A fisheye lens

Abstract

This invention discloses a fisheye lens, comprising lenses numbered from negative to positive to positive to negative to positive to negative to positive to negative to positive, with the first lens being closest to the object side. 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 concave. The object-side surface of the third lens is convex. Both the object-side and image-side surfaces of the fourth lens are convex. The object-side surface of the fifth lens is convex, and the image-side surface is concave. Both the object-side and image-side surfaces of the sixth lens are convex. The object-side surface of the seventh lens is concave, and the image-side surface is convex. The object-side surface of the eighth lens is convex, and the image-side surface is concave. The first, fourth, fifth, sixth, and seventh lenses are all glass spherical lenses. The third and eighth lenses are both plastic aspherical lenses. The second lens is either a plastic aspherical lens or a glass aspherical lens. Using this design, a high-throughput, large-area, and high-image-quality infrared confocal fisheye lens can be achieved.

Description

Technical Field

[0001] This invention relates to the field of lens technology, and more particularly to a fisheye lens. Background Technology

[0002] Fisheye lenses, due to their wide field of view, are now widely used in security monitoring, automotive applications, and other fields. Therefore, the requirements for fisheye lenses are becoming increasingly stringent.

[0003] However, fisheye lenses currently on the market still have shortcomings such as small aperture and small target surface. For example, patent CN117555118A has a maximum aperture of 1.8 and a maximum imaging circle diameter of 7mm, which cannot match a larger imaging target surface, and it is necessary to improve it. Summary of the Invention

[0004] This invention provides a fisheye lens that enables the design of an infrared confocal fisheye lens with large light transmission, large target area, and high image quality.

[0005] According to the present invention, a fisheye lens is provided, comprising: a first lens having negative optical power, a second lens having negative optical power, a third lens having positive optical power, a fourth lens having positive optical power, a fifth lens having negative optical power, a sixth lens having positive optical power, a seventh lens having negative optical power, and an eighth lens having positive optical power, arranged sequentially along the optical axis from the object side to the image side.

[0006] The object-side surface of the first lens is convex, and the image-side surface of the first lens is concave.

[0007] The object-side surface of the second lens is concave.

[0008] The object-side surface of the third lens is convex.

[0009] The object-side surface of the fourth lens is convex, and the image-side surface of the fourth lens is convex.

[0010] The object-side surface of the fifth lens is convex, and the image-side surface of the fifth lens is concave.

[0011] The object-side surface of the sixth lens is convex, and the image-side surface of the sixth lens is convex.

[0012] The object-side surface of the seventh lens is concave, and the image-side surface of the seventh lens is convex.

[0013] The object-side surface of the eighth lens is convex, and the image-side surface of the eighth lens is concave.

[0014] Wherein, the first lens, the fourth lens, the fifth lens, the sixth lens and the seventh lens are all glass spherical lenses;

[0015] Both the third lens and the eighth lens are plastic aspherical lenses;

[0016] The second lens is a plastic aspherical lens or a glass aspherical lens.

[0017] Optionally, the fifth lens, the sixth lens, and the seventh lens are cemented together to form a cemented triplet lens group.

[0018] Optionally, -0.53 ≤ Φ1 / Φ ≤ -0.43;

[0019] Wherein, Φ1 is the optical power of the first lens; Φ is the overall optical power of the fisheye lens.

[0020] Optional, -0.20≤L2S h / L2S t ≤0.14; L3S h / L3S t ≥0.01;

[0021] -0.48≤Φ2 / Φ≤-0.39;0.21≤Φ3 / Φ≤0.30;0.39≤Φ4 / Φ≤0.47;

[0022] Among them, L2S h L2S is the half-aperture sagittal of the image-side surface of the second lens. t L3S is the full aperture sagitta of the image-side surface of the second lens. h L3S is the half-aperture sagittal of the image-side surface of the third lens. t The full aperture sagitta of the image-side surface of the third lens;

[0023] Φ2 is the optical power of the second lens; Φ3 is the optical power of the third lens; Φ4 is the optical power of the fourth lens; and Φ is the overall optical power of the fisheye lens.

[0024] Optionally, -0.30≤Φ5 / Φ≤-0.18; 0.47≤Φ6 / Φ≤0.75; -0.55≤Φ7 / Φ≤-0.31;

[0025] Wherein, Φ5 is the optical power of the fifth lens; Φ6 is the optical power of the sixth lens; Φ7 is the optical power of the seventh lens; and Φ is the overall optical power of the fisheye lens.

[0026] Optional, 1.68 <Nd1<1.82,25<Vd1<60;

[0027] Wherein, Nd1 is the refractive index of the first lens, and Vd1 is the Abbe number of the first lens.

[0028] Optional, 50 <Vd2<58;17<Vd3<32;46<Vd4<74;

[0029] Wherein, Vd2 is the Abbe number of the second lens; Vd3 is the Abbe number of the third lens; and Vd4 is the Abbe number of the fourth lens.

[0030] Optional, 1.73 <Nd5<1.93;1.43<Nd6<1.52;-68<Vd5-Vd6+Vd7<2;

[0031] Wherein, Nd5 is the refractive index of the fifth lens, and Nd6 is the refractive index of the sixth lens;

[0032] Vd5 is the Abbe number of the fifth lens, Vd6 is the Abbe number of the sixth lens, and Vd7 is the Abbe number of the seventh lens.

[0033] Optional, 17 <Vd8<41;

[0034] Wherein, Vd8 is the Abbe number of the eighth lens.

[0035] Optionally, 0.09 ≤ SD1 / TTL*Sinθ / H ≤ 0.12;

[0036] Wherein, SD1 is the effective half-aperture of the light rays on the object side of the first lens; TTL is the total optical length of the fisheye lens from the vertex of the object side of the first lens to the image plane; and θ is the angle corresponding to the maximum half-image height that the fisheye lens can achieve.

[0037] The technical solution of this invention has the optical power of the first to eighth lenses in the order of negative-negative-positive-positive-negative-positive-negative-positive. By setting the optical power, position, shape and material of each lens in a reasonable way, the design of an infrared confocal fisheye lens with large light transmission, large target surface and high image quality can be realized. Finally, a fisheye lens with an aperture of 1.6 and an optical length of no more than 33.85mm can be achieved. The imaging target surface can be matched with a 1 / 1.6-inch 4K chip, which can match a larger imaging target surface, so as to make full use of the edge field of view of the fisheye lens and capture a more extreme field of view and more light information.

[0038] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of the present invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0039] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0040] Figure 1 This is a schematic diagram of the structure of a fisheye lens provided in Embodiment 1 of the present invention;

[0041] Figure 2 yes Figure 1 The spherical aberration curve of the fisheye lens is shown below;

[0042] Figures 3 to 12 yes Figure 1 The image shows the fan pattern of the fisheye lens;

[0043] Figure 13 yes Figure 1 The field curvature distortion curve of the fisheye lens is shown.

[0044] Figure 14 This is a schematic diagram of the structure of a fisheye lens provided in Embodiment 2 of the present invention;

[0045] Figure 15 yes Figure 14 The spherical aberration curve of the fisheye lens is shown below;

[0046] Figures 16 to 25 yes Figure 14 The image shows the fan pattern of the fisheye lens;

[0047] Figure 26 yes Figure 14 The field curvature distortion curve of the fisheye lens is shown.

