under different temperature conditions.

[0060] This lens satisfies: 4 < |f1 / f| < 5.5, 1.5 < |f2 / f| < 2, 2.5 < |f3 / f| < 3, 3 < |f4 / f| < 4.5, 1.5 < |f5 / f| < 2.5, 1.5 < |f6 / f| < 2, where f is the overall focal length value of the lens, and f1, f2, f3, f4, f5, f6 are the focal length values of the first lens 1, the second lens 2, the third lens 3, the fourth lens 4, the fifth lens 5, and the sixth lens 6 respectively.

[0061] This lens satisfies: -6 < f1 < -4.5, -2.5 < f2 < -1.5, 2 < f3 < 3, 3 < f4 < 4.5, -2.5 < f5 < -1.5, 1.5 < f6 < 2.5, where f1, f2, f3, f4, f5, f6 are the focal length values of the first lens 1, the second lens 2, the third lens 3, the fourth lens 4, the fifth lens 5, and the sixth lens 6 respectively.

[0062] The lens satisfies: 6.5 < f123 / f456 < 8.5, where f123 is the combined focal length value of the first lens 1, the second lens 2, and the third lens 3, and f456 is the combined focal length value of the fourth lens 4, the fifth lens 5, and the sixth lens 6. When the lens satisfies the above relationship, the optical power of the front and rear groups can be better distributed, which is beneficial to correcting the aberration between the front and rear groups and can have higher imaging quality. At the same time, reasonably distributing the optical power of the front and rear groups can better balance the defocus amount of the lens in visible light and infrared light, so that the central part can have a high imaging resolution under visible light and infrared conditions.

[0063] The lens satisfies: 0.95 < (f12 / f) < 1.2, where f12 is the combined focal length value of the first lens 1 and the second lens 2, and f is the overall focal length value of the lens. By reasonably configuring the ratio of the combined focal length of the first two lenses to the overall focal length of the lens, stray light in the front group can be more effectively controlled, meeting the requirement of good imaging effect of the lens under wide-angle conditions and also better correcting aberration.

[0064] The lens satisfies: 1.9 < ALT / AAG < 2.2, where ALT is the sum of the central thicknesses of the first to sixth lenses 6 on the optical axis, and AAG is the sum of the air gaps of the first to sixth lenses 6 on the optical axis. When the lens satisfies the above relationship, the optical power between the lenses can be better distributed, meeting the requirement of good imaging quality of the lens in both visible light and infrared light. At the same time, the overall length of the lens can be effectively compressed, which is more conducive to the assembly of the rear lens module.

[0065] The lens satisfies: TTL ≤ 13.4 mm, FOV ≤ 170°, 1.0 mm < f < 1.1 mm, where TTL is the overall optical length of the lens, FOV is the field angle of the lens, f is the overall focal length value of the lens, and the maximum aperture of the lens is F / NO = 2.0. The lens has a small overall volume and a large field angle, and the MTF at 125 lp / mm is greater than 0.45, having good imaging quality.

[0066] Among them, the second lens 2, the fourth lens 4, the fifth lens 5, and the sixth lens 6 are all aspherical lenses, and both surfaces of the aspherical lens are aspherical. The equation of the surface curve of the aspherical lens is expressed as follows:

[0067]

[0068] Among them,

[0069] z: the depth of the aspherical surface (the vertical distance between a point on the aspherical surface at a distance y from the optical axis and the tangent plane at the vertex of the aspherical surface on the optical axis);

[0070] c: The curvature of the vertex of the aspherical surface;

[0071] K: Conic constant;

[0072] Radial distance;

[0073] rn: Normalization radius (NRADIUS)

[0074] u:r / rn;

[0075] am: the mth Qcon coefficient;

[0076] Qmcon: The mth Qcon polynomial.

[0077] The day and night confocal lens of the present invention will be described in detail below with reference to specific embodiments.

[0078] Example 1

[0079] Reference Figure 1 As shown, the present invention discloses a day and night confocal lens, including a first lens 1, a second lens 2, a third lens 3, an aperture 7, a fourth lens 4, a fifth lens 5, and a sixth lens 6 arranged sequentially along an optical axis from the object side to the image side. Each of the first lens 1 to the sixth lens 6 includes an object side facing the object side and allowing imaging light to pass through, and an image side facing the image side and allowing imaging light to pass through.

