CN112505902B

CN112505902B - Wide-angle lens and imaging apparatus

Info

Publication number: CN112505902B
Application number: CN202010886524.0A
Authority: CN
Inventors: 李伟娜; 韩建; 高博; 鲍海江; 高航
Original assignee: Jiangxi Lianchuang Electronic Co Ltd
Current assignee: Jiangxi Lianchuang Electronic Co Ltd
Priority date: 2020-08-28
Filing date: 2020-08-28
Publication date: 2022-07-29
Anticipated expiration: 2040-08-28
Also published as: CN112505902A

Abstract

The invention provides a wide-angle lens and imaging equipment, wherein the wide-angle lens consists of a first lens, a second lens, a third lens, a fourth lens, a diaphragm, a fifth lens, a sixth lens, a seventh lens and an eighth lens in sequence from an object side to an imaging surface along an optical axis, and the first lens has negative focal power; the second lens has negative focal power; the third lens has positive focal power; the fourth lens has positive focal power; the fifth lens has positive focal power; the sixth lens has negative focal power, the seventh lens has positive focal power, and the eighth lens has negative focal power; the first lens is a glass spherical lens, the fifth lens is a glass aspheric lens, and the second lens, the third lens, the fourth lens, the sixth lens, the seventh lens and the eighth lens are plastic aspheric lenses. The wide-angle lens provided by the invention has the advantages of high imaging quality, less image plane drift in high and low temperature environments, good chip compatibility and the like, and effectively corrects high-order aberration.

Description

Wide-angle lens and imaging apparatus

Technical Field

The invention relates to the technical field of lens imaging, in particular to a wide-angle lens and imaging equipment.

Background

The development of mobile interconnection enables photos and images to show a network sharing trend so as to record the drips in life, and therefore, a motion camera is promoted. Because the motion camera is mostly used in the environments of severe vibration, high pressure, extreme temperature and the like, the requirement on the matched camera lens is extremely high, on one hand, the problem that random photographing in any place and any direction is required, namely, high-definition imaging effect is required, and a very large field angle is also required to meet the requirement of image photographing in a large field of view is solved. High definition wide angle motion camera has got into the market for a while, and the market has passed to the price ratio trade-off stage from initial modern design to along with the continuous development of chip technique, the price of the big CRA (ChiefRayAngle) chip of high pixel constantly reduces, becomes the main force army in market gradually, nevertheless because the field angle of general camera lens is less, and center and marginal visual field compression are relatively poor, and service environment stability is poor, the demand of meeting photography fan to high pixel motion camera lens that can not be fine.

Disclosure of Invention

Accordingly, the present invention provides a wide-angle lens and an imaging apparatus to solve the above problems.

In order to realize the purpose, the technical scheme of the invention is as follows:

in a first aspect, an embodiment of the present invention provides a wide-angle lens including eight lenses having optical powers, and including, in order from an object side to an image plane along an optical axis: the lens comprises a first lens with negative focal power, a second lens and a third lens, wherein the object side surface of the first lens is a convex surface, and the image side surface of the first lens is a concave surface; a second lens having a negative optical power; the third lens with positive focal power, the image side surface of the third lens is a convex surface; the fourth lens with positive focal power, the object side surface of the fourth lens is a concave surface, and the image side surface of the fourth lens is a convex surface; a diaphragm; the fifth lens has positive focal power, and both the object-side surface and the image-side surface of the fifth lens are convex surfaces; a sixth lens element having a negative optical power, the sixth lens element having concave object-side and image-side surfaces; the seventh lens has positive focal power, and both the object side surface and the image side surface of the seventh lens are convex surfaces; an eighth lens element having a negative optical power, an object-side surface of the eighth lens element being convex at a paraxial region, an image-side surface of the eighth lens element being concave at a paraxial region, and both the object-side surface and the image-side surface of the eighth lens element having at least one inflection point; the first lens is a glass spherical lens, the fifth lens is a glass aspheric lens, and the second lens, the third lens, the fourth lens, the sixth lens, the seventh lens and the eighth lens are plastic aspheric lenses.

In a second aspect, an embodiment of the present invention further provides an imaging device, which includes an imaging element and the wide-angle lens provided in the first aspect, where the imaging element is configured to convert an optical image formed by the wide-angle lens into an electrical signal.

