CN114355585B - Object space telecentric lens suitable for curved object plane - Google Patents
Object space telecentric lens suitable for curved object plane Download PDFInfo
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- CN114355585B CN114355585B CN202111624343.1A CN202111624343A CN114355585B CN 114355585 B CN114355585 B CN 114355585B CN 202111624343 A CN202111624343 A CN 202111624343A CN 114355585 B CN114355585 B CN 114355585B
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Abstract
The invention relates to an object space telecentric lens suitable for a curved object plane, wherein an optical system of the lens consists of a meniscus negative lens A, a biconvex positive lens B, a meniscus positive lens C with a convex surface facing the object plane, a biconvex positive lens D, a biconvex positive lens E, a biconcave negative lens F, a biconvex positive lens G, a meniscus lens H with a concave surface facing the object plane, a meniscus negative lens I with a convex surface facing the object plane, a biconcave negative lens J, a biconcave negative lens K, a biconvex positive lens L, a biconvex positive lens M and a meniscus positive lens N with a convex surface facing the object plane, which are sequentially arranged from the object side to the image side along an optical axis; the lens has the advantages of large numerical aperture, high amplification factor and high target surface brightness, is suitable for detecting spherical objects such as steel balls, can detect a curved spherical surface with an R value of 6, can effectively avoid the fuzzy profile during measurement due to telecentric design of an object space, has high imaging definition, and can realize good imaging effect on a large target surface with phi 16mm and 100 lp/mm.
Description
Technical Field
The invention relates to an object space telecentric lens suitable for a curved object plane.
Background
Along with the development of industrialization, for the size detection of precision parts, an important production link is gradually formed, the object space telecentric lens can effectively prevent the ghost problem generated by a conventional lens, then the focal length of the lens is often limited by the object plane detection range and the magnification factor, a larger numerical aperture is needed when a brighter image plane is required to be obtained, and the final result caused by the two factors is that the depth of field of the lens is often quite narrow, and objects with a certain depth are difficult to see.
Disclosure of Invention
In view of the defects of the prior art, in order to avoid the problem that the depth of field of the telecentric lens for conventional measurement conflicts with other parameters, the invention provides the object space telecentric lens suitable for a curved object plane.
In order to solve the technical problems, the technical scheme of the invention is as follows: the optical system of the lens consists of a meniscus negative lens A, a biconvex positive lens B, a meniscus positive lens C, a biconvex positive lens D, a biconvex positive lens E, a biconcave negative lens F, a biconvex positive lens G, a meniscus lens H with a concave surface facing the object plane, a meniscus negative lens I with a convex surface facing the object plane, a biconcave negative lens J, a biconcave negative lens K, a biconvex positive lens L, a biconvex positive lens M and a meniscus positive lens N with a convex surface facing the object plane, wherein the meniscus negative lens A, the biconvex positive lens B, the meniscus positive lens C with a convex surface facing the object plane are sequentially arranged from the object side to the image side along an optical axis.
Further, the first cemented lens formed by the meniscus negative lens A and the biconvex positive lens B in close contact, the second cemented lens formed by the biconvex positive lens E and the biconcave negative lens F in close contact, and the third cemented lens formed by the biconcave negative lens K and the biconvex positive lens L in close contact.
Further, the focal length of the lens is f, the focal lengths of the optical lenses from the image plane to the object plane are f1-f14 in sequence, the focal length of the first cemented lens is f15, the focal length of the second cemented lens is f16, the focal length of the third cemented lens is f17, wherein-0.4 < f1/f < -0.25, 0.22< f2/f <0.38, 1.0< f3/f <1.6, 0.5< f4/f <0.6, 0.25< f5/f <0.35, -0.25< f6/f < -0.15, 0.5< f7/f <0.6, 0.09< f8/f <0.15, -0.25< f9/f < -0.17, -0.04< f10/f < -0.02, -6.5< f11/f < -5.5, 0.08< f12/f <0.15, 0.012< f13/f <0.18, 2.5< f15/f 4, -0.65< f16/f < -0.55, -0.7< 17/f < 0.55.
Compared with the prior art, the invention has the following beneficial effects: the numerical aperture is large, the magnification is high, the brightness of the target surface is high, the device is suitable for detecting spherical objects such as steel balls, the curved spherical surface with the R value of 6 can be detected, the telecentric design of the object space can effectively avoid the fuzzy contour during measurement, the imaging definition is high, and good imaging effect can be realized for a large target surface with phi 16mm and 100 lp/mm.
The invention will be described in further detail with reference to the drawings and the detailed description.
Drawings
Fig. 1 is a schematic diagram of an optical system of the lens.
Fig. 2 is an MTF graph of the lens.