[0080] The first lens 1 has negative refractive power, and the object side of the first lens 1 is convex, while the image side is concave.

[0081] The second lens 2 has negative refractive power, and the object side of the second lens 2 is convex, while the image side is concave.

[0082] The third lens 3 has positive refractive power, and the object side and the image side of the third lens 3 are convex.

[0083] The fourth lens 4 has positive refractive power, and the object side and the image side of the fourth lens 4 are convex.

[0084] The fifth lens 5 has negative refractive power, and the object side and the image side of the fifth lens 5 are concave.

[0085] The sixth lens 6 has positive diopter, and the object side and the image side of the sixth lens 6 are both convex.

[0086] Detailed optical data for this specific embodiment are shown in Table 1-1.

[0087] Table 1-1 Detailed optical data for Example 1

[0088]

[0089]

[0090] The aspherical data in this embodiment are shown in Table 1-2.

[0091] Table 1-2 Aspherical data from Example 1

[0092]

[0093] In this embodiment, the specific values ​​of some parameters are shown in Tables 1-3.

[0094] Table 1-3 Parameter values ​​for Example 1

[0095] parameter f FOV TTL Fno IMH f1f2 / f ALT / AAG f123 / f456 numerical values 1.011 170 13.32 2.000 3.900 1.056 2.163 6.950

[0096] In this embodiment, please refer to the MTF curve of the lens in the visible light 435nm-650nm range. Figure 2 As can be seen from the figure, when the spatial frequency of this lens reaches 125 lp / mm, the MTF value is greater than 0.45, indicating excellent image quality and high lens resolution.

[0097] Please refer to the lens defocus curves for visible light (435nm-650nm) and infrared light (850nm) respectively. Figure 3 , Figure 4 As can be seen from the image, the lens has a small defocusing amount under both visible and infrared light, which satisfies the requirement of day and night co-focus.

[0098] Please refer to the lateral chromatic aberration curve of the lens in the visible light 435nm-650nm range. Figure 5 As can be seen from the figure, the color difference at all magnifications is less than 7um, indicating a small color difference and high image color reproduction.

[0099] Please refer to the longitudinal chromatic aberration curve of the lens in the visible light 435nm-650nm range. Figure 6 As can be seen from the figure, the axial color difference is less than ±0.03mm, indicating good color reproduction and small color difference.

[0100] Please refer to the field curvature and distortion diagrams of the lens in the visible light 435nm-650nm range. Figure 7As can be seen from the figure, the field curvatures of each wavelength basically overlap, the chromatic difference is small, and the optical distortion of the system is <|-90%|, which is small and controls wide-angle distortion.

[0101] Example 2

[0102] like Figure 8 As shown, the main difference between this embodiment and Embodiment 1 lies in the optical parameters such as the radius of curvature and lens thickness of each lens surface.

[0103] Detailed optical data for this specific embodiment are shown in Table 2-1.

[0104] Table 2-1 Detailed optical data for Example 2

[0105] surface type Mouth size (diameter) radius of curvature thickness Refractive index Dispersion coefficient focal length 0 Infinity Infinity 1.062 1 12.260 10.000 1.000 2 First lens 9.133 9.054 0.698 1.85 32.30 -4.948 3 5.121 2.703 2.080 4 Second lens 4.726 10.315 0.827 1.54 55.98 -2.006 5 3.096 0.951 0.733 6 Third lens 3.099 2.584 2.501 1.75 27.76 2.681 7 2.026 -5.176 0.249 8 aperture 1.385 Infinity 0.235 9 Fourth lens 1.639 28.597 1.062 1.54 55.98 4.287 10 2.139 -2.480 0.070 11 Fifth lens 2.168 -1.871 0.485 1.68 19.28 -2.282 12 2.890 9.839 0.098 13 Sixth lens 3.741 1.770 1.783 1.55 56.00 2.101 14 3.534 -2.102 1.782 15 Protective film 3.862 Infinity 0.700 1.52 64.20 Infinity 16 3.927 Infinity 0.100 17 3.942 Infinity 0.000

[0106] The aspherical data in this embodiment are shown in Table 2-2.

