CN209746250U

CN209746250U - optical imaging lens

Info

Publication number: CN209746250U
Application number: CN201920682886.0U
Authority: CN
Inventors: 张军光; 王世昌
Original assignee: Xiamen Li Ding Au Optronics Co
Current assignee: Xiamen Li Ding Au Optronics Co; Xiamen Leading Optics Co Ltd
Priority date: 2019-05-14
Filing date: 2019-05-14
Publication date: 2019-12-06
Anticipated expiration: 2029-05-14

Abstract

The utility model relates to a camera lens technical field. The utility model discloses an optical imaging lens, which comprises a first lens, a second lens, a third lens, a fourth lens, a diaphragm, a fifth lens, a sixth lens and a seventh lens from an object side to an image side along an optical axis in sequence; the first lens is a convex-concave lens with negative refractive index; the second lens is a concave lens with negative refractive index; the third lens is a convex lens with positive refraction; the fourth lens is a convex flat lens with positive refraction; the fifth lens is a convex lens with positive refraction; the sixth lens is a concave-convex lens with negative refractive index; the seventh lens element is a convex lens element with positive refractive power. The utility model has the advantages of good infrared confocal performance, high resolving power and small chromatic aberration.

Description

Optical imaging lens

Technical Field

the utility model belongs to the technical field of the camera lens, specifically relate to an optical imaging camera lens of collocation RGB-IR sensor.

Background

with the continuous progress of the technology, in recent years, the optical imaging lens is also rapidly developed and widely applied to various fields such as smart phones, tablet computers, video conferences, vehicle-mounted monitoring, security monitoring and the like. When the optical imaging lens is applied to the field of security monitoring, the optical imaging lens usually works continuously for 24 hours all day long, so the requirement on the infrared confocal performance of the optical imaging lens is higher and higher, particularly the optical imaging lens with an RGB-IR sensor is carried, but the prior infrared confocal lens has large defocusing amount when visible infrared is switched, needs a switching piece or an optical filter, and has a complex structure and high cost; when the infrared is switched, the loss of the transfer function is more, and the resolution is reduced; when the color difference is visible, the color reduction is inaccurate, the relative illumination is low, the imaging quality is poor in a dark environment, and the increasingly improved requirements cannot be met.

SUMMERY OF THE UTILITY MODEL

an object of the utility model is to provide an optical imaging lens is used for solving the technical problem that above-mentioned exists.

in order to achieve the above object, the utility model adopts the following technical scheme: an optical imaging lens sequentially comprises a first lens, a second lens, a third lens, a fourth lens, a diaphragm, a fifth lens, a sixth lens and a seventh lens from an object side to an image side along an optical axis; the first lens element to the seventh lens element each include an object-side surface facing the object side and passing the imaging light and an image-side surface facing the image side and passing the imaging light;

The first lens element with negative refractive index has a convex object-side surface and a concave image-side surface;

The second lens element with negative refractive index has a concave object-side surface and a concave image-side surface;

The third lens element with positive refractive index has a convex object-side surface and a convex image-side surface;

The fourth lens element with positive refractive index has a convex object-side surface and a flat image-side surface;

the fifth lens element with positive refractive index has a convex object-side surface and a convex image-side surface;

The sixth lens element with negative refractive index has a concave object-side surface and a convex image-side surface;

The seventh lens element with positive refractive power has a convex object-side surface and a convex image-side surface;

the optical imaging lens only has the seven lenses with the refractive index.

Further, the image side surface of the fifth lens and the object side surface of the sixth lens are cemented with each other.

Further, the optical imaging lens further satisfies: vd5-vd6>30, where vd5 and vd6 are the d-line abbe numbers of the fifth lens and the sixth lens, respectively.

further, the optical imaging lens further satisfies: 1.8< nd2<2, where nd2 is the refractive index of the second lens in the d-line.

further, the optical imaging lens further satisfies: 1.8< nd4<2, where nd4 is the refractive index of the fourth lens in the d-line.

Further, the optical imaging lens further satisfies: 1.8< nd3<1.9, where nd3 is the refractive index of the third lens in the d-line.

Further, the optical imaging lens further satisfies: D11/R11<1.8 and D12/R12<1.84, wherein D11 and D12 are light-passing calibers of an object-side surface and an image-side surface of the first lens respectively, and R11 and R12 are curvature radiuses of the object-side surface and the image-side surface of the first lens respectively.

Further, the optical imaging lens further satisfies: 0.3< | D72/R72 | <0.5, wherein D72 is a clear aperture of an image-side surface of the seventh lens element, and R72 is a radius of curvature of the image-side surface of the seventh lens element.

