A day and night dual-purpose monitoring lens and monitoring device

Abstract

The invention provides a day-night dual-purpose monitoring lens and a monitoring device using the day-night dual-purpose monitoring lens. The day-night dual-purpose monitoring lens has the advantages of simple structure, easy processing, high pixel, large aperture, good day-night confocality, and a small number of lenses. The lens comprises, from the object side to the image side along the optical axis, the following in sequence: a first lens having negative optical focal length, an object side surface of which is a convex surface, and an image side surface of which is a concave surface; a second lens having positive optical focal length, an object side surface of which is a concave surface, and an image side surface of which is a convex surface; a third lens having negative optical focal length, an object side surface of which is a convex surface, and an image side surface of which is a concave surface; a fourth lens having positive optical focal length, an object side surface of which is a convex surface, and an image side surface of which is a convex surface; a fifth lens having positive optical focal length, an object side surface of which is a convex surface, and an image side surface of which is a convex surface; and a sixth lens having negative optical focal length, an object side surface of which is a concave surface, and an image side surface of which is a concave surface. The aperture number F# of the optical lens of the day-night dual-purpose monitoring lens satisfies: 1.4≤F#≤2.

Description

Technical Field

[0001] The present invention relates to the field of optical imaging technology, and in particular to a day and night dual-purpose monitoring lens and a monitoring device. Background Art

[0002] With the rapid development of science and technology, people have higher technical requirements for security surveillance lenses. Most of the fixed-focus surveillance lenses currently on the market have a series of problems such as low resolution, small aperture, poor day and night confocality, and a large number of lenses used. Therefore, the demand for surveillance lenses with high pixels, large aperture, good day and night confocality, and a small number of lenses used is becoming more and more urgent. Summary of the invention

[0003] In view of the above problems, the present invention provides a day and night dual-purpose monitoring lens and a monitoring device using the day and night dual-purpose monitoring lens, which has a simple structure, is easy to process, has the advantages of high pixels, large aperture, good day and night confocality, and a small number of lenses used.

[0004] The technical solution is as follows: a day and night dual-purpose surveillance lens, which includes: a first lens, a second lens, a third lens, a fourth lens, a fifth lens and a sixth lens in sequence from the object side to the image side along the optical axis, characterized in that:

[0005] The first lens has negative optical power, its object side surface is convex, and its image side surface is concave;

[0006] The second lens has positive refractive power, its object side surface is concave, and its image side surface is convex;

[0007] The third lens has negative optical power, its object side surface is convex, and its image side surface is concave;

[0008] The fourth lens has positive refractive power, and its object side surface is convex, and its image side surface is convex;

[0009] The fifth lens has positive refractive power, and its object side surface is convex, and its image side surface is convex;

[0010] The sixth lens has negative optical power, and its object side surface is concave and its image side surface is concave.

[0011] Among them, the aperture number F# of the optical lens of the day and night dual-purpose monitoring lens satisfies: 1.4≤F#≤2.

[0012] Furthermore, it also includes an aperture, a color filter, and a protective glass. The aperture is arranged between the second lens and the third lens, the color filter is arranged on the image side of the sixth lens, and the protective glass is arranged on the image side of the color filter.

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

[0014] Furthermore, the fifth lens and the sixth lens are glued together to form a group of glued lenses.

[0015] Furthermore, the fifth lens and the sixth lens are respectively separated lenses.

[0016] Furthermore, the difference between the Abbe numbers V1 and V2 of at least two adjacent lenses of the day and night dual-purpose surveillance lens satisfies: 10<|V1-V2|<25, where V1 is the Abbe number of one of the lenses, and V2 is the Abbe number of the other lens.

[0017] Furthermore, the day and night dual-use surveillance camera meets the following conditions:

[0018] 0.12≤BFL / TTL≤0.32

[0019] Among them, BFL is the distance from the center of the image side of the sixth lens of the day and night dual-purpose monitoring lens to the imaging surface of the day and night dual-purpose monitoring lens on the optical axis; TTL is the distance from the center of the object side of the first lens to the imaging surface of the day and night dual-purpose monitoring lens on the optical axis.