[0107] Table 2-2 Aspherical data from Example 2

[0108]

[0109] In this embodiment, the specific values ​​of some parameters are shown in Table 2-3.

[0110] Table 2-3 Parameter values ​​for Example 2

[0111] parameter f FOV TTL Fno IMH f1f2 / f ALT / AAG f123 / f456 numerical values 1.062 170 13.4 2.000 3.900 0.985 2.122 7.671

[0112] In this embodiment, please refer to the MTF curve of the lens in the visible light 435nm-650nm range. Figure 9 As can be seen from the figure, when the spatial frequency of this lens reaches 125 lp / mm, the MTF value is greater than 0.5, indicating excellent image quality and high lens resolution.

[0113] Please refer to the lens defocus curves for visible light (435nm-650nm) and infrared light (850nm) respectively. Figure 10 , Figure 11 As can be seen from the image, the lens has a small defocusing amount under both visible and infrared light, which satisfies the requirement of day and night co-focus.

[0114] Please refer to the lateral chromatic aberration curve of the lens in the visible light 435nm-650nm range. Figure 12 As can be seen from the figure, the color difference at all magnifications is less than 9um, indicating a small color difference and high image color reproduction.

[0115] Please refer to the longitudinal chromatic aberration curve of the lens in the visible light 435nm-650nm range. Figure 13As can be seen from the figure, the axial color difference is less than ±0.02mm, indicating good color reproduction and small color difference.

[0116] Please refer to the field curvature and distortion diagrams of the lens in the visible light 435nm-650nm range. Figure 14 As can be seen from the figure, the field curvatures of each wavelength basically overlap, the chromatic difference is small, and the optical distortion of the system is <|-90%|, which is small and controls wide-angle distortion.

[0117] Example 3

[0118] like Figure 15 As shown, the main difference between this embodiment and Embodiment 1 lies in the optical parameters such as the radius of curvature and lens thickness of each lens surface.

[0119] Detailed optical data for this specific embodiment are shown in Table 3-1.

[0120] Table 3-1 Detailed optical data for Example 3

[0121] surface type Mouth size (diameter) radius of curvature thickness Refractive index Dispersion coefficient focal length 0 Infinity Infinity 1.083 1 12.380 10.000 1.000 2 First lens 9.304 9.091 0.696 1.82 46.56 -4.868 3 5.134 2.676 2.119 4 Second lens 4.761 7.976 0.824 1.54 55.98 -2.040 5 3.134 0.931 0.829 6 Third lens 3.166 2.484 2.302 1.79 25.72 2.673 7 2.210 -6.086 0.331 8 aperture 1.411 Infinity 0.191 9 Fourth lens 1.428 20.720 1.069 1.54 55.98 3.710 10 1.961 -2.172 0.061 11 Fifth lens 1.975 -1.684 0.488 1.68 19.28 -2.113 12 2.657 10.674 0.096 13 Sixth lens 3.495 1.785 1.787 1.55 56.00 2.124 14 3.489 -2.143 1.809 15 Protective film 3.845 Infinity 0.700 1.52 64.20 Infinity 16 3.913 Infinity 0.100 17 3.953 Infinity 0.000

[0122] The aspherical data in this embodiment are shown in Table 3-2.

[0123] Table 3-2 Aspherical data for Example 3

[0124]

[0125] In this embodiment, the specific values ​​of some parameters are shown in Table 3-3.

[0126] Table 3-3 Parameter values ​​for Example 3

[0127] parameter f FOV TTL Fno IMH f1f2 / f ALT / AAG f123 / f456 numerical values 1.083 170 13.4 2.000 3.900 0.965 1.975 8.462

[0128] In this embodiment, please refer to the MTF curve of the lens in the visible light 435nm-650nm range. Figure 16 As can be seen from the figure, when the spatial frequency of this lens reaches 125 lp / mm, the MTF value is greater than 0.5, indicating excellent image quality and high lens resolution.

[0129] Please refer to the lens defocus curves for visible light (435nm-650nm) and infrared light (850nm) respectively. Figure 17 , Figure 18 As can be seen from the image, the lens has a small defocusing amount under both visible and infrared light, which satisfies the requirement of day and night co-focus.

