CN108318995B - Lens system and lens - Google Patents
Lens system and lens Download PDFInfo
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- CN108318995B CN108318995B CN201810048398.4A CN201810048398A CN108318995B CN 108318995 B CN108318995 B CN 108318995B CN 201810048398 A CN201810048398 A CN 201810048398A CN 108318995 B CN108318995 B CN 108318995B
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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
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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
- G02B13/0055—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras employing a special optical element
- G02B13/006—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras employing a special optical element at least one element being a compound optical element, e.g. cemented elements
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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 provides a lens system and a lens, wherein the lens system is provided with a first lens group with positive focal power, an aperture diaphragm and a second lens group with positive focal power in sequence from an object side to an image side along an optical axis; the first lens group includes, in order from an object side to an image side along an optical axis: the zoom lens comprises a first lens with negative focal power, a second lens with negative focal power, a first sub-lens group with positive focal power, a second sub-lens group with positive or negative focal power and a third sub-lens group with positive focal power; the first lens is a meniscus lens with a convex surface facing the object side, and the second lens is a meniscus lens with a convex surface facing the object side; in the scheme, under the coordination of the structures, focal power, focal length and arrangement sequence of each lens and the lens group, the lens with the short viewpoint distance can be realized under the conditions of meeting the requirements of large target surface and large field angle.
Description
Technical Field
The present invention relates to the field of optical instruments, and in particular, to a lens system and a lens barrel.
Background
In the field of security protection, a network camera is a common device in a security protection system, a lens is a main constituent part of the network camera, the performance of the lens directly affects the imaging quality and the imaging view field, as the technical index requirement of the security protection system is continuously improved, an imaging element with a large target surface (3/4 inches) is used on the camera to enhance the imaging quality, but the imaging area of the lens is required to be adapted to the imaging element with the large target surface, and when the imaging area of the lens is increased, higher requirements are also provided for the spherical aberration, the coma aberration, the principal ray emergence angle (CRA) and the chromatic aberration correction capability of the lens.
At present, under the condition that a conventional wide-angle (i.e., having a large field angle) lens meets a large target surface (3/4 inches), a viewpoint distance (the viewpoint distance is a distance from a viewpoint position to a vertex of the lens, and the viewpoint position is an intersection point position of a ray incident at a maximum field angle and an optical axis of the lens) is generally long, the viewpoint distance is in direct proportion to a ratio of a diameter of a mirror surface of a lens closest to an object side in a lens system to a radius of curvature, and generally the ratio is greater than 1, and an excessively long viewpoint distance causes an oversize of a protective glass or a reflecting device in front of the lens in the camera, which causes a significant increase in cost, and even a structure cannot be. As shown in fig. 1, the distance from the viewpoint position a1 of the lens S1 to the vertex of the lens is H1 (i.e., the viewpoint distance of the lens S1 is H1), the distance from the viewpoint position a2 of the lens S2 to the vertex of the lens is H2 (i.e., the viewpoint distance of the lens S2 is H2), H2> H1, and the size L2 of the cover glass or the reflecting device 1 in front of the lens S2 is larger than the size L1 of the cover glass or the reflecting device 1 in front of the lens S1.
Therefore, it is necessary to develop a lens with a short viewpoint distance under the conditions of large target surface and large field angle.
Disclosure of Invention
The embodiment of the invention provides a lens system and a lens, which are used for realizing a lens with a short viewpoint distance under the conditions of meeting the requirements of a large target surface and a large field angle.
In the lens system provided in the embodiment of the present invention, a first lens group with positive focal power, an aperture stop, and a second lens group with positive focal power are sequentially disposed from an object side to an image side along an optical axis;
the first lens group includes, in order from an object side to an image side along an optical axis: the zoom lens comprises a first lens with negative focal power, a second lens with negative focal power, a first sub-lens group with positive focal power, a second sub-lens group with positive or negative focal power and a third sub-lens group with positive focal power; the first lens is a meniscus lens with a convex surface facing the object side, and the second lens is a meniscus lens with a convex surface facing the object side;
and, each lens satisfies the following conditions:
D1/R1≤0.73；
R1/f≥6；
wherein D is1Denotes a diameter, R, of a mirror surface of the first lens near the object side1Denotes a radius of curvature of a mirror surface of the first lens near the object side, and f denotes a focal length of the lens system.
Preferably, the first sub-lens group includes a third lens having positive power; the third lens is a meniscus lens with a convex surface facing the image side.
