CN114002825A - Fisheye lens - Google Patents
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- CN114002825A CN114002825A CN202111594582.7A CN202111594582A CN114002825A CN 114002825 A CN114002825 A CN 114002825A CN 202111594582 A CN202111594582 A CN 202111594582A CN 114002825 A CN114002825 A CN 114002825A
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- 230000003287 optical effect Effects 0.000 claims abstract description 31
- 238000003384 imaging method Methods 0.000 claims abstract description 21
- 239000011521 glass Substances 0.000 claims abstract description 16
- 230000014509 gene expression Effects 0.000 claims description 37
- 230000004075 alteration Effects 0.000 description 27
- 238000012634 optical imaging Methods 0.000 description 8
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- 239000000463 material Substances 0.000 description 3
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- 230000009286 beneficial effect Effects 0.000 description 2
- 239000006185 dispersion Substances 0.000 description 2
- 230000002349 favourable effect Effects 0.000 description 2
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B13/00—Optical objectives specially designed for the purposes specified below
- G02B13/001—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras
- G02B13/0015—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras characterised by the lens design
- G02B13/002—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras characterised by the lens design having at least one aspherical surface
- G02B13/0045—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras characterised by the lens design having at least one aspherical surface having five or more lenses
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B13/00—Optical objectives specially designed for the purposes specified below
- G02B13/06—Panoramic objectives; So-called "sky lenses" including panoramic objectives having reflecting surfaces
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Abstract
The invention discloses a fisheye lens, which comprises seven lenses in total, wherein the fisheye lens sequentially comprises the following components from an object side to an imaging surface along an optical axis: the first lens with negative focal power has a convex object-side surface and a concave image-side surface; a second lens with negative focal power, wherein the object side surface of the second lens is a convex surface, and the image side surface of the second lens is a concave surface; a third lens element having a positive optical power, the object-side surface of the third lens element being convex at a paraxial region and the image-side surface of the third lens element being convex; a diaphragm; a fourth lens having a positive refractive power, both the object-side surface and the image-side surface of the fourth lens being convex; a fifth lens element having a positive refractive power, the object-side surface and the image-side surface of the fifth lens element being convex; a sixth lens element having a negative refractive power, wherein both the object-side surface and the image-side surface are concave; the object side surface and the image side surface of the seventh lens with positive focal power are convex surfaces, and the fisheye lens at least comprises a glass lens and a plastic lens. The fisheye lens has the advantages of strong thermal stability, miniaturization, light weight, large aperture, super-large wide angle and the like.
Description
Technical Field
The invention relates to the technical field of imaging lenses, in particular to a fisheye lens.
Background
The development of mobile interconnection, in addition to the popularity of social contact, video and live broadcast software, people are more and more high to photographic liking degree, and the pursuit to the imaging effect is also more diversified, not only the image quality of high definition is required, but also the super large field of vision is required in order to shoot the strong picture of visual impact force on a large scale, and unmanned aerial vehicle has won the liking of consumer with its unique high altitude visual angle and wide shooting picture. At present, unmanned aerial vehicles develop rapidly, and the corresponding demand for optical lenses matched with the unmanned aerial vehicles is higher and higher.
Because the unmanned aerial vehicle is mostly used in complex environments such as severe vibration, high pressure, extreme temperature and the like, the requirement on the performance of the matched optical lens is extremely high, the unmanned aerial vehicle has good thermal stability to adapt to outdoor severe environments, and light appearance and small weight are required to increase the endurance time of the unmanned aerial vehicle during high-altitude flight shooting; still require the camera lens to have big light ring simultaneously in order to satisfy unmanned aerial vehicle can both shoot clear and vivid picture in changeable environment such as daytime night. At present, the diversified use requirements of the unmanned aerial vehicle can be hardly met by the conventional optical lens in the market.
Disclosure of Invention
Based on this, the invention aims to provide a fisheye lens which at least has the advantages of strong thermal stability, miniaturization, light weight, large aperture and super-large wide angle and can meet diversified use requirements in the fields of unmanned aerial vehicles, motion cameras and the like.
