High-resolution high-illumination fisheye lens and imaging method thereof

Abstract

An optical system of the high-resolution high-illumination fisheye lens is composed of 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 which are sequentially arranged from left to right along a light incident light path. The diaphragm is arranged between the fourth lens and the fifth lens. The first lens, the second lens, the fourth lens, the seventh lens and the eighth lens are glass spherical lenses, and the third lens, the fifth lens, the sixth lens and the ninth lens are plastic aspheric lenses. By reasonably distributing the focal power and the surface type of each lens, the central thickness of each lens, the axial distance between the lenses and the like, the fish-eye lens can realize an ultra-large field angle of more than 190 degrees, meanwhile, the large-aperture design that FNO is less than or equal to 2.0 is met, and the center and the edge are ensured to have more than 70% of high relative illumination. The fisheye lens supports high-resolution imaging with more than eight million pixels, is low in temperature drift through athermalization design, can stably image within the temperature range of-30 DEG C to 80 DEG C, and solves the problems that a traditional fisheye lens is insufficient in edge brightness, reduced in resolving power, out of focus at high and low temperatures and the like in a low-illumination environment.

Description

Technical Field

[0001] This invention relates to the field of optical imaging technology, and in particular to a high-resolution, high-illumination fisheye lens and its imaging method. Background Technology

[0002] Fisheye lenses are extreme wide-angle lenses, widely used in scene surveillance, satellite positioning, robot navigation, intelligent systems, and engineering surveying due to their ultra-wide field of view (typically 180° or even larger). In recent years, with the continuous development of optical technology and the security industry, the demand for fixed-focus optical imaging lenses in fields such as surveillance and automotive is gradually trending towards larger sensor sizes, higher resolutions, larger apertures, and wider field of view.

[0003] To meet the wide field-of-view requirements of surveillance, mainstream large-format lenses exhibit significant optical distortion, causing objects at the edges of the image to be easily compressed, resulting in severe image distortion for users. Technicians typically use backend software and algorithms to correct and process images to ensure image quality over a wider area. While this method addresses the distortion issue to some extent, it also increases system complexity and processing costs. Meanwhile, fisheye lenses on the market generally suffer from low relative illumination in the peripheral field of view, severely impacting image quality and user experience.

[0004] As application areas continue to expand, the market demands higher performance from fisheye lenses. High illumination, large image surface area, and high resolution have become key directions for the development of next-generation fisheye lenses. High illumination characteristics enable lenses to obtain clear images even in low-light conditions, greatly expanding the application scenarios and timeframes of fisheye lenses. Especially in fields such as security monitoring, automotive vision, and intelligent recognition, higher performance requirements are placed on lenses in nighttime or low-light environments. Summary of the Invention

[0005] In view of the above-mentioned shortcomings of the existing technical solutions, the purpose of the present invention is to provide a high-resolution, high-illumination fisheye lens and its imaging method, which can still obtain clear images under low light conditions.

[0006] This invention discloses a high-resolution, high-illumination fisheye lens, which, along its optical axis from the object side to the image side, may sequentially comprise: 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; the first lens is a meniscus lens with negative optical power, its object side being convex and its image side being concave; the second lens is a meniscus lens with negative optical power, its object side being convex and its image side being concave; the third lens is a meniscus lens with negative optical power, its object side being convex and its image side being concave; the fourth lens is a biconvex lens with positive optical power, its object side being convex and its image side being convex; the fifth lens is a biconvex lens with negative optical power... The first lens is a meniscus lens with a concave object side and a convex image side; the second lens is a meniscus lens with negative optical power, with a concave object side and a convex image side; the third lens is a biconvex lens with positive optical power, with a convex object side and a convex image side; the fourth lens is a meniscus lens with negative optical power, with a concave object side and a convex image side; the fifth lens is a biconvex lens with positive optical power, with a convex object side and a convex image side; the nine lenses are made of glass or plastic, wherein the first, second, fourth, seventh, and eighth lenses are glass spherical lenses, and the third, fifth, sixth, and ninth lenses are plastic aspherical lenses.