Preferably, the second sub-lens group includes, in order from the object side to the image side along the optical axis: a fourth lens with negative focal power and a fifth lens with positive focal power; the fourth lens is a biconcave lens, and the fifth lens is a biconvex lens.
Preferably, the fourth lens and the fifth lens are cemented to form a cemented lens group.
Preferably, the third sub-lens group includes a sixth lens having positive optical power; the sixth lens element is a plano-convex lens element with a planar surface facing the image side, a meniscus lens element with a convex surface facing the object side, or a biconvex lens element.
Preferably, the second lens group includes, in order from the object side to the image side along the optical axis: the zoom lens comprises a seventh lens with positive focal power, an eighth lens with negative focal power, a ninth lens with positive focal power, a tenth lens with negative focal power and a fourth sub-lens group with positive focal power; the seventh lens element is a meniscus lens element with a convex surface facing the image side, a biconvex lens element or a plano-convex lens element with a surface facing the object side being a flat surface, the eighth lens element is a meniscus lens element with a convex surface facing the image side, the ninth lens element is a biconvex lens element, and the tenth lens element is a biconcave lens element.
Preferably, the fourth sub-lens group includes, in order from the object side to the image side along the optical axis: an eleventh lens having positive refractive power and a twelfth lens having positive refractive power; the eleventh lens is a biconvex lens, a meniscus lens with a convex surface facing the image side, or a plano-convex lens with a surface facing the object side being a plane.
Preferably, the twelfth lens is a biconvex lens or a plano-convex lens with a planar surface facing the image side.
Preferably, the seventh lens element and the eighth lens element are cemented together to form a cemented lens group.
Preferably, the ninth lens element and the tenth lens element are cemented together to form a cemented lens group.
Preferably, the seventh lens and the ninth lens satisfy the condition: 0.015 or more of Nd7/Vd7≤Nd9/Vd9Less than or equal to 0.025; wherein N isd7A refractive index, V, of a glass material of the seventh lensd7Abbe number, N, of the glass material of the seventh lensd9A refractive index, V, of a glass material of the ninth lensd9And an abbe number of the glass material of the ninth lens.
Preferably, the refractive index N of the glass material of the tenth lens isd10The conditions are satisfied: n is more than or equal to 1.94d10≤2.05。
Preferably, the focal length f of the ninth lens9Focal length f of the tenth lens10The conditions are satisfied: | f is more than or equal to 1.559/f10|≤1.75。
An embodiment of the present invention further provides a lens, sequentially including, from an object side to an image side along an optical axis: any embodiment of the invention provides a lens system and an imaging surface.
Preferably, the lens barrel further includes: and the optical filter is arranged between the lens system and the imaging surface.
The embodiment of the invention has the following beneficial effects:
in the lens system and the lens provided by the embodiment of the invention, under the coordination of the structure, focal power, focal length and arrangement sequence of each lens and the lens group, the lens with short viewpoint distance can be realized under the conditions of meeting the requirements of large target surface and large field angle.
Drawings
FIG. 1 is a schematic diagram of the relationship between viewpoint distance and camera size;
FIG. 2(a) is a schematic structural diagram of a first lens system according to an embodiment of the present invention;
FIG. 2(b) is a schematic structural diagram of a second lens system according to an embodiment of the present invention;
FIG. 2(c) is a schematic structural diagram of a third lens system according to an embodiment of the present invention;
FIG. 2(d) is a schematic structural diagram of a fourth lens system according to an embodiment of the present invention;
FIG. 2(e) is a schematic structural diagram of a fifth lens system according to an embodiment of the present invention;
FIG. 2(f) is a schematic structural diagram of a sixth lens system according to an embodiment of the present invention;
FIG. 2(g) is a schematic structural diagram of a seventh lens system according to an embodiment of the present invention;
fig. 3 is a schematic structural diagram of a lens provided in an embodiment of the present invention;
fig. 4 is a schematic structural diagram of another lens provided in an embodiment of the present invention;
fig. 5 is a graph of an optical transfer function (MTF) of a visible light portion of a lens at normal temperature according to an embodiment of the present invention;
fig. 6 is another graph of an optical transfer function (MTF) of a visible light portion of the lens at normal temperature according to the first embodiment of the present invention;
fig. 7 is a graph of an optical transfer function (MTF) of a lens in a visible light range at-30 ℃ according to an embodiment of the present invention;
fig. 8 is a graph of an optical transfer function (MTF) of a lens in a visible light portion at 80 ℃ according to an embodiment of the present invention;
fig. 9 is a field curvature diagram of a visible portion of a lens according to a first embodiment of the present invention;
fig. 10 is a distortion diagram of a visible light portion of a lens according to an embodiment of the present invention;
fig. 11 is a graph of an optical transfer function (MTF) of a visible light portion of a lens at normal temperature according to a second embodiment of the present invention;
fig. 12 is another graph of an optical transfer function (MTF) of a visible light portion of the lens at normal temperature according to the second embodiment of the present invention;
fig. 13 is a graph of an optical transfer function (MTF) of a lens according to a second embodiment of the present invention in a visible light range at-30 ℃;
fig. 14 is a graph of an optical transfer function (MTF) of a visible light portion of a lens at 80 ℃ according to a second embodiment of the present invention;
fig. 15 is a field curvature diagram of a visible light portion of the lens according to the second embodiment of the present invention;
fig. 16 is a distortion diagram of a visible light portion of a lens according to a second embodiment of the present invention.