[0130] Please refer to the lateral chromatic aberration curve of the lens in the visible light 435nm-650nm range. Figure 19As can be seen from the figure, the color difference at all magnifications is less than 7um, indicating a small color difference and high image color reproduction.

[0131] Please refer to the longitudinal chromatic aberration curve of the lens in the visible light 435nm-650nm range. Figure 20 As can be seen from the figure, the axial color difference is less than ±0.03mm, indicating good color reproduction and small color difference.

[0132] Please refer to the field curvature and distortion diagrams of the lens in the visible light 435nm-650nm range. Figure 21 As can be seen from the figure, the field curvatures of each wavelength basically overlap, the chromatic difference is small, and the optical distortion of the system is <|-90%|, which is small and controls wide-angle distortion.

[0133] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A day and night confocal lens characterized in that: It includes a first lens, a second lens, a third lens, an aperture stop, a fourth lens, a fifth lens, and a sixth lens arranged in sequence along an optical axis from the object side to the image side. Each of the first lens to the sixth lens includes an object side facing the object side through which imaging light passes and an image side facing the image side through which imaging light passes. Among the above day-night confocal lenses, the optical elements with optical power are only the above six lenses. The first lens has a negative refractive power, and the object side of the first lens is convex, and the image side is concave. The second lens has a negative refractive power, and the object side of the second lens is convex, and the image side is concave. The third lens has a positive refractive power, and the object side of the third lens is convex, and the image side is convex. The fourth lens has a positive refractive power, and the object side of the fourth lens is convex, and the image side is convex. The fifth lens has a negative refractive power, and the object side of the fifth lens is concave, and the image side is concave. The sixth lens has a positive refractive power, and the object side of the sixth lens is convex, and the image side is convex. This lens satisfies: 6.5 < f123 / f456 < 8.5, where f123 is the combined focal length value of the first lens, the second lens, and the third lens, and f456 is the combined focal length value of the fourth lens, the fifth lens, and the sixth lens; 4 < |f1 / f| < 5.5, 1.5 < |f2 / f| < 2, 2.5 < |f3 / f| < 3, 3 < |f4 / f| < 4.5, 1.5 < |f5 / f| < 2.5, 1.5 < |f6 / f| < 2, where f is the overall focal length value of the lens, and f1, f2, f3, f4, f5, f6 are the focal length values of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, and the sixth lens respectively.

2. The day / night confocal lens as described in claim 1, characterized in that: Both the first lens and the third lens are glass spherical lenses, and the second lens, the fourth lens, the fifth lens, and the sixth lens are all plastic aspherical lenses.

3. A day / night confocal lens as described in claim 1, characterized in that: This lens satisfies: -6 < f1 < -4.5, -2.5 < f2 < -1.5, 2 < f3 < 3, 3 < f4 < 4.5, -2.5 < f5 < -1.5, 1.5 < f6 < 2.5, where f1, f2, f3, f4, f5, f6 are the focal length values of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, and the sixth lens respectively.

4. A day / night confocal lens as described in claim 1, characterized in that: This lens satisfies: 0.95 < (f12 / f) < 1.2, where f12 is the combined focal length value of the first lens and the second lens, and f is the overall focal length value of the lens.

5. A day / night confocal lens as described in claim 1, characterized in that: This lens satisfies: 1.9 < ALT / AAG < 2.2, where ALT is the sum of the central thicknesses of the first to sixth lenses on the optical axis, and AAG is the sum of the air gaps of the first to sixth lenses on the optical axis.

6. A day / night confocal lens as described in claim 1, characterized in that: This lens satisfies: TTL ≤ 13.4 mm, where TTL is the overall optical length of the lens.

7. A day / night confocal lens as described in claim 1, characterized in that: The field angle of this lens satisfies; FOV ≤ 170°.

8. A day / night confocal lens as described in claim 1, characterized in that: This lens satisfies: 1.0 < f < 1.1, where f is the overall focal length value of the lens.

9. A day / night confocal lens as described in claim 1, characterized in that: The maximum aperture of this lens is F / NO = 2.0.

Images