Disclosure of Invention
The invention mainly aims to provide an imaging lens and imaging equipment, and aims to solve the technical problem that the existing lens on the market is difficult to achieve wide angle, ultra-large aperture, large target surface and high relative illuminance.
In order to achieve the above objective, the imaging lens provided by the present invention includes a first lens group, a second lens group, a diaphragm, a third lens group and a fourth lens group sequentially arranged from an object side to an image side at intervals; the first lens group and the third lens group have negative focal power, and the second lens group and the fourth lens group have positive focal power;
the first lens group comprises a first lens and a second lens which are sequentially arranged along an optical axis; the first lens and the second lens are negative lenses;
The second lens group comprises a third lens, a fourth lens, a fifth lens, a sixth lens and a seventh lens which are sequentially arranged along the optical axis; the third lens and the seventh lens are negative lenses, and the fourth lens, the fifth lens and the sixth lens are positive lenses;
The third lens group comprises an eighth lens, a ninth lens, a tenth lens, an eleventh lens and a twelfth lens which are sequentially arranged along the optical axis; the eighth lens and the twelfth lens are negative lenses, and the ninth lens, the tenth lens and the eleventh lens are positive lenses;
the fourth lens group comprises a thirteenth lens, a fourteenth lens and a fifteenth lens which are sequentially arranged along the optical axis; the thirteenth lens and the fourteenth lens are positive lenses, and the fifteenth lens is a negative lens.
In an embodiment, the first lens is a negative meniscus lens, a convex surface of the first lens faces the object plane, and a concave surface of the first lens faces the image plane; the second lens is a biconcave negative lens.
In an embodiment, the third lens is a biconcave negative lens; the fourth lens is a biconvex positive lens; the fifth lens is a biconvex positive lens; the sixth lens is a biconvex positive lens; the seventh lens is a biconcave negative lens.
In an embodiment, the eighth lens is a biconcave negative lens; the ninth lens is a biconvex positive lens; the tenth lens is a biconvex positive lens; the eleventh lens is a biconvex positive lens; the twelfth lens is a biconcave negative lens.
In an embodiment, the thirteenth lens is a plano-convex positive lens, the convex surface of the thirteenth lens faces the object plane, and the plane of the thirteenth lens faces the image plane; the fourteenth lens is a plano-convex positive lens, the convex surface of the fourteenth lens faces the object plane, and the plane of the fourteenth lens faces the image plane; the fifteenth lens is a plano-concave negative lens, the concave surface of the fifteenth lens faces the object plane, and the plane of the fifteenth lens faces the image plane.
In an embodiment, the following relation is satisfied between the focal length of the fifth lens, the focal length of the tenth lens, and the overall focal length of the imaging lens:
1.0<f5/f10<1.3，2.5<f5/f<2.8
Wherein f5 is a focal length of the fifth lens, f10 is a focal length of the tenth lens, and f is an overall focal length of the imaging lens.
In one embodiment, the abbe number of the material of the fifth lens and the abbe number of the material of the tenth lens satisfy the following relation:
62<Vd5<72，62<Vd10<72
The refractive index of the material of the sixth lens satisfies the following relation:
1.91<Nd6<1.95
where Vd5 is an abbe number of the material of the fifth lens, vd10 is an abbe number of the material of the tenth lens, and Nd6 is a refractive index of the material of the sixth lens.
In one embodiment, the focal length of the second lens group and the focal length of the third lens group satisfy the following relationship:
21.40<|fG3/fG2|<60.00
wherein fG2 is the focal length of the second lens group and fG3 is the focal length of the third lens group.
In one embodiment, the field angle of the imaging lens satisfies the following relationship:
55.00°<2ω<65.00°
Wherein 2ω is the angle of view of the imaging lens.
In one embodiment, the F-number of the imaging lens satisfies the following relationship:
0.95<Fno<1.20
wherein FNo is the F number of the imaging lens.
In an embodiment, the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the eighth lens, the ninth lens, the tenth lens, the eleventh lens, the twelfth lens, the thirteenth lens, the fourteenth lens, and the fifteenth lens are all spherical lenses made of glass materials.
The invention also provides optical imaging equipment comprising the imaging lens.