Detailed Description
The embodiment of the invention provides a lens system and a lens, which are used for realizing a lens with a short viewpoint distance under the conditions of meeting the requirements of a large target surface and a large field angle.
In the lens system provided in the embodiment of the present invention, a first lens group with positive focal power, an aperture stop, and a second lens group with positive focal power are sequentially disposed from an object side to an image side along an optical axis;
the first lens group includes, in order from an object side to an image side along an optical axis: the zoom lens comprises a first lens with negative focal power, a second lens with negative focal power, a first sub-lens group with positive focal power, a second sub-lens group with positive or negative focal power and a third sub-lens group with positive focal power; the first lens is a meniscus lens with a convex surface facing the object side, and the second lens is a meniscus lens with a convex surface facing the object side;
and, each lens satisfies the following conditions:
D1/R1≤0.73；
R1/f≥6；
wherein D is1Denotes a diameter, R, of a mirror surface of the first lens near the object side1Denotes a radius of curvature of a mirror surface of the first lens near the object side, and f denotes a focal length of the lens system.
In the embodiment of the invention, under the coordination of the structures, focal powers, focal lengths and arrangement sequences of the lenses and the lens groups, the lens with the short viewpoint distance can be realized under the conditions of meeting the requirements of large target surface and large field angle.
On the basis of meeting the parameter requirements of the optical system, the structure of each lens group can be specifically adjusted according to needs, and the embodiments of the present invention are further described in detail below with reference to the drawings in the specification.
Fig. 2(a) is a schematic structural diagram of a lens system according to an embodiment of the present invention. The lens system is provided with a first lens group 1 with positive focal power, an aperture diaphragm 2 and a second lens group 3 with positive focal power in sequence from an object side to an image side along an optical axis.
As shown in fig. 2(a), the first lens group 1 includes, in order from the object side to the image side along the optical axis: a first lens 11 with negative focal power, a second lens 12 with negative focal power, a first sub-lens group with positive focal power, a second sub-lens group with negative focal power and a third sub-lens group with positive focal power; the first lens element 11 is a meniscus lens element with a convex surface facing the object side, and the second lens element 12 is a meniscus lens element with a convex surface facing the object side. Of course, the power of the second sub-lens group may also be positive, which is not limited in the embodiment of the present invention.
As shown in fig. 2(a), the first sub-lens group includes a third lens 13 whose power is positive; the third lens element 13 is a meniscus lens element with a convex surface facing the image side.
As shown in fig. 2(a), the second sub-lens group includes, in order from the object side to the image side along the optical axis: a fourth lens 14 having negative power and a fifth lens 15 having positive power; the fourth lens element 14 is a biconcave lens element, and the fifth lens element 15 is a biconvex lens element.
As shown in fig. 2(a), the third sub-lens group includes a sixth lens 16 whose power is positive; the sixth lens element 16 is a plano-convex lens whose surface facing the image side is flat.
As shown in fig. 2(a), the second lens group includes, in order from the object side to the image side along the optical axis: a seventh lens 17 with positive focal power, an eighth lens 18 with negative focal power, a ninth lens 19 with positive focal power, a tenth lens 20 with negative focal power, and a fourth sub-lens group with positive focal power; the seventh lens element 17 is a meniscus lens element with a convex surface facing the image side, the eighth lens element 18 is a meniscus lens element with a convex surface facing the image side, the ninth lens element 19 is a biconvex lens element, and the tenth lens element 20 is a biconcave lens element. The aperture stop 2 is located between the sixth lens 16 and the seventh lens 17.
