8M ultra-wide-angle fisheye lens suitable for panoramic looking-around system and imaging method

Abstract

The invention relates to an 8M ultra-wide-angle fisheye lens suitable for a panoramic looking-around system, an optical system of the lens is composed of a first lens, a second lens, a third lens, a diaphragm, a fourth lens, a fifth lens and a sixth lens which are sequentially arranged from left to right along a light incident light path, and the lenses are made of glass and plastic materials. The first lens and the third lens are glass spherical lenses, the second lens is a glass aspheric lens, the fourth lens, the fifth lens and the sixth lens are plastic aspheric lenses, and the fourth lens and the fifth lens form a bonding lens group. 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 imaging performance requirement of the lens is met, and the requirements of small volume and 8M ultra-wide-angle imaging are met at the same time.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of lenses, in particular to an 8M super-wide-angle fisheye lens suitable for a panoramic surround view system and an imaging method. BACKGROUND

[0002] The panoramic surround view system is one of the functions of ADAS, which can effectively solve the problem of the visual blind area of the automobile, provide the environmental information around the vehicle body for the driver, improve the comfort and safety of people when driving, and is an inevitable product of the progress of driving safety technology and an indispensable information portal in the vehicle driving assistance system. At present, the sensor fusion technology of the advanced driving assistance system of the automobile has become a new development direction of the automobile electronics, and the camera module as the eyes of the vehicle driving assistance system is one of the indispensable electronic devices.

[0003] In order to realize high-level active safety technology and automatic driving technology, a high-performance, high-stability, small-size vehicle-mounted camera module is needed in the market. Since the optical structure of the fisheye lens is relatively simple and can be designed to be small in size, it has become the mainstream solution in the market. However, the current conventional fisheye lens has a field of view angle less than 180°, and the surround view system constructed by using the conventional lens has a large limitation on the selection of the mounting position in the actual mounting process, and has a small allowable error for realizing the panoramic function. Once the installation position deviates, the image after panoramic splicing will have a blind area due to the incomplete display of the environmental information around the vehicle. Therefore, the high-performance, high-stability, small-size vehicle-mounted camera module with a larger field of view angle has a positive promoting significance for the current booming automobile ADAS market in China. SUMMARY

[0004] In view of the deficiencies of the prior art, the technical problem to be solved by the present application is to provide an 8M super-wide-angle fisheye lens suitable for a panoramic surround view system, which realizes small-size 8M high-resolution imaging and super-wide-angle imaging, is conducive to constructing a panoramic surround view system by using fewer lenses, and further reduces the cost.

[0005] In order to solve the above technical problems, the technical scheme of the present application is: an 8M ultra-wide-angle fisheye lens suitable for a panoramic surround view system, the optical system of the lens is composed of a first lens, a second lens, a third lens, a diaphragm, a fourth lens, a fifth lens and a sixth lens arranged in sequence from left to right along the light ray incident light path, under the condition that the reverse bending caused by the aspherical coefficient is not considered, the first lens is a meniscus concave negative lens, the second lens is a meniscus concave negative lens, the third lens is a double-convex positive lens, the fourth lens is a double-convex positive lens, the fifth lens is a double-concave negative lens, and the sixth lens is a double-convex positive lens, the first lens and the third lens are glass spherical lenses, the second lens is a glass aspherical lens, and the fourth lens, the fifth lens and the sixth lens are plastic aspherical lenses, wherein the fourth lens and the fifth lens are cemented lens groups.

[0006] Preferably, the object side surface of the first lens is convex, and the image side surface is concave; the object side surface of the second lens is convex, and the image side surface is concave; the object side surface of the third lens is convex, and the image side surface is convex; the object side surface of the fourth lens is convex, and the image side surface is concave; the object side surface of the fifth lens is concave, and the image side surface is concave; and the object side surface of the sixth lens is convex, and the image side surface is convex.

[0007] Preferably, the focal length of the optical system is f, and the focal lengths of the first lens, the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens are f1, f2, f3, f4, f5 and f6 respectively, wherein f1, f2, f3, f4, f5 and f6 satisfy the following ratios: -5.0 < f1 / f < -4.0, -2.0 < f2 / f < -1.0, 2.0 < f3 / f < 3.0, 2.0 < f4 / f < 3.0, -2.0 < f5 / f < -1.0, and 1.0 < f6 / f < 2.0.

[0008] Preferably, the first lens satisfies the relationship: 1.7 ≤ N d ≤ 2.0, V d ≤ 50.0; the second lens satisfies the relationship: 1.5 ≤ N d ≤ 1.8, V d ≤ 50.0; the third lens satisfies the relationship: 1.8 ≤ N d ≤ 2.1, V d ≤ 50.0; the fourth lens satisfies the relationship: 1.5 ≤ N d ≤ 1.8, V d ≥ 50.0; the fifth lens satisfies the relationship: 1.5 ≤ N d ≤ 1.8, V d ≤ 50.0; and the sixth lens satisfies the relationship: 1.5 ≤ N d ≤ 1.8, V d ≥ 50.0; wherein N d is the refractive index, and V d is the Abbe number.

