An ultra-wide-angle 8m forward-looking optical system and an imaging method thereof

Abstract

The application relates to an 8M super-wide-angle forward-looking optical system and an imaging method thereof, which comprises a first lens, a second lens, a third lens, a diaphragm, a fourth lens, a fifth lens, a sixth lens and a seventh lens arranged in sequence from left to right along a light path of light incidence; 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-convex positive lens, the sixth lens is a double-concave negative lens, and the seventh lens is a double-convex positive lens. The application has the advantages of reasonable design and simple structure, wherein the optical power, surface type, central thickness of each lens and the axial distance between the lenses are reasonably distributed, the total length of the lens and the radial size of each lens are reduced, and the lens group is miniaturized while meeting the requirements of the forward-looking wide-angle camera and the forward-looking narrow-angle camera.

Description

TECHNICAL FIELD

[0001] The application relates to an ultra-wide-angle 8M forward-looking optical system and an imaging method thereof. BACKGROUND

[0002] In an automatic driving vehicle, a perception system is mainly composed of sensors such as a camera, a millimeter wave radar, a laser radar (optional), etc. The camera, as a main environmental perception sensor, plays a very important role and can realize 360-degree comprehensive visual perception, making up for the defects of the radar in object identification and being the sensor closest to human vision. Therefore, the vehicle-mounted camera is one of the key devices in the automatic driving field. The forward-looking camera installed on the front windshield is used to realize the visual perception and identification function of driving, and can be divided into a forward-looking main camera, a forward-looking narrow-angle camera and a forward-looking wide-angle camera according to functions, but the adoption of the three cameras greatly increases the cost of the entire camera module, which is not conducive to market popularization. The function of the forward-looking wide-angle camera is mainly to identify objects at a relatively short distance, and it is mainly used in urban road working conditions, low-speed driving and other scenes, and the field of view angle is 120 DEG ~ 150 DEG, and the detection distance is about 50 m. Therefore, if the ultra-wide-angle 8MP lens is adopted on a large scale, the camera can be omitted, thereby reducing the cost and improving the market popularization. SUMMARY

[0003] The application improves the above problems, that is, the technical problem to be solved by the application is to provide an ultra-wide-angle 8M forward-looking optical system and an imaging method thereof, which realizes the visual perception and identification function of driving and 8MP ultra-wide-angle imaging, so as to replace the forward-looking wide-angle camera and the forward-looking narrow-angle camera, realize a single-lens forward-looking camera module, greatly reduce the cost and improve the market popularization.

[0004] The application is constituted as follows: it comprises a first lens, a second lens, a third lens, a diaphragm, a fourth lens, a fifth lens, a sixth lens and a seventh lens which are sequentially arranged from left to right along the light path of light incidence; the air gap between the first lens and the second lens is 1.0-1.5 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 air gap between the fourth lens and the fifth lens is 0.1-0.5 mm; the fifth lens and the sixth lens are a cemented lens group, and the air gap is 0 mm; and the air gap between the sixth lens and the seventh lens is 0.5-1.0 mm.

[0005] Further, the first lens satisfies the relationship formula: 1.7<=N d <=2.0, V d <=50.0; the second lens satisfies the relationship formula: 1.7<=N d≤ 2.0, V d ≤ 50.0; the third lens satisfies the relationship: 1.5≤N d ≤ 1.8, V d ≤ 50.0; the fourth lens satisfies the relationship: 1.7≤N d ≤ 2.0, 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: 1.7≤N d ≤ 2.0, V d ≤ 50.0; the seventh lens satisfies the relationship: 1.7≤N d ≤ 2.0, V d ≤ 50.0; wherein N d is the refractive index, V d is the Abbe number.

[0006] Further, the first lens is a meniscus concave negative lens, the object side surface of which is a convex surface, and the image side surface of which is a concave surface; the second lens is a meniscus concave negative lens, the object side surface of which is a convex surface, and the image side surface of which is a concave surface; the third lens is a biconvex positive lens, the object side surface of which is a convex surface, and the image side surface of which is a convex surface; the fourth lens is a biconvex positive lens, the object side surface of which is a convex surface, and the image side surface of which is a convex surface; the fifth lens is a biconvex positive lens, the object side surface of which is a convex surface, and the image side surface of which is a convex surface; the sixth lens is a biconcave negative lens, the object side surface of which is a concave surface, and the image side surface of which is a concave surface; and the seventh lens is a biconvex positive lens, the object side surface of which is a convex surface, and the image side surface of which is a convex surface.