Compared with the prior art, the wide-angle lens and the imaging equipment provided by the invention adopt the mixed collocation of 2 glass lenses and 6 plastic lenses, especially use of the aspheric lens at the specified bit sequence, can effectively correct the high-order aberration of the wide-angle lens, can match the imaging requirements of a large CRA and a high-pixel chip, and meet the requirements of the market on low-cost, large-target-surface and high-pixel lenses.

Drawings

In order to more clearly illustrate the technical solution in the embodiments of the present invention, the drawings required to be used in the embodiments will be briefly described below.

Fig. 1 is a schematic structural diagram of a wide-angle lens according to a first embodiment of the present invention;

FIG. 2 is a field curvature graph of a wide-angle lens according to a first embodiment of the present invention;

FIG. 3 is a distortion graph of a wide-angle lens in the first embodiment of the present invention;

fig. 4 is an MTF curve of the wide-angle lens in the first embodiment of the present invention;

fig. 5 is a schematic structural diagram of a wide-angle lens provided in a second embodiment of the present invention;

FIG. 6 is a field curvature graph of a wide-angle lens according to a second embodiment of the present invention;

FIG. 7 is a distortion graph of a wide-angle lens in a second embodiment of the present invention;

fig. 8 is an MTF curve of the wide-angle lens in the second embodiment of the present invention;

fig. 9 is a schematic configuration diagram of an image forming apparatus in a third embodiment of the present invention;

the following detailed description will further illustrate the invention in conjunction with the above-described figures.

Detailed Description

In order to facilitate a better understanding of the invention, the invention will be further explained below with reference to the accompanying drawings of embodiments. Embodiments of the present invention are shown in the drawings, but the present invention is not limited to the preferred embodiments described above. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

An embodiment of the present invention provides a wide-angle lens, which includes eight lenses having optical powers, and sequentially includes, from an object side to an image plane along an optical axis: the lens comprises a first lens with negative focal power, a second lens and a third lens, wherein the object side surface of the first lens is a convex surface, and the image side surface of the first lens is a concave surface; a second lens having a negative optical power; the third lens with positive focal power, the image side surface of the third lens is a convex surface; the fourth lens with positive focal power, the object side surface of the fourth lens is a concave surface, and the image side surface of the fourth lens is a convex surface; a diaphragm; the fifth lens has positive focal power, and both the object-side surface and the image-side surface of the fifth lens are convex surfaces; a sixth lens element having a negative optical power, the sixth lens element having concave object-side and image-side surfaces; the seventh lens has positive focal power, and both the object side surface and the image side surface of the seventh lens are convex surfaces; an eighth lens element having a negative optical power, an object-side surface of the eighth lens element being convex at a paraxial region, an image-side surface of the eighth lens element being concave at a paraxial region, and both the object-side surface and the image-side surface of the eighth lens element having at least one inflection point; the first lens is a glass spherical lens, the fifth lens is a glass aspheric lens, and the second lens, the third lens, the fourth lens, the sixth lens, the seventh lens and the eighth lens are plastic aspheric lenses.

In the wide-angle lens provided by the embodiment, the glass lens and the plastic lens are mixed for use, and especially, the other lenses except the first lens all use the aspheric lens, so that the high-order aberration of the wide-angle lens can be effectively corrected. For example, the target surface has a diagonal length greater than 8.0mm, which meets the specifications of large CRA (e.g., 1/2 inch) chips currently on the market. The fifth lens in the wide-angle lens is a glass aspheric lens, which has great influence on the overall focal power of the whole lens, so that the wide-angle lens has the advantage of small drift amount of the focal plane in high and low temperature environments, can adapt to different temperature occasions, has good temperature control, and has longer service life and stability.

In some embodiments, the wide-angle lens satisfies the following conditional expression:

B2>0，C2<0，B8<0，C8>0；(1)

where B2 denotes a sum of fourth-order surface coefficients of an object-side surface of the second lens and an image-side surface of the second lens, C2 denotes a sum of sixth-order surface coefficients of an object-side surface of the second lens and an image-side surface of the second lens, B8 denotes a sum of fourth-order surface coefficients of an object-side surface of the eighth lens and an image-side surface of the eighth lens, and C8 denotes a sum of sixth-order surface coefficients of an object-side surface of the eighth lens and an image-side surface of the eighth lens. Satisfying the conditional expression (1), the values of B2 and B8 are opposite in sign, and the values of C2 and C8 are opposite in sign, so that the concave-convex shapes of the image-side surface of the second lens and the object-side surface of the eighth lens are opposite, a symmetrical structure with the aperture as the center is formed, and the vertical axis aberration can be corrected well. When the sixth-order aberration C2< -0.007 of the second lens is adopted, the second lens is in an M shape, the compression ratio of the center field and the edge field is good, and the requirement of the market on the compression ratio of the center field and the edge field of a shot scene can be met; when the sixth-order aberration of the second lens is-0.005 < C2<0, the second lens takes a meniscus shape, which can meet the demand of the current market for ultra-high image quality. The positive and negative values of B8 are opposite to those of C8, and the shape (M type) of the eighth lens can be adjusted to meet the requirement of the market on the chief ray angle of different chips.