In order to achieve the purpose, the technical scheme of the invention is as follows:
the invention provides a fisheye lens, which comprises seven lenses in total, and the fisheye lens sequentially comprises the following components from an object side to an imaging surface:
the lens comprises a first lens with negative focal power, a second lens and a third lens, wherein the object side surface of the first lens is a convex surface, and the image side surface of the first lens is a concave surface;
the second lens with negative focal power is characterized in that the object side surface of the second lens is a convex surface, and the image side surface of the second lens is a concave surface;
a third lens having a positive optical power, an object-side surface of the third lens being convex at a paraxial region, an image-side surface of the third lens being convex;
a diaphragm;
the fourth lens is provided with positive focal power, and the object side surface and the image side surface of the fourth lens are convex surfaces;
the lens comprises a fifth lens with positive focal power, wherein both the object-side surface and the image-side surface of the fifth lens are convex surfaces;
a sixth lens element having a negative optical power, the sixth lens element having a concave object-side surface and a concave image-side surface;
a seventh lens having a positive optical power, the seventh lens having convex object and image side surfaces;
the fisheye lens at least comprises a glass lens and a plastic lens;
the fisheye lens meets the following conditional expression:
16＜TTL/f＜19；
wherein, TTL represents the optical total length of the fisheye lens, and f represents the effective focal length of the fisheye lens.
In some embodiments, the fisheye lens satisfies the following conditional expression:
0.98＜SD14/IH＜1.03；
wherein SD14 denotes a maximum effective diameter of an image-side surface of the seventh lens element, and IH denotes an image plane size corresponding to a field angle of the fisheye lens.
In some embodiments, the fisheye lens satisfies the following conditional expression:
0.6＜RS2/SD2＜0.7；
wherein RS2 represents the rise of the image side of the first lens and SD2 represents the maximum effective diameter of the image side of the first lens.
In some embodiments, the fisheye lens satisfies the following conditional expression:
0.1＜φ567/φ＜0.2；
wherein phi 567 represents the combined focal power of the fifth lens, the sixth lens and the seventh lens, and phi represents the focal power of the fisheye lens.
In some embodiments, the fisheye lens satisfies the following conditional expression:
0.2＜SD7/SD3＜0.4；
wherein SD3 represents the maximum effective diameter of the object side surface of the second lens, and SD7 represents the maximum effective diameter of the object side surface of the fourth lens.
In some embodiments, the fisheye lens satisfies the following conditional expression:
-0.13≤φ123/φ＜-0.08；
wherein phi 123 represents the combined focal power of the first lens, the second lens and the third lens, and phi represents the focal power of the fisheye lens.
In some embodiments, the fisheye lens satisfies the following conditional expression:
10°＜CRA＜18°；
wherein CRA represents an incident angle of a chief ray of the fisheye lens on an imaging plane.
In some embodiments, the fisheye lens satisfies the following conditional expression:
4.7＜TTL/IH＜5.5；
wherein IH denotes an image plane size corresponding to the field angle of the fisheye lens.
In some embodiments, the fisheye lens satisfies the following conditional expression:
0.17＜φ4/φ≤0.27；
wherein phi 4 represents the focal power of the fourth lens, and phi represents the focal power of the fisheye lens.
In some embodiments, the first lens and the fourth lens are all glass spherical lenses, and the second lens, the third lens, the fifth lens, the sixth lens and the seventh lens are all plastic aspheric lenses.
Compared with the prior art, the invention has the beneficial effects that: according to the invention, the mixed matching structure of the glass lens and the plastic lens is adopted, so that the influence of temperature change on imaging can be compensated, and the volume and the weight of the lens are effectively reduced; the diaphragm and each lens structure of camera lens set up rationally, can make the light quantity of wider scope get into the fuselage, satisfy the formation of image demand of light and shade environment. In other words, the fisheye lens provided by the invention at least has the characteristics of strong thermal stability, miniaturization, light weight, large aperture and super-large wide angle, and can meet diversified use requirements in the fields of unmanned aerial vehicles, motion cameras and the like.
Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
Drawings
The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
fig. 1 is a schematic structural diagram of a fisheye lens in embodiment 1 of the invention;
fig. 2 is a MTF graph of the fisheye lens in embodiment 1 of the invention;
FIG. 3 is a graph showing F-Theta distortion of a fisheye lens in example 1 of the present invention;
fig. 4 is a graph of axial chromatic aberration of the fisheye lens in embodiment 1 of the invention;
fig. 5 is a schematic structural view of a fisheye lens in embodiment 2 of the invention;
fig. 6 is a MTF graph of the fisheye lens in embodiment 2 of the invention;
FIG. 7 is a graph showing F-Theta distortion of a fisheye lens in example 2 of the present invention;
fig. 8 is a graph showing axial chromatic aberration of the fisheye lens in embodiment 2 of the present invention;
fig. 9 is a schematic structural view of a fisheye lens in embodiment 3 of the invention;
fig. 10 is a MTF graph of the fisheye lens in embodiment 3 of the invention;
fig. 11 is a graph showing F-Theta distortion of the fisheye lens in embodiment 3 of the invention;
fig. 12 is a graph showing axial chromatic aberration of the fisheye lens in embodiment 3 of the invention.
Description of the main element symbols:
the following detailed description will further illustrate the invention in conjunction with the above-described figures.
Detailed Description
For a better understanding of the present application, various aspects of the present application will be described in more detail with reference to the accompanying drawings. It should be understood that the detailed description is merely illustrative of embodiments of the application and does not limit the scope of the application in any way. Like reference numerals refer to like elements throughout the specification. The expression "and/or" includes any and all combinations of one or more of the associated listed items.
It should be noted that in this specification, the expressions first, second, third, etc. are used only to distinguish one feature from another, and do not represent any limitation on the features. Thus, the first lens discussed below may also be referred to as the second lens or the third lens without departing from the teachings of the present invention.
In the drawings, the thickness, size, and shape of the lens have been slightly exaggerated for convenience of explanation. In particular, the shapes of the spherical or aspherical surfaces shown in the drawings are shown by way of example. That is, the shape of the spherical surface or the aspherical surface is not limited to the shape of the spherical surface or the aspherical surface shown in the drawings. The figures are purely diagrammatic and not drawn to scale.
Herein, the paraxial region refers to a region near the optical axis. If the lens surface is convex and the convex position is not defined, it means that the lens surface is convex at least in the paraxial region; if the lens surface is concave and the concave position is not defined, it means that the lens surface is concave at least in the paraxial region. The surface of each lens closest to the object is called the object side surface of the lens, and the surface of each lens closest to the imaging surface is called the image side surface of the lens.
It will be further understood that the terms "comprises," "comprising," "has," "having," "includes" and/or "including," when used in this specification, specify the presence of stated features, elements, and/or components, but do not preclude the presence or addition of one or more other features, elements, components, and/or groups thereof. Moreover, when a statement such as "at least one of" appears after a list of listed features, the entirety of the listed features is modified rather than modifying individual elements in the list. Furthermore, when describing embodiments of the present application, the use of "may" mean "one or more embodiments of the present application. Also, the term "exemplary" is intended to refer to an example or illustration.
Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present application will be described in detail below with reference to the embodiments with reference to the attached drawings.
The invention provides a fisheye lens, which comprises seven lenses in total, and the seven lenses sequentially comprise the following components from an object side to an imaging surface along an optical axis: the optical center of each lens is positioned on the same straight line.
The first lens has negative focal power, the object side surface of the first lens is a convex surface, and the image side surface of the first lens is a concave surface;
the second lens has negative focal power, the object side surface of the second lens is a convex surface, and the image side surface of the second lens is a concave surface;
the third lens has positive focal power, the object side surface of the third lens is convex at a paraxial region, and the image side surface of the third lens is convex;
the fourth lens has positive focal power, and both the object side surface and the image side surface of the fourth lens are convex surfaces;
the fifth lens has positive focal power, and both the object side surface and the image side surface of the fifth lens are convex surfaces;
the sixth lens has negative focal power, and the object side surface and the image side surface of the sixth lens are both concave surfaces;
the seventh lens has positive focal power, and both the object-side surface and the image-side surface of the seventh lens are convex surfaces.