Further, the fourth lens has a Z value of 0.22.

Further, the first lens has a Z value greater than 0.25.

The utility model has the advantages of:

The utility model adopts seven lenses, and through correspondingly designing each lens, the infrared confocal performance is good (the infrared offset is less than 3 μm), the RGB-IR sensor can be carried, no switching piece or optical filter is needed, the structure is simple, and the cost is lower; when the infrared and visible environments are switched, the transfer function loss is less, and the resolution is high; the chromatic aberration is small, and the chromatic aberration is less than 3 mu m at 5 wavelengths; large light transmission, high contrast in low-light environment and stable imaging quality.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.

Fig. 1 is a schematic structural diagram of a first embodiment of the present invention;

FIG. 2 is a graph of MTF of visible light 435-;

FIG. 3 is a graph of MTF at 850nm (200lp/mm) in the infrared according to the first embodiment of the present invention;

FIG. 4 is a defocus graph of 435-;

Fig. 5 is a graph of infrared 850nm defocus curve of the first embodiment of the present invention;

Fig. 6 is a schematic view of curvature of field and distortion according to a first embodiment of the present invention;

Fig. 7 is a schematic view of a longitudinal aberration diagram according to a first embodiment of the present invention;

Fig. 8 is a graph of chromatic aberration according to the first embodiment of the present invention;

Fig. 9 is a schematic structural view of a second embodiment of the present invention;

FIG. 10 is a graph of MTF of visible light 435-;

FIG. 11 is a graph of MTF at 850nm (200lp/mm) in the infrared of the second embodiment of the present invention;

FIG. 12 is a defocus plot for visible light 435-;

fig. 13 is a graph of infrared 850nm defocus curve of the second embodiment of the present invention;

Fig. 14 is a schematic view of curvature of field and distortion according to a second embodiment of the present invention;

Fig. 15 is a schematic view of longitudinal aberration diagram of the second embodiment of the present invention;

fig. 16 is a color difference graph according to the second embodiment of the present invention;

fig. 17 is a schematic structural view of a third embodiment of the present invention;

FIG. 18 is the MTF graph of visible light 435-;

FIG. 19 is a graph of MTF at 850nm (200lp/mm) in the infrared of the third embodiment of the present invention;

FIG. 20 is a defocus plot of 435-;

Fig. 21 is a graph of infrared 850nm defocus curve of the third embodiment of the present invention;

fig. 22 is a schematic view of curvature of field and distortion according to a third embodiment of the present invention;

Fig. 23 is a schematic view of longitudinal aberration diagram of a third embodiment of the present invention;

fig. 24 is a color difference graph of a third embodiment of the present invention;

Fig. 25 is a schematic structural diagram of a fourth embodiment of the present invention;

FIG. 26 is a graph of MTF of visible light 435-;

FIG. 27 is a graph of the MTF at 850nm (200lp/mm) in the infrared of example four of the present invention;

FIG. 28 is a defocus graph of 435-;

fig. 29 is a graph of infrared 850nm defocus curve of the fourth embodiment of the present invention;

Fig. 30 is a schematic view of curvature of field and distortion according to a fourth embodiment of the present invention;

fig. 31 is a schematic view of longitudinal aberration diagram of the fourth embodiment of the present invention;

Fig. 32 is a color difference graph according to a fourth embodiment of the present invention;

fig. 33 is a schematic structural diagram of a fifth embodiment of the present invention;

FIG. 34 is the MTF graph of visible light 435-;

FIG. 35 is a graph of the MTF at 850nm (200lp/mm) in the infrared of inventive example V;

FIG. 36 is a diagram of a defocus plot of 435-;

Fig. 37 is a graph of infrared 850nm defocus curve of the fifth embodiment of the present invention;

Fig. 38 is a schematic view of curvature of field and distortion according to an embodiment of the present invention;

fig. 39 is a schematic view of longitudinal aberration diagram of a fifth embodiment of the present invention;

Fig. 40 is a color difference graph of a fifth embodiment of the present invention;

Fig. 41 is a table showing values of important parameters according to five embodiments of the present invention.