Fig. 3 is a distortion curve of the lens.
Fig. 4 is a dot diagram of the lens.
Fig. 5 is a defocus graph of the lens.
Fig. 6 is an axial chromatic aberration diagram of the lens.
Fig. 7 is a vertical axis chromatic aberration diagram of the lens.
Fig. 8 is a field curvature diagram of the lens.
In the figure: 1-a meniscus negative lens a; 2-biconvex positive lens B; 3-biconvex positive lens C; 4-biconvex positive lens D; 5-biconvex positive lens E; 6-biconcave negative lens F; 7-biconvex positive lens G; 8-meniscus lens H; 9-meniscus negative lens I; 10-biconcave negative lens J; 11-biconcave negative lens K; 12-biconvex positive lens L; 13-biconvex positive lens M; 14-meniscus positive lens N.
Detailed Description
In order to make the above features and advantages of the present invention more comprehensible, embodiments accompanied with figures are described in detail below.
As shown in fig. 1-8, an optical system of the lens is composed of a meniscus negative lens a with a convex surface facing the object plane, a biconvex positive lens B, a meniscus positive lens C with a convex surface facing the object plane, a biconvex positive lens D, a biconvex positive lens E, a biconcave negative lens F, a biconvex positive lens G, a meniscus lens H with a concave surface facing the object plane, a meniscus negative lens I with a convex surface facing the object plane, a biconcave negative lens J, a biconcave negative lens K, a biconvex positive lens L, a biconvex positive lens M, and a meniscus positive lens N with a convex surface facing the object plane, which are sequentially arranged from the object side to the image side along an optical axis;
and the first bonding lens formed by closely connecting the meniscus negative lens A and the biconvex positive lens B, the second bonding lens formed by closely connecting the biconvex positive lens E and the biconcave negative lens F, and the third bonding lens formed by closely connecting the biconcave negative lens K and the biconvex positive lens L.
The focal length of the lens is f, the focal length of each optical lens from the image surface to the object surface is f1-f14, the focal length of the first cemented lens is f15, the focal length of the second cemented lens is f16, and the focal length of the third cemented lens is f17, wherein-0.4 < f1/f < -0.25, 0.22< f2/f <0.38, 1.0< f3/f <1.6, 0.5< f4/f <0.6, 0.25< f5/f <0.35, -0.25< f6/f < -0.15, 0.5< f7/f <0.6, 0.09< f8/f <0.15, -0.25< f9/f < -0.17, -0.04< f10/f < -0.02, -6.5< f < -5.5, 0.08< f12/f <0.15, -0.08 < f <0.15, 0.8 < 7/f < 0.55, -0.55 < 5.55.
In this embodiment, the first 6 lenses form a front group and the last 8 lenses form a rear group with the diaphragm disposed between the front and rear groups.
In the embodiment, three lenses of a front group of a meniscus negative lens A, a biconvex positive lens B and a biconvex positive lens C are added to eliminate chromatic aberration while realizing object telecentricity, so that subsequent aberration correction pressure is reduced from the source, wherein the first cemented lens can be replaced by a single sheet with high refractive index and low dispersion under the condition of loose index; the front group of biconvex positive lens D, biconvex positive lens E and biconcave negative lens F are similar to the front half part of the double Gaussian lens in function, mainly play a role in eliminating coma on the left side of the diaphragm, meanwhile, correction of wide-beam aperture aberration is needed here, and a split lens can be selected to reduce generation of advanced aberration.
The specific parameters of each lens are as follows:
in this embodiment, the distribution of the back group power is of great importance, and because of the object plane curvature, a more extreme negative power component is required to balance the petzval sum, so that the field curvature becomes a major contradictory point of the whole lens. And because the field curvature is off-axis aberration, the optimal position of the balanced field curvature is the position where the on-axis chief ray and the off-axis chief ray start to be separated, namely, the position near the biconcave negative lens J bears huge negative focal power, the refractive angle is large, and the thickness and the eccentric of the lens have tiny disturbance which can greatly influence the height of the chief ray on the subsequent surface, so that the tolerance is very sensitive, and the focal power of the lens needs to be slightly distributed to the surrounding position, so that the light path is folded more smoothly. It should be added that, due to the sensitivity of the off-axis light falling point at the J-piece, the thickness of the GHI piece on the beam-converging path of the optical path becomes more sensitive, which is the biggest challenge brought by the large sum of the requirements of the curved object plane petzval, if the optical path is lowered too slowly, the effect of sufficient field curvature correction cannot be achieved, if the optical path is lowered rapidly, the sensitivity is further improved, so that the trade-off between the two needs to be repeatedly balanced, and fine adjustment is made.