The technical scheme of the invention realizes a wider field angle through the first lens group with negative focal power; the second lens group with positive focal power is matched with the third lens group with negative focal power, so that an ultra-large aperture is realized; a large target surface is realized through a fourth lens group with positive focal power; based on the collocation mode between each lens group and between each lens in each lens group, the light intercepted by the lenses is reduced, namely vignetting is reduced, and high relative illumination is realized. Therefore, the technical scheme of the invention ensures that the imaging lens has the advantages of wider field angle, oversized aperture, large target surface and high relative illumination compared with the existing lens through reasonable focal power collocation among the first lens group, the second lens group, the third lens group and the fourth lens group, and can better meet the increasingly diversified and complicated requirements of the lens in the market.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are only some, but not all embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
It should be noted that, if directional indications (such as up, down, left, right, front, and rear … …) are included in the embodiments of the present invention, the directional indications are merely used to explain the relative positional relationship, movement conditions, etc. between the components in a specific posture, and if the specific posture is changed, the directional indications are correspondingly changed.
In addition, if there is a description of "first", "second", etc. in the embodiments of the present invention, the description of "first", "second", etc. is for descriptive purposes only and is not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In addition, if "and/or" and/or "are used throughout, the meaning includes three parallel schemes, for example," a and/or B "including a scheme, or B scheme, or a scheme where a and B are satisfied simultaneously. In addition, the technical solutions of the embodiments may be combined with each other, but it is necessary to base that the technical solutions can be realized by those skilled in the art, and when the technical solutions are contradictory or cannot be realized, the combination of the technical solutions should be considered to be absent and not within the scope of protection claimed in the present invention.
The F number (F number) of the lens in the market at present is usually required to be set above a certain value, and the lens with a smaller F number is difficult to achieve high relative illuminance and a larger target surface.
In order to solve the technical problem, the invention provides an imaging lens which meets the requirements of wide angle, ultra-large aperture, large target surface and high relative illumination, thereby meeting the requirements of increasingly diversified and complicated lenses in the market.
Referring to fig. 1, in an embodiment of the present invention, the imaging lens includes a first lens group 100, a second lens group 200, a diaphragm 500, a third lens group 300 and a fourth lens group 400 sequentially arranged from an object side to an image side at intervals; the first lens group 100 and the third lens group 300 have negative optical power, and the second lens group 200 and the fourth lens group 400 have positive optical power;
the first lens group 100 includes a first lens 101 and a second lens 102 disposed in order along an optical axis; the first lens 101 and the second lens 102 are negative lenses;
the second lens group 200 includes a third lens 201, a fourth lens 202, a fifth lens 203, a sixth lens 204, and a seventh lens 205, which are disposed in order along the optical axis; the third lens 201 and the seventh lens 205 are negative lenses, and the fourth lens 202, the fifth lens 203 and the sixth lens 204 are positive lenses;
The third lens group 300 includes an eighth lens 301, a ninth lens 302, a tenth lens 303, an eleventh lens 304, and a twelfth lens 305, which are disposed in order along the optical axis; the eighth lens 301 and the twelfth lens 305 are negative lenses, and the ninth lens 302, the tenth lens 303 and the eleventh lens 304 are positive lenses;
The fourth lens group 400 includes a thirteenth lens 401, a fourteenth lens 402, and a fifteenth lens 403, which are sequentially disposed along the optical axis; the thirteenth lens 401 and the fourteenth lens 402 are positive lenses, and the fifteenth lens 403 is a negative lens.
In this embodiment, a wider field of view is achieved by the first lens group 100 having negative optical power; by the interaction of the second lens group 200 with positive optical power and the third lens group 300 with negative optical power, an oversized aperture is achieved; by the fourth lens group 400 having positive optical power, a large target surface is achieved; based on the collocation mode between each lens group and between each lens in each lens group, the light intercepted by the lenses is reduced, namely vignetting is reduced, and high relative illumination is realized.
