A fish-eye lens with a 180° field of view that can be used for vehicle-mounted monitoring

Abstract

The present invention relates to an improvement in the design of a lens for vehicle use, in particular to a fisheye lens surface with a 180° field of view that can be used for vehicle monitoring; along the optical axis direction from the object side to the image side, it sequentially includes a first lens with a negative optical power, a second lens with a negative optical power, a third lens with a negative optical power, a fourth lens with a positive optical power, a fifth lens with a positive optical power, a sixth lens with a negative optical power, a seventh lens with a negative optical power, an eighth lens with a positive optical power, a ninth lens with a positive optical power, a tenth lens with a positive optical power, and an eleventh lens with a positive optical power. Among them, the fourth lens, the fifth lens, and the sixth lens form a triple cemented lens, the seventh lens and the eighth lens form a double cemented lens, and the tenth lens and the eleventh lens form a double cemented lens; the acceptance aperture is F / #3.5, and it has high imaging performance resolution, a simple structure, and is a compact ultra-wide field of view and large aperture vehicle fisheye lens.

Description

Technical Field

[0001] The present invention relates to an improvement in the design of a lens for vehicle use, particularly a fisheye lens with a 180° field of view that can be used for vehicle monitoring. Background Art

[0002] In recent years, with the continuous increase in the demand for security and monitoring in various fields, especially the increase in the number of automobiles, vehicle monitoring has become increasingly important. However, the resolution of current vehicle-mounted lenses on the market is relatively low, and the light transmission aperture is small. Especially in the case of a large field of view and low light, the clarity and sharpness of the captured images are significantly not good enough to meet the resolution requirements of vehicle monitoring images. The lens system is the core of vehicle imaging equipment, and with the development of the security monitoring industry, the breadth and depth of its application are constantly expanding, and the required image resolution is also getting higher and higher, and the demand for the lens system and the imaging quality are also constantly increasing. At the same time, current vehicle monitoring lenses are developing towards the trends of high imaging quality, large working field of view, large light transmission aperture, miniaturization, light weight, and simple structure. Currently, the lenses used for vehicle monitoring cannot meet the requirements of high imaging performance in terms of clarity. At the same time, the lenses are large in size, have many lenses, and have a small field of view for imaging, resulting in unsatisfactory application effects. Summary of the Invention

[0003] To solve the problems mentioned in the background art, the present invention provides a fisheye lens with a 180° field of view that can be used for vehicle monitoring, with a receiving aperture of F / #3.5, which has high imaging performance resolution, is simple in structure, and is a compact ultra-large field of view and large-aperture vehicle fisheye lens.

[0004] The above technical object of the present invention is achieved through the following technical solutions: A fisheye lens with a 180° field of view that can be used for vehicle monitoring, along the optical axis direction from the object side to the image side, successively includes a first lens with a negative focal power, a second lens with a negative focal power, a third lens with a negative focal power, a fourth lens with a positive focal power, a fifth lens with a positive focal power, a sixth lens with a negative focal power, a seventh lens with a negative focal power, an eighth lens with a positive focal power, a ninth lens with a positive focal power, a tenth lens with a positive focal power, and an eleventh lens with a positive focal power, wherein the fourth lens, the fifth lens, and the sixth lens form a three-glued lens, the seventh lens and the eighth lens form a two-glued lens, and the tenth lens and the eleventh lens form a two-glued lens;

[0005] Among them, the first lens, the second lens, and the third lens are all negative meniscus lenses, and the optical surfaces facing the object side and the image side are both convex towards the object side;

[0006] The optical surface of the fourth lens facing the object side is concave towards the object side, and the optical surface facing the image side is convex towards the object side;

[0007] The optical surface of the fifth lens facing the object side bulges towards the object side, and the optical surface facing the image side bulges towards the image side;

[0008] The optical surface of the sixth lens facing the object side bulges towards the image side, and the optical surface facing the image side concaves towards the image side;