Detailed Description

To further illustrate the embodiments, the present invention provides the accompanying drawings. The accompanying drawings, which are incorporated in and constitute a part of this disclosure, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the embodiments. With these references, one of ordinary skill in the art will appreciate other possible embodiments and advantages of the present invention. Elements in the figures are not drawn to scale and like reference numerals are generally used to indicate like elements.

the present invention will now be further described with reference to the accompanying drawings and detailed description.

the term "a lens element having positive refractive index (or negative refractive index)" means that the paraxial refractive index of the lens element calculated by Gaussian optics theory is positive (or negative). The term "object-side (or image-side) of a lens" is defined as the specific range of imaging light rays passing through the lens surface. The determination of the surface shape of the lens can be performed by the judgment method of a person skilled in the art, i.e., by the sign of the curvature radius (abbreviated as R value). The R value may be commonly used in optical design software, such as Zemax or CodeV. The R value is also commonly found in lens data sheets (lens data sheets) of optical design software. When the R value is positive, the object side is judged to be a convex surface; and when the R value is negative, judging that the object side surface is a concave surface. On the contrary, regarding the image side surface, when the R value is positive, the image side surface is judged to be a concave surface; when the R value is negative, the image side surface is judged to be convex.

the utility model provides an optical imaging lens, which comprises a first lens, a second lens, a third lens, a fourth lens, a diaphragm, a fifth lens, a sixth lens and a seventh lens from an object side to an image side along an optical axis in sequence; the first lens element to the seventh lens element each include an object-side surface facing the object side and passing the image light and an image-side surface facing the image side and passing the image light.

the first lens element with negative refractive index has a convex object-side surface and a concave image-side surface, and can compress a larger field angle to a relatively small image plane.

the second lens element with negative refractive index has a concave object-side surface and a concave image-side surface.

The third lens element with positive refractive power has a convex object-side surface and a convex image-side surface.

The fourth lens element with positive refractive power has a convex object-side surface and a flat image-side surface.

The fifth lens element with positive refractive power has a convex object-side surface and a convex image-side surface.

The sixth lens element with negative refractive index has a concave object-side surface and a convex image-side surface.

the seventh lens element with positive refractive power has a convex object-side surface and a convex image-side surface.

The optical imaging lens only has the seven lenses with the refractive index. The utility model adopts seven lenses, and through the corresponding design of each lens, the infrared confocal performance is good (the infrared offset is less than 3 μm), and the RGB-IR sensor can be carried; when the infrared and visible environments are switched, the transfer function loss is less, and the resolution is high; the chromatic aberration is small, and the chromatic aberration is less than 3 mu m at 5 wavelengths; large light transmission, high contrast in low-light environment and stable imaging quality.

Preferably, the image side surface of the fifth lens and the object side surface of the sixth lens are cemented with each other to further optimize chromatic aberration.

More preferably, the optical imaging lens further satisfies: vd5-vd6>30, wherein vd5 and vd6 are the d-line abbe numbers of the fifth lens and the sixth lens respectively, and further optimize chromatic aberration so that chromatic aberration is small.

preferably, the optical imaging lens further satisfies: 1.8< nd2<2, wherein nd2 is the refractive index of the second lens in the d line, the resolution power is further improved, and the imaging quality is better.

Preferably, the optical imaging lens further satisfies: 1.8< nd4<2, wherein nd4 is the refractive index of the fourth lens in the d line, the resolution power is further improved, and the imaging quality is better.

preferably, the optical imaging lens further satisfies: 1.8< nd3<1.9, wherein nd3 is the refractive index of the third lens in the d line, so that the resolution power is further improved, and the imaging quality is better.

preferably, the optical imaging lens further satisfies: D11/R11<1.8 and D12/R12<1.84, wherein D11 and D12 are clear calibers of an object side surface and an image side surface of the first lens respectively, and R11 and R12 are curvature radii of the object side surface and the image side surface of the first lens respectively, so that the assembly processing is facilitated while the distortion is optimized.

preferably, the optical imaging lens further satisfies: 0.3< | D72/R72 | <0.5, wherein D72 is a clear aperture of an image-side surface of the seventh lens, and R72 is a radius of curvature of the image-side surface of the seventh lens, enables a smaller chief ray angle while optimizing aberration.

Preferably, the fourth lens has a Z value (coring coefficient) of 0.22, which facilitates processing and improves processing yield.

preferably, the Z value of the first lens is larger than 0.25, so that the processing is convenient, and the processing yield is improved.

the optical imaging lens of the present invention will be described in detail with reference to specific embodiments.

Implement one

as shown in fig. 1, an optical imaging lens includes, in order along an optical axis I, a first lens 1, a second lens 2, a third lens 3, a fourth lens 4, a stop 8, a fifth lens 5, a sixth lens 6, a seventh lens 7, a protective glass 9, and an image plane 10 from an object side a1 to an image side a 2; the first lens element 1 to the seventh lens element 7 each include an object-side surface facing the object side a1 and passing the image light, and an image-side surface facing the image side a2 and passing the image light.