[0020] Furthermore, the day and night dual-use surveillance camera meets the following conditions:

[0021] D / h / FOV≤0.03

[0022] Among them, FOV is the maximum field of view of the day and night dual-purpose monitoring lens; D is the maximum light clearance aperture of the object side of the first lens corresponding to the maximum field of view of the day and night dual-purpose monitoring lens; h is the image height corresponding to the maximum field of view of the day and night dual-purpose monitoring lens.

[0023] Furthermore, the day and night dual-use surveillance camera meets the following requirements:

[0024] TTL / F≤4.0

[0025] (FOV×F) / h≥50

[0026] Among them, TTL is the distance from the center of the object side surface of the first lens to the imaging surface of the optical lens on the optical axis, F is the total focal length value of the day and night dual-purpose monitoring lens, FOV is the maximum field of view angle of the day and night dual-purpose monitoring lens, and h is the image height corresponding to the maximum field of view angle.

[0027] Furthermore, the first lens also satisfies the following conditions: 1.4<Nd1<1.6, 60<Vd1<70; wherein Nd1 is the light refractive index of the first lens, and Vd1 is the Abbe constant of the first lens;

[0028] The second lens also satisfies the following conditions: 1.5<Nd2<1.7, 50<Vd2<70; wherein Nd2 is the light refractive index of the second lens, and Vd2 is the Abbe constant of the second lens;

[0029] The third lens also satisfies the following conditions: 1.5<Nd3<1.7, 50<Vd3<70; wherein Nd3 is the light refractive index of the third lens, and Vd3 is the Abbe constant of the third lens;

[0030] The fourth lens also satisfies the following conditions: 1.4<Nd4<1.6, 60<Vd4<80; wherein Nd4 is the light refractive index of the fourth lens, and Vd4 is the Abbe constant of the fourth lens;

[0031] The fifth lens also satisfies the following conditions: 1.5<Nd5<1.7, 50<Vd5<70; wherein Nd5 is the light refractive index of the fifth lens, and Vd5 is the Abbe constant of the fifth lens;

[0032] The sixth lens also satisfies the following conditions: 1.6<Nd6<1.8, 20<Vd6<60; wherein, Nd6 is the light refractive index of the sixth lens, and Vd6 is the Abbe constant of the sixth lens.

[0033] A monitoring device, characterized by using any one of the day and night dual-purpose monitoring lenses described above.

[0034] The day and night dual-purpose monitoring lens of the present application uses only six lenses, has a compact structure, and uses a small number of lenses, which effectively reduces the overall volume of the lens. By reasonably designing the structure of each lens and optimizing its positive and negative optical focal length distribution, gluing state, refractive index, Abbe coefficient and other parameters, the aperture of the day and night dual-purpose monitoring lens of the present application reaches F1.4, which is better than most F2.0 products on the market. It can have better imaging performance in low-light environments such as night. At the same time, by reducing the axial chromatic aberration of the system, the day and night confocal function of visible light and infrared light is realized. In addition, it also has the advantages of achieving high pixels and high imaging quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 A structural assembly diagram of a day and night dual-purpose surveillance camera of the present invention;

[0036] Figure 2The MTF curve diagram of the day and night dual-purpose monitoring lens in the embodiment in the visible light band (435nm-656nm);

[0037] Figure 3 : is an MTF curve diagram of the day and night dual-purpose monitoring lens in the infrared band (940nm) in the embodiment;

[0038] Figure 4 is a defocus curve diagram of the day and night dual-purpose monitoring lens in the embodiment in the visible light band (435nm-656nm) at 20°C;

[0039] Figure 5 is a defocus curve diagram of the day and night dual-purpose monitoring lens in the embodiment in the visible light band (435nm-656nm) at 70°C;

[0040] Figure 6 1 is a defocus curve diagram of the day and night dual-purpose monitoring lens in the embodiment in the visible light band (435nm-656nm) at -20°C. DETAILED DESCRIPTION

[0041] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0042] The present invention provides a day and night dual-purpose monitoring lens, which comprises, from the object side to the image side along the optical axis, a first lens 1, a second lens 2, a third lens 3, a fourth lens 4, a fifth lens 5 and a sixth lens 6. Figure 1 In the figure, the object side is on the left side, and the image side is on the right side. From the left side to the right side of the figure is from the object side to the image side. Specifically:

[0043] The first lens 1 has negative optical power, and its object side surface S1 is convex, and its image side surface S2 is concave;

[0044] The second lens 2 has positive refractive power, its object side surface S3 is concave, and its image side surface S4 is convex;

[0045] The third lens 3 has negative power, its object side surface S6 is convex, and its image side surface S7 is concave;

[0046] The fourth lens 4 has positive refractive power, and its object-side surface S8 is convex, and its image-side surface S9 is convex;

[0047] The fifth lens 5 has positive refractive power, and its object-side surface S10 is convex, and its image-side surface S11 is convex;

[0048] The sixth lens element 6 has negative refractive power, and its object-side surface S12 is a concave surface, and its image-side surface S13 is a concave surface.

[0049] In this embodiment, the aperture of the day and night dual-use surveillance lens reaches F1.4, which is better than most F2.0 products on the market, and can have better imaging performance in low-light environments such as at night.

[0050] In order to further optimize the performance of the optical lens, the day and night dual-purpose monitoring lens of this embodiment also includes an aperture 7, a color filter 8, and a protective glass 9. The aperture 7 is arranged between the second lens 2 and the third lens 3, and the color filter 8 is arranged on the image plane side of the sixth lens 6. The main function of the filter 8 is to filter the interference of the infrared band on the imaging. The protective glass 9 is arranged on the image plane side of the color filter 8. The main function of the protective glass 9 is to protect the image sensor.

[0051] In this embodiment, the first lens 1 and the fourth lens 4 are both glass spherical lenses, and the second lens 2, the third lens 3, the fifth lens 5 and the sixth lens 6 are all plastic aspherical lenses. Since the plastic aspherical lens has a larger optimization space, the lens structure can be made more compact compared to the all-glass structure in the prior art. By adopting the aspherical lens design, the molded image is effectively corrected, and the problem of field of view distortion is solved. At the same time, the lens is made lighter, thinner and flatter. In addition, the aspherical lens has excellent impact resistance to ensure its service life. The use of different materials improves the comprehensive performance of the lens and saves costs.

[0052] In this embodiment, the fifth lens 5 and the sixth lens 6 are glued together to form a group of glued lenses, which can reduce system chromatic aberration; of course, in other embodiments of the present invention, the fifth lens 5 and the sixth lens 6 can also be separate lenses.

[0053] In this embodiment, the difference between the Abbe numbers V1 and V2 of at least two adjacent lenses of the day and night dual-purpose surveillance lens satisfies: 10<|V1-V2|<25, where V1 is the Abbe number of one lens, and V2 is the Abbe number of the other lens. Specifically:

[0054] The first lens 1 also satisfies the following conditions: 1.4<Nd1<1.6, 60<Vd1<70; wherein Nd1 is the light refractive index of the first lens, and Vd1 is the Abbe constant of the first lens;

[0055] The second lens 2 also satisfies the following conditions: 1.5<Nd2<1.7, 50<Vd2<70; wherein Nd2 is the light refractive index of the second lens, and Vd2 is the Abbe constant of the second lens;

[0056] The third lens 3 also satisfies the following conditions: 1.5<Nd3<1.7, 50<Vd3<70; wherein Nd3 is the light refractive index of the third lens, and Vd3 is the Abbe constant of the third lens;

[0057] The fourth lens 4 also satisfies the following conditions: 1.4<Nd4<1.6, 60<Vd4<80; wherein Nd4 is the light refractive index of the fourth lens, and Vd4 is the Abbe constant of the fourth lens;

[0058] The fifth lens 5 also satisfies the following conditions: 1.5<Nd5<1.7, 50<Vd5<70; wherein Nd5 is the light refractive index of the fifth lens, and Vd5 is the Abbe constant of the fifth lens;

[0059] The sixth lens 6 also satisfies the following conditions: 1.6<Nd6<1.8, 20<Vd6<60; wherein Nd6 is the light refractive index of the sixth lens, and Vd6 is the Abbe constant of the sixth lens.

