A lens and an image pickup apparatus

Abstract

The application discloses a lens and a camera device, which are composed of a first negative focal length lens, a first positive focal length lens, a second negative focal length lens, a third negative focal length lens, a second positive focal length lens, a positive focal length lens group, a third positive focal length lens, a filter and an image plane arranged in sequence from an object side to an image side; the positive focal length lens group is composed of a lenticular lens and a meniscus lens arranged in sequence from the object side to the image side; and the lens satisfies the following conditions: wherein f is a focal length of the lens, and TTL is an optical total length of the lens. The optical lens has high resolving power, large visual field angle, small optical distortion and large aperture.

Description

Technical Field

[0001] This invention relates to the field of optical imaging technology, and more particularly to a lens and a camera device. Background Technology

[0002] Thanks to the rapid development of the security monitoring field in recent years, optical lenses are being used more and more in the security sector, especially in areas such as smart buildings and intelligent transportation, where the pixel requirements for optical imaging lenses are becoming increasingly higher. More and more companies are investing more in ultra-high definition research, hoping to develop products with higher pixel counts and smaller sizes.

[0003] Video surveillance is widely used in various scenarios such as entrances and exits, and access control. In building applications, such as villas, cameras need to balance wide field-of-view monitoring capabilities with distortion-free identification of specific targets at close range. Currently, most lenses suffer from problems such as small field of view and limited monitoring range for low-distortion lenses, large distortion and severe image deformation for wide-angle lenses, poor infrared performance at night, and low resolution.

[0004] Therefore, there is an urgent need in the market for an optical lens that combines high resolution with a wide field of view, low optical distortion, and a large aperture. Summary of the Invention

[0005] This invention provides a lens and a camera device to provide an optical lens with high resolution, a wide field of view, low optical distortion, and a large aperture.

[0006] This invention provides a lens comprising, from the object side to the image side, a first negative power lens, a first positive power lens, a second negative power lens, a third negative power lens, a second positive power lens, a positive power lens group, a third positive power lens, a filter, and an image plane arranged sequentially; the positive power lens group comprises a biconvex lens and a meniscus lens arranged sequentially from the object side to the image side.

[0007] The lens meets the following conditions:

[0008] Where f is the focal length of the lens, and TTL is the total optical length of the lens.

[0009] Furthermore, the lens satisfies:

[0010]

[0011]

[0012]

[0013]

[0014]

[0015]

[0016]

[0017] Wherein, f1 is the focal length of the first negative power lens, f2 is the focal length of the first positive power lens, f3 is the focal length of the second negative power lens, f4 is the focal length of the third negative power lens, and f5 is the focal length of the second positive power lens. g1 f is the focal length of the positive optical power lens group, and f8 is the focal length of the third positive optical power lens.

[0018] Furthermore, the biconvex lens and meniscus lens in the positive power lens group are cemented together.

[0019] Furthermore, the first negative power lens is a meniscus lens, and its object-facing side is convex.

[0020] The first positive power lens is a meniscus lens, and its object-facing side is convex.

[0021] The second negative power lens is a meniscus lens, and its object-facing side is convex.

[0022] The third negative power lens is a meniscus lens, with its object-side surface being convex, or its image-side surface being convex.

[0023] The second positive power lens is a biconvex lens;

[0024] The third positive power lens is a biconvex lens.

[0025] Furthermore, the first negative power lens, the first positive power lens, the second positive power lens, the biconvex lens, and the meniscus lens are all spherical lenses.

[0026] Furthermore, the second negative power lens, the third negative power lens, and the third positive power lens are all aspherical lenses.

[0027] Furthermore, the Abbe number V of each lens in the lens... d Satisfy: 17≤V d ≤81.6.

[0028] Furthermore, the refractive index N of each lens in the lens d Satisfies: 1.49≤N d ≤2.1.

[0029] Furthermore, an aperture stop is provided between the second positive power lens and the positive power lens group.

[0030] On the other hand, embodiments of the present invention provide a camera device, the camera device comprising: performing imaging using a lens as described in any of the above claims.