The first lens element 1 has a negative refractive index, the object-side surface 11 of the first lens element 1 is convex, and the image-side surface 12 of the first lens element 1 is concave.

The second lens element 2 has a negative refractive index, and an object-side surface 21 of the second lens element 2 is concave and an image-side surface 22 of the second lens element 2 is concave.

The third lens element 3 has a positive refractive index, and an object-side surface 31 of the third lens element 3 is convex and an image-side surface 32 of the third lens element 3 is convex.

the fourth lens element 4 has a positive refractive index, the object-side surface 41 of the fourth lens element 4 is a convex surface, and the image-side surface 42 of the fourth lens element 4 is a flat surface.

The fifth lens element 5 has a positive refractive index, and an object-side surface 51 of the fifth lens element 5 is convex and an image-side surface 52 of the fifth lens element 5 is convex.

The sixth lens element 6 with negative refractive index has a concave object-side surface 61 of the sixth lens element 6 and a convex image-side surface 62 of the sixth lens element 6.

the seventh lens element 7 has a positive refractive index, and an object-side surface 71 of the seventh lens element 7 is convex and an image-side surface 72 of the seventh lens element 7 is convex.

In this embodiment, the image-side surface 52 of the fifth lens element 5 and the object-side surface 61 of the sixth lens element 6 are cemented to each other.

The detailed optical data of this embodiment are shown in Table 1-1.

Table 1-1 detailed optical data for example one

Please refer to fig. 41 for the values of the conditional expressions related to the present embodiment.

the resolution of the present embodiment is shown in fig. 2 and 3, and it can be seen from the drawings that the resolution is good and the resolution is high when the infrared and visible environments are switched, and the confocality of visible light and infrared 850nm is shown in fig. 4 and 5, and it can be seen that the confocality of visible light and infrared is good, the infrared offset is less than 3 μm, and the field curvature and distortion diagram is shown in (a) and (B) of fig. 6, so that the distortion is small and the imaging quality is high; the longitudinal aberration diagram is detailed in fig. 7, and it can be seen that the aberration is small; the color difference graph is detailed in fig. 8, and it can be seen that the color difference is small, and at 5 wavelengths, the color difference is less than 3 μm.

In the present embodiment, FNO is 2.0, and TTL is 21.60mm, where FNO is an aperture value, and TTL is a distance from the object-side surface 11 of the first lens element 1 to the imaging surface 10 on the optical axis I.

Example two

as shown in fig. 9, in this embodiment, the surface convexoconcave and the refractive index of each lens are the same as those of the first embodiment, and only the optical parameters such as the curvature radius of the surface of each lens and the thickness of the lens are different. In order to more clearly show the structure of the present embodiment, the same reference numerals of the concavo-convex surface type are omitted.

The detailed optical data of this embodiment is shown in Table 2-1.

TABLE 2-1 detailed optical data for example two

the resolution of the present embodiment is shown in fig. 10 and 11, and it can be seen from the drawings that the resolution is good and the resolution is high when the infrared and visible environments are switched, and the confocality of visible light and infrared 850nm is shown in fig. 12 and 13, and it can be seen that the confocality of visible light and infrared is good, the infrared offset is less than 3 μm, and the field curvature and distortion diagram is shown in (a) and (B) of fig. 14, so that the distortion is small and the imaging quality is high; the longitudinal aberration diagram is detailed in fig. 15, and it can be seen that the aberration is small; the color difference graph is detailed in fig. 16, and it can be seen that the color difference is small, and at 5 wavelengths, the color difference is less than 3 μm.

In this specific example, FNO is 2.0; TTL is 21.36 mm.

EXAMPLE III

As shown in fig. 17, in this embodiment, the surface convexoconcave and the refractive index of each lens are the same as those of the first embodiment, and only the optical parameters such as the curvature radius of the surface of each lens and the thickness of the lens are different. In order to more clearly show the structure of the present embodiment, the same reference numerals of the concavo-convex surface type are omitted.

the detailed optical data of this embodiment is shown in Table 3-1.

TABLE 3-1 detailed optical data for EXAMPLE III

The resolution of the present embodiment is shown in fig. 18 and 19, and it can be seen from the drawings that the resolution is good and the resolution is high when the infrared and visible environments are switched, and the confocality of visible light and infrared 850nm is shown in fig. 20 and 21, and it can be seen that the confocality of visible light and infrared is good, the infrared offset is less than 3 μm, and the field curvature and distortion diagram is shown in (a) and (B) of fig. 22, so that the distortion is small and the imaging quality is high; the longitudinal aberration diagram is shown in detail in fig. 23, and it can be seen that the aberration is small; the color difference graph is detailed in fig. 24, and it can be seen that the color difference is small, and at 5 wavelengths, the color difference is less than 3 μm.

in this specific example, FNO is 2.0; TTL is 21.20 mm.