As shown in fig. 2(a), the fourth sub-lens group includes, in order from the object side to the image side along the optical axis: an eleventh lens 21 having positive power and a twelfth lens 22 having positive power; the eleventh lens element 21 is a biconvex lens element, and the twelfth lens element 22 is a biconvex lens element.
And, each lens satisfies the following conditions:
D1/R1≤0.73；
R1/f≥6；
wherein D is1Denotes the diameter, R, of the mirror surface of the first lens 11 on the object side1Denotes a radius of curvature of a mirror surface of the first lens 11 near the object side, and f denotes a focal length of the above-described lens system.
In a preferred embodiment, D is 0.62 ≦ D1/R1≤0.73；6≤R1/f≤8。
In a preferred embodiment, in order to effectively reduce the chromatic aberration of the system, the seventh lens 17 and the ninth lens 19 satisfy the condition: 0.015 or more of Nd7/Vd7≤Nd9/Vd9Less than or equal to 0.025; wherein N isd7Refractive index, V, of the glass material of the seventh lens element 17d7Abbe number N of the glass material of the seventh lens element 17d9Refractive index, V, of glass material of the ninth lens 19d9The abbe number of the glass material of the ninth lens 19 is shown.
In a preferred embodiment, the refractive index N of the glass material of the tenth lens 20 is selected to reduce the overall length of the systemd10The conditions are satisfied: n is more than or equal to 1.94d10≤2.05。
In a preferred embodiment, the focal length f of the ninth lens 19 is set to achieve good confocal effect at high and low temperatures9Focal length f of the tenth lens 2010The conditions are satisfied: | f is more than or equal to 1.559/f10|≤1.75。
In a preferred embodiment, as shown in fig. 2(a), the fourth lens element 14 and the fifth lens element 15 are cemented together to form a cemented lens group.
In a preferred embodiment, as shown in FIG. 2(a), the seventh lens element 17 and the eighth lens element 18 are cemented together to form a cemented lens group.
In a preferred embodiment, as shown in FIG. 2(a), the ninth lens element 19 and the tenth lens element 20 are cemented together to form a cemented lens group.
It should be noted that the lenses in the cemented lens group may also be only close together without being cemented, and the cemented lens group may be one or more cemented groups, which are not limited in the embodiments of the present invention.
As shown in fig. 2(b), the sixth lens 16 in the third sub-lens group may also be a meniscus lens with the convex surface facing the object side, and the seventh lens 17 in the second lens group may also be a biconvex lens.
As shown in fig. 2(c), the sixth lens 16 in the third sub-lens group may also be a biconvex lens.
As shown in fig. 2(d), the seventh lens 17 in the second lens group may also be a plano-convex lens whose surface facing the object side is planar.
As shown in fig. 2(e), the eleventh lens 21 in the fourth sub-lens group may also be a meniscus lens with the convex surface facing the image side.
As shown in fig. 2(f), the eleventh lens 21 in the fourth sub-lens group may also be a plano-convex lens whose surface facing the object side is planar.
As shown in fig. 2(g), the twelfth lens 22 in the fourth sub-lens group may also be a plano-convex lens whose surface facing the image side is planar.
Alternatively, the first sub-lens group may be a lens group in which a biconcave lens having negative power and a biconvex lens having positive power are cemented.
Optionally, the second sub-lens group may be further replaced by a meniscus lens, wherein a convex surface of the meniscus lens faces the image side.
Optionally, the third sub-lens group may further be a lens group formed by a meniscus lens with negative focal power and a plano-convex lens with positive focal power, wherein a convex surface of the meniscus lens faces the object side, and a surface of the plano-convex lens facing the image side is a plane.
In summary, in the embodiment of the present invention, the first sub-lens group, the second sub-lens group, and the third sub-lens group may be either a single lens or a lens group cemented by lenses.
Alternatively, the fourth sub-lens group may be further replaced by a biconvex lens whose optical power is positive.
In the examples of the present invention, unless otherwise specified, the refractive index refers to the refractive index of the optical glass material with respect to d-light (i.e., the refractive index of the optical glass material measured by d-light), and the abbe number refers to the abbe number of the optical glass material with respect to d-light (i.e., the abbe number obtained from the refractive index of the optical glass material measured by d-light). Wherein d light represents sodium yellow light with a wavelength of 589.3 nm.