[0031] This invention provides a lens and a camera device. The lens comprises, from the object side to the image side, a first negative power lens, a first positive power lens, a second negative power lens, a third negative power lens, a second positive power lens, a positive power lens group, a third positive power lens, a filter, and an image plane arranged sequentially. The positive power lens group comprises a biconvex lens and a meniscus lens arranged sequentially from the object side to the image side. The lens satisfies the following conditions: Where f is the focal length of the lens, and TTL is the total optical length of the lens. In this embodiment of the invention, eight lenses of specific optical power are arranged sequentially from the object side to the image side in a specific order, satisfying the above conditions, thus achieving an optical lens with high resolution, a large field of view, low optical distortion, and a large aperture. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 This is a schematic diagram of the lens structure provided in an embodiment of the present invention;

[0034] Figure 2 The optical transfer function (MTF) curve of the lens provided in Embodiment 1 of the present invention at room temperature in the visible light band;

[0035] Figure 3 The field curvature and distortion diagram of the lens in the visible light band provided in Embodiment 1 of the present invention;

[0036] Figure 4 The defocus MTF of the lens provided in Embodiment 1 of the present invention in the visible light band;

[0037] Figure 5 The defocus MTF of the lens provided in Embodiment 1 of the present invention in the infrared band at room temperature;

[0038] Figure 6 The optical transfer function (MTF) curve of the lens in the visible light band at room temperature provided in Embodiment 2 of the present invention;

[0039] Figure 7 The field curvature and distortion diagram of the lens in the visible light band provided in Embodiment 2 of the present invention;

[0040] Figure 8 The defocus MTF of the lens provided in Embodiment 2 of the present invention in the visible light band;

[0041] Figure 9 The defocus MTF of the lens provided in Embodiment 2 of the present invention in the infrared band at room temperature. Detailed Implementation

[0042] The present invention will now be described in further detail with reference to the accompanying drawings. Obviously, the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0043] Figure 1 This is a schematic diagram of a lens provided in Embodiment 1 of the present invention. The lens consists of a first negative power lens L1, a first positive power lens L2, a second negative power lens L3, a third negative power lens L4, a second positive power lens L5, a positive power lens group G, a third positive power lens L8, a filter M, and an image plane arranged sequentially from the object side to the image side to form N. The positive power lens group G is composed of a biconvex lens L6 and a meniscus lens L7 arranged sequentially from the object side to the image side.

[0044] The lens meets the following conditions:

[0045] Where f is the focal length of the lens, and TTL is the total optical length of the lens.

[0046] To further improve the image quality of the lens, the lens satisfies the following:

[0047]

[0048]

[0049]

[0050]

[0051]

[0052]

[0053]

[0054] Wherein, f1 is the focal length of the first negative power lens, f2 is the focal length of the first positive power lens, f3 is the focal length of the second negative power lens, f4 is the focal length of the third negative power lens, and f5 is the focal length of the second positive power lens. g1 f is the focal length of the positive optical power lens group, and f8 is the focal length of the third positive optical power lens.

[0055] An aperture stop P is provided between the second positive power lens and the positive power lens group. The size of the aperture stop determines the aperture value of the system and the depth of field during shooting. Its aperture size can be fixed, or an adjustable aperture stop can be placed as needed to achieve adjustable light transmission aperture, that is, to have the purpose of changing the system aperture value and changing the depth of field.

[0056] An optical filter is an optical device used to select a desired radiation wavelength. By setting a filter, simulating the filter in an imaging system equipped with the lens provided in this embodiment of the invention, the optical path difference of the filter in the imaging system is taken into account in the lens design, resulting in a lens that satisfies: At that time, the lens performance was better.

[0057] In this embodiment of the invention, eight lenses of a specific optical power are arranged in a specific order from the object side to the image side in the lens, and the above conditions are met, thus realizing an optical lens with high resolution, a large field of view, small optical distortion, and a large aperture.

[0058] To further enable a compact lens, in this embodiment of the invention, the biconvex lens and the meniscus lens in the positive power lens group are cemented together.

[0059] In order to further improve the imaging quality of the lens, in this embodiment of the invention, the first negative power lens is a meniscus lens, and its object-facing side is convex.

[0060] The first positive power lens is a meniscus lens, and its object-facing side is convex.

[0061] The second negative power lens is a meniscus lens, and its object-facing side is convex.