[0060] Through the reasonable combination of lenses and the use of high Abbe number lenses, functions such as chromatic aberration correction, temperature drift correction and infrared correction can be achieved. The different temperature characteristics of plastic lenses and glass lenses are used for compensation design to achieve focus temperature drift correction under a large temperature range. The lens can adapt to complex temperature environments and can be used under different environmental conditions, which has broad market value.

[0061] In addition, in this implementation, the day and night surveillance camera meets the following conditions:

[0062] 0.12≤BFL / TTL≤0.32

[0063] Among them, BFL is the distance from the center of the image side of the sixth lens of the day and night dual-purpose monitoring lens to the imaging surface of the day and night dual-purpose monitoring lens on the optical axis; TTL is the distance from the center of the object side of the first lens to the imaging surface of the day and night dual-purpose monitoring lens on the optical axis.

[0064] Specifically in this implementation, the day and night dual-use surveillance camera meets the following conditions:

[0065] D / h / FOV≤0.03

[0066] Among them, FOV is the maximum field of view of the day and night dual-purpose monitoring lens; D is the maximum light clearance diameter of the object side of the first lens corresponding to the maximum field of view of the day and night dual-purpose monitoring lens; h is the image height corresponding to the maximum field of view of the day and night dual-purpose monitoring lens.

[0067] Specifically in this implementation, the day and night surveillance camera meets the following requirements:

[0068] TTL / F≤4.0

[0069] (FOV×F) / h≥50

[0070] Among them, TTL is the distance from the center of the object side of the first lens to the imaging surface of the optical lens on the optical axis, F is the total focal length of the day and night dual-purpose monitoring lens, FOV is the maximum field of view angle of the day and night dual-purpose monitoring lens, and h is the image height corresponding to the maximum field of view angle. In this way, by controlling the parameters such as the focal length and maximum field of view angle of the optical lens, it has relatively small optical distortion and image deformation during the imaging process, ensuring the imaging quality, facilitating the subsequent identification and judgment of its imaging details, and providing good imaging assistance for security monitoring.

[0071] Based on the above description, the present invention provides a surveillance lens with high pixels reaching more than 2 million pixels, large aperture reaching FNO1.4, good day and night confocality reaching 430nm-940nm, and a small number of lenses used, 2G4P. Through the combination of glass lenses and plastic lenses and the matching of the materials of each lens, the 2G4P structure is adopted to effectively solve the problem of inconsistent confocality of the lens during the day and night, and to achieve day and night confocality while ensuring high resolution. The lens only uses two glass lenses and four plastic aspherical surfaces, so the lens has the advantages of obvious streamlined structure, reduced lens weight, and reduced production costs.

[0072] The optical parameters of the day and night dual-purpose surveillance lens of this embodiment are shown in Table 1:

[0073]

[0074] Table 1

[0075] In Table 1, when the radius of curvature of the aperture, IR filter, and protective glass surface is Infinity, it means that the surface is a plane.

[0076] The optical performance parameters of the day and night dual-purpose monitoring lens of this embodiment are shown in Table 2:

[0077] parameter BFL TTL(mm) FOV(°) D(mm) H(mm) F(mm) Numeric 4.968 22.2 110 9.10 6.6 3.62

[0078] Table 2

[0079] In this embodiment, the maximum field of view FOV of the day and night dual-purpose monitoring lens, the maximum light clearance D of the object side surface S1 of the first lens 1 corresponding to the maximum field of view of the optical lens, and the image height h corresponding to the maximum field of view of the optical lens satisfy D / h / FOV=0.0125; the optical back focus BFL of the optical lens and the total optical length TTL of the optical lens satisfy BFL / TTL=0.224; and the total optical length TTL of the optical lens, the maximum field of view FOV of the optical lens, and the image height h corresponding to the maximum field of view of the optical lens satisfy: TTL / h / FOV=0.031.

[0080] In this embodiment, the second lens 2, the third lens 3, the fifth lens 5 and the sixth lens 6 are all aspherical lenses, and the surface shape of each aspherical surface is described as follows:

[0081]

[0082] Among them, Z(h) is the distance vector height from the vertex of the aspherical surface when the aspherical surface is at a height of h along the optical axis, c=1 / r, r represents the radius of curvature of the aspherical mirror surface, k is the cone coefficient conic, and A, B, C, D, and E are the coefficients of the high-order terms of the aspherical surface.