Example four

As shown in fig. 25, the lens elements of this embodiment have the same surface irregularities and refractive index as those of the first embodiment, and only the optical parameters such as the curvature radius of the surface of each lens element and the lens element thickness are different. In order to more clearly show the structure of the present embodiment, the same reference numerals of the concavo-convex surface type are omitted.

The detailed optical data of this embodiment is shown in Table 4-1.

TABLE 4-1 detailed optical data for example four

the resolution of the present embodiment is shown in fig. 26 and 27, and it can be seen from the drawings that the resolution is good and the resolution is high when the infrared and visible environments are switched, and the confocality between visible light and infrared 850nm is shown in fig. 28 and 29, and it can be seen that the confocality between visible light and infrared is good, the infrared offset is less than 3 μm, and the field curvature and distortion diagram is shown in (a) and (B) of fig. 30, so that the distortion is small and the imaging quality is high; the longitudinal aberration diagram is detailed in fig. 31, and it can be seen that the aberration is small; the color difference graph is detailed in fig. 32, and it can be seen that the color difference is small, and at 5 wavelengths, the color difference is less than 3 μm.

In this specific example, FNO is 2.0; TTL is 20.94 mm.

EXAMPLE five

As shown in fig. 23, in this embodiment, the surface convexoconcave and the refractive index of each lens are the same as those of the first embodiment, and only the optical parameters such as the curvature radius of the surface of each lens and the thickness of the lens are different. In order to more clearly show the structure of the present embodiment, the same reference numerals of the concavo-convex surface type are omitted.

the detailed optical data of this embodiment is shown in Table 5-1.

TABLE 5-1 detailed optical data for EXAMPLE V

the resolution of the present embodiment is shown in fig. 34 and 35, and it can be seen from the drawings that the resolution is good and the resolution is high when the infrared and visible environments are switched, and the confocality between visible light and infrared 850nm is shown in fig. 36 and 37, and it can be seen that the confocality between visible light and infrared is good, the infrared offset is less than 3 μm, and the field curvature and distortion diagram is shown in (a) and (B) of fig. 38, so that the distortion is small and the imaging quality is high; the longitudinal aberration diagram is detailed in fig. 39, and it can be seen that the aberration is small; the color difference graph is detailed in fig. 40, and it can be seen that the color difference is small, and at 5 wavelengths, the color difference is less than 3 μm.

in this specific example, FNO is 2.0; TTL is 20.94 mm.

While the invention has been particularly shown and described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

1. An optical imaging lens characterized in that: the lens comprises a first lens, a second lens, a third lens, a fourth lens, a diaphragm, a fifth lens, a sixth lens and a seventh lens from the object side to the image side along an optical axis in sequence; the first lens element to the seventh lens element each include an object-side surface facing the object side and passing the imaging light and an image-side surface facing the image side and passing the imaging light;

The optical imaging lens only has the seven lenses with the refractive index.

2. The optical imaging lens according to claim 1, characterized in that: the image side surface of the fifth lens and the object side surface of the sixth lens are mutually cemented.

3. The optical imaging lens of claim 2, further satisfying: vd5-vd6>30, where vd5 and vd6 are the d-line abbe numbers of the fifth lens and the sixth lens, respectively.

4. the optical imaging lens of claim 1, further satisfying: 1.8< nd2<2, where nd2 is the refractive index of the second lens in the d-line.

5. the optical imaging lens of claim 1, further satisfying: 1.8< nd4<2, where nd4 is the refractive index of the fourth lens in the d-line.

6. the optical imaging lens of claim 1, further satisfying: 1.8< nd3<1.9, where nd3 is the refractive index of the third lens in the d-line.

7. The optical imaging lens of claim 1, further satisfying: D11/R11<1.8 and D12/R12<1.84, wherein D11 and D12 are light-passing calibers of an object-side surface and an image-side surface of the first lens respectively, and R11 and R12 are curvature radiuses of the object-side surface and the image-side surface of the first lens respectively.

8. the optical imaging lens of claim 1, further satisfying: 0.3< | D72/R72 | <0.5, wherein D72 is a clear aperture of an image-side surface of the seventh lens element, and R72 is a radius of curvature of the image-side surface of the seventh lens element.

9. The optical imaging lens according to claim 1, characterized in that: the Z value of the fourth lens is 0.22.

10. The optical imaging lens according to claim 1, characterized in that: the first lens has a Z value greater than 0.25.