Based on the same inventive concept, an embodiment of the present invention further provides a lens, sequentially including, from an object side to an image side along an optical axis: any of the embodiments of the present invention provides a lens system and an imaging surface 24. Two kinds of schematic structural diagrams are respectively shown in fig. 3 and fig. 4, wherein fig. 3 includes the lens system shown in fig. 2(a), and fig. 4 includes the lens system shown in fig. 2 (b).
In a preferred embodiment, in order to reduce color cast, as shown in fig. 3 and 4, the lens barrel may further include: and an optical filter 25 disposed between the zoom lens system and the imaging surface 24.
Due to the lens system adopted by the lens barrel of the embodiment of the invention, aberration is well corrected, the image plane size is large (14.7mm), the imaging resolution is high (the maximum support is 1200 ten thousand pixels of cameras), the field angle is large, and the viewpoint distance is short (the diameter D of the mirror surface of the first lens close to the object side is small)1And radius of curvature R1The ratio of (d) is less than 0.73), the image quality is excellent.
Two preferred embodiments are illustrated below to facilitate an understanding of the lenses provided by the embodiments of the invention.
The first embodiment is as follows:
in specific implementation, in the lens barrel shown in fig. 3, the curvature radius R, the central thickness Tc (i.e. the distance between the center points of adjacent mirror surfaces), and the refractive index N of the mirror surface of each lens from the object side to the image side along the optical axisdAbbe number VdThe diameter D and the focal length f of the mirror surface satisfy the conditions listed in Table 1:
TABLE 1
Wherein STO represents an aperture stop and Infinity represents Infinity; the mirror surfaces of the lenses are arranged in order along the optical axis from the object side to the image side, for example: the mirror surfaces of the lens 11 are the mirror surfaces 1 and 2, the mirror surfaces of the lens 12 are the mirror surfaces 3 and 4, the mirror surfaces of the lens 13 are the mirror surfaces 5 and 6, and so on, because the lens 14 and the lens 15 are glued together, the glued surfaces of the lens 14 and the lens 15 are the same mirror surface (namely, the mirror surface 8), and other glued surfaces are similar, in the table i, R1 represents the curvature radius of the mirror surface 1, T1 represents the distance between the center points of the mirror surface 1 and the mirror surface 2, n1 represents the refractive index of the optical glass material of the mirror surface 1 relative to D light, V1 represents the abbe number of the optical glass material of the mirror surface 1 relative to D light, D1 represents the diameter of the mirror surface 1, f1 represents the focal length of the lens 11, and so on other parameters in the table i, the meanings can be analogi.
From the data of table 1, one can obtain:
the focal length f of the lens system is: 4.81 mm;
D1/R1＝23.233/33.3＝0.698；
R1/f＝33.3/4.81＝6.923；
Nd7/Vd7＝1.497/81.608＝0.018；
Nd9/Vd9＝1.593/67.002＝0.024；
refractive index N of glass material of tenth lensd10Comprises the following steps: 2.003;
the focal length f9 of the ninth lens is: 14.056, the tenth lens has a focal length f10 of: 8.608, so | f9/f10| ═ 14.056/(-8.608) | 1.633.
The focal power of the cemented lens group composed of the fourth lens and the fifth lens is negative.
It should be noted that the lens according to the first embodiment of the present invention has the following optical technical indexes:
focal length f of the lens: 4.81 mm;
angle of view of lens: 190 °;
f Theta distortion of lens: -8%;
aperture of lens system (F/#): 2.0;
size of a lens image plane: 14.7 mm.
The lens system and the lens provided by the first embodiment of the present invention are further described below by performing a detailed optical system analysis on the first embodiment of the present invention.
The optical transfer function is used for evaluating the imaging quality of an optical system in a more accurate, visual and common mode, the higher and smoother curve of the optical transfer function shows that the imaging quality of the system is better, and various aberrations (such as spherical aberration, coma aberration, astigmatism, field curvature, axial chromatic aberration, vertical axis chromatic aberration and the like) are well corrected.
As shown in fig. 5 and 6, fig. 5 is a graph showing an optical transfer function (MTF) in a visible light range at normal temperature (20 ℃) of the lens, and fig. 6 is another graph showing an optical transfer function (MTF) in a visible light range at normal temperature (20 ℃) of the lens. As can be seen from fig. 5, the optical transfer function (MTF) graph of the visible light portion of the lens is relatively smooth and concentrated, and the average MTF value of the entire field of view can still be ensured to be above 0.4 at 100lp/mm, the abscissa in fig. 6 is the field angle, the ordinate is the MTF, the curve represents the variation trend of the imaging quality from the center to the edge from left to right, wherein, the MTF curves generated when S3 and T3 are 60lp/mm, the MTF curves generated when S4 and T4 are 100lp/mm, and the MTF curves generated when S5 and T5 are 160lp/mm are shown in fig. 6, and the optical transfer function (MTF) graph of the visible light portion of the lens is relatively smooth and concentrated; therefore, the lens provided by the first embodiment can achieve high resolution and meet the imaging requirement of a camera with 1200 ten thousand pixels.