[0007] Furthermore, the focal length of the optical system is The focal lengths of the first lens, second lens, third lens, fourth lens, fifth lens, sixth lens, seventh lens, eighth lens, and ninth lens are respectively , , , , , , , , ,in , , , , , , , , and Meets the following ratio: -9.5< / <-9.0, -6.5< / <-6.0, -4.5< / <-4.0, 4.0< / <4.5, -400.0< / <-399.0, -35.0< / <-34.0, 2.0< / <2.5, -2.5< / <-2.0, 3.5< / <4.0.

[0008] Furthermore, the first lens satisfies the relationship: 1.8 ≤ ≤2.0, ≤50.0; The second lens satisfies the relationship: 1.5≤ ≤1.8, ≥50.0; The third lens satisfies the relationship: 1.5≤ ≤1.8, ≥50.0; The fourth lens satisfies the relationship: 1.8≤ ≤2.0, ≤50.0; The fifth lens satisfies the relationship: 1.5≤ ≤1.8, ≤50.0; The sixth lens satisfies the relationship: 1.5≤ ≤1.8, ≤50.0; The seventh lens satisfies the relationship: 1.5≤ ≤1.8, ≤50.0; The eighth lens satisfies the relation: 1.8≤ ≤2.0, ≤50.0; The ninth lens satisfies the relation: 1.5≤ ≤1.8, ≥50.0; of which For refractive index, Let be Abbe's constant.

[0009] Furthermore, the on-axis distances of the optical system satisfy the following relationships: the air gap between the first lens and the second lens is 3.0~3.5mm; the air gap between the second lens and the third lens is 2.0~2.5mm; the air gap between the third lens and the fourth lens is 3.0~3.5mm; the air gap between the fourth lens and the fifth lens is 2.0~2.5mm; the air gap between the fifth lens and the sixth lens is 0~0.5mm; the air gap between the sixth lens and the seventh lens is 0~0.5mm; the seventh lens and the eighth lens are cemented lenses with an air gap of 0mm; and the air gap between the eighth lens and the ninth lens is 0~0.5mm.

[0010] Furthermore, the third, fifth, sixth, and ninth lenses are plastic aspherical lenses, and the equation for the aspherical curve is expressed as follows:

[0011]

[0012] Where Z is the distance from the vertex of the aspherical surface to the optical axis at a position of height r; c is the paraxial curvature of the aspherical surface; and k is the conic constant. , , , , , , , All are coefficients of higher-order terms.

[0013] Furthermore, the total optical length TTL of the optical system and the focal length f of the optical system satisfy the following condition: 17.0 ≤ TTL / f ≤ 17.5.

[0014] Furthermore, the F-number of the optical system is ≤2.0.

[0015] Furthermore, the image height H of the optical system and the focal length f of the optical system satisfy the following condition: H / f ≥ 4.0.

[0016] Furthermore, the aperture stop of the optical system is located between the fourth lens and the fifth lens.

[0017] Furthermore, a filter is provided on the rear side of the ninth lens.

[0018] Compared with the prior art, the present invention has the following advantages:

[0019] The lens of this invention adopts a glass-plastic hybrid optical system, consisting of five glass spherical lenses and four plastic aspherical lenses. By rationally allocating the optical power of each lens and adjusting the surface shape and on-axis distance of each lens, the lens meets the requirements of a large target area and a large aperture, with a field of view exceeding 190 degrees. It has high imaging resolution and high resolving power, and the edge field of view has high relative illumination, so the imaging remains clear in night or low-light environments. At the same time, the lens has a small image plane shift in environments ranging from -30℃ to 80℃, and has good environmental reliability.