[0009] Preferably, the axial distance between each lens satisfies the following relationship, the air gap between the first lens and the second lens is 2.0-2.5mm; the air gap between the second lens and the third lens is 1.5-2.0mm; the air gap between the third lens and the diaphragm is 0.1-0.5mm; the air gap between the diaphragm and the fourth lens is 0.1-0.5mm; the fourth lens and the fifth lens are cemented lenses, the air gap is 0mm; the air gap between the fifth lens and the sixth lens is 0.1-0.5mm.

[0010] Preferably, the second, fourth, fifth and sixth lenses are all aspherical lenses.

[0011]

[0012] Wherein, Z is the sagittal height of the aspherical surface at the height of r along the optical axis; c is the paraxial curvature of the aspherical surface; k is the conic constant; and alpha1, alpha2, alpha3, alpha4, alpha5, alpha6, alpha7 and alpha8 are all high-order coefficients.

[0013] Preferably, the optical total length TTL of the optical system and the focal length f of the optical system satisfy: TTL / f≤15.0.

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

[0015] Preferably, the image height H of the optical system and the focal length f of the optical system satisfy: H / f≥1.0.

[0016] Preferably, the rear side of the sixth lens is provided with a filter, and the filter is selected from an equivalent glass flat plate.

[0017] An imaging method of an 8M super-wide-angle fisheye lens suitable for a panoramic surround view system is performed according to the following steps: light rays pass through the first lens, the second lens, the third lens, the diaphragm, the fourth lens, the fifth lens and the sixth lens in sequence from left to right and then are imaged on an imaging surface.

[0018] Compared with the prior art, the present application has the following beneficial effects:

[0019] 1. The lens has the advantages of an imaging angle greater than 200 degrees for an object, high imaging clarity, large light aperture, low tolerance sensitivity and good high-low temperature stability, etc.

[0020] 2. By reasonably matching each optical lens, the system structure is compact and reasonable, easy to assemble, low tolerance sensitivity, and more suitable for large-scale high-yield production;

[0021] 3. Two glass lenses are matched with four plastic lenses, which has lighter system mass compared with the all-glass system, stronger optical performance stability compared with the all-plastic system, reduces the cost while adapting to the environment;

[0022] 4. The focusing surface displacement can be compensated well at high and low temperatures, and the system has complex environment adaptability;

[0023] 5. Each axial chromatic aberration, sagittal chromatic aberration and high-order chromatic aberration is corrected, so that the imaging system can also have high imaging quality at a large angle;

[0024] 6. The aspheric surface characteristics are fully utilized to improve the performance, which is beneficial to the miniaturization of the lens.

[0025] The application will be further described in detail below in combination with the drawings and specific embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0026] Fig. 1 The optical structure of the embodiment of the application is shown in the figure;

[0027] Fig. 2 The full working waveband axial chromatic aberration diagram of the embodiment of the application is shown in the figure;

[0028] Fig. 3 The full working waveband sagittal chromatic aberration diagram of the embodiment of the application is shown in the figure;

[0029] Fig. 4 The full working waveband field curvature distortion diagram of the embodiment of the application is shown in the figure.

[0030] In the figure, STO is an optical stop, L1 is a first lens, L2 is a second lens, L3 is a third lens, L4 is a fourth lens, L5 is a fifth lens, L6 is a sixth lens, L7 is an equivalent glass flat plate, L8 is an equivalent glass flat plate, and IMA is an imaging surface. DETAILED DESCRIPTION

[0031] In order to make the above features and advantages of the application more obvious and easy to understand, the following embodiments are described in detail below, and the drawings are described as follows.

[0032] As Figs. 1-4As shown, an 8M super wide-angle fisheye lens suitable for a panoramic surround view system, the optical lens is sequentially provided with a first lens L1, a second lens L2, a third lens L3, a stop STO, a fourth lens L4, a fifth lens L5, and a sixth lens L6 from an object side to an image side. The first lens and the third lens are glass spherical lenses, the second lens is a glass aspherical lens, and the fourth, fifth and sixth lenses are plastic aspherical lenses. Among them, the first lens and the second lens are lenses with negative focal length, which adjusts the large-angle light at the same time, and the plastic aspherical lens has the effect of reducing the distortion of the optical system. The fourth lens and the fifth lens form an achromatic double cemented lens. Reasonable lens matching makes the optical system realize super wide-angle, large aperture, day and night focus, low temperature drift design, and at the same time, the on-axis and off-axis aberrations are well corrected, and the imaging quality is good.

[0033] The technical indicators realized by the optical system of the embodiment are as follows:

[0034] (1) focal length: 1.0≤EFFL≤2.0mm;

[0035] (2) aperture F≤2.0;

[0036] (3) field of view angle: 2w≥200°;

[0037] (4) working waveband: visible light waveband.

[0038] To realize the above design parameters, the specific design adopted by the optical system of the embodiment is shown in the following table:

[0039] The aspherical coefficients of each aspherical lens of the optical system of the embodiment are as follows:

[0040]

[0041] The optical system of the embodiment meets the requirements of small size and 8M super wide-angle imaging by reasonably distributing the focal length, surface shape, center thickness of each lens, and on-axis distance between each lens, while meeting the imaging performance requirements of the lens.