The diaphragm can be made of shading paper with a light through hole in the center, and the light through aperture of the diaphragm is smaller than the space ring, so that the light through amount of the fisheye lens is determined by the light through aperture of the diaphragm. The diaphragm is arranged between the third lens and the fourth lens, so that the field angle of the fisheye lens can be improved, and the incidence angle of the chip can be better matched; the shading paper with the light through hole in the center is used as the diaphragm, so that the requirement of the light through hole of the lens cone can be reduced, the forming difficulty of the light through hole of the lens cone is reduced, the production efficiency is improved, and the production cost is reduced.
In some embodiments, to reduce the weight and the unit price of the lens, the fisheye lens comprises at least one lens made of plastic; meanwhile, in order to enable the lens to have good thermal stability, the fisheye lens further comprises at least one lens made of glass. Specifically, the fish-eye lens consists of five plastic lenses and two glass lenses, and the mixed structure is molded by adopting the glass, so that the volume and the weight of the lens can be greatly reduced, the fish-eye lens is suitable for mass production, and meanwhile, the stability of the imaging performance of the lens in a high-temperature and low-temperature environment is ensured to the greatest extent.
In some embodiments, in order to improve the resolving power of the lens and effectively reduce the vertical axis chromatic aberration of the lens, the fisheye lens adopts a plurality of aspheric lenses, and the use of the aspheric lenses can better correct the aberration of the lens, improve the resolution of the lens and enable the imaging to be clearer. Specifically, a first lens and a fourth lens in the fisheye lens are glass spherical lenses, and a second lens, a third lens, a fifth lens, a sixth lens and a seventh lens are plastic aspheric lenses.
In some embodiments, the first lens and the fourth lens are both glass lenses, wherein the first lens is made of a hard glass material and is plated with a scratch-proof hard film, so as to ensure that the lens is not easy to scratch during use and assembly, and the imaging quality is affected. The fourth lens can adopt glass spherical surface or aspheric surface glass, can effectively correct chromatic aberration, and compensate image quality change caused by temperature change.
In some embodiments, the fish-eye lens satisfies the following conditional expression:
16＜TTL/f＜19；
wherein, TTL represents the optical total length of the fisheye lens, and f represents the effective focal length of the fisheye lens. By limiting the relation between the total optical length of the optical imaging system and the effective focal length of the optical imaging system, the total optical length of the optical imaging system is controlled while the field angle range of the optical imaging system is met, and the characteristic of miniaturization of the optical imaging system is met. The optical imaging system is too long in total length to be beneficial to miniaturization due to the fact that the upper limit of the relational expression is exceeded; if the optical imaging system has an excessively long focal length exceeding the lower limit of the conditional expression, it is not favorable to satisfy the field angle range of the optical imaging system, and sufficient object space information cannot be obtained.
In some embodiments, the fish-eye lens satisfies the following conditional expression:
0.5＜CT1/CT3＜0.8；
wherein CT1 represents the center thickness of the first lens and CT3 represents the center thickness of the third lens. Satisfy above-mentioned conditional expression, can the reasonable thickness ratio of controlling first lens and third lens, under the prerequisite of guaranteeing the normal processing of lens, the reduction system leads to the drift of imaging surface because of being heated. If the value of CT1/CT3 exceeds the lower limit, the thermal expansion of the first lens element and the third lens element cannot effectively compensate the thermal expansion of the rear lens element under high temperature condition of the lens, which results in large back focus of the lens and reduced imaging quality; on the contrary, if the value of CT1/CT3 exceeds the upper limit, the back focus of the lens is reduced, and the imaging quality is reduced.
In some embodiments, in order to satisfy the requirement of good light reception of the lens chip, the fisheye lens satisfies the following conditional expression:
0.98＜SD14/IH＜1.03；
SD14 denotes the maximum effective diameter of the image-side surface of the seventh lens, and IH denotes the image plane size corresponding to the field angle of the fisheye lens. The condition formula is satisfied, light rays passing through the lens group can be smoothly received into the chip, and the requirement of the optimal CRA (principal ray incident angle) of the chip is satisfied.
In some embodiments, the fisheye lens satisfies the conditional expression:
0.6＜RS2/SD2＜0.7；
wherein RS2 represents the rise of the image side of the first lens and SD2 represents the maximum effective diameter of the image side of the first lens. The first lens can have enough field angle to meet the light entering requirement of an ultra-large field of view by meeting the conditional expression.