[0020] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the optical structure of the present invention;

[0022] Figure 2 This is the transverse chromatic aberration diagram of the entire working band of the present invention;

[0023] Figure 3 This is the axial chromatic aberration diagram of the entire working band of the present invention;

[0024] Figure 4 This is the field curvature distortion diagram of the entire working band of the present invention;

[0025] Figure 5 This is a relative illumination curve diagram of the entire working band of the present invention;

[0026] Figure 6 This is the MTF curve diagram of the entire operating band of this invention;

[0027] Figure 7 This is the MTF curve of the infrared operating band of the present invention;

[0028] In the diagram: STO - aperture stop; L1 - first lens; L2 - second lens; L3 - third lens; L4 - fourth lens; L5 - fifth lens; L6 - sixth lens; L7 - seventh lens; L8 - eighth lens; L9 - ninth lens; L10 - equivalent glass plate; IMA - imaging plane. Detailed Implementation

[0029] The present invention will be further described below with reference to the accompanying drawings and specific implementation methods.

[0030] like Figure 1As shown, a high-resolution, high-illumination fisheye lens comprises, from the object side to the image side, a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7, an eighth lens L8, and a ninth lens L9. An aperture stop is positioned between the fourth and fifth lenses. The first, second, fourth, seventh, and eighth lenses are glass spherical lenses, while the third, fifth, sixth, and ninth lenses are plastic aspherical lenses. The first lens is a meniscus lens with negative optical power, its object side being convex and its image side being concave. The second lens is also a meniscus lens with negative optical power, its object side being convex and its image side being concave. The first lens has a concave side; the second lens is a meniscus lens with negative power, its object side is convex, and its image side is concave; the third lens is a biconvex lens with positive power, its object side is convex, and its image side is convex; the fourth lens is a biconvex lens with positive power, its object side is convex, and its image side is convex; the fifth lens is a meniscus lens with negative power, its object side is concave, and its image side is convex; the sixth lens is a meniscus lens with negative power, its object side is concave, and its image side is convex; the seventh lens is a biconvex lens with positive power, its object side is convex, and its image side is convex; the eighth lens is a meniscus lens with negative power, its object side is concave, and its image side is convex; the ninth lens is a biconvex lens with positive power, its object side is convex, and its image side is convex. Through the reasonable combination of the power and surface shape of the nine lenses and the use of four plastic aspherical surfaces, the optical system possesses excellent aberration correction and resolving capabilities, such as... Figures 2 to 7 As shown.

[0031] The focal length of the optical system is The focal lengths of the first lens, second lens, third lens, fourth lens, fifth lens, sixth lens, seventh lens, eighth lens, and ninth lens are respectively , , , , , , , , ,in , , , , , , , , and Meets the following ratio: -9.5< / <-9.0, -6.5< / <-6.0, -4.5< / <-4.0, 4.0< / <4.5, -400.0< / <-399.0, -35.0< / <-34.0, 2.0< / <2.5, -2.5< / <-2.0, 3.5< / <4.0.

[0032] The first lens satisfies the relationship: 1.8 ≤ ≤2.0, ≤50.0; The second lens satisfies the relationship: 1.5≤ ≤1.8, ≥50.0; The third lens satisfies the relationship: 1.5≤ ≤1.8, ≥50.0; The fourth lens satisfies the relationship: 1.8≤ ≤2.0, ≤50.0; The fifth lens satisfies the relationship: 1.5≤ ≤1.8, ≤50.0; The sixth lens satisfies the relationship: 1.5≤ ≤1.8, ≤50.0; The seventh lens satisfies the relationship: 1.5≤ ≤1.8, ≤50.0; The eighth lens satisfies the relation: 1.8≤ ≤2.0, ≤50.0; The ninth lens satisfies the relation: 1.5≤ ≤1.8, ≥50.0; of which For refractive index, Let be Abbe's constant.

[0033] The on-axis distances of the optical system satisfy the following relationships: the air gap between the first and second lenses is 3.0~3.5mm; the air gap between the second and third lenses is 2.0~2.5mm; the air gap between the third and fourth lenses is 3.0~3.5mm; the air gap between the fourth and fifth lenses is 2.0~2.5mm; the air gap between the fifth and sixth lenses is 0~0.5mm; the air gap between the sixth and seventh lenses is 0~0.5mm; the seventh and eighth lenses are cemented lenses, and the air gap is 0mm; the air gap between the eighth and ninth lenses is 0~0.5mm.