As shown in fig. 7 and 8, fig. 7 is a graph of an optical transfer function (MTF) in a visible light portion at-30 degrees celsius (c) of the lens, and fig. 8 is a graph of an optical transfer function (MTF) in a visible light portion at +80 degrees celsius (c) of the lens. As can be seen from fig. 7, at-30 ℃, the optical transfer function (MTF) curve of the visible portion of the lens is relatively smooth and concentrated, and the average MTF of the full field of view still reaches above 0.3 at 100lp/mm, as can be seen from fig. 8, at 80 ℃, the optical transfer function (MTF) curve of the visible portion of the lens is relatively smooth and concentrated, and the average MTF of the full field of view still reaches above 0.4 at 100lp/mm, as can be seen from fig. 5, 7 and 8, the working temperature is-30 ℃ to 80 ℃, and the lens provided in this embodiment still can ensure that the imaging is as clear as that at normal temperature without refocusing.
The field curve diagram corresponding to the visible part of the lens consists of three curves T and three curves S; wherein, the three curves T respectively represent the aberration of the meridional beams (tagential Rays) corresponding to the three wavelengths (486nm, 587nm and 656nm), the three curves S respectively represent the aberration of the sagittal beams (Sagittial Rays) corresponding to the three wavelengths (486nm, 587nm and 656nm), and the smaller the meridional field curvature value and the sagittal field curvature value are, the better the imaging quality is. As shown in FIG. 9, the meridional curvature of field of the lens is controlled within the range of-0.018-0.067 mm, and the sagittal curvature of field is controlled within the range of-0.016-0.067 mm.
And F Theta distortion graphs corresponding to visible light parts of the lens, wherein the distortion rate is smaller as the curve is closer to the y axis. As shown in fig. 10, in which the optical distortion rate is controlled within the range of-8% to 0.
Example two:
in specific implementation, in the lens barrel shown in fig. 4, the radius of curvature R, the central thickness Tc, and the refractive index N of the mirror surface of each lens from the object side to the image side along the optical axisdAbbe number VdThe diameter D and the focal length f of the mirror satisfy the conditions listed in table 2:
TABLE 2
From the data of table 2, one can obtain:
the focal length f of the lens system is: 4.85 mm;
D1/R1＝21.303/29.723＝0.717；
R1/f＝29.723/4.85＝6.128；
Nd7/Vd7＝1.437/95.1＝0.015；
Nd9/Vd9＝1.593/68.624＝0.023；
refractive index N of glass material of tenth lensd10Comprises the following steps: 1.946;
the focal length f9 of the ninth lens is: 13.576, the tenth lens has a focal length f10 of: -8.131, so | f9/f10| ═ 13.576/(-8.131) | 1.67.
The focal power of the cemented lens group composed of the fourth lens and the fifth lens is positive.
It should be noted that the lens of the second embodiment of the present invention has the following optical technical indexes:
focal length f of the lens: 4.85 mm;
angle of view of lens: 190 °;
f Theta distortion of lens: -7%;
aperture of lens system (F/#): 2.0;
size of a lens image plane: 14.7 mm.
The lens system and the lens provided by the second embodiment of the present invention are further described below by performing a detailed optical system analysis on the second embodiment of the present invention.
As shown in fig. 11 and 12, fig. 11 is a graph showing an optical transfer function (MTF) in a visible light range at a normal temperature (20 ℃) of the lens, and fig. 12 is a graph showing another optical transfer function (MTF) in a visible light range at a normal temperature (20 ℃) of the lens. As can be seen from fig. 11, the optical transfer function (MTF) graph of the visible light portion of the lens is relatively smooth and concentrated, and the average MTF value of the entire field of view can still be guaranteed to be above 0.3 at 100lp/mm, the abscissa in fig. 12 is the field angle, the ordinate is the MTF, the curve represents the variation trend of the imaging quality from the center to the edge from left to right, wherein, the MTF curves generated when S3 and T3 are 60lp/mm, the MTF curves generated when S4 and T4 are 100lp/mm, and the MTF curves generated when S5 and T5 are 160lp/mm are shown in fig. 12, and the optical transfer function (MTF) graph of the visible light portion of the lens is relatively smooth and concentrated; therefore, the lens provided by the second embodiment can achieve high resolution and meet the imaging requirement of a camera with 1200 ten thousand pixels.