In some embodiments, the fish-eye lens satisfies the following conditional expression:
-0.13≤φ123/φ＜-0.08；
wherein phi 123 represents the combined focal power of the first lens, the second lens and the third lens, and phi represents the focal power of the fisheye lens. Satisfying the above conditional expression, can rationally distribute the focal power of each lens, be favorable to reducing high-order aberration, make the camera lens obtain higher image quality.
In some embodiments, the fish-eye lens satisfies the following conditional expression:
0.2＜SD7/SD3＜0.4；
where SD3 denotes the maximum effective diameter of the object-side surface of the second lens, and SD7 denotes the maximum effective diameter of the object-side surface of the fourth lens. The aperture of the lens before and after the diaphragm is set to achieve a good light receiving effect, so that the lens has a sufficient field angle and ensures the maximum light transmission amount.
In some embodiments, the fisheye lens satisfies the conditional expression:
0.1＜φ567/φ＜0.2；
wherein phi 567 represents the combined focal power of the fifth lens, the sixth lens and the seventh lens, and phi represents the focal power of the fisheye lens. When the value of phi 567/phi exceeds the upper limit, the focal power of the fifth lens, the sixth lens and the seventh lens is too strong, although the purpose of quickly converging light rays can be achieved, the total length of the system can be reduced, various aberrations generated by the lenses are too large and difficult to correct, the curvature of the lenses is increased, the processing difficulty is improved, and the system error is increased; when the value of φ 567/φ exceeds the lower limit, the combined power of the fifth lens, the sixth lens and the seventh lens decreases, and the above various aberrations relatively decrease, but the optical power decreases, resulting in an increase in the total length of the system.
In some embodiments, the fish-eye lens satisfies the following conditional expression:
10°＜CRA＜18°；
wherein CRA represents an incident angle of a chief ray of the fisheye lens on an imaging plane. The condition formula is met, the chief ray incident angle of the chip can be well matched, the luminous efficiency received by the photosensitive area of the chip is effectively improved, and the optimal imaging effect is achieved.
In some embodiments, the fish-eye lens satisfies the following conditional expression:
4.7＜TTL/IH＜5.5；
wherein, TTL represents the optical total length of the fisheye lens, and IH represents the image surface size corresponding to the field angle of the fisheye lens. The condition formula is satisfied, and the total length and the volume of the lens are effectively controlled while the lens is ensured to have a larger imaging surface.
In some embodiments, the fish-eye lens satisfies the following conditional expression:
0.17＜φ4/φ≤0.27；
wherein phi 4 represents the focal power of the fourth lens, and phi represents the focal power of the fisheye lens. When the condition formula is met, the lens is ensured to have better imaging performance at different temperatures.
In some embodiments, in order to better correct chromatic aberration, the fisheye lens satisfies the following conditional expression:
30＜|Vd5-Vd6|＜40；
wherein Vd5 denotes an abbe number of the fifth lens, and Vd6 denotes an abbe number of the sixth lens. The abbe number is an index indicating the dispersive power of the transparent medium. Generally, the smaller the abbe number of the lens, the more severe the dispersion; conversely, the larger the abbe number of the lens, the more slight the dispersion. In general, the chromatic aberration generated by the positive and negative lenses can compensate each other, but the abbe number difference is selected to be proper. When the value of Vd5-Vd6 exceeds the lower limit, the chromatic aberration of the system is insufficiently corrected; when the value of | Vd5-Vd6| exceeds the upper limit, the local chromatic aberration correction is too large, and material selection difficulty may occur.
The invention is further illustrated below in the following examples. In each embodiment, the thickness, the curvature radius, and the material selection part of each lens in the fisheye lens are different, and specific differences can be referred to the parameter table of each embodiment. The following examples are only preferred embodiments of the present invention, but the embodiments of the present invention are not limited only by the following examples, and any other changes, substitutions, combinations or simplifications which do not depart from the innovative points of the present invention should be construed as being equivalent substitutions and shall be included within the scope of the present invention.
