An ultra-large aperture, low-distortion, high-definition fixed-focus lens

Abstract

The present invention discloses an ultra-large aperture, low-distortion, high-definition fixed-focus lens, comprising 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, arranged in order from the object side to the image side; the first lens and the second lens are convex-concave negative lenses, the third lens is a convex-concave cemented negative lens, the fourth lens is a biconvex positive lens, the fifth lens is a convex-concave positive lens, the sixth lens is a biconcave negative lens, the seventh lens is a concave-convex cemented negative lens, the eighth lens is a biconvex positive lens, and the ninth lens is a convex-concave positive lens. The present invention provides an ultra-large aperture, low-distortion, high-definition fixed-focus lens, which has a larger aperture, smaller distortion, higher pixel count, and lower cost, thereby enabling the observation of target scenes under starlight and lower illumination conditions, thereby driving the application and development of night vision imaging in the security and automotive fields, and has broad market prospects.

Description

Technical Field

[0001] The present invention relates to a high-definition fixed-focus lens, in particular to an ultra-large aperture low-distortion high-definition fixed-focus lens, and belongs to the technical field of optical imaging. Background Art

[0002] Improving surveillance image quality at night and in low-light conditions is a major challenge in the security surveillance and vehicle-mounted systems. One existing solution is to install an infrared fill light. When ambient brightness is low, the infrared fill light activates, simultaneously switching the camera to infrared mode. This operating mode is currently the most common, offering the advantage of a relatively simple and easy-to-implement solution. However, the infrared fill light has a limited range, making targets invisible beyond its effective range. Furthermore, in certain application scenarios, the fill light is not permitted to operate to prevent exposure. This mode is gradually failing to meet the demand for high-quality surveillance. Another approach is to reduce the frame rate and extend the exposure time to improve image quality. However, this results in blurred images for moving targets or in mobile environments, significantly limiting its application.

[0003] With the advancement of chip technology, the application of new photosensitive materials, back-illumination and other technical processes, high-sensitivity imaging chips have significantly improved the image quality of night vision. If paired with a large aperture lens, the night vision image quality will be greatly improved.

[0004] However, the most common large-aperture lenses on the market typically have a maximum aperture of F1.4, with a few reaching F1.1 or below. However, these lenses exhibit significant distortion (over 20%), which can cause visual fatigue after prolonged observation. Furthermore, some lenses have plastic aspherical surfaces, which degrade imaging performance at temperatures below -40°C. Therefore, there is a need for an ultra-large-aperture, high-definition, low-distortion fixed-focus lens. Summary of the Invention

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

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is: an ultra-large aperture, low-distortion, high-definition fixed-focus lens, comprising 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 arranged in order from the object side to the image side;

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

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

[0009] 3.5<|f1 / f|<4.5;

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

[0011] Preferably, 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|<4;

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

[0014] Preferably, the first lens is a high-refractive-index lens with a refractive index greater than 1.92.

[0015] Preferably, the third lens is a cemented lens, and the refractive index of the positive lens is greater than 1.92.

[0016] Preferably, the seventh lens is a cemented lens, and its negative lens refractive index is greater than 1.92.

[0017] Preferably, the focal length f of the entire lens is 4-8 mm, and the F number is 1.0-1.2.

[0018] Preferably, a stop is provided between the fourth lens and the fifth lens.

[0019] The present invention provides an ultra-large aperture, low-distortion, high-definition fixed-focus lens with a larger aperture, smaller distortion, higher pixel count, and lower cost, thereby enabling observation of target scenes under starlight and lower illumination conditions, thereby driving the application and development of night vision imaging in security and automotive fields, and has broad market prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a structural diagram of the optical system of the present invention.

[0021] Figure 2 2 is an optical distortion diagram of an embodiment of the present invention.

[0022] Figure 3 FIG. 4 is an MTF resolution curve diagram of an embodiment of the present invention.