[0034] The third, fifth, sixth, and ninth lenses are plastic aspherical lenses, and the equation for their aspherical curves is as follows:

[0035]

[0036] Where Z is the distance from the vertex of the aspherical surface to the optical axis at a position of height r; c is the paraxial curvature of the aspherical surface; and k is the conic constant. , , , , , , , All are coefficients of higher-order terms.

[0037] The total optical length (TTL) of the optical system and the focal length (f) of the optical system satisfy the following conditions: 17.0 ≤ TTL / f ≤ 17.5; the F-number of the optical system ≤ 2.0; the image height (H) of the optical system and the focal length (f) of the optical system satisfy the following condition: H / f ≥ 4.0.

[0038] The aperture of the optical system is located between the fourth lens and the fifth lens; a filter is provided on the rear side of the ninth lens.

[0039] The technical specifications achieved by the optical system in this embodiment are as follows:

[0040] (1) Focal length: 1.5≤EFFL≤2.0mm;

[0041] (2) Aperture F≤2.0;

[0042] (3) Field of view: 2w ≥ 190°;

[0043] (4) Operating bands: visible light and short-wave infrared bands.

[0044] To achieve the above design parameters, the specific design of the optical system adopted in this embodiment is shown in the table below:

[0045]

[0046] The aspherical coefficients of the aspherical lenses in the optical system of this embodiment are shown in the table below:

[0047]

[0048] The optical system in this embodiment achieves the design requirements of a large aperture, large target surface, and large fisheye by rationally allocating the optical power, surface shape, center thickness of each lens, and on-axis distance between each lens. The design uses five glass spherical lenses and four aspherical lenses, which not only effectively corrects the aberrations of the optical system and improves the lens resolution, but also ensures the overall transmittance of the lens, so that the edge field of view also has high relative illumination, realizing high-definition imaging of the fisheye lens in night and low-light environments.

[0049] By rationally allocating the optical power, surface shape, center thickness of each lens, and on-axis distance between lenses, this fisheye lens achieves an ultra-wide field of view exceeding 190° while meeting the requirements of a large aperture design with FNO ≤ 2.0, ensuring a high relative illumination of over 70% between the center and edges. It supports high-resolution imaging of over eight megapixels and features a thermal-free design with low temperature drift, enabling stable imaging within a temperature range of -30℃ to 80℃. This solves the problems of insufficient edge brightness, decreased resolution, and defocusing at high and low temperatures inherent in traditional fisheye lenses in low-light environments.

[0050] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A high-resolution, high-illumination fisheye lens, characterized in that: The lens, from object side to image side, is provided with 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, with an aperture stop positioned between the fourth and fifth lenses. The first, second, fourth, seventh, and eighth lenses are glass spherical lenses, while the third, fifth, sixth, and ninth lenses are plastic aspherical lenses. Specifically, the first lens is a meniscus lens with negative optical power, its object side being convex and its image side being concave; the second lens is a meniscus lens with negative optical power, its object side being convex and its image side being concave; the third lens is a... The first lens is a meniscus lens with a convex object side and a concave image side; the second lens is a biconvex lens with positive optical power, with a convex object side and a convex image side; the third lens is a meniscus lens with negative optical power, with a concave object side and a convex image side; the fourth lens is a biconvex lens with positive optical power, with a convex object side and a convex image side; the fifth lens is a meniscus lens with negative optical power, with a concave object side and a convex image side; the sixth lens is a meniscus lens with negative optical power, with a concave object side and a convex image side; the seventh lens is a biconvex lens with positive optical power, with a convex object side and a convex image side; the eighth lens is a meniscus lens with negative optical power, with a concave object side and a convex image side; and the ninth lens is a biconvex lens with positive optical power, with a convex object side and a convex image side.