In the embodiments of the present invention, when the lenses in the fisheye lens are aspheric lenses, each aspheric surface type satisfies the following equation:
wherein,zis aspheric and has a height ofhThe distance from the aspheric surface vertex is higher,cis the paraxial curvature of the surface,A 2iis aspheric surface type coefficient of 2i order, k is conic coefficient, when k is less than-1, the curve is hyperbolic curve, when k is equal to-1, it is parabolic curve, when k is between-1 and 0, it is elliptic curve, when k is equal to 0, it is circular curve, when k is greater than 0, it is oblate curve. The surface shape and size of the front and back aspheric surfaces of the lens can be accurately set through the parameters. The aspheric surface shape meets an even-order aspheric surface equation, and different aspheric surface coefficients are utilized, so that the aspheric surface plays the most role in the system, and more perfect resolving power is obtained.
Example 1
Referring to fig. 1, a schematic structural diagram of a fisheye lens 100 according to embodiment 1 of the present invention is shown, where the fisheye lens sequentially includes, from an object side to an image plane along an optical axis: the optical center of each lens is positioned on the same straight line, namely, a first lens L1, a second lens L2, a third lens L3, a diaphragm ST, a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7 and a filter G1.
The first lens L1 has negative focal power, the object-side surface S1 of the first lens is convex, and the image-side surface S2 of the first lens is concave;
the second lens L2 has negative focal power, the object-side surface S3 of the second lens is convex, and the image-side surface S4 of the second lens is concave;
the third lens L3 has positive optical power, the object-side surface S5 of the third lens is convex at the paraxial region, and the image-side surface S6 of the third lens is convex;
the fourth lens L4 has positive optical power, and both the object-side surface S7 and the image-side surface S8 of the fourth lens are convex;
the fifth lens L5 has positive optical power, and both the object-side surface S9 and the image-side surface S10 of the fifth lens are convex;
the sixth lens L6 has negative power, and both the object-side surface S11 and the image-side surface S12 of the sixth lens are concave;
the seventh lens L7 has positive optical power, and both the object-side surface S13 and the image-side surface S14 of the seventh lens are convex.
The first lens L1 and the fourth lens L4 are all glass spherical lenses, and the second lens L2, the third lens L3, the fifth lens L5, the sixth lens L6 and the seventh lens L7 are all plastic aspheric lenses.
The parameters related to each lens of the fisheye lens 100 provided by the present embodiment are shown in table 1-1.
TABLE 1-1
The relevant parameters of the aspherical lens of the fisheye lens in this embodiment are shown in tables 1-2.
Tables 1 to 2
In the present embodiment, the MTF graph, the F-Theta distortion graph, and the on-axis aberration graph of the fisheye lens 100 are shown in fig. 2, 3, and 4, respectively.
Referring to fig. 2, a graph of MTF of the fisheye lens of the present embodiment is shown, wherein the horizontal axis represents spatial frequency (lp/mm), and the vertical axis represents MTF value. As can be seen from the figure, the MTF value of the lens within the field of view of 91 degrees of half-field angle of view at a spatial frequency of 200lp/mm is above 0.4, indicating that the fisheye lens has a higher resolution.
Referring to fig. 3, an F-Theta distortion diagram of the fisheye lens of the present embodiment is shown, wherein the horizontal axis represents F-Theta distortion (unit:%), and the vertical axis represents half field angle (unit:%). As can be seen from the figure, the F-Theta distortion of the lens is smaller and less than 8%, which indicates that the distortion of the fisheye lens is well corrected.
Referring to fig. 4, a graph of axial chromatic aberration of a fisheye lens according to an embodiment of the invention is shown, wherein the horizontal axis represents axial chromatic aberration (unit: mm) and the vertical axis represents normalized pupil radius. As can be seen from the figure, the offset of chromatic aberration is controlled within +/-0.01 mm, which shows that the fisheye lens can effectively correct the on-axis point spherical aberration.
Example 2
Referring to fig. 5, a schematic structural diagram of a fisheye lens 200 according to embodiment 2 of the present invention is shown, where the fisheye lens 200 in this embodiment is substantially the same as the fisheye lens 100 in embodiment 1 in terms of surface type unevenness, and the difference is that: the radius of curvature, thickness of each lens and air space between each lens are different.
The parameters related to each lens of the fisheye lens 200 provided by the present embodiment are shown in table 2-1.
TABLE 2-1
The parameters of the aspherical lens of the fisheye lens 200 in this embodiment are shown in table 2-2.