In some embodiments, to ensure that the wide-angle lens has a sufficiently good imaging quality, the wide-angle lens satisfies the following conditional expression:

13mm<TL<17mm，4mm<OL<7mm； (2)

0.3<OL/TL<0.6； (3)

where TL denotes an optical total length of the wide-angle lens, and OL denotes a sum of thicknesses of the first lens to the eighth lens on the optical axis.

When the OL/TL value exceeds the upper limit, the total thickness of the lens is too thick, the air interval is too thin, the assembly difficulty of the lens is increased, and meanwhile, the influence of high and low temperature on the lens imaging is difficult to correct; when the value of OL/TL exceeds the lower limit, the total thickness of the lens is too thin, the air interval is too thick, the whole structure of the lens is too loose, the whole space is wasted, and the resolution capability is obviously reduced; therefore, satisfying the above conditional expressions (2) and (3) shows that the wide-angle lens has good resolution capability and can satisfy the requirement of high-definition imaging.

2mm<f<4mm，4mm<h≤4.1mm，155°<2θ≤156°； (4)

1.3mm≤BL≤1.4mm； (5)

wherein f represents the focal length of the wide-angle lens, 2 theta represents the full field angle of the wide-angle lens, and h represents the actual half-image height of the wide-angle lens; BL denotes an optical back focus of the wide-angle lens, i.e., a distance from a vertex of the image-side surface of the eighth lens element to the image plane, and this distance is too short, which increases the difficulty in processing and assembling.

In some embodiments, in order to provide a suitable lens size while satisfying good correction aberration, the wide-angle lens satisfies the following conditional expression:

0.4mm ^-1 <1/R11-1/R12<0.6mm ^-1 ； (6)

Where R11 denotes a radius of curvature of the object-side surface of the fifth lens, and R12 denotes a radius of curvature of the image-side surface of the fifth lens.

When the value of 1/R11-1/R12 exceeds the upper limit, the refraction angle of the edge part of the lens of the fifth lens is too large, and the edge imaging illumination is too low; when the value of 1/R11-1/R12 exceeds the lower limit, the refractive angle of the peripheral part of the fifth lens is too small, and the ability to bear the optical power is lost, so that the lens is too long as a whole.

wherein, the first and the second end of the pipe are connected with each other,

denotes a combined power of the first lens, the second lens, the third lens and the fourth lens,

represents the combined power of the fifth lens, the sixth lens, the seventh lens and the eighth lens,

indicating the power of the wide-angle lens.

The lens before the diaphragm forms a front lens group which comprises a first lens, a second lens, a third lens and a fourth lens; and the lens behind the diaphragm forms a rear lens group which comprises a fifth lens, a sixth lens, a seventh lens and an eighth lens. The front lens group can effectively converge object plane light with a wide field angle into the lens, and does not generate large aberration. When in use

When the value of (b) exceeds the upper limit, the focal power of the front lens group is too strong, and the total length of the entire lens can be made small, but the spherical aberration generated thereby is too large and is difficult to correct; when in use

When the value of (b) exceeds the lower limit, the power of the front lens group decreases, the spherical aberration relatively decreases, but the refractive power of the front lens group decreases, resulting in an increase in the total optical length of the system. Combined focal power of rear lens group

Can correspond to the front lens group

Values of (A) are in the above rangeWhen in the enclosure, the front lens group can be effectively matched, and aberration can be reasonably removed.

6.285mm≤Sd1<7.5mm； 1.5<Sd1/h<2； 1.2mm<GT1≤1.5mm； (10)

where Sd1 denotes an effective half aperture of the first lens, GT1 denotes a center thickness of the first lens, and h denotes an actual half image height of the wide-angle lens. Since the object side surface of the first lens is in contact with the external environment, when the GT1 is lower than 1.2mm, the overall thickness of the lens is too thin, and the overall anti-falling performance of the lens is greatly reduced; when the value of Sd1/h exceeds the upper limit, the overall outer diameter of the first lens is too large, so that the overall volume of the lens is too large, and the miniaturization is not facilitated; when the value of Sd1/h exceeds the lower limit, the overall outer diameter of the first lens is too small, so that the overall volume of the lens is too small, and the overall aberration of the lens is difficult to be well corrected.