[0048] Figure 27 This is a schematic diagram of the structure of a fisheye lens provided in Embodiment 3 of the present invention;

[0049] Figure 28 yes Figure 27 The spherical aberration curve of the fisheye lens is shown below;

[0050] Figures 29 to 38 yes Figure 27 The image shows the fan pattern of the fisheye lens;

[0051] Figure 39 yes Figure 27 The field curvature distortion curve of the fisheye lens is shown.

[0052] Figure 40 This is a schematic diagram of the structure of a fisheye lens provided in Embodiment 4 of the present invention;

[0053] Figure 41 yes Figure 40 The spherical aberration curve of the fisheye lens is shown below;

[0054] Figures 42 to 51 yes Figure 40 The image shows the fan pattern of the fisheye lens;

[0055] Figure 52 yes Figure 40 The field curvature distortion curve of the fisheye lens is shown.

[0056] Figure 53 This is a schematic diagram of the structure of a fisheye lens provided in Embodiment 5 of the present invention;

[0057] Figure 54 yes Figure 53 The spherical aberration curve of the fisheye lens is shown below;

[0058] Figures 55 to 64 yes Figure 53 The image shows the fan pattern of the fisheye lens;

[0059] Figure 65 yes Figure 53 The field curvature distortion curve of the fisheye lens is shown. Detailed Implementation

[0060] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0061] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0062] Example 1

[0063] Figure 1This is a schematic diagram of the structure of a fisheye lens provided in Embodiment 1 of the present invention, for reference. Figure 1 The fisheye lens includes a first lens L1 with negative optical power, a second lens L2 with negative optical power, a third lens L3 with positive optical power, a fourth lens L4 with positive optical power, a fifth lens L5 with negative optical power, a sixth lens L6 with positive optical power, a seventh lens L7 with negative optical power, and an eighth lens L8 with positive optical power, arranged sequentially along the optical axis from the object side to the image side. The object-side surface of the first lens L1 is convex, and the image-side surface of the first lens L1 is concave; the object-side surface of the second lens L2 is concave; the object-side surface of the third lens L3 is convex; the object-side surface of the fourth lens L4 is convex, and the image-side surface of the fourth lens L4 is convex; the object-side surface of the fifth lens L5 is convex, and the image-side surface of the fifth lens L5 is concave; the object-side surface of the sixth lens L6 is convex, and the image-side surface of the sixth lens L6 is convex; the object-side surface of the seventh lens L7 is concave, and the image-side surface of the seventh lens L7 is convex; the object-side surface of the eighth lens L8 is convex, and the image-side surface of the eighth lens L8 is concave; wherein, the first lens L1, the fourth lens L4, the fifth lens L5, the sixth lens L6, and the seventh lens L7 are all glass spherical lenses; the third lens L3 and the eighth lens L8 are both plastic aspherical lenses; and the second lens L2 is either a plastic aspherical lens or a glass aspherical lens.

[0064] Optical power is equal to the difference between the convergence of the image-side beam and the convergence of the object-side beam; it characterizes the ability of an optical system to deflect light. The larger the absolute value of the optical power, the stronger its ability to bend light; the smaller the absolute value, the weaker its ability to bend light. When the optical power is positive, the refraction of light is converging; when the optical power is negative, the refraction of light is diverging. Optical power can be used to characterize a single refractive surface of a lens (i.e., one surface of the lens), a single lens, or a system of multiple lenses (i.e., a lens group).

[0065] Specifically, each lens from the first lens L1 to the eighth lens L8 can be fixed in a single lens barrel. Figure 1(Not shown) By setting the optical power of the first lens L1 to a negative value, a larger field of view can be achieved, and the light entering the first lens L1 can smoothly enter the subsequent optical system, reducing the proportion of higher-order aberrations. Setting the optical power of the second lens L2 to a negative value results in a smaller angle of deflection of the light passing through the first lens L1 after passing through the second lens L2, which is beneficial for the correction of system aberrations. Setting the optical power of the third lens L3 and the fourth lens L4 to positive values ​​allows the light passing through the first lens L1 and the second lens L2 to transition slowly through the third lens L3 and the fourth lens L4 into the subsequent optical system, thereby enabling... One-step correction of system aberrations helps reduce assembly tolerances between lenses, simplifies the assembly of the entire optical system, and improves the assemblability of the entire optical system. By setting the optical power of the fifth lens L5 to a negative value, the sixth lens L6 to a positive value, the seventh lens L7 to a negative value, and the eighth lens L8 to a positive value, the lenses with positive optical power cooperate with the lenses with negative optical power. This ensures that the light reaches the image plane smoothly while further correcting system aberrations, resulting in high imaging quality under ambient light of different brightness levels, while meeting the imaging requirements of large light transmission, large target area, and high image quality.

[0066] The first lens L1 allows object-side rays to enter the fisheye lens's optical system, enabling the light to enter the second lens L2 at a smaller incident angle, thus reducing the proportion of higher-order aberrations. The second lens L2 effectively narrows the ray angle, reducing aberrations and improving the image quality of the fisheye lens. The third lens L3 and the fourth lens L4 further smooth out the ray deflection angle, allowing for more relaxed assembly tolerances in the optical system, which is beneficial for improving production yield. The fifth lens L5, the sixth lens L6, and the seventh lens L7 work together to facilitate the correction of system aberrations. The eighth lens L8 enables the fisheye lens to reach the target image height, achieving a large target surface, and also facilitates system aberration correction. By optimizing the power distribution, position, and shape of each lens element, both imaging requirements and structural compactness can be achieved.

[0067] The fisheye lens provided in this embodiment of the invention comprises eight lenses, which can be five glass spherical lenses and three plastic aspherical lenses, or a hybrid combination of five glass spherical lenses, one glass aspherical lens, and two plastic aspherical lenses. This combination allows for better aberration correction, ensures sufficiently good image quality, and provides high imaging resolution. Furthermore, this fisheye lens can be paired with 4K, 1 / 1.6-inch type chips, making it widely applicable. Additionally, the first lens L1 is made of glass, which protects the entire optical system and provides more stable optical performance. The use of glass lenses for the fourth lens L4, fifth lens L5, sixth lens L6, and seventh lens L7 enables the fisheye lens to maintain good resolution over a relatively wide temperature range. Glass lenses also play a good role in correcting chromatic aberration in the fisheye lens. Therefore, through the cooperation of the fourth lens L4, fifth lens L5, sixth lens L6, and seventh lens L7, the fisheye lens's ability to correct infrared wavelengths can be significantly improved, achieving infrared confocality and meeting the needs of more application scenarios.

[0068] The second lens L2 can be a plastic aspherical lens or a glass aspherical lens. In an optional embodiment, when the second lens L2 is a glass aspherical lens, the first lens L1 can be designed to be detachable to meet special functional requirements, such as protection (the first lens L1 as a sacrificial component), functional expansion (filter replacement), environmental adaptation, etc. When the first lens L1 is detached, the second lens L2 being a glass aspherical lens is beneficial to the reliability, durability, and image quality stability of the entire fisheye lens.