[0007] Further, 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, the sixth lens and the seventh lens are f1, f2, f3, f4, f5, f6, f7 respectively, wherein f1, f2, f3, f4, f5, f6, f7 and f satisfy the following proportions: -2.0

[0008] Further, the first lens, the second lens and the seventh lens are glass aspheric lenses, and the third lens, the fourth lens, the fifth lens and the sixth lens are glass spherical lenses, wherein the fifth lens and the sixth lens are cemented lens groups.

[0009] Further, the first lens, the second lens and the seventh lens are all aspheric lenses, and the aspheric curve equation expression is:

[0010] ;

[0011] Wherein, Z is the sagittal height of the aspheric surface from the vertex of the aspheric surface along the optical axis at a position with a height of r; c is the paraxial curvature of the aspheric surface; k is the conic constant; α1, α2, α3, α4, α5, α6, α7, α8 are all high-order coefficients.

[0012] Further, the rear side of the seventh lens is sequentially provided with a first equivalent glass flat plate, a second equivalent glass flat plate and an imaging surface.

[0013] Further, the total optical length TTL of the optical system and the focal length f of the optical system satisfy: TTL / f≤5.0.

[0014] Further, the image height H of the optical system and the focal length f of the optical system satisfy: H / f≤1.0.

[0015] Further, the F number of the optical system is ≤1.6.

[0016] Further, the imaging method of the super-wide-angle 8M forward-looking optical system is that when light is incident, the light path sequentially enters the first lens, the second lens, the third lens, the diaphragm, the fourth lens, the fifth lens, the sixth lens and the seventh lens to perform imaging.

[0017] Compared with the prior art, the present application has the following beneficial effects: 1. The lens has an imaging angle of more than 170 degrees for an object, and has the advantages of super-high 8M imaging clarity, super-wide angle, large light aperture, low tolerance sensitivity and good high-low temperature stability, etc. At the same time, the vehicle exterior scene can be monitored more comprehensively; 2. By reasonably matching each optical lens, the system structure is compact and reasonable, easy to assemble, low in tolerance sensitivity, and more suitable for large-scale high-yield production; 3. The all-glass structure has high stability, can adapt to harsh environments, fully utilizes the advantages of aspheric lenses in correcting aberrations, meets the requirements of high-definition imaging, has smaller lens outer diameter and shorter total optical length, and ensures the miniaturization of the lens; 4. The focusing surface displacement can be compensated well at high and low temperatures, and the adaptability to complex environments is good; 5. The axial color difference, the vertical axial color difference and the high-order color difference are corrected, and the imaging system can also have high imaging quality at a large angle. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 is the optical structure schematic diagram of the embodiment of the present application;

[0019] Figure 2 is the full working waveband axial color difference diagram of the embodiment of the present application;

[0020] Figure 3 is the full working waveband vertical axial color difference diagram of the embodiment of the present application;

[0021] Figure 4 This is a field curvature distortion diagram of the entire working band of this invention embodiment;

[0022] In the diagram: L1 - First lens; L2 - Second lens; L3 - Third lens; L4 - Fourth lens; L5 - Fifth lens; L6 - Sixth lens; L7 - Seventh lens; L8 - First equivalent glass plate; L9 - Second equivalent glass plate; IMA - Imaging plane; STO - Aperture stop. Detailed Implementation

[0023] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0024] Example: Figures 1-4 As shown, the present invention provides an ultra-wide-angle 8M forward-looking optical system, including a first lens L1, a second lens L2, a third lens L3, an aperture stop STO, a fourth lens L4, a fifth lens L5, a sixth lens L6 and a seventh lens L7 arranged sequentially from left to right along the incident light path.

[0025] Without considering the curvature caused by aspherical coefficients, the first lens is a meniscus negative lens with a convex object side and a concave image side; the second lens is a meniscus negative lens with a convex object side and a concave image side; the third lens is a biconvex positive lens with a convex object side and a convex image side; the fourth lens is a biconvex positive lens with a convex object side and a convex image side; the fifth lens is a biconvex positive lens with a convex object side and a convex image side; the sixth lens is a biconcave negative lens with a concave object side and a concave image side; and the seventh lens is a biconvex positive lens with a convex object side and a convex image side.

[0026] The first and second lenses, being aspherical glass lenses, reduce optical system distortion, with the latter, possessing negative optical power, capable of adjusting large-angle light. The fifth and sixth lenses form an achromatic cemented doublet. This well-matched lens combination enables the optical system to achieve an 8M focal length, ultra-wide angle, large aperture, day / night confocal focus, and low temperature drift design. Simultaneously, it effectively corrects on-axis and off-axis aberrations, resulting in good image quality.