2. The high-resolution, high-illumination fisheye lens according to claim 1, characterized in that: The focal length of the optical system of the lens is The focal lengths of the first lens, second lens, third lens, fourth lens, fifth lens, sixth lens, seventh lens, eighth lens, and ninth lens are respectively , , , , , , , , ,in , , , , , , , , and Meets the following ratio: -9.5< / <-9.0, -6.5< / <-6.0, -4.5< / <-4.0, 4.0< / <4.5, -400.0< / <-399.0, -35.0< / <-34.0, 2.0< / <2.5, -2.5< / <-2.0, 3.5< / <4.

0.

3. The high-resolution, high-illumination fisheye lens according to claim 1, characterized in that: The first lens satisfies the following relationship: 1.8 ≤ ≤2.0, ≤50.0; The second lens satisfies the relationship: 1.5≤ ≤1.8, ≥50.0; The third lens satisfies the relationship: 1.5≤ ≤1.8, ≥50.0; The fourth lens satisfies the relationship: 1.8≤ ≤2.0, ≤50.0; The fifth lens satisfies the relationship: 1.5≤ ≤1.8, ≤50.0; The sixth lens satisfies the relationship: 1.5≤ ≤1.8, ≤50.0; The seventh lens satisfies the relationship: 1.5≤ ≤1.8, ≤50.0; The eighth lens satisfies the relation: 1.8≤ ≤2.0, ≤50.0; The ninth lens satisfies the relation: 1.5≤ ≤1.8, ≥50.0; of which For refractive index, Let be Abbe's constant.

4. The high-resolution, high-illumination fisheye lens according to claim 1, characterized in that: The optical system of the lens satisfies the following relationships on the axis: the air gap between the first lens and the second lens is 3.0~3.5mm; the air gap between the second lens and the third lens is 2.0~2.5mm; the air gap between the third lens and the fourth lens is 3.0~3.5mm; the air gap between the fourth lens and the fifth lens is 2.0~2.5mm; the air gap between the fifth lens and the sixth lens is 0~0.5mm; the air gap between the sixth lens and the seventh lens is 0~0.5mm; the seventh lens and the eighth lens are cemented lenses with an air gap of 0mm; and the air gap between the eighth lens and the ninth lens is 0~0.5mm.

5. The high-resolution, high-illumination fisheye lens according to claim 1, characterized in that: The third, fifth, sixth, and ninth lenses are plastic aspherical lenses, and the equation for their aspherical curves is as follows: ， Where Z is the distance from the vertex of the aspherical surface to the optical axis at a position of height r; c is the paraxial curvature of the aspherical surface; and k is the conic constant. , , , , , , , All are coefficients of higher-order terms.

6. The high-resolution, high-illumination fisheye lens according to claim 1, characterized in that: The total optical length (TTL) of the optical system of the lens satisfies the following relationship with the focal length (f): 17.0 ≤ TTL / f ≤ 17.5; the F-number of the optical system ≤ 2.0; the image height (H) of the optical system satisfies the following relationship with the focal length (f): H / f ≥ 4.0; a filter is provided on the rear side of the ninth lens.

7. The high-resolution, high-illumination fisheye lens according to claim 1, characterized in that: The optical system of the lens achieves the following technical specifications: (1) Focal length: 1.5≤EFFL≤2.0mm; (2) Aperture F≤2.0; (3) Field of view: 2w ≥ 190°; (4) Operating bands: visible light and short-wave infrared bands.

8. The high-resolution, high-illumination fisheye lens according to claim 1, characterized in that: The specific design of the optical system of the lens is shown in the table below: 。 9. The high-resolution, high-illumination fisheye lens according to claim 1, characterized in that: The aspherical coefficients of the aspherical lenses in the optical system of the lens are shown in the table below: 。 10. An imaging method for a high-resolution, high-illumination fisheye lens, characterized in that: The incident light rays pass sequentially through the first lens, second lens, third lens, fourth lens, fifth lens, sixth lens, seventh lens, eighth lens, ninth lens and the equivalent glass plate, and then form an image on the IMA-imaging plane.

Images