[0083] The aspheric coefficients are shown in Table 3 below:

[0084] Surface number K A B C D E S3 0 0 -2.161e-4 6.739e-5 3.774e-7 -5.369e-9 S4 0 0 2.217e-3 1.235e-5 3.208e-6 3.983e-8 S6 0 0 2.774e-3 -3.149e-5 -5.069e-6 1.371e-7 S7 0 0 1.59e-3 5.494e-5 -7.272e-7 1.522e-7 S10 0 0 -4.204e-4 -5.374e-5 -9.046e-6 -3.767e-7 S11 0 0 6.786e-4 2.977e-4 -5.836e-5 6.155e-7 S12 0 0 8.476e-3 -7.88e-4 3.045e-5 -3.157e-7 S13 0 0 9.56e-3 -6.614e-4 6.111e-5 -1.535e-6

[0085] Table 3

[0086] The optical test of the day and night dual-purpose monitoring lens in the above embodiment is carried out. Figure 2 is the MTF curve of the day and night dual-purpose surveillance lens in the above embodiment in the visible light band (435nm-656nm), Figure 3 is the MTF curve of the day and night dual-purpose surveillance lens in the above embodiment in the infrared band (940nm), Figure 2 , 3 The horizontal axis is the spatial frequency, and the vertical axis is the contrast; TSDiff.Limit is the diffraction limit in the meridian and sagittal directions, and TS 0.00 (deg) represents the diffraction curve in the meridian and sagittal directions at the image plane 0.00 field of view; MTF is a commonly used image quality evaluation index, called modulation transfer function. Modulation transfer function MTF: the ratio of the image contrast to the object contrast at a certain spatial frequency. It can reflect the transmission ability of different spatial frequencies and different contrasts. The modulation transfer function MTF can be used to represent the characteristics of the optical system. The larger the MTF, the better the imaging quality of the system. Figure 2 , 3 It can be seen that the day and night dual-purpose monitoring lens in this embodiment has a small distortion characteristic, which is sufficient to meet the image clarity requirement and has good imaging stability.

[0087] Figure 4 It is a defocus curve diagram of the day and night dual-purpose monitoring lens in the embodiment of the present invention in the visible light band (435nm-656nm) at 20°C; wherein the abscissa is the defocus amount in millimeters, and the ordinate is the contrast; TS 0.00 (deg) represents the diffraction curves in the meridian and sagittal directions on the image plane 0.00 field of view.

[0088] Figure 5It is a defocus curve diagram of the day and night dual-purpose monitoring lens in the embodiment of the present invention in the visible light band (435nm-656nm) at 70°C; wherein the abscissa is the defocus amount in millimeters, and the ordinate is the contrast; TS 0.00 (deg) represents the diffraction curves in the meridian and sagittal directions on the image plane 0.00 field of view.

[0089] Figure 6 1 is a defocus curve diagram of the day and night dual-purpose monitoring lens in the embodiment of the present invention in the visible light band (435nm-656nm) at -20°C; wherein the abscissa is the defocus amount in millimeters, and the ordinate is the contrast; TS 0.00 (deg) represents the diffraction curves in the meridian and sagittal directions on the image plane 0.00 field of view.

[0090] Depend on Figure 4 , Figure 5 , Figure 6 It can be seen that the day and night dual-purpose monitoring lens in the embodiment of the present invention has a concentrated defocus curve in the visible light band, which shows that its confocal degree is good, which means that the lens has good resolution capability and temperature compensation function, ensuring that the high-definition image quality of the lens remains unchanged within the temperature range of -20°C to +70°C.

[0091] As an application of the above-mentioned optical lens, the present invention also discloses a monitoring device, which has the day and night dual-purpose monitoring lens described in any of the above-mentioned embodiments. The monitoring device has a low production cost, a high degree of restoration of monitoring facts, and a strong ability to resist environmental interference while maintaining a small field of view and high detail resolution capability of the lens and a short and lightweight lens.