Tables 2 to 2
In the present embodiment, the MTF graph, the F-Theta distortion graph, and the on-axis aberration graph of the fisheye lens 200 are shown in fig. 6, 7, and 8, respectively.
Referring to fig. 6, a graph of MTF of the fisheye lens of the present embodiment is shown, wherein the horizontal axis represents spatial frequency (lp/mm), and the vertical axis represents MTF value. As can be seen from the figure, the MTF value of the lens within the field of view of 89 degrees of half-field angle of view at a spatial frequency of 200lp/mm is above 0.4, indicating that the fisheye lens has a higher resolution.
Referring to fig. 7, an F-Theta distortion diagram of the fisheye lens of the present embodiment is shown, wherein the horizontal axis represents F-Theta distortion (unit:%), and the vertical axis represents half field angle (unit:%). As can be seen from the figure, the F-Theta distortion of the lens is small and less than 4%, indicating that the distortion of the fisheye lens is well corrected.
Referring to fig. 8, a graph of axial chromatic aberration of a fisheye lens according to an embodiment of the invention is shown, wherein the horizontal axis represents axial chromatic aberration (unit: mm) and the vertical axis represents normalized pupil radius. As can be seen from the figure, the offset of chromatic aberration is controlled within +/-0.01 mm, which shows that the fisheye lens can effectively correct the on-axis point spherical aberration.
Example 3
Referring to fig. 9, which is a schematic structural diagram of a fisheye lens 300 according to embodiment 3 of the present invention, the fisheye lens 300 in this embodiment is substantially the same as the fisheye lens 100 in embodiment 1 in terms of surface roughness, except that: the radius of curvature, thickness of each lens and air space between each lens are different.
The parameters related to each lens of the fisheye lens 300 provided by the present embodiment are shown in table 3-1.
TABLE 3-1
The parameters of the aspherical lens of the fisheye lens 300 in this embodiment are shown in table 3-2.
TABLE 3-2
In the present embodiment, the MTF graph, the F-Theta distortion graph, and the on-axis difference graph of the fisheye lens 300 are shown in fig. 10, 11, and 12, respectively.
Referring to fig. 10, a graph of MTF of the fisheye lens of the present embodiment is shown, wherein the horizontal axis represents spatial frequency (lp/mm), and the vertical axis represents MTF value. As can be seen from the figure, the MTF value of the lens within the field of view of 91 degrees of half-field angle of view at a spatial frequency of 200lp/mm is above 0.4, indicating that the fisheye lens has a higher resolution.
Referring to fig. 11, an F-Theta distortion diagram of the fisheye lens of the present embodiment is shown, wherein the horizontal axis represents F-Theta distortion (unit:%), and the vertical axis represents half field angle (unit:%). As can be seen from the figure, the F-Theta distortion of the lens is small and less than 4%, indicating that the distortion of the fisheye lens is well corrected.
Referring to fig. 12, a graph of axial chromatic aberration of a fisheye lens according to an embodiment of the invention is shown, in which the horizontal axis represents axial chromatic aberration (unit: mm) and the vertical axis represents normalized pupil radius. As can be seen from the figure, the offset of chromatic aberration is controlled within +/-0.01 mm, which shows that the fisheye lens can effectively correct the on-axis point spherical aberration.
Please refer to table 4, which shows the optical characteristics corresponding to the fisheye lens provided in each of the three embodiments, including the effective focal length F, F # and total optical length TTL of the fisheye lens, and further including the related values corresponding to each of the conditional expressions.
TABLE 4
In conclusion, the fish-eye lens provided by the invention adopts a glass-plastic mixed matching structure, and particularly adopts two glass lenses and five plastic lenses in a specified position sequence, so that the lens has good imaging quality in high and low temperature environments, the weight and the volume of the lens are effectively reduced, and the processing cost is reduced; meanwhile, the lenses are compactly arranged, so that the length of the lens is effectively reduced, and the head of the lens is smaller, so that the lens has smaller volume; and because the diaphragm and each lens structure of camera lens set up rationally, can make the light quantity of wider scope get into the fuselage, satisfy the imaging demand of light and shade environment.