In this embodiment, the biconvex positive lens M and the meniscus positive lens N are mainly used for adjusting CRA, and can achieve image-side telecentric optical path if necessary, and also have the function of adjusting distortion, so that two sheets are used for splitting focal power to reduce monochromatic aberration, and glass materials with high refractive index and low dispersion are selected as much as possible, and if the performance overflows, only one sheet can be reserved.
The technical indexes of the lens are as follows: (1) focal length: effl= 79.12mm; (2) object space numerical aperture: 0.1; (3) object plane R value: 6, preparing a base material; (4) object height: 5.33; (5) imaging circle diameter is greater than phi 16.0; (6) working spectral range: 420 nm-680 nm; (7) The object distance is more than or equal to 70mm, the conjugate distance is less than or equal to 230mm, and the optical back intercept is more than or equal to 19mm; (8) optical distortion is less than or equal to 3 percent.
As can be seen from fig. 2-8, the present lens spherical aberration coma aberration aberrations are relatively easy to correct and give good results, whereas field curvature is the most challenging part of them. In this embodiment, the object plane R value is 6, the object height is 5.33, which is equivalent to a sphere close to half a circle, and it can be seen that the field curvature of the field from 0 to 0.9 is well corrected, the field curvature at the edge has a situation that the field curvature is greatly increased after the tolerance is considered, if the object height is adjusted to 5.5 from 5.33, the difficulty can be greatly increased, but the object height cannot really reach the hemisphere due to the fact that the light on the edge field can be tangent to the object plane at most, so that a margin is left for the optical design, and the field curvature of the edge field does not cause destructive striking on the off-axis image.
While the foregoing is directed to the preferred embodiment, other and further embodiments of the invention will be apparent to those skilled in the art from the following description, wherein the invention is described, by way of illustration and example only, and it is intended that the invention not be limited to the specific embodiments illustrated and described, but that the invention is to be limited to the specific embodiments illustrated and described.
Claims (3)
1. An object space telecentric lens suitable for a curved object plane, characterized in that: the optical system of the lens consists of a meniscus negative lens A, a biconvex positive lens B, a meniscus positive lens C, a biconvex positive lens D, a biconvex positive lens E, a biconcave negative lens F, a biconvex positive lens G, a meniscus lens H with a concave surface facing the object plane, a meniscus negative lens I with a convex surface facing the object plane, a biconcave negative lens J, a biconcave negative lens K, a biconvex positive lens L, a biconvex positive lens M and a meniscus positive lens N with a convex surface facing the object plane, which are sequentially arranged from the object side to the image side along the optical axis.
2. The object-side telecentric lens for curved object surfaces according to claim 1, wherein: and the first bonding lens formed by closely connecting the meniscus negative lens A and the biconvex positive lens B, the second bonding lens formed by closely connecting the biconvex positive lens E and the biconcave negative lens F, and the third bonding lens formed by closely connecting the biconcave negative lens K and the biconvex positive lens L.
3. The object-side telecentric lens for curved object surfaces according to claim 1, wherein: the focal length of the lens is f, the focal length of each optical lens from the image surface to the object surface is f1-f14, the focal length of the first cemented lens is f15, the focal length of the second cemented lens is f16, and the focal length of the third cemented lens is f17, wherein-0.4 < f1/f < -0.25, 0.22< f2/f <0.38, 1.0< f3/f <1.6, 0.5< f4/f <0.6, 0.25< f5/f <0.35, -0.25< f6/f < -0.15, 0.5< f7/f <0.6, 0.09< f8/f <0.15, -0.25< f9/f < -0.17, -0.04< f10/f < -0.02, -6.5< f < -5.5, 0.08< f12/f <0.15, -0.08 < f <0.15, 0.8 < 7/f < 0.55, -0.55 < 5.55.
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| CN202111624343.1A CN114355585B (en) | 2021-12-28 | 2021-12-28 | Object space telecentric lens suitable for curved object plane |
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| CN202111624343.1A CN114355585B (en) | 2021-12-28 | 2021-12-28 | Object space telecentric lens suitable for curved object plane |
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| CN114355585B true CN114355585B (en) | 2023-07-28 |
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| GB2467788B (en) * | 2009-02-16 | 2014-05-07 | Qioptiq Ltd | An optical adaptor |
| US9086558B2 (en) * | 2013-03-05 | 2015-07-21 | Apple Inc. | Small form factor high-resolution camera |
| CN109375344A (en) * | 2018-12-12 | 2019-02-22 | 深圳市视清科技有限公司 | A kind of high-resolution lens of curved planar reformation |
| CN113311573B (en) * | 2021-03-18 | 2022-11-08 | 上海大学 | Comprises an aspheric catadioptric panoramic imaging optical system |
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