[0069] For example, refer to Figure 1 The fisheye lens also includes an aperture stop STO and a filter L0. The aperture stop STO can be located between the second lens L2 and the third lens L3, and the filter L0 is located on the side of the eighth lens L8 away from the seventh lens L7. By placing the aperture stop STO in front and allocating optical power, an effective chromatic aberration correction unit can be formed, achieving high light transmission capability, large target area coverage, relatively compact size, and excellent optical performance (especially wide-band confocal) in the infrared band.

[0070] In embodiments of the present invention, the optical power of the first to eighth lenses is negative-negative-positive-positive-negative-positive-negative-positive. By setting the above, and rationally matching the optical power, position, shape and material of each lens, a design for an infrared confocal fisheye lens with large light transmission, large target surface and high image quality can be achieved. Ultimately, a fisheye lens with an aperture of f / 1.6, an optical length of no more than 33.85 mm, and an imaging target surface that can be matched with a 1 / 1.6-inch 4K chip can be achieved. It can match a larger imaging target surface to make full use of the edge field of view of the fisheye lens and capture a more extreme field of view and more light information.

[0071] Optionally, the fifth lens L5, the sixth lens L6, and the seventh lens L7 can be cemented together to form a cemented triplet lens group.

[0072] Specifically, the cemented lens group composed of the fifth lens L5, the sixth lens L6, and the seventh lens L7 can control the chromatic aberration of the fisheye lens to the greatest extent, ensure the imaging quality in nighttime infrared conditions, and expand the application range of the fisheye lens.

[0073] Optionally, -0.53≤Φ1 / Φ≤-0.43; where Φ1 is the optical power of the first lens L1; and Φ is the overall optical power of the fisheye lens.

[0074] Specifically, the object side of the first lens L1 is designed as a convex surface to converge light into the system, while the image side is designed as a concave surface to allow light to enter the system at a smaller deflection angle. At the same time, setting the optical power of the first lens L1 within the aforementioned range enables light to be converged into the system as much as possible, which is beneficial for achieving the fisheye lens angle.

[0075] Optional, -0.20≤L2S h / L2S t ≤0.14; L3S h / L3S t ≥0.01; -0.48≤Φ2 / Φ≤-0.39; 0.21≤Φ3 / Φ≤0.30; 0.39≤Φ4 / Φ≤0.47; where L2S h L2S is the half-aperture sagitta of the image-side surface of the second lens L2. t L3S is the full aperture sagitta of the image-side surface of the second lens L2; h L3S is the half-aperture sagitta of the image-side surface of the third lens L3. t Φ1 is the full aperture sagitta of the image side of the third lens L3; Φ2 is the optical power of the second lens L2; ​​Φ3 is the optical power of the third lens L3; Φ4 is the optical power of the fourth lens L4; and Φ is the overall optical power of the fisheye lens.

[0076] Thus, by controlling the shape of the image side of the second lens L2 and the third lens L3, and when the optical power of the second lens L2, the third lens L3, and the fourth lens L4 are within the above range, the direction of light can be effectively controlled, which is beneficial for the use of fisheye lenses at high and low temperatures and for achieving a large aperture.

[0077] Optionally, -0.30 ≤ Φ5 / Φ ≤ -0.18; 0.47 ≤ Φ6 / Φ ≤ 0.75; -0.55 ≤ Φ7 / Φ ≤ -0.31; where Φ5 is the optical power of the fifth lens L5, Φ6 is the optical power of the sixth lens L6, Φ7 is the optical power of the seventh lens L7, and Φ is the overall optical power of the fisheye lens. With this optical power ratio, it is beneficial to correct the chromatic aberration and other aberrations of the system, thereby facilitating the realization of infrared confocal of the system and improving the image quality of the system.

[0078] Optionally, 1.68 < Nd1 < 1.82, 25 < Vd1 < 60; where Nd1 is the refractive index of the first lens L1 and Vd1 is the Abbe number of the first lens L1. In this way, it can ensure that the system can pass light rays at large angles and is beneficial to reducing the aperture of the lens, thereby facilitating the reduction of the overall volume of the lens.

[0079] Optionally, 50 < Vd2 < 58; 17 < Vd3 < 32; 46 < Vd4 < 74; where Vd2 is the Abbe number of the second lens L2, Vd3 is the Abbe number of the third lens L3, and Vd4 is the Abbe number of the fourth lens L4. In this way, it can ensure the material combination of the system, thereby ensuring the chromatic aberration of the system and the smooth turning of light rays, thus ensuring the assembly tolerance. And through the combination with the optical power, it can reduce the astigmatism and field curvature of the optical system and improve the image quality of the optical system.

[0080] Optionally, 1.73 < Nd5 < 1.93; 1.43 < Nd6 < 1.52; -68 < Vd5 - Vd6 + Vd7 < 2; where Nd5 is the refractive index of the fifth lens L5, Nd6 is the refractive index of the sixth lens L6; Vd5 is the Abbe number of the fifth lens L5, Vd6 is the Abbe number of the sixth lens L6, and Vd7 is the Abbe number of the seventh lens L7. With this material combination, it is beneficial to correct the chromatic aberration and other aberrations of the system, thereby facilitating the realization of infrared confocal of the system and improving the image quality of the system.

[0081] Optionally, 17 < Vd8 < 41; where Vd8 is the Abbe number of the eighth lens L8. In this way, combined with the shape of the eighth lens L8, it is beneficial to the realization of a large target surface of the optical system and the correction of the field curvature and astigmatism of the system.

[0082] Optionally, 0.09 ≤ SD1 / TTL*Sinθ / H ≤ 0.12; where SD1 is the effective radius semi-aperture of the light rays on the object side of the first lens L1, TTL is the overall optical length of the fisheye lens from the vertex of the object side of the first lens L1 to the image plane, and θ is the angle corresponding to the maximum semi-image height that the fisheye lens can reach. In this way, it can ensure the angle of the lens and the realization of the target surface, and at the same time control the aperture size of the first lens L1 and the overall length of the lens, so as to meet the assembly requirements of the structure.

[0083] In summary, by rationally allocating parameters such as the material, optical power, center thickness of each lens, and on-axis spacing between each lens, the aberrations of the fisheye lens in the wavelength range of 436–850 nm can be reasonably corrected and balanced, achieving beneficial effects such as large light transmission, large target surface, high image quality, infrared confocality, and large angle.

[0084] In one feasible embodiment, Table 1 details a feasible implementation method. Figure 1 The specific optical physical parameters of the fisheye lens are shown.

[0085] Table 1. Physical parameter design of the fisheye lens in Example 1

[0086]

[0087] In this embodiment, the focal length f is 3.955mm, the aperture F# is 1.598, and the angle corresponding to the fisheye head height φ10.3mm is 182.36°.

[0088] Table 2 shows the design parameters of a fisheye lens, including lens surface type, radius of curvature, thickness, and material, which correspond to those in Table 1.

[0089] Table 2. Parameter design of each lens in the fisheye lens in Example 1.

