A super-large aperture, low-distortion, large-area, high-definition fixed-focus lens

Abstract

The present invention discloses an ultra-large aperture, low-distortion, large target surface, high-definition fixed-focus lens. It comprises nine lenses arranged sequentially from the object side to the image side, wherein the first and second lenses are convex-concave negative lenses, the third lens is a biconvex positive lens, the fourth lens is a concave-convex cemented positive lens, the fifth lens is a biconvex positive lens, the sixth lens is a biconcave negative lens, the seventh lens is a biconvex cemented positive lens, the eighth lens is a biconvex positive lens, and the ninth lens is a convex-concave glass aspherical negative lens. Through the rational optimization of the lens arrangement, the present invention can achieve a larger aperture, smaller distortion, higher pixel count, and a larger imaging target surface, thereby meeting the requirements for observing target scenes under low-light conditions and below, thereby promoting the application and development of night vision in the security and automotive markets.

Description

Technical Field

[0001] The present invention relates to a lens, and in particular to an ultra-large aperture, low-distortion, large target surface, high-definition fixed-focus lens. Background Art

[0002] A major technical challenge facing the security surveillance and vehicle-mounted systems is improving image quality at night and in low-light conditions. One solution is to reduce the frame rate and extend the exposure time to improve image quality. However, this can result in blurred images for moving targets or in mobile environments, limiting its application. Another solution is to add infrared fill lights, currently the most common operating mode. This light compensates for insufficient ambient brightness and switches the camera to infrared mode. This mode offers the advantages of simplicity and ease of implementation. However, in real-world applications, infrared fill lights have a limited range, making it difficult to see targets outside their effective range. Furthermore, in certain scenarios, the fill light cannot be used to prevent exposure. Consequently, infrared fill light is no longer suitable for high-quality surveillance.

[0003] Advances in chip technology, the application of new photosensitive materials, and back-illumination techniques have significantly improved night vision image quality with high-sensitivity imaging chips. Pairing these with wide-aperture lenses can significantly improve night vision image quality. However, such applications are rare in existing technology. Furthermore, the typical wide-aperture lenses on the market typically have a maximum aperture of F1.4, with a limited number reaching F1.1 or below. However, these lenses exhibit significant distortion, often exceeding 20%, which can cause visual fatigue after prolonged observation. Furthermore, some plastic aspherical lenses can experience poor imaging performance at temperatures below -40°C.

[0004] Based on this, there is an urgent need to improve an ultra-large aperture, low distortion, large target area, high-definition fixed-focus lens that can achieve a larger aperture, smaller distortion, higher pixels, and a larger imaging target area to meet the observation of target scenes under low light conditions and below, thereby promoting the application development in the night vision field of the security and automotive markets. Summary of the Invention

[0005] In order to solve the shortcomings of the above technologies, the present invention provides a high-definition fixed-focus lens with ultra-large aperture, low distortion, large target surface, and high definition.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is: an ultra-large aperture, low-distortion, large target surface, high-definition fixed-focus lens, which includes nine lenses arranged in sequence from the object side to the image side, namely a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens, and a ninth lens;

[0007] The first and second lenses are convex-concave negative lenses, the third lens is a biconvex positive lens, the fourth lens is a concave-convex cemented positive lens, the fifth lens is a biconvex positive lens, the sixth lens is a biconcave negative lens, the seventh lens is a biconvex cemented positive lens, the eighth lens is a biconvex positive lens, and the ninth lens is a convex-concave glass aspherical negative lens.

[0008] Furthermore, the ratio of the focal length of the first lens to the focal length of the entire lens satisfies the following relationship:

[0009] 3<|f1 / f|<4;

[0010] Among them, f is the focal length of the entire lens, and f1 is the focal length of the first lens.