[0092] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

Claims

1. A day and night surveillance lens, comprising, in order from the object side to the image side along the optical axis: The first lens, the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens are characterized by: The first lens has negative optical power, its object side surface is convex, and its image side surface is concave; The second lens has positive refractive power, its object side surface is concave, and its image side surface is convex; The third lens has negative optical power, its object side surface is convex, and its image side surface is concave; The fourth lens has positive refractive power, and its object side surface is convex, and its image side surface is convex; The fifth lens has positive refractive power, and its object side surface is convex, and its image side surface is convex; The sixth lens has negative optical power, and its object side surface is concave, and its image side surface is concave; Among them, the aperture number F# of the optical lens of the day and night dual-purpose surveillance lens meets the following requirements: 1.4≤F#≤2; The difference between the Abbe numbers V1 and V2 of at least two adjacent lenses of the day and night dual-purpose surveillance lens satisfies: 10<|V1-V2|<25, where V1 is the Abbe number of one lens, and V2 is the Abbe number of the other lens; The first lens also satisfies the following conditions: 1.4<Nd1<1.6, 60<Vd1<70; wherein Nd1 is the light refractive index of the first lens, and Vd1 is the Abbe constant of the first lens; The second lens also satisfies the following conditions: 1.5<Nd2<1.7, 50<Vd2<70; wherein Nd2 is the light refractive index of the second lens, and Vd2 is the Abbe constant of the second lens; The third lens also satisfies the following conditions: 1.5<Nd3<1.7, 50<Vd3<70; wherein Nd3 is the light refractive index of the third lens, and Vd3 is the Abbe constant of the third lens; The fourth lens also satisfies the following conditions: 1.4<Nd4<1.6, 60<Vd4<80; wherein Nd4 is the light refractive index of the fourth lens, and Vd4 is the Abbe constant of the fourth lens; The fifth lens also satisfies the following conditions: 1.5<Nd5<1.7, 50<Vd5<70; wherein Nd5 is the light refractive index of the fifth lens, and Vd5 is the Abbe constant of the fifth lens; The sixth lens also satisfies the following conditions: 1.6<Nd6<1.8, 20<Vd6<60; wherein Nd6 is the light refractive index of the sixth lens, and Vd6 is the Abbe constant of the sixth lens; The day and night dual-use surveillance camera meets the following conditions: 0.12≤BFL / TTL≤0.32 Wherein, BFL is the distance from the center of the image side surface of the sixth lens of the day and night dual-purpose monitoring lens to the imaging surface of the day and night dual-purpose monitoring lens on the optical axis; TTL is the distance from the center of the object side surface of the first lens to the imaging surface of the day and night dual-purpose monitoring lens on the optical axis; The day and night dual-use surveillance camera meets the following conditions: D / h / FOV≤0.03 Wherein, FOV is the maximum field of view of the day and night dual-purpose monitoring lens; D is the maximum aperture of the object side of the first lens corresponding to the maximum field of view of the day and night dual-purpose monitoring lens; h is the image height corresponding to the maximum field of view of the day and night dual-purpose monitoring lens; The day and night dual-use surveillance camera also meets the following requirements: TTL / F≤4.0 (FOV×F) / h≥50 Among them, TTL is the distance from the center of the object side surface of the first lens to the imaging surface of the optical lens on the optical axis, F is the total focal length value of the day and night dual-purpose monitoring lens, FOV is the maximum field of view angle of the day and night dual-purpose monitoring lens, and h is the image height corresponding to the maximum field of view angle.

2. The day and night dual-purpose surveillance camera according to claim 1, characterized in that: It also includes an aperture, a color filter, and a protective glass. The aperture is arranged between the second lens and the third lens, the color filter is arranged on the image side of the sixth lens, and the protective glass is arranged on the image side of the color filter.

3. The day and night dual-purpose surveillance camera according to claim 1, characterized in that: The first lens and the fourth lens are both glass spherical lenses, and the second lens, the third lens, the fifth lens and the sixth lens are all plastic aspherical lenses.

4. The day and night dual-purpose surveillance camera according to claim 1, characterized in that: The fifth lens and the sixth lens are cemented together to form a group of cemented lenses.

5. The day and night dual-purpose surveillance camera according to claim 1, characterized in that: The fifth lens and the sixth lens are respectively separated lenses.

6. A monitoring device, characterized in that: A day and night dual-purpose surveillance camera as described in any one of claims 1 to 5 is used.

Images