CN210742594U - Rear-view optical system - Google Patents
Rear-view optical system Download PDFInfo
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- CN210742594U CN210742594U CN201921156619.6U CN201921156619U CN210742594U CN 210742594 U CN210742594 U CN 210742594U CN 201921156619 U CN201921156619 U CN 201921156619U CN 210742594 U CN210742594 U CN 210742594U
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Abstract
The utility model relates to a back vision optical system sets gradually the focal power for the preceding group of negative lens A, the focal power is positive rear mirror group B and is located the fixed diaphragm between preceding group of lens A and the rear mirror group B along light incidence direction from the left hand right side, preceding group of lens A includes first meniscus negative lens, the meniscus negative lens of second and first biconvex positive lens, rear mirror group B includes third meniscus negative lens and the biconvex positive lens of second. The utility model discloses rational in infrastructure, easy and simple to handle, the whole reliability of system is higher, and the assembly sensitivity of group of mirror is low, the yield is high, and optics aberration becomes low simultaneously, and the resolution is high.
Description
Technical Field
The utility model relates to a back vision optical system.
Background
The vehicle-mounted rearview mirror head has wide application in a vehicle-mounted monitoring system, and provides functions such as automobile rearview image and backing assistance for a driver. With the development of the automobile industry, higher requirements are put forward on the performance of the vehicle-mounted rearview lens. The main problems faced by the rearview mirror head on the market at present are: 1. the small aperture causes insufficient edge light flux of a large field angle, so that edge imaging is not clear enough and imaging quality is poor; 2. the common rearview mirror head generally adopts a 5-6 full glass lens structure, has larger size and heavier weight, can not meet the requirement of miniaturization and has higher manufacturing cost; 3. the vehicle-mounted lens has a complex working environment, particularly has large working temperature change, and requires the lens to ensure the imaging quality within a large working temperature range.
Disclosure of Invention
In view of this, an object of the present invention is to provide a rear-view optical system, which has a reasonable structure, is easy to operate, has higher overall reliability, has low assembly sensitivity and high yield of lens groups, and has low optical distortion and high resolution.
The technical scheme of the utility model is that: the utility model provides a rear-view optical system, sets gradually along light incidence direction from the left hand right side has the focal power to be the fixed diaphragm of the preceding group A of mirror of negative, focal power to be positive back group B and be located preceding group A of mirror and back group B between, preceding group A of mirror includes first meniscus negative lens, the meniscus negative lens of second and first biconvex positive lens, back group B of mirror includes the meniscus negative lens of third and the biconvex positive lens of second.
Furthermore, the third negative meniscus lens and the second double convex positive lens form an aspheric lens glue combination.
Further, along the incident direction of light rays, the air space between the front lens group A and the rear lens group B is 0.8 mm; the air space between the front lens group A and the fixed diaphragm is 0.3 mm; the air space between the fixed diaphragm and the rear lens group B is 0.5 mm.
Further, in the front lens group a, the air space between the first negative meniscus lens and the second negative meniscus lens is 0.4mm along the light incidence direction; the air space between the second negative meniscus lens and the first positive biconvex lens was 5.5 mm.
Furthermore, the first negative meniscus lens and the second negative meniscus lens are spherical lenses and are made of glass materials; the first biconvex positive lens, the third meniscus negative lens and the second biconvex positive lens are aspheric lenses and are all made of plastic materials.
Furthermore, an imaging surface is arranged at the rear end of the second biconvex positive lens, and flat protective glass is arranged between the second biconvex positive lens and the imaging surface.