[0009] The optical surface of the seventh lens facing the object side is a plane, and the optical surface facing the image side bulges towards the object side;

[0010] The optical surface of the eighth lens facing the object side bulges towards the object side, and the optical surface facing the image side bulges towards the image side;

[0011] The optical surface of the ninth lens facing the object side bulges towards the image side, and the optical surface facing the image side bulges towards the image side;

[0012] The optical surface of the tenth lens facing the object side bulges towards the object side, and the optical surface facing the image side bulges towards the object side;

[0013] The optical surface of the eleventh lens facing the object side bulges towards the object side, and the optical surface facing the image side bulges towards the image side.

[0014] Preferably, the optical surface of the third lens facing the image side is an aspherical surface, and the optical surface facing the object side is a spherical surface.

[0015] Preferably, the optical surfaces of the first lens, the second lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the eighth lens, the ninth lens, the tenth lens, and the eleventh lens facing the object side and the image side are all spherical surfaces.

[0016] Preferably, the working field of view range of the lens can reach 180°, the total focal length is 1.13 mm, the F / # value is 3.5, the total length is 19.69 mm, the detectable wavelength range is 400 nm - 700 nm, and the main wavelength is 586.7 nm.

[0017] Preferably, the material of the first lens is BK7HT, with a refractive index n = 1.5163; the material of the second lens is SK4, with a refractive index n = 1.6127; the material of the third lens is SSK3, with a refractive index n = 1.6148; the material of the fourth lens is N-FK5, with a refractive index n = 1.4875; the material of the fifth lens is SF56A, with a refractive index n = 1.7847; the material of the sixth lens is P-LAF37, with a refractive index n = 1.7555; the material of the seventh lens is SF56A, with a refractive index n = 1.7847; the material of the eighth lens is N-LAF35, with a refractive index n = 1.7433; the material of the ninth lens is P-LAF37, with a refractive index n = 1.7555; the material of the tenth lens is SF56A, with a refractive index n = 1.7847; the material of the eleventh lens is N-SK16, with a refractive index n = 1.6204.

[0018] In summary, the present invention has the following beneficial effects: The fisheye lens with a 180° field of view for vehicle-mounted monitoring in the present invention uses lens one, lens two, and lens three with negative optical power to compress the object field angle, ensuring the imaging of the fisheye lens for the ultra-wide working field; the types of lens materials used in the optical system are relatively few and the number of lenses used in the design is small, only 11 lenses, thus making the manufacturing cost of the fisheye lens relatively low; in addition, an optical aspheric surface, two doublet lenses, and a triplet lens are used in the optical system to correct the aberration of the system, so that the fisheye lens has the advantages of an ultra-wide field of view, high image plane resolution, good image plane uniformity, compact structure, small size, and easy processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a schematic structural diagram of the present invention;

[0020] Figure 2 is a MTF curve graph of the present invention;

[0021] Figure 3 is a spot diagram of the present invention;

[0022] Figure 4 is a field curvature and distortion curve of the present invention;

[0023] Figure 5 is a relative illumination curve of the present invention;

[0024] Figure 6 is an optical path diagram of the present invention.

[0025] In the figure: L1, lens one; L2, lens two; L3, lens three; L4, lens four; L5, lens five; L6, lens six; L7, lens seven; L8, lens eight; L9, lens nine; L 10 , lens ten; L 11 , lens eleven. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0026] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0027] The 180° field of view fisheye lens applicable to vehicle-mounted monitoring according to the present invention comprises a total of 11 lenses. Along the optical axis direction from the object side to the image side, it successively includes lens one L1 with negative optical power, lens two L2 with negative optical power, lens three L3 with negative optical power, lens four L4 with positive optical power, lens five L5 with positive optical power, lens six L6 with negative optical power, lens seven L7 with negative optical power, lens eight L8 with positive optical power, lens nine L9 with positive optical power, lens ten L 10 and lens eleven L 11 ; the lens four L4, lens five L5 and lens six L6 form a triple cemented lens, the lens seven L7 and lens eight L8 form a double cemented lens, and the lens ten L 10 and lens eleven L 11 form a double cemented lens.