The above examples are merely illustrative of several embodiments of the present invention, and the description thereof is more specific and detailed, but not to be construed as limiting the scope of the invention. It should be noted that, for those skilled in the art, various changes and modifications can be made without departing from the spirit of the invention, and these changes and modifications are all within the scope of the invention. Therefore, the protection scope of the present invention should be subject to the appended claims.
Claims (10)
1. A fisheye lens, comprising seven lenses, sequentially arranged along an optical axis from an object side to an image plane, comprising:
the lens comprises a first lens with negative focal power, a second lens and a third lens, wherein the object side surface of the first lens is a convex surface, and the image side surface of the first lens is a concave surface;
the second lens with negative focal power is characterized in that the object side surface of the second lens is a convex surface, and the image side surface of the second lens is a concave surface;
a third lens having a positive optical power, an object-side surface of the third lens being convex at a paraxial region, an image-side surface of the third lens being convex;
a diaphragm;
the fourth lens is provided with positive focal power, and the object side surface and the image side surface of the fourth lens are convex surfaces;
the lens comprises a fifth lens with positive focal power, wherein both the object-side surface and the image-side surface of the fifth lens are convex surfaces;
a sixth lens element having a negative optical power, the sixth lens element having a concave object-side surface and a concave image-side surface;
a seventh lens having a positive optical power, the seventh lens having convex object and image side surfaces;
the fisheye lens at least comprises a glass lens and a plastic lens;
the fisheye lens meets the following conditional expression:
16＜TTL/f＜19；
wherein, TTL represents the optical total length of the fisheye lens, and f represents the effective focal length of the fisheye lens.
2. The fisheye lens of claim 1, wherein the fisheye lens satisfies the following conditional expression:
0.98＜SD14/IH＜1.03；
wherein SD14 denotes a maximum effective diameter of an image-side surface of the seventh lens element, and IH denotes an image plane size corresponding to a field angle of the fisheye lens.
3. The fisheye lens of claim 1, wherein the fisheye lens satisfies the following conditional expression:
0.6＜RS2/SD2＜0.7；
wherein RS2 represents the rise of the image side of the first lens and SD2 represents the maximum effective diameter of the image side of the first lens.
4. The fisheye lens of claim 1, wherein the fisheye lens satisfies the following conditional expression:
0.1＜φ567/φ＜0.2；
wherein phi 567 represents the combined focal power of the fifth lens, the sixth lens and the seventh lens, and phi represents the focal power of the fisheye lens.
5. The fisheye lens of claim 1, wherein the fisheye lens satisfies the following conditional expression:
0.2＜SD7/SD3＜0.4；
wherein SD3 represents the maximum effective diameter of the object side surface of the second lens, and SD7 represents the maximum effective diameter of the object side surface of the fourth lens.
6. The fisheye lens of claim 1, wherein the fisheye lens satisfies the following conditional expression:
-0.13≤φ123/φ＜-0.08；
wherein phi 123 represents the combined focal power of the first lens, the second lens and the third lens, and phi represents the focal power of the fisheye lens.
7. The fisheye lens of claim 1, wherein the fisheye lens satisfies the following conditional expression:
10°＜CRA＜18°；
wherein CRA represents an incident angle of a chief ray of the fisheye lens on an imaging plane.
8. The fisheye lens of claim 1, wherein the fisheye lens satisfies the following conditional expression:
4.7＜TTL/IH＜5.5；
wherein, TTL represents the optical total length of the fisheye lens, and IH represents the image surface size corresponding to the field angle of the fisheye lens.
9. The fisheye lens of claim 1, wherein the fisheye lens satisfies the following conditional expression:
0.17＜φ4/φ≤0.27；
wherein phi 4 represents the focal power of the fourth lens, and phi represents the focal power of the fisheye lens.
10. The fisheye lens of claim 1, wherein the first lens and the fourth lens are all glass spherical lenses, and the second lens, the third lens, the fifth lens, the sixth lens and the seventh lens are all plastic aspheric lenses.
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Application publication date: 20220201 Assignee: Zhongshan Liantuo Optical Co.,Ltd. Assignor: JIANGXI LIANCHUANG ELECTRONIC Co.,Ltd. Contract record no.: X2023980040632 Denomination of invention: Fisheye lens Granted publication date: 20220531 License type: Common License Record date: 20230828 |