[0090]

[0091] The fisheye lens provided in this embodiment includes a first lens L1, a second lens L2, an aperture stop STO, 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 filter L0 arranged sequentially along the optical axis from the object side to the image side. The surface numbers in Table 2 are assigned according to the surface sequence of each lens. "OBJ" represents the object plane of the fisheye lens; "STO" represents the aperture of the fisheye lens; "IMA" represents the image plane of the fisheye lens; the radius of curvature represents the curvature of the lens surface, with a positive value indicating that the surface bends towards the image plane and a negative value indicating that the surface bends towards the object plane. "Infinity" indicates that the surface is flat, with an infinite radius of curvature and an infinite distance; the thickness represents the central axial distance between the current surface and the next surface; the refractive index represents the ability of the material between the current surface and the next surface to deflect light, with a blank space indicating that the current position is air and the refractive index is 1; the Abbe number represents the dispersion characteristics of the material between the current surface and the next surface, with a blank space indicating that the current position is air; half-aperture represents the effective diameter of the lens; and the k-value represents the magnitude of the conic coefficient of the aspherical surface. This represents the relative dispersion deviation compared to normal glass.

[0092] Among them, the relative partial dispersion of the lens wavelengths x and y or Expressed as follows:

[0093] ;

[0094] ;

[0095] in, It is the refractive index of the lens measured at wavelength x. It is the refractive index of the lens measured at the y-wavelength. The refractive index of the lens is measured at the wavelength of the hydrogen blue line (486.13 nm). The refractive index of the lens is measured at the hydrogen red line wavelength (656.27 nm). The refractive index of the lens is measured at the wavelength of the cadmium blue line (479.99 nm). The refractive index of the lens is measured at the cadmium red line wavelength (643.85nm); This refers to the relative partial dispersion of the lens at the wavelengths of the mercury blue line and the hydrogen blue line. This represents the relative partial dispersion of the lens at the wavelengths of the mercury blue line and the cadmium blue line.

[0096] According to Abbe's formula, the following linear relationship holds for most so-called "normal glass":

[0097] ;

[0098] in, The Abbe number of the lens. The slope The intercept is used to define the linear relationship. The vertical axis is , It is represented by the horizontal axis.

[0099] Understandably, correction of the second-order spectrum, i.e., achromatic correction of more than two wavelengths, requires at least one type of glass that does not conform to the above formula (i.e., its... The value deviates from Abbe's empirical formula), and the deviation is used to... This means that each The point has been translated relative to the "normal line" that conforms to the above formula. Quantity. Thus, the lens's... The value can be obtained using the following formula:

[0100] ;

[0101] therefore, It quantitatively represents the deviation of the special dispersion characteristics compared to "normal glass". The calculation formula is as follows:

[0102] .

[0103] In this embodiment, the aspherical conic coefficient of the fisheye lens can be defined by the following aspherical formula, but is not limited to the following representation:

[0104] ;

[0105] Where z is the axial sagitta in the Z direction of the aspherical surface; r is the height of the aspherical surface; c is the curvature of the fitted sphere, which is numerically the reciprocal of the radius of curvature; k is the coefficient of the fitted cone; A, B, C, D, E, and F are the coefficients of the 4th, 6th, 8th, 10th, 12th, and 14th order terms of the aspherical polynomial, respectively.

[0106] Table 3 Aspheric coefficients of fisheye lenses in Example 1

[0107]

[0108] Where -4.33933E-03 indicates that the coefficient A of surface number S4 is... .

[0109] Figure 2 yes Figure 1 The spherical aberration curve of the fisheye lens shown is as follows: Figure 2 The axial aberration curves shown have the following dimensions: the vertical direction represents the normalized aperture (0 indicates on the optical axis), and the vertical vertex represents the maximum pupil radius; the horizontal direction represents the offset relative to the ideal focal point, in millimeters (mm). Different linear curves in the figure represent different wavelengths of the system imaging, determined by... Figure 2 It can be seen that the axial aberrations at different wavelengths are all controlled within the range of (-0.05mm, +0.05mm), indicating that the spherical aberration of the fisheye lens at each wavelength is well controlled and can meet the requirements of wide spectrum applications.

[0110] Figures 3 to 12 yes Figure 1 The fan pattern of the fisheye lens shown is as follows: Figures 3 to 12 As shown, the horizontal axis represents the beam aperture, and the vertical axis represents the transverse aberration. The fan diagram is one of the most commonly used evaluation methods in modern optical design. The ideal curve is a straight line coinciding with the horizontal axis, indicating that all rays converge at the same point on the image plane. The interval on the vertical axis of the curve represents the maximum dispersion range of the beam on the ideal image plane. The fan diagram can reflect not only monochromatic aberrations of different wavelengths but also the magnitude of transverse chromatic aberration. Figures 3 to 12It can be seen that the system closely approximates the horizontal axis at each wavelength in each field of view, indicating that the transverse aberration of each wavelength is well corrected. At the same time, there is no obvious dispersion of each wavelength, indicating that the chromatic aberration of the system is also well corrected, thus ensuring that the optical system can achieve the high-resolution imaging requirements.

[0111] Figure 13 yes Figure 1 The field curvature distortion curve of the fisheye lens shown is as follows: Figure 13 As shown, in the coordinate system on the left, the horizontal coordinate represents the magnitude of the field curvature, in mm; the vertical coordinate represents the normalized image height, which has no unit; where T represents the meridion and S represents the sagitta; from Figure 13 As can be seen, the fisheye lens provided in this embodiment effectively controls the field curvature from light with wavelengths from 436nm to 850nm, meaning that during imaging, the difference in image quality between the center and the periphery is small. In the coordinate system on the right, the horizontal axis represents the magnitude of distortion, expressed as a percentage; the vertical axis represents the normalized image height, which has no unit; from Figure 13 It can be seen that the distortion of the fisheye lens provided in this embodiment has been well corrected.

[0112] Example 2

[0113] Figure 14 This is a schematic diagram of the structure of a fisheye lens provided in Embodiment 2 of the present invention. The similarities with the above embodiments will not be repeated here.

[0114] In one feasible embodiment, Table 4 details a feasible implementation method. Figure 14 The specific optical physical parameters of the fisheye lens are shown.

[0115] Table 4. Physical parameter design of the fisheye lens in Example 2

[0116]

[0117] In this embodiment, the focal length f is 3.888mm, the aperture F# is 1.594, and the angle corresponding to the fisheye head height φ10.3mm is 182.10°.

[0118] Table 5 shows the design parameters of a fisheye lens, including lens surface type, radius of curvature, thickness, and material, which correspond to those in Table 4.

[0119] Table 5. Parameter design of each lens in the fisheye lens in Example 2.

[0120]

[0121] The fisheye lens provided in this embodiment includes a first lens L1, a second lens L2, an aperture stop STO, 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 filter L0 arranged sequentially along the optical axis from the object side to the image side. The surface numbers in Table 2 are assigned according to the surface sequence of each lens. "OBJ" represents the object plane of the fisheye lens; "STO" represents the aperture of the fisheye lens; "IMA" represents the image plane of the fisheye lens; the radius of curvature represents the curvature of the lens surface, with a positive value indicating that the surface bends towards the image plane and a negative value indicating that the surface bends towards the object plane. "Infinity" indicates that the surface is flat, with an infinite radius of curvature and an infinite distance; the thickness represents the central axial distance between the current surface and the next surface; the refractive index represents the ability of the material between the current surface and the next surface to deflect light, with a blank space indicating that the current position is air and the refractive index is 1; the Abbe number represents the dispersion characteristics of the material between the current surface and the next surface, with a blank space indicating that the current position is air; half-aperture represents the effective diameter of the lens; and the k-value represents the magnitude of the conic coefficient of the aspherical surface. This represents the relative dispersion deviation compared to normal glass.