As shown in fig. 13 and 14, fig. 13 is a graph of an optical transfer function (MTF) in a visible light portion at-30 degrees celsius (c) of the lens, and fig. 14 is a graph of an optical transfer function (MTF) in a visible light portion at +80 degrees celsius (c) of the lens. As can be seen from fig. 13, at-30 ℃, the optical transfer function (MTF) curve of the visible portion of the lens is relatively smooth and concentrated, and the average MTF of the full field of view still reaches above 0.3 at 100lp/mm, as can be seen from fig. 14, at 80 ℃, the optical transfer function (MTF) curve of the visible portion of the lens is relatively smooth and concentrated, and the average MTF of the full field of view still reaches above 0.3 at 100lp/mm, as can be seen from fig. 11, 13 and 14, the operating temperature is-30 ℃ to 80 ℃, and the lens provided by the second embodiment can still ensure that the imaging is still as clear as that at normal temperature without refocusing.
The field curve diagram corresponding to the visible part of the lens consists of three curves T and three curves S; wherein, the three curves T respectively represent the aberration of the meridional beams (tagential Rays) corresponding to the three wavelengths (486nm, 587nm and 656nm), the three curves S respectively represent the aberration of the sagittal beams (Sagittial Rays) corresponding to the three wavelengths (486nm, 587nm and 656nm), and the smaller the meridional field curvature value and the sagittal field curvature value are, the better the imaging quality is. As shown in FIG. 15, the meridional curvature of field of the lens is controlled within the range of-0.018-0.08 mm, and the sagittal curvature of field is controlled within the range of-0.016-0.08 mm.
And F Theta distortion graphs corresponding to visible light parts of the lens, wherein the distortion rate is smaller as the curve is closer to the y axis. As shown in fig. 16, in which the optical distortion rate is controlled within the range of-7% to 0.
In summary, the embodiments of the present invention provide a lens system and a lens, where twelve optical lenses with specific structural shapes are adopted, and are sequentially arranged from an object side to an image side in sequence, and through distribution of focal powers of the optical lenses, and simultaneously, a suitable optical glass material is adopted, so that parameters such as the structural shape of the lens, the focal power distribution of the lenses, the refractive index of the lenses, the abbe number, and the like are matched with imaging conditions, and further spherical aberration, coma, astigmatism, field curvature, vertical chromatic aberration, and axial chromatic aberration of the lens are well corrected, so that an ultra-wide angle lens with a large target surface, a short viewpoint distance, and a high resolution is implemented, and an edge image is slightly compressed, so as to well restore a real scene; meanwhile, the heat difference elimination of the lens is realized, the lens cannot be burnt even when the lens is used in an environment of-30-80 ℃, and the imaging clarity can be ensured without refocusing the lens when the environment temperature changes; all optical lenses adopt the glass spherical surface design, the cold processing technology performance is good, and the production cost is low.
While preferred embodiments of the present invention have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including preferred embodiments and all such alterations and modifications as fall within the scope of the invention.
It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.
Claims (14)
1. A lens system is characterized in that a first lens group with positive focal power, an aperture diaphragm and a second lens group with positive focal power are arranged in sequence from an object side to an image side along an optical axis;
the first lens group includes, in order from an object side to an image side along an optical axis: the zoom lens comprises a first lens with negative focal power, a second lens with negative focal power, a first sub-lens group with positive focal power, a second sub-lens group with positive or negative focal power and a third sub-lens group with positive focal power; the first lens is a meniscus lens with a convex surface facing the object side, and the second lens is a meniscus lens with a convex surface facing the object side;
and, each lens satisfies the following conditions:
D1/R1≤0.73；
R1/f≥6；
wherein D is1Indicating that the first lens is close toDiameter of the mirror surface at the object side, R1Denotes a radius of curvature of a mirror surface of the first lens near the object side, f denotes a focal length of the lens system;
the second sub-lens group comprises in order from the object side to the image side along the optical axis: a fourth lens with negative focal power and a fifth lens with positive focal power; the fourth lens is a biconcave lens, and the fifth lens is a biconvex lens.
2. The lens system of claim 1, wherein the first sub-lens group includes a third lens having positive optical power; the third lens is a meniscus lens with a convex surface facing the image side.