[0028] The lens one L1, lens two L2 and lens three L3 are all negative meniscus lenses, and the optical surfaces facing the object side and the image side are both convex towards the object side; the optical surface of the lens four L4 facing the object side is concave towards the object side, and the optical surface facing the image side is convex towards the object side; the optical surface of the lens five L5 facing the object side is convex towards the object side, and the optical surface facing the image side is convex towards the image side; the optical surface of the lens six L6 facing the object side is convex towards the image side, and the optical surface facing the image side is concave towards the image side; the optical surface of the lens seven L7 facing the object side is a plane, and the optical surface facing the image side is convex towards the object side; the optical surface of the lens eight L8 facing the object side is convex towards the object side, and the optical surface facing the image side is convex towards the image side; the optical surface of the lens nine L9 facing the object side is convex towards the image side, and the optical surface facing the image side is convex towards the image side; the optical surface of the lens ten L 10 facing the object side is convex towards the object side, and the optical surface facing the image side is convex towards the object side; the optical surface of the lens eleven L 11 facing the object side is convex towards the object side, and the optical surface facing the image side is convex towards the image side.

[0029] Further, the optical surface of the lens three facing the image side is an aspherical surface, and the optical surface facing the object side is a spherical surface; the optical surfaces of the lens one, lens two, lens four, lens five, lens six, lens seven, lens eight, lens nine, lens ten, and lens eleven facing the object side and the image side are all spherical surfaces.

[0030] Further, the aberration of the fisheye lens is analyzed by applying the aberration theory of the plane-symmetric optical system, and the calculation expression is:

[0031]

[0032]

[0033]

[0034]

[0035] W sph = w 400 x 4 + w 220 x 2 y 2 + w 040 y 4 (5)

[0036] W coma = w 300 x 3 + w 120 xy 2 (6)

[0037] where W sph and W coma are the meridional field curvature wave aberration, sagittal field curvature wave aberration, axial chromatic aberration wave aberration, lateral chromatic aberration wave aberration, spherical aberration wave aberration, and coma aberration wave aberration, respectively.

[0038] Applying formulas (1)-(6) for calculation and analysis, it is found that using aspherical surfaces for the optical surfaces of lens three facing the image side has a relatively obvious effect on correcting large-field aberrations and thus improving the imaging resolution.

[0039] Furthermore, the surface shape coefficients of the optical aspherical surfaces satisfy the quadratic conic surface equation, and its quadratic rotational conic surface equation is:

[0040] x′ 2 + y′ 2 = a1z′ + a2z′ 2 (7)

[0041] In expression (7), a1 = 2R0, where R0 represents the radius of curvature at the vertex of the aspherical surface curve of the optical surface of the lens, and a2 is the coefficient determining the type of the quadratic conic surface, i.e., the aspherical coefficient. When a2 > 0, it is a hyperboloid; when a2 = 0, it is a paraboloid; when -1 < a2 < 0, it is a prolate ellipsoid; when a2 = -1, it is a sphere; when a2 < -1, it is an oblate ellipsoid.

[0042] In this embodiment, the surface shape coefficient of the optical surface of lens three facing the image side is a2 = -1.065, and the surface shape coefficients of the remaining optical surfaces of lens three and the optical surfaces of all the other lenses are all -1.

[0043] The working field of view of the lens is 180°, the total focal length is 1.13 mm, the F / # value is 3.5, the total length is 19.69 mm, the detectable wavelength range is 400 nm - 700 nm, and the main wavelength is 586.7 nm.