[0122] Among them, the relative partial dispersion of the lens wavelengths x and y or Expressed as follows:

[0123] ;

[0124] ;

[0125] in, It is the refractive index of the lens measured at wavelength x. It is the refractive index of the lens measured at the y-wavelength. The refractive index of the lens is measured at the wavelength of the hydrogen blue line (486.13 nm). The refractive index of the lens is measured at the hydrogen red line wavelength (656.27 nm). The refractive index of the lens is measured at the wavelength of the cadmium blue line (479.99 nm). The refractive index of the lens is measured at the cadmium red line wavelength (643.85nm); This refers to the relative partial dispersion of the lens at the wavelengths of the mercury blue line and the hydrogen blue line. This represents the relative partial dispersion of the lens at the wavelengths of the mercury blue line and the cadmium blue line.

[0126] According to Abbe's formula, the following linear relationship holds for most so-called "normal glass":

[0127] ;

[0128] in, The Abbe number of the lens. The slope The intercept is used to define the linear relationship. The vertical axis is , It is represented by the horizontal axis.

[0129] Understandably, correction of the second-order spectrum, i.e., achromatic correction of more than two wavelengths, requires at least one type of glass that does not conform to the above formula (i.e., its... The value deviates from Abbe's empirical formula), and the deviation is used to... This means that each The point has been translated relative to the "normal line" that conforms to the above formula. Quantity. Thus, the lens's... The value can be obtained using the following formula:

[0130] ;

[0131] therefore, It quantitatively represents the deviation of the special dispersion characteristics compared to "normal glass". The calculation formula is as follows:

[0132] .

[0133] In this embodiment, the aspherical conic coefficient of the fisheye lens can be defined by the following aspherical formula, but is not limited to the following representation:

[0134] ;

[0135] Where z is the axial sagitta in the Z direction of the aspherical surface; r is the height of the aspherical surface; c is the curvature of the fitted sphere, which is numerically the reciprocal of the radius of curvature; k is the coefficient of the fitted cone; A, B, C, D, E, and F are the coefficients of the 4th, 6th, 8th, 10th, 12th, and 14th order terms of the aspherical polynomial, respectively.

[0136] Table 6 Aspheric coefficients of fisheye lenses in Example 2

[0137]

[0138] Where -4.24154E-03 indicates that the coefficient A of surface number S4 is... .

[0139] Figure 15 yes Figure 14 The spherical aberration curve of the fisheye lens shown is as follows: Figure 15The axial aberration curves shown have the following dimensions: the vertical direction represents the normalized aperture (0 indicates on the optical axis), and the vertical vertex represents the maximum pupil radius; the horizontal direction represents the offset relative to the ideal focal point, in millimeters (mm). Different linear curves in the figure represent different wavelengths of the system imaging, determined by... Figure 15 It can be seen that the axial aberrations at different wavelengths are all controlled within the range of (-0.05mm, +0.05mm), indicating that the spherical aberration of the fisheye lens at each wavelength is well controlled and can meet the requirements of wide spectrum applications.

[0140] Figures 16 to 25 yes Figure 14 The fan pattern of the fisheye lens shown is as follows: Figures 16 to 25 As shown, the horizontal axis represents the beam aperture, and the vertical axis represents the transverse aberration. The fan diagram is one of the most commonly used evaluation methods in modern optical design. The ideal curve is a straight line coinciding with the horizontal axis, indicating that all rays converge at the same point on the image plane. The interval on the vertical axis of the curve represents the maximum dispersion range of the beam on the ideal image plane. The fan diagram can reflect not only monochromatic aberrations of different wavelengths but also the magnitude of transverse chromatic aberration. Figures 16 to 25 It can be seen that the system closely approximates the horizontal axis at each wavelength in each field of view, indicating that the transverse aberration of each wavelength is well corrected. At the same time, there is no obvious dispersion of each wavelength, indicating that the chromatic aberration of the system is also well corrected, thus ensuring that the optical system can achieve the high-resolution imaging requirements.

[0141] Figure 26 yes Figure 14 The field curvature distortion curve of the fisheye lens shown is as follows: Figure 26 As shown, in the coordinate system on the left, the horizontal coordinate represents the magnitude of the field curvature, in mm; the vertical coordinate represents the normalized image height, which has no unit; where T represents the meridion and S represents the sagitta; from Figure 26 As can be seen, the fisheye lens provided in this embodiment effectively controls the field curvature from light with wavelengths from 436nm to 850nm, meaning that during imaging, the difference in image quality between the center and the periphery is small. In the coordinate system on the right, the horizontal axis represents the magnitude of distortion, expressed as a percentage; the vertical axis represents the normalized image height, which has no unit; from Figure 26 It can be seen that the distortion of the fisheye lens provided in this embodiment has been well corrected.

[0142] Example 3

[0143] Figure 27 This is a schematic diagram of the structure of a fisheye lens provided in Embodiment 3 of the present invention. The similarities with the above embodiments will not be repeated here.

[0144] In one feasible embodiment, Table 7 details a feasible implementation method. Figure 27The specific optical physical parameters of the fisheye lens are shown.

[0145] Table 7. Physical parameter design of the fisheye lens in Example 3.

[0146]

[0147] In this embodiment, the focal length f is 3.771mm, the aperture F# is 1.594, and the angle corresponding to the fisheye head height φ10.3mm is 181.50°.

[0148] Table 8 shows the design parameters of a fisheye lens, including lens surface type, radius of curvature, thickness, and material, corresponding to those in Table 7.

[0149] Table 8. Parameter design of each lens in the fisheye lens in Example 3.

[0150]

[0151] The fisheye lens provided in this embodiment includes a first lens L1, a second lens L2, an aperture stop STO, 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 filter L0 arranged sequentially along the optical axis from the object side to the image side. The surface numbers in Table 2 are assigned according to the surface sequence of each lens. "OBJ" represents the object plane of the fisheye lens; "STO" represents the aperture of the fisheye lens; "IMA" represents the image plane of the fisheye lens; the radius of curvature represents the curvature of the lens surface, with a positive value indicating that the surface bends towards the image plane and a negative value indicating that the surface bends towards the object plane. "Infinity" indicates that the surface is flat, with an infinite radius of curvature and an infinite distance; the thickness represents the central axial distance between the current surface and the next surface; the refractive index represents the ability of the material between the current surface and the next surface to deflect light, with a blank space indicating that the current position is air and the refractive index is 1; the Abbe number represents the dispersion characteristics of the material between the current surface and the next surface, with a blank space indicating that the current position is air; half-aperture represents the effective diameter of the lens; and the k-value represents the magnitude of the conic coefficient of the aspherical surface. This represents the relative dispersion deviation compared to normal glass.

[0152] Among them, the relative partial dispersion of the lens wavelengths x and y or Expressed as follows:

[0153] ;

[0154] ;

[0155] in, It is the refractive index of the lens measured at wavelength x. It is the refractive index of the lens measured at the y-wavelength. The refractive index of the lens is measured at the wavelength of the hydrogen blue line (486.13 nm). The refractive index of the lens is measured at the hydrogen red line wavelength (656.27 nm). The refractive index of the lens is measured at the wavelength of the cadmium blue line (479.99 nm). The refractive index of the lens is measured at the cadmium red line wavelength (643.85nm); This refers to the relative partial dispersion of the lens at the wavelengths of the mercury blue line and the hydrogen blue line. This represents the relative partial dispersion of the lens at the wavelengths of the mercury blue line and the cadmium blue line.