Further, the total focal length of the optical system is set to f, the focal length of the first negative meniscus lens is set to f1, the focal length of the second negative meniscus lens is set to f2, the focal length of the first double convex positive lens is set to f3, the focal length of the third negative meniscus lens is set to f4, and the focal length of the second double convex positive lens is set to f5, which are as follows:
。
further, the refractive index of the first negative meniscus lens is set to Nd1Setting the refractive index of the second negative meniscus lens to Nd2Setting the refractive index of the first biconvex positive lens to Nd3Setting the refractive index of the third negative meniscus lens to Nd4Setting the refractive index of the second biconvex positive lens to Nd5The refractive index of each lens satisfies the following relationship: n is a radical ofd1≥1.5；Nd2≥1.5；Nd3≥1.7；Nd4≥1.5；Nd5≥1.5。
Further, the abbe number of the first meniscus negative lens is set to Vd1Setting Abbe's coefficient of the second meniscus negative lens to Vd2Setting Abbe's coefficient of the first biconvex positive lens to Vd3Setting Abbe's coefficient of the third meniscus negative lens to Vd4Setting Abbe's coefficient of the second biconvex positive lens to Vd5The abbe number of each lens satisfies the following relationship: vd1≥45；Vd2≥50；Vd3≤25；Vd4≤25；Vd5≥50。
Compared with the prior art, the beneficial effects of the utility model are that:
(1) the utility model adopts the design structure of 2G3P, compared with the full glass design, the utility model has smaller size and mass; the system has higher overall reliability, low assembly sensitivity and high yield of the lens group, has larger cost advantage and is beneficial to large-scale production;
(2) the light transmission aperture is larger, the light entering amount of the edge is ensured, and the edge imaging quality is improved; the reasonable focal power of the glass lens and the plastic aspheric lens is reasonably distributed, the surface type of the aspheric lens is optimally designed, the high-level aberration and chromatic aberration of the whole optical system are effectively corrected, and meanwhile, the optical distortion of the system is low and the resolving power is high;
(3) the utility model discloses have good high low temperature characteristic, according to the utility model provides a under the prerequisite of lens combination, material combination, the utility model discloses a best resolution ratio image forming position that the camera lens had guaranteed-40 ℃ - +85 ℃ temperature range internal lens is unchangeable.
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below.
Drawings
Fig. 1 is a schematic view of an optical structure according to an embodiment of the present invention;
fig. 2 is a graph of visible light MTF of an embodiment of the present invention;
FIG. 3 is a graph of defocus at-40 ℃ in the embodiment of the present invention;
fig. 4 is a graph of defocus at high temperature +85 ℃ according to an embodiment of the present invention;
fig. 5 is a graph of optical distortion curves for an embodiment of the present invention;
in the figure: 100-anterior lens group A; 110-first negative meniscus lens 120-second negative meniscus lens; 130-a first biconvex positive lens; 200-rear mirror group B; 210-third negative meniscus lens; 220-a second biconvex positive lens; 300-fixed diaphragm; 400-imaging surface; 500-plate cover glass.
Detailed Description
As shown in fig. 1-5, a rear-view optical system is provided with a front lens group a with negative focal power, a rear lens group B with positive focal power and a fixed diaphragm between the front lens group a and the rear lens group B in sequence from left to right along a light incidence direction, wherein the front lens group a comprises a first negative meniscus lens, a second negative meniscus lens and a first double-convex positive lens, and the rear lens group B comprises a third negative meniscus lens and a second double-convex positive lens. The negative focal power of the front lens group A can correct the positive focal power aberration of the rear lens group B.
In this embodiment, the third negative meniscus lens and the second double convex positive lens form an aspheric lens cemented combination.
In this embodiment, along the incident direction of light, the air space between the front lens group a and the rear lens group B is 0.8 mm; the air space between the front lens group A and the fixed diaphragm is 0.3 mm; the air space between the fixed diaphragm and the rear lens group B is 0.5 mm.
In this embodiment, along the light incident direction, in the front lens group a, the air space between the first negative meniscus lens and the second negative meniscus lens is 0.4 mm; the air space between the second negative meniscus lens and the first positive biconvex lens was 5.5 mm.
In this embodiment, the first negative meniscus lens and the second negative meniscus lens are spherical lenses and are made of glass material; the first biconvex positive lens, the third meniscus negative lens and the second biconvex positive lens are aspheric lenses and are all made of plastic materials.
In this embodiment, an imaging surface is provided at the rear end of the second biconvex positive lens, and a flat protective glass is provided between the second biconvex positive lens and the imaging surface.
In this embodiment, the total focal length of the optical system is set to f, the focal length of the first negative meniscus lens is set to f1, the focal length of the second negative meniscus lens is set to f2, the focal length of the first double-convex positive lens is set to f3, the focal length of the third negative meniscus lens is set to f4, and the focal length of the second double-convex positive lens is set to f5, where the focal lengths of the lenses are as follows:
。
in the present embodiment, the refractive index of the first negative meniscus lens is set to Nd1, the refractive index of the second negative meniscus lens is set to Nd2, the refractive index of the first double convex positive lens is set to Nd3, the refractive index of the third negative meniscus lens is set to Nd4, the refractive index of the second double convex positive meniscus lens is set to Nd5, and the refractive indexes of the respective lenses satisfy the following relationships: nd1 is more than or equal to 1.5; nd2 is more than or equal to 1.5; nd3 is more than or equal to 1.7; nd4 is more than or equal to 1.5; nd5 is more than or equal to 1.5.