[0044] The material of the first lens is BK7HT with a refractive index n = 1.5163; the material of the second lens is SK4 with a refractive index n = 1.6127; the material of the third lens is SSK3 with a refractive index n = 1.6148; the material of the fourth lens is N-FK5 with a refractive index n = 1.4875; the material of the fifth lens is SF56A with a refractive index n = 1.7847; the material of the sixth lens is P-LAF37 with a refractive index n = 1.7555; the material of the seventh lens is SF56A with a refractive index n = 1.7847; the material of the eighth lens is N-LAF35 with a refractive index n = 1.7433; the material of the ninth lens is P-LAF37 with a refractive index n = 1.7555; the material of the tenth lens is SF56A with a refractive index n = 1.7847; the material of the eleventh lens is N-SK16 with a refractive index n = 1.6204.

[0045] The optical surface of the third lens L3 facing the image side is an aspherical surface; the fourth lens L4, the fifth lens L5 and the sixth lens L6 form a triple cemented lens, the seventh lens L7 and the eighth lens L8 form a double cemented lens, and the tenth lens L 10 and the eleventh lens L 11 form a double cemented lens, which play a very important role in correcting the aberration of the fish-eye lens.

[0046] Figure 2 , Figure 3 , Figure 4 and Figure 5 are respectively the modulation transfer function (MTF) curve, the image point scatter diagram, the field curvature, the F-theta distortion diagram and the image plane illuminance curve diagram of the vehicle-mounted fish-eye lens. From Figure 2 and Figure 3 , it can be obtained that the imaging quality of the vehicle-mounted fish-eye lens is very high. When the working field of view ≤ 87° and there are 30 lines, the MTF values in the meridional and sagittal directions can reach more than 0.8; from Figure 4 , it can be concluded that the field curvature of the fish-eye lens is very small and the distortion also meets the usage requirements; from the relative illuminance curve of Figure 5 , it can be seen that the relative illuminance of the present invention is better.

[0047] The optical structure parameters of the vehicle-mounted fish-eye lens described in this embodiment are shown in Table 1.

[0048] Table 1 Optical structure parameters of the vehicle-mounted fish-eye lens

[0049]

[0050]

[0051]

[0052] In Table 1, along the optical axis direction from the object plane to the image plane, 1 and 2 respectively correspond to the optical surfaces of lens one (L1) facing the object side and the image side; 3 and 4 respectively correspond to the optical surfaces of lens two L2 facing the object side and the image side; 5 and 6 respectively correspond to the optical surfaces of lens three L3 facing the object side and the image side; 7 and 8 respectively correspond to the optical surfaces of lens four L4 facing the object side and the image side; 8 and 9 respectively correspond to the optical surfaces of lens five L5 facing the object side and the image side; 9 and 10 respectively correspond to the optical surfaces of lens six L6 facing the object side and the image side; 11 is the position of the aperture stop; 12 and 13 respectively correspond to the optical surfaces of lens seven L7 facing the object side and the image side; 13 and 14 respectively correspond to the optical surfaces of lens eight L8 facing the object side and the image side; 15 and 16 respectively correspond to the optical surfaces of lens nine L9 facing the object side and the image side; 17 and 18 respectively correspond to the optical surfaces of lens ten L 10 facing the object side and the image side; 18 and 19 respectively correspond to the optical surfaces of lens eleven L 11 facing the object side and the image side. Among them, lens four L4, lens five L5 and lens six L6 form a triple cemented lens. Therefore, 8 is both the optical surface of lens four L4 facing the image side and the optical surface of lens five L5 facing the object side, and 9 is both the optical surface of lens five L5 facing the image side and the optical surface of lens six L6 facing the object side; lens seven L7 and lens eight L8 form a double cemented lens. Therefore, 13 is both the optical surface of lens seven L7 facing the image side and the optical surface of lens eight L8 facing the object side; lens ten L 10 and lens eleven L 11 form a double cemented lens. Therefore, 18 is both the optical surface of lens ten L 10 facing the image side and the optical surface of lens eleven L 11 facing the object side.