[0062] The third negative power lens is a meniscus lens, with its object-side surface being convex, or its image-side surface being convex.

[0063] The second positive power lens is a biconvex lens;

[0064] The third positive power lens is a biconvex lens.

[0065] To ensure better lens manufacturing performance, in this embodiment of the invention, the first negative power lens, the first positive power lens, the second positive power lens, the biconvex lens, and the meniscus lens are all spherical lenses. The second negative power lens, the third negative power lens, and the third positive power lens are all aspherical lenses.

[0066] In this embodiment of the invention, in order to achieve clear imaging over a wide temperature range and reduce chromatic aberration, thereby improving image quality, the Abbe number V of each lens in the lens is [specified]. d Satisfy: 17≤V d ≤81.6.

[0067] To improve the image quality of the lens, reduce its overall length, and decrease spherical aberration, in this embodiment of the invention, the refractive index N of each lens in the lens is... d Satisfies: 1.49≤N d ≤2.1.

[0068] On the other hand, embodiments of the present invention provide a camera device, which includes: imaging using the above-described lens.

[0069] The optical performance achieved by the lens provided in this invention embodiment is as follows: The lens proposed in this application has a diagonal field of view of up to 120 degrees, and optical distortion of less than 1.2% within a 0.5 field of view (60 degrees). It achieves a large angle while ensuring minimal image distortion in the central area, supporting up to a 1 / 2.5-inch image sensor. It also incorporates an infrared confocal design, making it suitable for both daytime and nighttime environments. The focal length is 2.9mm, achieving a 120° wide field of view; the lens exhibits 1.2% optical distortion within a 0.5 field of view (60 degrees) and less than 25% optical distortion across the entire field of view, avoiding severe image distortion; it supports sensors up to 1 / 2.5 inches with an aperture of F2.0; the MTF value reaches above 0.5 at 100lp / mm across the entire field of view, supporting resolution requirements up to 4 megapixels; the total length of the optical system is within 22.1mm; and the lens's infrared confocal design ensures compatibility with both daytime and nighttime use scenarios.

[0070] The following provides examples of lens parameters provided in embodiments of the present invention.

[0071] Example 1:

[0072] In the specific implementation process, the radius of curvature R, center thickness Tc, refractive index Nd, Abbe constant Vd, and conic coefficient k of each lens of the lens satisfy the conditions listed in Table 1:

[0073]

[0074]

[0075] Table 1

[0076] It should be noted that the mirror serial numbers in Table 1 are Figure 1 The lens surface numbers from left to right in the schematic diagram of the lens structure shown;

[0077] Its aspherical conic coefficient can be defined by the following equation for the shape of the aspherical surface, but is not limited to the following expression:

[0078]

[0079] Where Z is the distance vector from the vertex of the aspherical surface at a height of y along the optical axis; c is the curvature of the fitted sphere, which is numerically the reciprocal of the radius of curvature, i.e., c = 1 / R, where R represents the paraxial radius of curvature of the mirror; k is the conic coefficient; and A, B, C, D, E, and F are higher-order aspherical coefficients.

[0080] The design values ​​of the aspherical coefficients of each lens in the optical lens are shown in Table 2:

[0081]

[0082] Table 2

[0083] The focal length f and the total optical length TTL of the system satisfy the following relationship:

[0084] The focal lengths of each lens and the system focal length f satisfy the following formula:

[0085]

[0086]

[0087]

[0088]

[0089]

[0090]

[0091]

[0092] The lens provided in this embodiment of the invention has the following optical technical specifications:

[0093] Total optical length: TTL≤22.1mm;

[0094] The lens focal length is f = 2.9mm;

[0095] The lens's field of view (FOV) is ≥120°;

[0096] Lens full-field optical distortion: -24.2%, 0.5 field of view (60 degrees) optical distortion -1.2%;

[0097] The aperture FNO of the lens system is: FNO ≤ 2.0;

[0098] Lens image plane diameter: ≥7mm.

[0099] The imaging system provided in this embodiment will be further described below through a detailed analysis of the embodiments.

[0100] The optical transfer function is a relatively accurate, intuitive, and common way to evaluate the imaging quality of an imaging system. The higher and smoother the curve, the better the imaging quality of the system, and the better it corrects for various aberrations (such as spherical aberration, coma, astigmatism, field curvature, axial chromatic aberration, and transverse chromatic aberration).