[0027] In this embodiment of the invention, the first lens satisfies the relationship: 1.7 ≤ N d ≤2.0, V d ≤50.0; The second lens satisfies the relationship: 1.7≤N d ≤2.0, V d ≤50.0; The third lens satisfies the relationship: 1.5≤N d ≤1.8, V d ≤50.0; The fourth lens satisfies the relation: 1.7≤N d ≤2.0, 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: 1.7 ≤ N d ≤ 2.0, V d ≤ 50.0; the seventh lens satisfies the relationship: 1.7 ≤ N d ≤ 2.0, V d ≤ 50.0; wherein N d is the refractive index, and V d is the Abbe number.

[0028] In the embodiment of the present application, the air gap between the first lens and the second lens is 1.0-1.5mm; 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 air gap between the fourth lens and the fifth lens is 0.1-0.5mm; the fifth lens and the sixth lens are cemented lens groups, and the air gap is 0mm; the air gap between the sixth lens and the seventh lens is 0.5-1.0mm.

[0029] In the embodiment of the present application, 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, the sixth lens and the seventh lens are f1, f2, f3, f4, f5, f6, f7 respectively, wherein f1, f2, f3, f4, f5, f6, f7 and f satisfy the following ratios: -2.0 < f1 / f < -1.0, 4.0 < f2 / f < 5.0, 2.0 < f3 / f < 3.0, 1.0 < f4 / f < 2.0, 1.0 < f5 / f < 2.0, -1.0 < f6 / f < 0.0, 1.0 < f7 / f < 2.0.

[0030] In the embodiment of the present application, the first lens, the second lens and the seventh lens are glass aspheric lenses, and the third lens, the fourth lens, the fifth lens and the sixth lens are glass spherical lenses, wherein the fifth lens and the sixth lens are cemented lens groups.

[0031] In the embodiment of the present application, the first lens, the second lens and the seventh lens are all aspheric lenses, and the aspheric curve equation expression is as follows:

[0032] ;

[0033] wherein Z is the sagittal height of the aspheric surface at a height of r along the optical axis; c is the paraxial curvature of the aspheric surface; k is the conic constant; and α1, α2, α3, α4, α5, α6, α7, α8 are all high-order coefficients.

[0034] In the embodiment of the present application, the back side of the seventh lens is sequentially provided with a first equivalent glass flat plate L8, a second equivalent glass flat plate L9 and an imaging surface IMA.

[0035] In the embodiment of the present application, the total optical length TTL of the optical system and the focal length f of the optical system satisfy: TTL / f≤5.0.

[0036] In the embodiment of the present application, the image height H of the optical system and the focal length f of the optical system satisfy: H / f≤1.0.

[0037] In the embodiment of the present application, the F number of the optical system is ≤1.6.

[0038] In the embodiment of the present application, the stop of the optical system is located behind the third lens S2.

[0039] In the embodiment of the present application, when imaging, the light path sequentially enters the first lens, the second lens, the third lens, the stop, the fourth lens, the fifth lens, the sixth lens and the seventh lens in sequence after the light is incident.

[0040] The technical indexes realized by the optical system in the embodiment of the present application are as follows: (1) focal length: 4.0≤EFFL≤5.0 mm; (2) aperture F≤1.6; (3) field of view angle: 2w≥170°; (4) working waveband: visible light waveband.

[0041] In order to realize the above design parameters, the specific design parameters of the optical system in the embodiment of the present application are shown in Table 1 below:

[0042]

[0043] Table 1

[0044] The aspheric coefficients of each aspheric lens of the optical system in the embodiment of the present application are shown in Table 2 below:

[0045]

[0046] Table 2

[0047] In the embodiment of the present application, the optical system reasonably allocates the optical power of each lens, the surface shape, the central thickness of each lens and the axial distance between each lens, etc., so as to meet the 8M super wide-angle imaging performance requirements of the lens, reduce the total length of the lens and the radial size of each lens, and realize the miniaturization of the lens group.

[0048] Any of the technical solutions disclosed in the present application above, if not otherwise stated, if a numerical range is disclosed, the disclosed numerical range is a preferred numerical range, any person skilled in the art should understand that the preferred numerical range is only one of the many implementable numerical values with more obvious technical effects or representative values. Because there are too many values, it is impossible to enumerate them all, so the present application discloses some values to illustrate the technical solutions of the present application, and the above-mentioned enumerated values should not constitute a limitation on the protection scope of the present application.

[0049] At the same time, if the above-mentioned present application discloses or involves mutually fixed connecting parts or structural parts, except otherwise stated, the fixed connection can be understood as: detachable fixed connection (for example, using bolt or screw connection), and can also be understood as: non-detachable fixed connection (for example, riveting, welding), of course, the mutually fixed connection can also be replaced by an integral structure (for example, using casting process to make an integral shape) (except for obvious cases that cannot use integral forming process).