[0053] Figure 6 is based on Figure 1 the optical path diagram of the on-vehicle fish-eye lens shown.

[0054] In summary, by means of the above technical solution of the invention, the image plane uniformity of the lens can be better, the imaging quality can be higher, the structure is simple and compact, and it is more convenient for processing and installation.

[0055] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principle and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A fisheye lens with a 180° field of view range that can be used for vehicle-mounted monitoring, characterized in that, From the object side to the image side along the optical axis direction, successively include lens one (L1) with negative optical power, lens two (L2) with negative optical power, lens three (L3) with negative optical power, lens four (L4) with positive optical power, lens five (L5) with positive optical power, lens six (L6) with negative optical power, lens seven (L7) with negative optical power, lens eight (L8) with positive optical power, lens nine (L9) with positive optical power, lens ten (L 10 ), lens eleven (L 11 ), where lens four (L4), lens five (L5) and lens six (L6) form a triple cemented lens, lens seven (L7) and lens eight (L8) form a double cemented lens, lens ten (L 10 ) and lens eleven (L 11 ) form a double cemented lens; Among them, lens one (L1), lens two (L2), and lens three (L3) are all negative meniscus lenses, and the optical surfaces facing the object side and the image side are both convex toward the object side; The optical surface of lens four (L4) facing the object side is concave toward the object side, and the optical surface facing the image side is convex toward the object side; The optical surface of lens five (L5) facing the object side is convex toward the object side, and the optical surface facing the image side is convex toward the image side; The optical surface of lens six (L6) facing the object side is convex toward the image side, and the optical surface facing the image side is concave toward the image side; The optical surface of lens seven (L7) facing the object side is a plane, and the optical surface facing the image side is convex toward the object side; The optical surface of lens eight (L8) facing the object side is convex toward the object side, and the optical surface facing the image side is convex toward the image side; The optical surface of lens nine (L9) facing the object side is convex toward the image side, and the optical surface facing the image side is convex toward the image side; Lens ten (L 10 ) The optical surface facing the object side bulges towards the object side, and the optical surface facing the image side bulges towards the object side; Lens eleven (L 11 ) The optical surface facing the object side bulges towards the object side, and the optical surface facing the image side bulges towards the image side; The optical surface of the said lens three (L3) facing the image side is an aspherical surface, and the optical surface facing the object side is a spherical surface; Lens 1 (L1), Lens 2 (L2), Lens 4 (L4), Lens 5 (L5), Lens 6 (L6), Lens 7 (L7), Lens 8 (L8), Lens 9 (L9), Lens 10 (L 10 ), Lens 11 (L 11 ) have spherical optical surfaces facing the object side and the image side respectively; The working field of view of the lens can reach 180°, the total focal length is 1.13 mm, the F / # value is 3.5, the total length is 19.69 mm, the detectable wavelength range is 400 nm - 700 nm, and the main wavelength is 586.7 nm; The material of the first lens (L1) is BK7HT with a refractive index n = 1.5163; the material of the second lens (L2) is SK4 with a refractive index n = 1.6127; the material of the third lens (L3) is SSK3 with a refractive index n = 1.6148; the material of the fourth lens (L4) is N-FK5 with a refractive index n = 1.4875; the material of the fifth lens (L5) is SF56A with a refractive index n = 1.7847; the material of the sixth lens (L6) is P-LAF37 with a refractive index n = 1.7555; the material of the seventh lens (L7) is SF56A with a refractive index n = 1.7847; the material of the eighth lens (L8) is N-LAF35 with a refractive index n = 1.7433; the material of the ninth lens (L9) is P-LAF37 with a refractive index n = 1.7555; the material of the tenth lens (L 10 ) is SF56A with a refractive index n = 1.7847; the eleventh lens (L 11 ) is N-SK16 with a refractive index n = 1.6204.

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