[0156] According to Abbe's formula, the following linear relationship holds for most so-called "normal glass":

[0157] ;

[0158] in, The Abbe number of the lens. The slope The intercept is used to define the linear relationship. The vertical axis is , It is represented by the horizontal axis.

[0159] Understandably, correction of the second-order spectrum, i.e., achromatic correction of more than two wavelengths, requires at least one type of glass that does not conform to the above formula (i.e., its... The value deviates from Abbe's empirical formula), and the deviation is used to... This means that each The point has been translated relative to the "normal line" that conforms to the above formula. Quantity. Thus, the lens's... The value can be obtained using the following formula:

[0160] ;

[0161] therefore, It quantitatively represents the deviation of the special dispersion characteristics compared to "normal glass". The calculation formula is as follows:

[0162] .

[0163] In this embodiment, the aspherical conic coefficient of the fisheye lens can be defined by the following aspherical formula, but is not limited to the following representation:

[0164] ;

[0165] Where z is the axial sagitta in the Z direction of the aspherical surface; r is the height of the aspherical surface; c is the curvature of the fitted sphere, which is numerically the reciprocal of the radius of curvature; k is the coefficient of the fitted cone; A, B, C, D, E, and F are the coefficients of the 4th, 6th, 8th, 10th, 12th, and 14th order terms of the aspherical polynomial, respectively.

[0166] Table 9 Aspheric coefficients of fisheye lenses in Example 3

[0167]

[0168] Where -4.30652E-03 indicates that the coefficient A of surface number S4 is... .

[0169] Figure 28 yes Figure 27 The spherical aberration curve of the fisheye lens shown is as follows: Figure 28 The axial aberration curves shown have the following dimensions: the vertical direction represents the normalized aperture (0 indicates on the optical axis), and the vertical vertex represents the maximum pupil radius; the horizontal direction represents the offset relative to the ideal focal point, in millimeters (mm). Different linear curves in the figure represent different wavelengths of the system imaging, determined by... Figure 28 It can be seen that the axial aberrations at different wavelengths are all controlled within the range of (-0.05mm, +0.05mm), indicating that the spherical aberration of the fisheye lens at each wavelength is well controlled and can meet the requirements of wide spectrum applications.

[0170] Figures 29 to 38 yes Figure 27 The fan pattern of the fisheye lens shown is as follows: Figures 29 to 38 As shown, the horizontal axis represents the beam aperture, and the vertical axis represents the transverse aberration. The fan diagram is one of the most commonly used evaluation methods in modern optical design. The ideal curve is a straight line coinciding with the horizontal axis, indicating that all rays converge at the same point on the image plane. The interval on the vertical axis of the curve represents the maximum dispersion range of the beam on the ideal image plane. The fan diagram can reflect not only monochromatic aberrations of different wavelengths but also the magnitude of transverse chromatic aberration. Figures 29 to 38 It can be seen that the system closely approximates the horizontal axis at each wavelength in each field of view, indicating that the transverse aberration of each wavelength is well corrected. At the same time, there is no obvious dispersion of each wavelength, indicating that the chromatic aberration of the system is also well corrected, thus ensuring that the optical system can achieve the high-resolution imaging requirements.

[0171] Figure 39 yes Figure 27 The field curvature distortion curve of the fisheye lens shown is as follows: Figure 39 As shown, in the coordinate system on the left, the horizontal coordinate represents the magnitude of the field curvature, in mm; the vertical coordinate represents the normalized image height, which has no unit; where T represents the meridion and S represents the sagitta; from Figure 39As can be seen, the fisheye lens provided in this embodiment effectively controls the field curvature from light with wavelengths from 436nm to 850nm, meaning that during imaging, the difference in image quality between the center and the periphery is small. In the coordinate system on the right, the horizontal axis represents the magnitude of distortion, expressed as a percentage; the vertical axis represents the normalized image height, which has no unit; from Figure 39 It can be seen that the distortion of the fisheye lens provided in this embodiment has been well corrected.

[0172] Example 4

[0173] Figure 40 This is a schematic diagram of the structure of a fisheye lens provided in Embodiment 4 of the present invention. The similarities with the above embodiments will not be repeated here.

[0174] In one feasible embodiment, Table 10 details a feasible implementation. Figure 40 The specific optical physical parameters of the fisheye lens are shown.

[0175] Table 10. Physical parameter design of the fisheye lens in Example 4

[0176]

[0177] In this embodiment, the focal length f is 3.926mm, the aperture F# is 1.594, and the angle corresponding to the fisheye head height φ10.3mm is 182.54°.

[0178] Table 11 shows the design parameters of a fisheye lens, including lens surface type, radius of curvature, thickness, and material, corresponding to Table 10.

[0179] Table 11 Parameter design of each lens in the fisheye lens in Example 4

[0180]

[0181] The fisheye lens provided in this embodiment includes a first lens L1, a second lens L2, an aperture stop STO, 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 filter L0 arranged sequentially along the optical axis from the object side to the image side. The surface numbers in Table 2 are assigned according to the surface sequence of each lens. "OBJ" represents the object plane of the fisheye lens; "STO" represents the aperture of the fisheye lens; "IMA" represents the image plane of the fisheye lens; the radius of curvature represents the curvature of the lens surface, with a positive value indicating that the surface bends towards the image plane and a negative value indicating that the surface bends towards the object plane. "Infinity" indicates that the surface is flat, with an infinite radius of curvature and an infinite distance; the thickness represents the central axial distance between the current surface and the next surface; the refractive index represents the ability of the material between the current surface and the next surface to deflect light, with a blank space indicating that the current position is air and the refractive index is 1; the Abbe number represents the dispersion characteristics of the material between the current surface and the next surface, with a blank space indicating that the current position is air; half-aperture represents the effective diameter of the lens; and the k-value represents the magnitude of the conic coefficient of the aspherical surface. This represents the relative dispersion deviation compared to normal glass.

[0182] Among them, the relative partial dispersion of the lens wavelengths x and y or Expressed as follows:

[0183] ;

[0184] ;

[0185] in, It is the refractive index of the lens measured at wavelength x. It is the refractive index of the lens measured at the y-wavelength. The refractive index of the lens is measured at the wavelength of the hydrogen blue line (486.13 nm). The refractive index of the lens is measured at the hydrogen red line wavelength (656.27 nm). The refractive index of the lens is measured at the wavelength of the cadmium blue line (479.99 nm). The refractive index of the lens is measured at the cadmium red line wavelength (643.85nm); This refers to the relative partial dispersion of the lens at the wavelengths of the mercury blue line and the hydrogen blue line. This represents the relative partial dispersion of the lens at the wavelengths of the mercury blue line and the cadmium blue line.

[0186] According to Abbe's formula, the following linear relationship holds for most so-called "normal glass":

[0187] ;

[0188] in, The Abbe number of the lens. The slope The intercept is used to define the linear relationship. The vertical axis is , It is represented by the horizontal axis.