3. The lens system of claim 1, wherein the fourth lens and the fifth lens are cemented together to form a cemented lens group.
4. The lens system of claim 1 wherein the third sub-lens group comprises a sixth lens having positive optical power; the sixth lens element is a plano-convex lens element with a planar surface facing the image side, a meniscus lens element with a convex surface facing the object side, or a biconvex lens element.
5. The lens system of any of claims 1-4, wherein the second lens group comprises, in order from the object side to the image side along the optical axis: the zoom lens comprises a seventh lens with positive focal power, an eighth lens with negative focal power, a ninth lens with positive focal power, a tenth lens with negative focal power and a fourth sub-lens group with positive focal power; the seventh lens element is a meniscus lens element with a convex surface facing the image side, a biconvex lens element or a plano-convex lens element with a surface facing the object side being a flat surface, the eighth lens element is a meniscus lens element with a convex surface facing the image side, the ninth lens element is a biconvex lens element, and the tenth lens element is a biconcave lens element.
6. The lens system of claim 5, wherein the fourth sub-lens group comprises, in order from the object side to the image side along the optical axis: an eleventh lens having positive refractive power and a twelfth lens having positive refractive power; the eleventh lens is a biconvex lens, a meniscus lens with a convex surface facing the image side, or a plano-convex lens with a surface facing the object side being a plane.
7. The lens system of claim 6, wherein the twelfth lens is a biconvex lens or a plano-convex lens with a planar surface facing the image side.
8. The lens system of claim 7, wherein the seventh lens element and the eighth lens element are cemented together to form a cemented lens group.
9. The lens system of claim 5, wherein the ninth lens and the tenth lens are cemented together to form a cemented lens group.
10. The lens system of claim 5, wherein the seventh lens and the ninth lens satisfy a condition: 0.015 or more of Nd7/Vd7≤Nd9/Vd9Less than or equal to 0.025; wherein N isd7A refractive index, V, of a glass material of the seventh lensd7Abbe number, N, of the glass material of the seventh lensd9A refractive index, V, of a glass material of the ninth lensd9And an abbe number of the glass material of the ninth lens.
11. The lens system of claim 5, wherein a refractive index N of the glass material of the tenth lens isd10The conditions are satisfied: n is more than or equal to 1.94d10≤2.05。
12. The lens system of claim 5, wherein the ninth lens has a focal length f9Focal length f of the tenth lens10The conditions are satisfied: | f is more than or equal to 1.559/f10|≤1.75。
13. A lens barrel, comprising, in order from an object side to an image side along an optical axis: a lens system and an imaging surface as claimed in any one of claims 1 to 12.
14. The lens barrel as claimed in claim 13, further comprising: and the optical filter is arranged between the lens system and the imaging surface.
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| TWI684024B (en) * | 2018-07-04 | 2020-02-01 | 大立光電股份有限公司 | Photographing optical lens assembly, imaging apparatus and electronic device |
| CN109445075B (en) * | 2018-12-29 | 2024-04-16 | 深圳市点睛创视技术有限公司 | Miniature projection lens |
| CN110646927B (en) * | 2019-09-30 | 2024-12-31 | 江西特莱斯光学有限公司 | An ultra-wide-angle and ultra-large aperture optical lens |
| CN112817119B (en) * | 2019-11-15 | 2021-11-16 | 中国科学院长春光学精密机械与物理研究所 | An aerospace optical lens |
| CN112817121B (en) * | 2019-11-18 | 2022-02-01 | 成都理想境界科技有限公司 | Projection objective and scanning display device |
| CN111781714B (en) * | 2020-06-20 | 2024-04-05 | 广东弘景光电科技股份有限公司 | Ultra-wide-angle ultra-high pixel optical system |
| CN111694135B (en) * | 2020-07-15 | 2024-05-31 | 北创光电科技(邵阳)有限公司 | Large wide-angle video lens with focal length of 8mm |
| CN218995757U (en) * | 2021-12-15 | 2023-05-09 | 东莞市宇瞳汽车视觉有限公司 | Fixed focus lens |
| CN114488485B (en) * | 2022-02-14 | 2023-07-07 | 合肥埃科光电科技股份有限公司 | Large-target-surface wide-angle low-distortion industrial lens with f22mm |
| CN116582738B (en) * | 2023-07-13 | 2023-10-27 | 珠海市川富光学技术有限公司 | Long-focus large-aperture short-flange video lens with focal length of 85mm |
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