In this embodiment, abbe number of the first negative meniscus lens is Vd1, abbe number of the second negative meniscus lens is Vd2, abbe number of the first double convex positive lens is Vd3, abbe number of the third negative meniscus lens is Vd4, abbe number of the second double convex positive lens is Vd5, and abbe number of each lens satisfies the following relationship: vd1 is more than or equal to 45; vd2 is more than or equal to 50; vd3 is less than or equal to 25; vd4 is less than or equal to 25; vd5 is greater than or equal to 50.
TABLE 1 specific lens parameters are as follows
In the embodiment, five lenses are taken as an example, and by reasonably distributing the focal power, the surface type, the central thickness of each lens, the on-axis air interval between each lens and the like, the field angle of the lens is effectively enlarged, the total length of the lens is shortened, and the small distortion and the high illumination of the lens are ensured; meanwhile, various aberrations are corrected, and the resolution and the imaging quality of the lens are improved. Each aspherical surface type Z is defined by the following formula:
wherein the content of the first and second substances,
is at a position of height h from the aspheric surface along the optical axis(ii) the rise;
is the paraxial curvature of the aspheric surface,
(i.e., paraxial curvature)
Is the radius of curvature in Table 1 above
The reciprocal of (d);
is the conic constant; A. b, C, D, E are all high order term coefficients. Table 2 shows a conic constant k and a high-order term coefficient A, B, C, D, E that can be used for each aspherical lens surface in the present embodiment.
TABLE 2 aspherical lens parameters
In this embodiment, the technical indexes of the optical system are as follows:
(1) focal length: EFFL =1.91 mm; (2) aperture F = 2.1; (3) the field angle: 2w is more than or equal to 140 degrees; (4) optical distortion: < -33%; (5) the diameter of the imaging circle is larger than phi 4.8; (6) the working wave band is as follows: 420-700 nm; (7) the total optical length TTL is less than or equal to 13.2mm, and the optical back intercept BFL is more than or equal to 2.6 mm; (8) the lens is suitable for a megapixel CCD or CMOS camera.
The specific implementation process comprises the following steps: when light enters, an optical path sequentially enters the front lens group A, the fixed diaphragm and the rear lens group B to form an image, when the light passes through the front lens group A, the first negative meniscus lens of the front lens group A has larger refractive index and focal power to ensure that the system has a larger field of view, the second negative meniscus lens adopts an aspheric lens and is responsible for correcting the distortion of the whole optical system, and the first double convex positive lens adopts high-refractive-index ultrahigh-dispersion glass and is used for adjusting the high-low temperature characteristic of the whole optical system; when light passes through the rear lens group B, the third negative meniscus lens with medium refractive index and ultrahigh dispersion effectively corrects chromatic aberration and astigmatism of the imaging system.
The embodiment of the utility model provides an in, four aspherical mirror corrects all high-grade aberrations and spherical aberration, through reasonable refracting index and focal power proportion distribution, guarantees the equilibrium of the angle of incidence size of preceding group A's lens and rear mirror group B's lens, has reduced optical system's field curvature.
Through the optical system formed by the lenses, the total length of the optical path is short, so that the lens is small in size and large in back focus, and can be matched with cameras with various interfaces for use; the second negative meniscus lens, the third negative meniscus lens and the second biconvex positive lens are plastic aspheric lenses, so that the image quality is good and the cost is low; the system has a large designed aperture, can ensure the light entering amount of a large field angle, and has clear edge imaging.