[0189] Understandably, correction of the second-order spectrum, i.e., achromatic correction of more than two wavelengths, requires at least one type of glass that does not conform to the above formula (i.e., its... The value deviates from Abbe's empirical formula), and the deviation is used to... This means that each The point has been translated relative to the "normal line" that conforms to the above formula. Quantity. Thus, the lens's... The value can be obtained using the following formula:

[0190] ;

[0191] therefore, It quantitatively represents the deviation of the special dispersion characteristics compared to "normal glass". The calculation formula is as follows:

[0192] .

[0193] In this embodiment, the aspherical conic coefficient of the fisheye lens can be defined by the following aspherical formula, but is not limited to the following representation:

[0194] ;

[0195] Where z is the axial sagitta in the Z direction of the aspherical surface; r is the height of the aspherical surface; c is the curvature of the fitted sphere, which is numerically the reciprocal of the radius of curvature; k is the coefficient of the fitted cone; A, B, C, D, E, and F are the coefficients of the 4th, 6th, 8th, 10th, 12th, and 14th order terms of the aspherical polynomial, respectively.

[0196] Table 12 Aspheric coefficients of fisheye lenses in Example 4

[0197]

[0198] Where -4.43135E-03 indicates that the coefficient A of surface number S4 is... .

[0199] Figure 41 yes Figure 40 The spherical aberration curve of the fisheye lens shown is as follows: Figure 41The axial aberration curves shown have the following dimensions: the vertical direction represents the normalized aperture (0 indicates on the optical axis), and the vertical vertex represents the maximum pupil radius; the horizontal direction represents the offset relative to the ideal focal point, in millimeters (mm). Different linear curves in the figure represent different wavelengths of the system imaging, determined by... Figure 41 It can be seen that the axial aberrations at different wavelengths are all controlled within the range of (-0.05mm, +0.05mm), indicating that the spherical aberration of the fisheye lens at each wavelength is well controlled and can meet the requirements of wide spectrum applications.

[0200] Figures 42 to 51 yes Figure 40 The fan pattern of the fisheye lens shown is as follows: Figures 42 to 51 As shown, the horizontal axis represents the beam aperture, and the vertical axis represents the transverse aberration. The fan diagram is one of the most commonly used evaluation methods in modern optical design. The ideal curve is a straight line coinciding with the horizontal axis, indicating that all rays converge at the same point on the image plane. The interval on the vertical axis of the curve represents the maximum dispersion range of the beam on the ideal image plane. The fan diagram can reflect not only monochromatic aberrations of different wavelengths but also the magnitude of transverse chromatic aberration. Figures 42 to 51 It can be seen that the system closely approximates the horizontal axis at each wavelength in each field of view, indicating that the transverse aberration of each wavelength is well corrected. At the same time, there is no obvious dispersion of each wavelength, indicating that the chromatic aberration of the system is also well corrected, thus ensuring that the optical system can achieve the high-resolution imaging requirements.

[0201] Figure 52 yes Figure 40 The field curvature distortion curve of the fisheye lens shown is as follows: Figure 52 As shown, in the coordinate system on the left, the horizontal coordinate represents the magnitude of the field curvature, in mm; the vertical coordinate represents the normalized image height, which has no unit; where T represents the meridion and S represents the sagitta; from Figure 52 As can be seen, the fisheye lens provided in this embodiment effectively controls the field curvature from light with wavelengths from 436nm to 850nm, meaning that during imaging, the difference in image quality between the center and the periphery is small. In the coordinate system on the right, the horizontal axis represents the magnitude of distortion, expressed as a percentage; the vertical axis represents the normalized image height, which has no unit; from Figure 52 It can be seen that the distortion of the fisheye lens provided in this embodiment has been well corrected.

[0202] Example 5

[0203] Figure 53 This is a schematic diagram of the structure of a fisheye lens provided in Embodiment 5 of the present invention. The similarities with the above embodiments will not be repeated here.

[0204] In one feasible embodiment, Table 13 details a feasible implementation method. Figure 53The specific optical physical parameters of the fisheye lens are shown.

[0205] Table 13 Physical parameter design of the fisheye lens in Example 5

[0206]

[0207] In this embodiment, the focal length f is 3.687mm, the aperture F# is 1.594, and the angle corresponding to the fisheye head height φ10.3mm is 181.12°.

[0208] Table 14 shows the design parameters of a fisheye lens, including lens surface type, radius of curvature, thickness, and material, corresponding to Table 13.

[0209] Table 14 shows the parameter design of each lens in Example 5 of the fisheye lens.

[0210]

[0211] The fisheye lens provided in this embodiment includes a first lens L1, a second lens L2, an aperture stop STO, 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 filter L0 arranged sequentially along the optical axis from the object side to the image side. The surface numbers in Table 2 are assigned according to the surface sequence of each lens. "OBJ" represents the object plane of the fisheye lens; "STO" represents the aperture of the fisheye lens; "IMA" represents the image plane of the fisheye lens; the radius of curvature represents the curvature of the lens surface, with a positive value indicating that the surface bends towards the image plane and a negative value indicating that the surface bends towards the object plane. "Infinity" indicates that the surface is flat, with an infinite radius of curvature and an infinite distance; the thickness represents the central axial distance between the current surface and the next surface; the refractive index represents the ability of the material between the current surface and the next surface to deflect light, with a blank space indicating that the current position is air and the refractive index is 1; the Abbe number represents the dispersion characteristics of the material between the current surface and the next surface, with a blank space indicating that the current position is air; half-aperture represents the effective diameter of the lens; and the k-value represents the magnitude of the conic coefficient of the aspherical surface. This represents the relative dispersion deviation compared to normal glass.

[0212] Among them, the relative partial dispersion of the lens wavelengths x and y or Expressed as follows:

[0213] ;

[0214] ;

[0215] in, It is the refractive index of the lens measured at wavelength x. It is the refractive index of the lens measured at the y-wavelength. The refractive index of the lens is measured at the wavelength of the hydrogen blue line (486.13 nm). The refractive index of the lens is measured at the hydrogen red line wavelength (656.27 nm). The refractive index of the lens is measured at the wavelength of the cadmium blue line (479.99 nm). The refractive index of the lens is measured at the cadmium red line wavelength (643.85nm); This refers to the relative partial dispersion of the lens at the wavelengths of the mercury blue line and the hydrogen blue line. This represents the relative partial dispersion of the lens at the wavelengths of the mercury blue line and the cadmium blue line.

[0216] According to Abbe's formula, the following linear relationship holds for most so-called "normal glass":

[0217] ;

[0218] in, The Abbe number of the lens. The slope The intercept is used to define the linear relationship. The vertical axis is , It is represented by the horizontal axis.

[0219] Understandably, correction of the second-order spectrum, i.e., achromatic correction of more than two wavelengths, requires at least one type of glass that does not conform to the above formula (i.e., its... The value deviates from Abbe's empirical formula), and the deviation is used to... This means that each The point has been translated relative to the "normal line" that conforms to the above formula. Quantity. Thus, the lens's... The value can be obtained using the following formula:

[0220] ;

[0221] therefore, It quantitatively represents the deviation of the special dispersion characteristics compared to "normal glass". The calculation formula is as follows:

[0222] .