More specifically, the negative lens has an effect of moving the light propagation direction away from the optical axis, i.e., a divergent effect; the positive lens has the effect of bringing the direction of propagation of the light close to the optical axis, i.e. converging. The direction of propagation of the light rays with a large angle can be gradually far away from the optical axis through the divergent action of the two negative lenses of the first lens group 100, so that the light rays can be incident on the following lens group with a small angle relative to the optical axis, and a wider field angle is realized; the second lens group 200 has a similar structure to the third lens group 300, and the focal power of the second lens group and the third lens group is positive or negative, so that large aberration caused by the oversized aperture can be well corrected and compensated, and the oversized aperture is realized; meanwhile, the second lens group 200 and the third lens group 300 have similar structures, which can reduce the light intercepted by the lenses, i.e. reduce vignetting, and realize high relative illuminance; residual aberrations of light rays passing through the front three lens groups are corrected by the fourth lens group 400, and the light rays are diverged by the fifteenth lens 403, which is a negative lens, so that the light rays are far from the optical axis at the landing point of the image plane 600, and a large target plane is realized.
Therefore, the technical scheme of the invention ensures that the imaging lens of the invention has the advantages of wider field angle, oversized aperture, large target surface and high relative illumination compared with the existing lens through reasonable focal power collocation among the first lens group 100, the second lens group 200, the third lens group 300 and the fourth lens group 400, and can better meet the requirements of increasingly diversified and complicated lenses in the market.
Optionally, referring to fig. 1 and 2, the first lens 101 is a negative meniscus lens, the convex surface of the first lens 101 faces the object plane, and the concave surface of the first lens 101 faces the image plane 600; the second lens 102 is a biconcave negative lens.
Alternatively, referring to fig. 1 and 2, the third lens 201 is a biconcave negative lens; the fourth lens 202 is a biconvex positive lens; the fifth lens 203 is a biconvex positive lens; the sixth lens 204 is a biconvex positive lens; the seventh lens 205 is a biconcave negative lens.
Alternatively, referring to fig. 1 and 2, the eighth lens 301 is a biconcave negative lens; the ninth lens 302 is a biconvex positive lens; the tenth lens 303 is a biconvex positive lens; the eleventh lens 304 is a biconvex positive lens; the twelfth lens 305 is a biconcave negative lens.
Optionally, referring to fig. 1 and 2, the thirteenth lens 401 is a plano-convex positive lens, the convex surface of the thirteenth lens 401 faces the object plane, and the plane of the thirteenth lens 401 faces the image plane 600; the fourteenth lens element 402 is a plano-convex positive lens element, wherein the convex surface of the fourteenth lens element 402 faces the object plane, and the plane of the fourteenth lens element 402 faces the image plane 600; the fifteenth lens 403 is a plano-concave negative lens, the concave surface of the fifteenth lens 403 faces the object plane, and the plane of the fifteenth lens 403 faces the image plane 600.
Wherein the third lens 201 is cemented with the fourth lens 202, the sixth lens 204 is cemented with the seventh lens 205, the eighth lens 301 is cemented with the ninth lens 302, and the eleventh lens 304 is cemented with the twelfth lens 305.
Alternatively, referring to fig. 1 and 2, the following relation is satisfied between the focal length of the fifth lens 203, the focal length of the tenth lens 303, and the overall focal length of the imaging lens:
1.0<f5/f10<1.3，2.5<f5/f<2.8
where f5 is the focal length of the fifth lens 203, f10 is the focal length of the tenth lens 303, and f is the overall focal length of the imaging lens.
Alternatively, referring to fig. 1 and 2, the abbe number of the material of the fifth lens 203 and the abbe number of the material of the tenth lens 303 satisfy the following relation:
62<Vd5<72，62<Vd10<72
the refractive index of the material of the sixth lens 204 satisfies the following relation:
1.91<Nd6<1.95
where Vd5 is the abbe number of the material of the fifth lens 203, vd10 is the abbe number of the material of the tenth lens 303, and Nd6 is the refractive index of the material of the sixth lens 204.
Optionally, referring to fig. 1 and 2, the focal length of the second lens group 200 and the focal length of the third lens group 300 satisfy the following relationship:
21.40<|fG3/fG2|<60.00
where fG2 is the focal length of the second lens assembly 200 and fG3 is the focal length of the third lens assembly 300.
Alternatively, referring to fig. 1 and 2, the field angle of the imaging lens satisfies the following relation:
55.00°<2ω<65.00°
Wherein 2ω is the field angle of the imaging lens.
Alternatively, referring to fig. 1 and 2, the F-number of the imaging lens satisfies the following relationship:
0.95<Fno<1.20
wherein FNo is the F number of the imaging lens.