[0011] Furthermore, the ratio of the focal length of the second lens to the focal length of the entire lens satisfies the following relationship:

[0012] 3<|f2 / f|<5;

[0013] Among them, f is the focal length of the entire lens, and f2 is the focal length of the second lens.

[0014] Furthermore, the focal length of the entire lens is 13-16mm and the F number is 1.0-1.1.

[0015] Furthermore, the negative lens refractive index of the seventh lens element is greater than 1.92.

[0016] Furthermore, a stop is provided between the fourth lens and the fifth lens.

[0017] The present invention discloses an ultra-large aperture, low-distortion, large target surface, high-definition fixed-focus lens. Through the rational optimization setting of the lens, it can achieve a larger aperture, smaller distortion, higher pixels, and a larger imaging target surface, so as to meet the target scene observation conditions under low light conditions and below, thereby promoting the development of monitoring image quality in the security and vehicle-mounted fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Schematic diagram of the optical system of the present invention.

[0019] Figure 2 This is a distortion curve diagram of the optical system of the present invention.

[0020] Figure 3 This is the MTF diagram for image quality evaluation of the optical system of the present invention.

[0021] In the figure: 1, first lens; 2, second lens; 3, third lens; 4, fourth lens; 5, fifth lens; 6, sixth lens; 7, seventh lens; 8, eighth lens; 9, ninth lens. DETAILED DESCRIPTION

[0022] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0023] The present invention provides a large aperture, low distortion, large target surface, high-definition fixed-focus lens, wherein the focal length of the entire lens is 13-16 mm, and the F number is 1.0-1.1; preferably, the focal length of the lens is 14.4 mm, and the F number is 1.05; specifically, Figure 1 As shown, it includes 9 lenses arranged in sequence from the object side to the image side, namely a first lens 1, a second lens 2, a third lens 3, a fourth lens 4, a fifth lens 5, a sixth lens 6, a seventh lens 7, an eighth lens 8, and a ninth lens 9.

[0024] Among them, the first lens 1 and the second lens 2 are convex-concave negative lenses, the third lens 3 is a biconvex positive lens, the fourth lens 4 is a concave-convex cemented positive lens, the fifth lens 5 is a biconvex positive lens, the sixth lens 6 is a biconcave negative lens, the seventh lens 7 is a biconvex cemented positive lens, the eighth lens 8 is a biconvex positive lens, and the ninth lens 9 is a convex-concave glass aspherical negative lens.

[0025] Preferably, the ratio of the focal length of the first lens 1 to the focal length of the entire lens satisfies the following relationship:

[0026] 3<|f1 / f|<4;

[0027] Wherein, f is the focal length of the entire lens, and f1 is the focal length of the first lens; when the focal length of the entire lens f=14.4, the focal length of the first lens f1=-36.66.

[0028] Preferably, the ratio of the focal length of the second lens 2 to the focal length of the entire lens satisfies the following relationship:

[0029] 3<|f2 / f|<5;

[0030] Among them, f is the focal length of the entire lens, and f2 is the focal length of the second lens; when the focal length of the entire lens is f=14.4, the focal length of the second lens is f2=-66.95.

[0031] Preferably, a stop is provided between the fourth lens 4 and the fifth lens 5 to limit the light beam.

[0032] Preferably, the seventh lens is a biconvex cemented positive lens, and its negative lens refractive index is greater than 1.92.

[0033] [Example]

[0034] The ultra-large aperture, low-distortion, large target surface, high-definition fixed-focus lens of this embodiment comprises nine lenses, including a cemented lens, with a total of twenty lenses, numbered sequentially from the first lens to the ninth lens. Their curvature radius, lens center thickness, lens center distance, and lens refractive index meet the following conditions:

[0035]

[0036] In the table above, surfaces numbered 19 and 20 are aspherical surfaces. Aspherical lenses satisfy the following formula:

[0037]

[0038] Among them, c = 1 / R, R is the radius of curvature of the aspheric surface, r is the number from 0 to the maximum effective aperture of the lens, k is the quadratic surface parameter, A is the 4th order coefficient, B is the 6th order coefficient, C is the 8th order coefficient, and so on.