[0223] In this embodiment, the aspherical conic coefficient of the fisheye lens can be defined by the following aspherical formula, but is not limited to the following representation:

[0224] ;

[0225] Where z is the axial sagitta in the Z direction of the aspherical surface; r is the height of the aspherical surface; c is the curvature of the fitted sphere, which is numerically the reciprocal of the radius of curvature; k is the coefficient of the fitted cone; A, B, C, D, E, and F are the coefficients of the 4th, 6th, 8th, 10th, 12th, and 14th order terms of the aspherical polynomial, respectively.

[0226] Table 15 Aspheric coefficients of fisheye lenses in Example 5

[0227]

[0228] Where -4.21973E-03 indicates that the coefficient A of surface number S4 is... .

[0229] Figure 54 yes Figure 53 The spherical aberration curve of the fisheye lens shown is as follows: Figure 54 The axial aberration curves shown have the following dimensions: the vertical direction represents the normalized aperture (0 indicates on the optical axis), and the vertical vertex represents the maximum pupil radius; the horizontal direction represents the offset relative to the ideal focal point, in millimeters (mm). Different linear curves in the figure represent different wavelengths of the system imaging, determined by... Figure 54 It can be seen that the axial aberrations at different wavelengths are all controlled within the range of (-0.05mm, +0.05mm), indicating that the spherical aberration of the fisheye lens at each wavelength is well controlled and can meet the requirements of wide spectrum applications.

[0230] Figures 55 to 64 yes Figure 53 The fan pattern of the fisheye lens shown is as follows: Figures 55 to 64 As shown, the horizontal axis represents the beam aperture, and the vertical axis represents the transverse aberration. The fan diagram is one of the most commonly used evaluation methods in modern optical design. The ideal curve is a straight line coinciding with the horizontal axis, indicating that all rays converge at the same point on the image plane. The interval on the vertical axis of the curve represents the maximum dispersion range of the beam on the ideal image plane. The fan diagram can reflect not only monochromatic aberrations of different wavelengths but also the magnitude of transverse chromatic aberration. Figures 55 to 64 It can be seen that the system closely approximates the horizontal axis at each wavelength in each field of view, indicating that the transverse aberration of each wavelength is well corrected. At the same time, there is no obvious dispersion of each wavelength, indicating that the chromatic aberration of the system is also well corrected, thus ensuring that the optical system can achieve the high-resolution imaging requirements.

[0231] Figure 65 yes Figure 53 The field curvature distortion curve of the fisheye lens shown is as follows: Figure 65 As shown, in the coordinate system on the left, the horizontal coordinate represents the magnitude of the field curvature, in mm; the vertical coordinate represents the normalized image height, which has no unit; where T represents the meridion and S represents the sagitta; from Figure 65As can be seen, the fisheye lens provided in this embodiment effectively controls the field curvature from light with wavelengths from 436nm to 850nm, meaning that during imaging, the difference in image quality between the center and the periphery is small. In the coordinate system on the right, the horizontal axis represents the magnitude of distortion, expressed as a percentage; the vertical axis represents the normalized image height, which has no unit; from Figure 65 It can be seen that the distortion of the fisheye lens provided in this embodiment has been well corrected.

[0232] Note that the above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of the present invention, the scope of which is determined by the scope of the appended claims.

Claims

1. A fisheye lens, characterized in that, include: The fisheye lens comprises, along the optical axis from the object side to the image side, a first lens with negative optical power, a second lens with negative optical power, a third lens with positive optical power, a fourth lens with positive optical power, a fifth lens with negative optical power, a sixth lens with positive optical power, a seventh lens with negative optical power, and an eighth lens with positive optical power; the fisheye lens contains eight lenses with optical power. The object-side surface of the first lens is convex, and the image-side surface of the first lens is concave. The object-side surface of the second lens is concave. The object-side surface of the third lens is convex. The object-side surface of the fourth lens is convex, and the image-side surface of the fourth lens is convex. The object-side surface of the fifth lens is convex, and the image-side surface of the fifth lens is concave. The object-side surface of the sixth lens is convex, and the image-side surface of the sixth lens is convex. The object-side surface of the seventh lens is concave, and the image-side surface of the seventh lens is convex. The object-side surface of the eighth lens is convex, and the image-side surface of the eighth lens is concave. Wherein, the first lens, the fourth lens, the fifth lens, the sixth lens and the seventh lens are all glass spherical lenses; Both the third lens and the eighth lens are plastic aspherical lenses; The second lens is a plastic aspherical lens or a glass aspherical lens; Wherein, -0.53≤Φ1 / Φ≤-0.43, Φ1 is the optical power of the first lens; Φ is the overall optical power of the fisheye lens.

2. The fisheye lens according to claim 1, characterized in that, The fifth lens, the sixth lens, and the seventh lens are cemented together to form a three-cemented lens group.

3. The fisheye lens according to claim 1, characterized in that, -0.20 < L2S h / L2S t ≤ 0.14; L3S h / L3S t ≥ 0.01; -0.48≤Φ2 / Φ≤-0.39;0.21≤Φ3 / Φ≤0.30;0.39≤Φ4 / Φ≤0.47; Among them, L2S h L2S is the half-aperture sagittal of the image-side surface of the second lens. t L3S is the full aperture sagitta of the image-side surface of the second lens. h L3S is the half-aperture sagittal of the image-side surface of the third lens. t The full aperture sagitta of the image-side surface of the third lens; Φ2 is the optical power of the second lens; Φ3 is the optical power of the third lens; Φ4 is the optical power of the fourth lens; and Φ is the overall optical power of the fisheye lens.

4. The fisheye lens according to claim 1, characterized in that, -0.30≤Φ5 / Φ≤-0.18; 0.47≤Φ6 / Φ≤0.75; -0.55≤Φ7 / Φ≤-0.31; Wherein, Φ5 is the optical power of the fifth lens; Φ6 is the optical power of the sixth lens; Φ7 is the optical power of the seventh lens; and Φ is the overall optical power of the fisheye lens.

5. The fisheye lens according to claim 1, characterized in that, 1.68 <Nd1<1.82,25<Vd1<60; Wherein, Nd1 is the refractive index of the first lens, and Vd1 is the Abbe number of the first lens.

6. The fisheye lens according to claim 1, characterized in that, 50 <Vd2<58;17<Vd3<32;46<Vd4<74; Wherein, Vd2 is the Abbe number of the second lens; Vd3 is the Abbe number of the third lens; and Vd4 is the Abbe number of the fourth lens.

7. The fisheye lens according to claim 1, characterized in that, 1.73 <Nd5<1.93;1.43<Nd6<1.52;-68<Vd5-Vd6+Vd7<2; Wherein, Nd5 is the refractive index of the fifth lens, and Nd6 is the refractive index of the sixth lens; Vd5 is the Abbe number of the fifth lens, Vd6 is the Abbe number of the sixth lens, and Vd7 is the Abbe number of the seventh lens.

8. The fisheye lens according to claim 1, characterized in that, 17 <Vd8<41; Wherein, Vd8 is the Abbe number of the eighth lens.

9. The fisheye lens according to claim 1, characterized in that, 0.09≤SD1 / TTL*Sinθ / H≤0.12; Wherein, SD1 is the effective half-aperture of the light rays on the object side of the first lens; TTL is the total optical length of the fisheye lens from the vertex of the object side of the first lens to the image plane; and θ is the angle corresponding to the maximum half-image height that the fisheye lens can achieve.

Images