Optionally, referring to fig. 1 and 2, the first lens 101, the second lens 102, the third lens 201, the fourth lens 202, the fifth lens 203, the sixth lens 204, the seventh lens 205, the eighth lens 301, the ninth lens 302, the tenth lens 303, the eleventh lens 304, the twelfth lens 305, the thirteenth lens 401, the fourteenth lens 402, and the fifteenth lens 403 are all spherical lenses made of glass materials.
Based on the parameter settings and material collocations of each lens group and each lens in the embodiment, the imaging lens obtains the advantages of wider field angle, ultra-large aperture, large target surface, high relative illuminance and the like, and also realizes confocal of visible light and near infrared wave bands, thereby further improving the performance and imaging effect of the imaging lens.
Referring to fig. 2, in a specific embodiment, parameters such as a surface curvature radius, a thickness, a refractive index, an abbe number, and the like of each lens included in the imaging lens are shown in table 1. Wherein thickness refers to the distance between each lens surface to the next lens surface; for example, the thickness of S1 refers to the distance between the center of S1 to the center of S2, i.e., the center thickness of the first lens 101; the thickness of S2 refers to the distance between the center of S2 to the center of S3, i.e., the air thickness between the first lens 101 and the second lens 102.
TABLE 1
According to the data of table 1, the focal length f=16 mm, the field angle 2ω=61.7°, the F-number fno=1.04, and the imaging target surface circle diameter Φ=17.6 mm; thus f5/f10=1.127, f5/f=2.70, vd5=71.3, vd10=71.3, nd6=1.92, |fg3/fg2|=39.57 can be obtained; in addition, the lenses used in this embodiment are all glass spherical lenses; the above parameters all meet the requirements. The fifth lens 203 and the tenth lens 303 use low-dispersion materials with higher abbe numbers, and are matched with the four glued lenses of the second lens group 200 and the third lens group 300, so that chromatic aberration of visible light and near infrared light can be corrected, and visible light and near infrared confocal is realized. Based on the above embodiment, the actual test effect of the imaging lens is as follows:
Fig. 3 and 6 are respectively MTF diagrams (Modulation Transfer Function, modulation transfer function graphs) of the imaging lens in the above embodiments under visible light with a wavelength of 435nm to 650 nm and MTF diagrams (Modulation Transfer Function, modulation transfer function graphs) under near infrared light with a wavelength of 750nm to 1100 nm. As can be seen from fig. 3 and fig. 6, the MTF values of the imaging lens under the visible spectrum and the near infrared spectrum are relatively consistent, that is, confocal between the visible light and the near infrared band is realized.
Fig. 4 and 7 are a relative illuminance map of the imaging lens in the above embodiment under visible light having a wavelength of 546nm and a relative illuminance map under near infrared light having a wavelength of 850nm, respectively. According to fig. 4 and 7, the relative illuminance of the imaging lens in the visible spectrum and the near infrared spectrum is consistent, and the relative illuminance is up to 70%, i.e. the high relative illuminance of the imaging lens is realized.
Fig. 5 and 8 are respectively an optical distortion chart of the imaging lens in the above embodiment under visible light with a wavelength of 435nm to 650 nm and an optical distortion chart under near infrared light with a wavelength of 750nm to 1100 nm. As can be seen from fig. 5 and 8, the optical distortion of the imaging lens is small, and is maintained at substantially 8%. It will be appreciated that the optical distortion differences at the several wavelengths shown in fig. 5 and 8 are small, and thus the distortion curves corresponding to the respective wavelengths are shown as overlapping each other in fig. 5 and 8, which is described.
The invention also provides an optical imaging device, which comprises an imaging lens, wherein the specific structure of the imaging lens refers to the embodiment, and because the optical imaging device adopts all the technical schemes of all the embodiments, the optical imaging device at least has all the beneficial effects brought by the technical schemes of the embodiments, and the detailed description is omitted.
The optical imaging apparatus may be a camera, a projector, a scanner, or the like, as long as imaging is achieved by using the imaging lens provided by the above-described embodiments and based on the optical imaging technique, which is an optical imaging apparatus according to the present invention.
The foregoing description is only exemplary embodiments of the present invention and is not intended to limit the scope of the invention, and all equivalent structural changes made by the description of the present invention and the accompanying drawings or direct/indirect application in other related technical fields are included in the scope of the present invention.