[0050] If the words "first", "second" and the like are used herein to limit the parts, those skilled in the art should know that the use of "first", "second" is only for the convenience of describing the parts to distinguish them, and the above words have no special meaning unless otherwise stated.

[0051] In addition, the terms used to represent the position relationship or shape in any of the technical solutions disclosed in the above-mentioned present application include the approximate, similar or close state or shape unless otherwise stated.

[0052] Any of the components provided by the present application can be assembled from multiple individual components, or can be a single component manufactured by an integral forming process.

[0053] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application and not to limit them; although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the specific embodiments of the present application can be modified or some technical features can be replaced by equivalent ones; without departing from the spirit of the technical solutions of the present application, they should all be covered in the technical solution range of the present application claimed.

Claims

1. An ultra-wide angle 8M forward looking optical system characterized by, The first lens, the second lens, the third lens, the diaphragm, the fourth lens, the fifth lens, the sixth lens and the seventh lens are sequentially arranged from left to right along the light path of the incident light; the air gap between the first lens and the second lens is 1.0-1.5mm; 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 air gap between the fourth lens and the fifth lens is 0.1-0.5mm; the fifth lens and the sixth lens are a cemented lens group, and the air gap is 0mm; the air gap between the sixth lens and the seventh lens is 0.5-1.0mm; the first lens satisfies the relationship: 1.7 ≤ N d ≤ 2.0, V d ≤ 50.0; the second lens satisfies the relationship: 1.7 ≤ N d ≤ 2.0, V d ≤ 50.0; the third lens satisfies the relationship: 1.5 ≤ N d ≤ 1.8, V d ≤ 50.0; the fourth lens satisfies the relationship: 1.7 ≤ N d ≤ 2.0, 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: 1.7 ≤ N d ≤ 2.0, V d ≤ 50.0; the seventh lens satisfies the relationship: 1.7 ≤ N d ≤ 2.0, V d ≤ 50.0; wherein N d is the refractive index, and V d is the Abbe number. The first lens is a meniscus concave negative lens, the object side surface of which is a convex surface, and the image side surface is a concave surface; the second lens is a meniscus concave negative lens, the object side surface of which is a convex surface, and the image side surface is a concave surface; the third lens is a biconvex positive lens, the object side surface of which is a convex surface, and the image side surface is a convex surface; the fourth lens is a biconvex positive lens, the object side surface of which is a convex surface, and the image side surface is a convex surface; the fifth lens is a biconvex positive lens, the object side surface of which is a convex surface, and the image side surface is a convex surface; the sixth lens is a biconcave negative lens, the object side surface of which is a concave surface, and the image side surface is a concave surface; the seventh lens is a biconvex positive lens, the object side surface of which is a convex surface, and the image side surface is a convex surface.

2. The ultra-wide angle 8M forward looking optical system of 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, the sixth lens and the seventh lens are f1, f2, f3, f4, f5, f6 and f7 respectively, wherein f1, f2, f3, f4, f5, f6 and f7 and f satisfy the following ratios: -2.0 3. The ultra-wide angle 8M forward looking optical system of claim 1, wherein, The first lens, the second lens and the seventh lens are glass aspheric lenses, and the third lens, the fourth lens, the fifth lens and the sixth lens are glass spherical lenses, wherein the fifth lens and the sixth lens are a cemented lens group.

4. The ultra-wide angle 8M forward looking optical system of claim 1, wherein, The first lens, the second lens and the seventh lens are aspheric lenses, and the aspheric curve equation is: ； Wherein, Z is the sagittal height of the aspheric surface at a height of r along the optical axis; c is the paraxial curvature of the aspheric surface; k is the conic constant; α1, α2, α3, α4, α5, α6, α7 and α8 are high-order coefficients.

5. The ultra-wide angle 8M forward looking optical system of claim 1, wherein, The rear side of the seventh lens is sequentially provided with a first equivalent glass flat plate, a second equivalent glass flat plate and an imaging surface.

6. The ultra-wide angle 8M forward looking optical system of claim 1, wherein, The total optical length TTL of the optical system and the focal length f of the optical system satisfy: TTL / f≤5.

0.

7. The ultra-wide angle 8M forward looking optical system of 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; the F number of the optical system is ≤1.

6.

8. An imaging method using the super-wide-angle 8M forward-looking optical system according to claim 1, characterized by, When the light is incident, the light path enters the first lens, the second lens, the third lens, the diaphragm, the fourth lens, the fifth lens, the sixth lens and the seventh lens in sequence to form an image.

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