[0039] The aspheric surface parameters in this embodiment are detailed in the table below:

[0040] Surface number k A B C 19 0 -5e-5 0 0 20 0 4.81e-5 -8.09e-7 1e-8

[0041] Furthermore, if Figure 2 As shown in the figure, it is the distortion curve of the high-definition fixed-focus lens of this embodiment. Figure 2 It can be seen that the maximum distortion is only -5%. Figure 3 As shown in FIG. 1 , the image quality evaluation MTF diagram of the high-definition fixed-focus lens of the present invention is shown, wherein the horizontal axis represents the spatial frequency of line pairs / mm, and the vertical axis represents the MTF value; Figure 3 It can be seen that the central area of this embodiment shows good contrast within the spatial frequency of 40lp / mm and the overall comprehensive resolution is relatively high.

[0042] In summary, the ultra-large aperture, low distortion, large target surface, high-definition fixed-focus lens disclosed in the present invention has the following technical advantages:

[0043] First, through reasonable optimization, the present invention can achieve day and night confocal imaging functions, use glass lenses, and have temperature compensation functions, that is, it will not shift focus when used in an environment of -40℃ to +80℃.

[0044] Second, the present invention can achieve more than 2 million pixels under visible light. Through the rational use of glass, the imaging is good, the aperture can reach F1.05, and clear imaging can be achieved under low-light conditions at night. More importantly, the maximum distortion is less than 5%, and the image distortion is greatly reduced, which is also conducive to image splicing and fusion.

[0045] Third, the present invention gives full play to the feature of glass lenses being easy to process, the aspheric surface is made of glass with a low melting point, and the aspheric surface is not of high order and is easy to mold.

[0046] Fourth, the maximum image area of the lens can reach 1".

[0047] The above embodiments are not limitations of the present invention, and the present invention is not limited to the above examples. Any changes, modifications, additions or substitutions made by technicians in this technical field within the scope of the technical solution of the present invention also fall within the scope of protection of the present invention.

Claims

1. An ultra-large aperture, low-distortion, large image surface, high-definition fixed-focus lens, characterized by: The lens can realize the confocal imaging function during the day and at night. The number of lens elements arranged in sequence from the object side to the image side is 9, namely the first lens (1), the second lens (2), the third lens (3), the fourth lens (4), the fifth lens (5), the sixth lens (6), the seventh lens (7), the eighth lens (8), and the ninth lens (9); The first lens (1) and the second lens (2) are convex-concave negative lenses, the third lens (3) is a biconvex positive lens, the fourth lens (4) is a concave-convex cemented positive lens, the fifth lens (5) is a biconvex positive lens, the sixth lens (6) is a biconcave negative lens, the seventh lens (7) is a biconvex cemented positive lens, the eighth lens (8) is a biconvex positive lens, and the ninth lens (9) is a convex-concave glass aspheric negative lens; The ratio of the focal length of the first lens (1) to the focal length of the entire lens satisfies the following relationship: 3<|f1 / f|<4; Where f is the focal length of the entire lens, f1 is the focal length of the first lens; The ratio of the focal length of the second lens (2) to the focal length of the entire lens satisfies the following relationship: 3<|f2 / f|<5; Where f is the focal length of the entire lens, and f2 is the focal length of the second lens; The entire lens has a focal length of 13-16mm and an F number of 1.0-1.

1.

2. The ultra-large aperture, low-distortion, large image surface, high-definition fixed-focus lens according to claim 1, characterized in that: The negative lens refractive index of the seventh lens is greater than 1.

92.

3. The ultra-large aperture, low-distortion, large target surface, high-definition fixed-focus lens according to claim 2, characterized in that: A stop is provided between the fourth lens (4) and the fifth lens (5).

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