[0042] The above is only a preferred embodiment of the present application, and is not intended to limit the present application in other forms. Any skilled person in the art can modify or change the above disclosed technical content to equivalent embodiments. However, any simple modification, equivalent change and modification made according to the technical essence of the present application to the above embodiments, without departing from the technical solution content of the present application, still belongs to the protection scope of the technical solution of the present application.

Claims

1. An 8M ultra-wide fisheye lens suitable for a surround view system, comprising an optical system, characterized in that: The optical system of the lens is composed of a first lens, a second lens, a third lens, a diaphragm, a fourth lens, a fifth lens and a sixth lens arranged in sequence from left to right along the light incident path, wherein, without considering the reverse bending caused by the aspherical surface coefficient, the first lens is a meniscus concave negative lens, the second lens is a meniscus concave negative lens, the third lens is a biconvex positive lens, the fourth lens is a biconvex positive lens, the fifth lens is a biconcave negative lens, and the sixth lens is a biconvex positive lens; the first lens and the third lens are glass spherical lenses, the second lens is a glass aspherical lens, and the fourth lens, the fifth lens and the sixth lens are plastic aspherical lenses, wherein the fourth lens and the fifth lens are cemented lens groups. 2.The 8M ultra-wide fisheye lens suitable for a surround view system according to claim 1, wherein: The object side surface of the first lens is a convex surface, and the image side surface is a concave surface; the object side surface of the second lens is a convex surface, and the image side surface is a concave surface; the object side surface of the third lens is a convex surface, and the image side surface is a convex surface; the object side surface of the fourth lens is a convex surface, and the image side surface is a concave surface; the object side surface of the fifth lens is a concave surface, and the image side surface is a concave surface; and the object side surface of the sixth lens is a convex surface, and the image side surface is a convex surface. 3.The 8M ultra-wide fisheye lens suitable for a surround view system according to claim 1, wherein: The focal length of the optical system is f, and the focal lengths of the first lens, the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens are f1, f2, f3, f4, f5 and f6 respectively, wherein f1, f2, f3, f4, f5 and f6 satisfy the following ratios: -5.0 < f1 / f < -4.0, -2.0 < f2 / f < -1.0, 2.0 < f3 / f < 3.0, 2.0 < f4 / f < 3.0, -2.0 < f5 / f < -1.0, and 1.0 < f6 / f < 2.

0. The on-axis distances between the lenses satisfy the following relationships: the air gap between the first lens and the second lens is 2.0-2.5 mm; the air gap between the second lens and the third lens is 1.5-2.0 mm; the air gap between the third lens and the diaphragm is 0.1-0.5 mm; the air gap between the diaphragm and the fourth lens is 0.1-0.5 mm; the fourth lens and the fifth lens are cemented lenses with an air gap of 0 mm; and the air gap between the fifth lens and the sixth lens is 0.1-0.5 mm. 4.The 8M ultra-wide fisheye lens suitable for a surround view system according to claim 1, wherein: The first lens satisfies the relationship: 1.7 ≤ N d ≤ 2.0, V d ≤ 50.0; the second lens satisfies the relationship: 1.5 ≤ N d ≤ 1.8, V d ≤ 50.0; the third lens satisfies the relationship: 1.8≤N d ≤2.1, V d ≥50.0; the fourth lens satisfies the relationship: 1.5≤N d ≤1.8, V d ≤50.0; the fifth lens satisfies the relationship: 1.5≤N d ≤1.8, V d ≥50.0; the sixth lens satisfies the relationship: 1.5≤N d ≤1.8, V d ≥50.0; wherein N d is the refractive index, and V d is the Abbe number. 5.The 8M ultra-wide fisheye lens suitable for a surround view system according to claim 1, wherein: The second lens, the fourth lens, the fifth lens and the sixth lens are all aspherical lenses, and the aspherical curve equation is expressed as: 6.The 8M ultra-wide fisheye lens suitable for a surround view system according to claim 1, wherein: wherein Z is the sagittal height of the aspherical surface at a height of r along the optical axis; c is the paraxial curvature of the aspherical surface; k is the conic constant; and α1, α2, α3, α4, α5, α6, α7 and α8 are high-order coefficients. The optical total length TTL of the optical system and the focal length f of the optical system satisfy: TTL / f ≤ 15.

0. 7.The 8M ultra-wide fisheye lens suitable for a surround view system according to claim 1, wherein: The F number of the optical system is ≤ 2.

0. 8.The 8M ultra-wide fisheye lens suitable for a surround view system according to claim 1, wherein: The image height H of the optical system and the focal length f of the optical system satisfy: H / f ≥ 1.

0. 9.The 8M ultra-wide fisheye lens suitable for a surround view system according to claim 1, wherein: The light rays pass through the first lens, the second lens, the third lens, the diaphragm, the fourth lens, the fifth lens and the sixth lens in sequence from left to right and then form an image on the imaging surface.

10. An imaging method applied to the 8M ultra-wide-angle fisheye lens for panoramic surround view system according to claim 2, characterized in that, ​

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