[0023] 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

[0024] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0025] This embodiment provides an ultra-large aperture, low-distortion, high-definition fixed-focus lens, the focal length f of which is 6.4 mm, the F number is 1.1, and the lens includes 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, which are arranged in order from the object side to the image side. The specific structure is as follows: Figure 1 shown.

[0026] Among them, the first lens 1 and the second lens 2 are convex-concave negative lenses, the third lens 3 is a convex-concave cemented negative lens, the fourth lens 4 is a biconvex positive lens, the fifth lens 5 is a convex-concave positive lens, the sixth lens 6 is a biconcave negative lens, the seventh lens 7 is a concave-convex cemented negative lens, the eighth lens 8 is a biconvex positive lens, and the ninth lens 9 is a convex-concave positive lens.

[0027] Preferably, the ratio of the focal length of the first lens 1 to the focal length of the entire lens satisfies the following relationship:

[0028] 3.5<|f1 / f|<4.5;

[0029] Wherein, f is the focal length of the entire lens, and f1 is the focal length of the first lens. Preferably, f=6.4 mm, and f1=-23.67.

[0030] Preferably, the ratio of the focal length of the second lens 2 to the focal length of the entire lens satisfies the following relationship:

[0031] 3<|f2 / f|<4;

[0032] Wherein, f is the focal length of the entire lens, and f2 is the focal length of the second lens. Preferably, f=6.4 mm, and f2=-22.2.

[0033] Preferably, a stop is provided between the fourth lens 4 and the fifth lens 5 to limit the light beam.

[0034] The ultra-large aperture, low-distortion, high-definition fixed-focus lens of this embodiment comprises nine lenses, including a cemented lens, and has a total of twenty faces. These lenses are 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]

[0037] like Figure 2 As shown in FIG. 1 , it is an optical distortion diagram of this embodiment, Figure 2 It can be seen that the maximum distortion is only -5%. Figure 3The figure shows the MTF resolution curve of this embodiment, where 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 this embodiment exhibits good contrast and high overall resolution within a spatial frequency of 120 lp / mm.

[0038] In summary, the ultra-large aperture, low-distortion, high-definition fixed-focus lens disclosed in the present invention has the following beneficial effects:

[0039] First, through reasonable optimization, the present invention can achieve day and night confocal imaging functions, and at the same time has a temperature compensation function, that is, it will not defocus when used in an environment of -40℃ to +80℃.

[0040] 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 F1.1, 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.

[0041] Third, the present invention gives full play to the feature of glass lenses that are easy to process, and the maximum image surface of the lens exceeds 1 / 1.8.

[0042] 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, high-definition fixed-focus lens, characterized by: The lens has nine lenses, including 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) arranged in sequence from the object side to the image side. The lens can realize a day and night confocal imaging function. The first lens (1) and the second lens (2) are convex-concave negative lenses, the third lens (3) is a convex-concave cemented negative lens, the fourth lens (4) is a biconvex positive lens, the fifth lens (5) is a convex-concave positive lens, the sixth lens (6) is a biconcave negative lens, the seventh lens (7) is a concave-convex cemented negative lens, the eighth lens (8) is a biconvex positive lens, and the ninth lens (9) is a convex-concave positive lens; The ratio of the focal length of the first lens (1) to the focal length of the entire lens satisfies the following relationship: 3.5<|f1 / f|<4.5; 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|<4; Where f is the focal length of the entire lens, and f2 is the focal length of the second lens; The focal length of the entire lens is f4-8mm and the F number is 1.0-1.

2.

2. The ultra-large aperture, low-distortion, high-definition fixed-focus lens according to claim 1, characterized in that: The first lens (1) is a high-refractive-index lens with a refractive index greater than 1.

92.

3. The ultra-large aperture, low-distortion, high-definition fixed-focus lens according to claim 2, characterized in that: The positive lens refractive index of the third lens (3) is greater than 1.

92.

4. The ultra-large aperture, low-distortion, high-definition fixed-focus lens according to claim 3, characterized in that: The negative lens refractive index of the seventh lens (7) is greater than 1.

92.

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

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