[0101] like Figure 2 The image shows the optical transfer function (MTF) curve of the lens at room temperature in the visible light band; as shown... Figure 3 The image shown depicts the field curvature and distortion of the lens in the visible light band; as shown... Figure 4 The image shows the lens's defocus MTF in the visible light band; as shown... Figure 5 The image shows the defocus MTF of the lens at room temperature in the infrared band.

[0102] from Figure 2 As can be seen, the optical transfer function (MTF) curve of the lens in the visible light region at room temperature is relatively smooth and concentrated, and the minimum MTF value of the full field of view (half image height Y' = 3.2 mm) reaches more than 0.5; it can be seen that the imaging system provided by the embodiment of the present invention can achieve a very high resolution and meet the imaging requirements of a 1 / 2.8-inch 4-megapixel camera.

[0103] from Figure 3 As can be seen, the optical distortion of the lens is within -25% in the full field of view of 120 degrees, and within -1.5% in the 0.5 field of view of 60 degrees; the field curvature is controlled within ±0.05mm, which is relatively small.

[0104] from Figure 4 and Figure 5 As can be seen from the data, the lens has a small defocusing amount between the visible and infrared fields, which is within 0.01mm. The visible and infrared fields can be focused clearly at the same time, indicating that the lens has infrared confocal focus, which can meet the needs of both day and night use scenarios.

[0105] Example 2:

[0106] In the specific implementation process, the radius of curvature R, center thickness Tc, refractive index Nd, Abbe constant Vd, and conic coefficient k of each lens of the lens satisfy the conditions listed in Table 3:

[0107]

[0108] Table 3

[0109] Its aspherical conic coefficient can be defined by the following equation for the shape of the aspherical surface, but is not limited to the following expression:

[0110]

[0111] Where Z is the distance vector from the vertex of the aspherical surface at a height of y along the optical axis; c is the curvature of the fitted sphere, which is numerically the reciprocal of the radius of curvature, i.e., c = 1 / R, where R represents the paraxial radius of curvature of the mirror; k is the conic coefficient; and A, B, C, D, E, and F are higher-order aspherical coefficients.

[0112] The design values ​​of the aspherical coefficients of each lens in the optical lens are shown in Table 4:

[0113]

[0114] Table 4

[0115] The focal length f and the total optical length TTL of the system satisfy the following relationship:

[0116] The focal lengths of each lens and the system focal length f satisfy the following formula:

[0117]

[0118]

[0119]

[0120]

[0121]

[0122]

[0123]

[0124] The lens provided in this embodiment of the invention has the following optical technical specifications:

[0125] Overall optical length: TTL≤22.2mm;

[0126] The lens focal length is f = 2.45mm;

[0127] The lens's field of view (FOV) is ≥120°;

[0128] Lens full-field optical distortion: -20%, 0.5 field-of-view optical distortion -0.7%;

[0129] The aperture FNO of the lens system is: FNO ≤ 2.0;

[0130] Lens image plane diameter: ≥6.8mm.

[0131] The imaging system provided in this embodiment will be further described below through a detailed analysis of the embodiments.

[0132] The optical transfer function is a relatively accurate, intuitive, and common way to evaluate the imaging quality of an imaging system. The higher and smoother the curve, the better the imaging quality of the system, and the better it corrects for various aberrations (such as spherical aberration, coma, astigmatism, field curvature, axial chromatic aberration, and transverse chromatic aberration).

[0133] like Figure 6 The image shows the optical transfer function (MTF) curve of the lens at room temperature in the visible light band; as shown... Figure 7 The image shown depicts the field curvature and distortion of the lens in the visible light band; as shown... Figure 8 The image shows the lens's defocus MTF in the visible light band; as shown... Figure 9 The image shows the defocus MTF of the lens at room temperature in the infrared band.

[0134] from Figure 6 As can be seen, the optical transfer function (MTF) curve of the lens in the visible light region at room temperature is relatively smooth and concentrated, and the minimum MTF value of the full field of view of 120 degrees (half image height Y' = 3.2 mm) reaches more than 0.5; it can be seen that the lens provided by the embodiment of the present invention can achieve a very high resolution and meet the imaging requirements of a 1 / 2.8-inch 4-megapixel camera.