As can be seen from FIG. 2, the MTF of the optical system in the visible light band is well-behaved, the MTF value is greater than 0.5 at the spatial frequency of 45pl/mm, and the MTF value is greater than 0.3 at the spatial frequency of 80pl/mm, so that the requirement of high resolution of megapixels can be met. FIGS. 3 and 4 are graphs of MTF defocus at-40 ℃ and +85 ℃ for this optical system, respectively. As can be seen from the figure, the defocusing amount of the central visual field of the optical system is-7.2 μm at-40 ℃, and the defocusing amount of the central visual field is 6.6 μm at 85 ℃. The defocusing amount is within an acceptable range, and the image quality performance completely meets the use requirements of the vehicle-mounted lens in high and low temperature environments. FIG. 5 is a graph of optical distortion of the optical system, and it can be seen that the optical distortion is controlled within-33% at the maximum field angle of 140 ° of the lens, and the edge image is clear and is not distorted.
Above-mentioned operation flow and software and hardware configuration only do as the preferred embodiment of the utility model discloses a not therefore restrict the patent scope of the utility model, all utilize the utility model discloses the equivalent transform of doing of description and attached drawing content, or directly or indirectly use in relevant technical field, all the same reason is included in the patent protection scope of the utility model.
Claims (9)
1. A rearview optical system, comprising: set gradually along light incidence direction from left to right and have that focal power is the preceding group A of the mirror, focal power be positive back group B and lie in preceding group A of the mirror and the fixed diaphragm between the group B of the mirror, preceding group A of the mirror includes first meniscus negative lens, second meniscus negative lens and first biconvex positive lens, back group B of the mirror includes third meniscus negative lens and second biconvex positive lens.
2. A rearview optical system as claimed in claim 1, wherein: and the third negative meniscus lens and the second double convex positive lens form an aspheric lens glue combination.
3. A rearview optical system as claimed in claim 2, wherein: along the incident direction of light, the air space between the front lens group A and the rear lens group B is 0.8 mm; the air space between the front lens group A and the fixed diaphragm is 0.3 mm; the air space between the fixed diaphragm and the rear lens group B is 0.5 mm.
4. A rearview optical system as claimed in claim 3, wherein: in the front lens group A, the air space between the first negative meniscus lens and the second negative meniscus lens is 0.4mm along the incident direction of light; the air space between the second negative meniscus lens and the first positive biconvex lens was 5.5 mm.
5. The rearview optical system of claim 4, wherein: the first negative meniscus lens and the second negative meniscus lens are spherical lenses and are made of glass materials; the first biconvex positive lens, the third meniscus negative lens and the second biconvex positive lens are aspheric lenses and are all made of plastic materials.
6. A rearview optical system as claimed in claim 5, wherein: an imaging surface is arranged at the rear end of the second biconvex positive lens, and flat protective glass is arranged between the second biconvex positive lens and the imaging surface.
7. A rearview optical system as claimed in claim 6, wherein: setting the total focal length of the optical system to f, the focal length of the first negative meniscus lens to f1, the focal length of the second negative meniscus lens to f2, the focal length of the first double convex positive lens to f3, the focal length of the third negative meniscus lens to f4, and the focal length of the second double convex positive lens to f5, the respective focal lengths of the lenses are as follows:
。
8. a rearview optical system as claimed in claim 7, wherein: setting the refractive index of the first meniscus negative lens to Nd1Setting the refractive index of the second negative meniscus lens to Nd2Setting the refractive index of the first biconvex positive lens to Nd3Setting the refractive index of the third negative meniscus lens to Nd4Setting the refractive index of the second biconvex positive lens to Nd5The refractive index of each lens satisfies the following relationship: n is a radical ofd1≥1.5；Nd2≥1.5；Nd3≥1.7；Nd4≥1.5；Nd5≥1.5。
9. A rearview optical system as claimed in claim 8, wherein: setting Abbe's coefficient of the first meniscus negative lens to Vd1Setting Abbe's coefficient of the second meniscus negative lens to Vd2Setting Abbe's coefficient of the first biconvex positive lens to Vd3Setting Abbe's coefficient of the third meniscus negative lens to Vd4Setting Abbe's coefficient of the second biconvex positive lens to Vd5The abbe number of each lens satisfies the following relationship: vd1≥45；Vd2≥50；Vd3≤25；Vd4≤25；Vd5≥50。
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| CN201921156619.6U CN210742594U (en) | 2019-07-23 | 2019-07-23 | Rear-view optical system |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110346916A (en) * | 2019-07-23 | 2019-10-18 | 福建福光天瞳光学有限公司 | A kind of backsight optical system and its working method |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110346916A (en) * | 2019-07-23 | 2019-10-18 | 福建福光天瞳光学有限公司 | A kind of backsight optical system and its working method |
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