[0135] from Figure 7 As can be seen, the optical distortion of the lens is within -25% in the full field of view of 120 degrees, and within -1% in the 0.5 field of view of 60 degrees; the field curvature is controlled within ±0.05mm, which is relatively small.

[0136] from Figure 8 and Figure 9 As can be seen from the data, the lens has a small defocusing amount between the visible and infrared fields, which is within 0.01mm. The visible and infrared fields can be focused clearly at the same time, indicating that the lens has infrared confocal focus, which can meet the needs of both day and night use scenarios.

[0137] The lens provided by this invention supports a maximum imaging area of ​​1 / 2.5' inch sensor (CCD / CMOS), an aperture of F2.0, a focal length of 2.9mm, and achieves a 120° wide field of view, enabling a wide-angle observation range. Optical distortion is less than -1.5% within a 60° field of view (0.5 field of view) and less than -25% across the entire 120° field of view. The MTF value reaches above 0.5 at 100lp / mm across the entire field of view, effectively meeting the resolution requirements of current 4-megapixel cameras. The lens incorporates an infrared confocal design, making it compatible with both day and night use scenarios.

[0138] This invention provides a lens and a camera device. The lens comprises, from the object side to the image side, a first negative power lens, a first positive power lens, a second negative power lens, a third negative power lens, a second positive power lens, a positive power lens group, a third positive power lens, a filter, and an image plane arranged sequentially. The positive power lens group comprises a biconvex lens and a meniscus lens arranged sequentially from the object side to the image side. The lens satisfies the following conditions: Where f is the focal length of the lens, and TTL is the total optical length of the lens. In this embodiment of the invention, eight lenses of specific optical power are arranged sequentially from the object side to the image side in a specific order, satisfying the above conditions, thus achieving an optical lens with high resolution, a large field of view, low optical distortion, and a large aperture.

[0139] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0140] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0141] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0142] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the invention.

[0143] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A lens, characterized in that, The lens consists of a first negative power lens, a first positive power lens, a second negative power lens, a third negative power lens, a second positive power lens, a positive power lens group, a third positive power lens, a filter, and an image plane arranged sequentially from the object side to the image side; the positive power lens group consists of a biconvex lens and a meniscus lens arranged sequentially from the object side to the image side. The lens meets the following conditions: ; Where f is the focal length of the lens, and TTL is the total optical length of the lens; The lens satisfies: ； ； ； ； ； ； ； Wherein, f1 is the focal length of the first negative power lens, f2 is the focal length of the first positive power lens, f3 is the focal length of the second negative power lens, f4 is the focal length of the third negative power lens, and f5 is the focal length of the second positive power lens. g1 f is the focal length of the positive optical power lens group, and f8 is the focal length of the third positive optical power lens.

2. The lens as described in claim 1, characterized in that, The biconvex lens and meniscus lens in the positive power lens group are cemented together.

3. The lens as described in claim 1, characterized in that, The first negative power lens is a meniscus lens, and its object-facing side is convex. The first positive power lens is a meniscus lens, and its object-facing side is convex. The second negative power lens is a meniscus lens, and its object-facing side is convex. The third negative power lens is a meniscus lens, with its object-side surface being convex, or its image-side surface being convex. The second positive power lens is a biconvex lens; The third positive power lens is a biconvex lens.

4. The lens as described in claim 1, characterized in that, The first negative power lens, the first positive power lens, the second positive power lens, the biconvex lens, and the meniscus lens are all spherical lenses.

5. The lens as described in claim 1, characterized in that, The second negative power lens, the third negative power lens, and the third positive power lens are all aspherical lenses.

6. The lens as described in claim 1, characterized in that, The Abbe number V of each lens in the lens d satisfy: .

7. The lens as described in claim 1, characterized in that, The refractive index N of each lens in the lens is described. d satisfy: .

8. The lens as described in claim 1, characterized in that, An aperture stop is provided between the second positive focal length lens and the positive focal length lens group.

9. A camera device, characterized in that, The camera device comprises: imaging using a lens as described in any one of claims 1 to 8.

Images