0.8mm<GT5≤0.989mm； (11)

50<V5-V6<70； (12)

where GT5 denotes the center thickness of the fifth lens, V5 denotes the abbe number of the fifth lens, and V6 denotes the abbe number of the sixth lens. When the value of V5-V6 exceeds the lower limit, the correction of chromatic aberration is insufficient; when the value of V5-V6 exceeds the upper limit, the material selection is difficult; when the optical axis is within the above range, the fifth lens and the sixth lens correspond to each other at this time, and chromatic aberration is corrected.

(dn/dt)5>-10×10 ^-6 /℃；(13)

wherein, (dn/dt)5 represents the material temperature refractive index coefficient of the fifth lens, and when (dn/dt)5 exceeds a limited range, the optimal focal plane of the lens changes greatly when the temperature changes, so that the actual use requirement cannot be met.

The aspheric surface shape of the wide-angle lens in various embodiments of the present invention satisfies the following equation:

wherein z represents the distance in the optical axis direction from the curved surface vertex, c represents the curvature of the curved surface vertex, K represents the conic coefficient, h represents the distance from the optical axis to the curved surface, and B, C, D, E and F represent the fourth, sixth, eighth, tenth and twelfth order curved surface coefficients, respectively.

In the following embodiments, the thickness, the radius of curvature, and the material selection of each lens in the wide-angle lens are different, and specific differences can be referred to the parameter tables of the embodiments.

First embodiment

Referring to fig. 1, a schematic structural diagram of a wide-angle lens 100 according to a first embodiment of the present invention is shown, which sequentially includes, from an object side to an image plane IM: the lens system comprises a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, an aperture ST, a fifth lens L5, a sixth lens L6, a seventh lens L7, an eighth lens L8 and a filter G1.

The first lens L1 has negative focal power, the object-side surface S1 of the first lens is a convex surface, the image-side surface S2 of the first lens is a concave surface, and the first lens L1 is a glass spherical lens; the first lens L1 can be made of a glass material with a high refractive index, and the high refractive index material can achieve the effects of quickly collecting light and reducing the plane inclination angle of the image side surface S2 of the first lens, and can also effectively reduce the processing cost.

The second lens element L2 has negative power, the object-side surface S3 of the second lens element is convex, the image-side surface S4 of the second lens element is concave, and the second lens element L2 is a plastic aspheric lens element.

The third lens element L3 has positive refractive power, the object-side surface S5 and the image-side surface S6 of the third lens element are both convex, and the third lens element L3 is a plastic aspheric lens.

The fourth lens element L4 has positive power, the object-side surface S7 of the fourth lens element is concave, the image-side surface S8 of the fourth lens element is convex, and the fourth lens element L4 is a plastic aspheric lens element.

The fifth lens L5 has positive power, the object-side surface S9 and the image-side surface S10 of the fifth lens are both convex surfaces, and the fifth lens L5 is a glass aspheric lens.

The sixth lens element L6 has negative power, and the object-side surface S11 and the image-side surface S12 of the sixth lens element are both concave, and the sixth lens element L6 is a plastic aspheric lens element.

The seventh lens element L7 has positive power, the object-side surface S13 and the image-side surface S14 of the seventh lens element are both convex, and the seventh lens element L7 is a plastic aspheric lens.

The eighth lens element L8 has negative power, the object-side surface S15 of the eighth lens element is convex at the paraxial region, the image-side surface S16 of the eighth lens element is concave at the paraxial region, and the object-side surface S15 and the image-side surface S16 of the eighth lens element each have at least one inflection point, i.e., the overall shape of the eighth lens element L8 is M-shaped, and the eighth lens element L8 is a plastic aspheric lens.

The wide-angle lens 100 further includes a stop ST which may be individually disposed between the fourth lens L4 and the fifth lens L5 using a light-shielding paper; the lens can also be arranged on the object side surface S9 of the fifth lens L5, and during production and processing, a light shielding material can be arranged on the periphery of the optical effective diameter of the object side surface S9 of the fifth lens, for example, ink coating is carried out, so that the processing cost is greatly reduced, and the assembly difficulty is reduced. In the present embodiment, the stop ST is an ink applied to the outer periphery of the optical effective diameter of the object side surface S9 of the fifth lens. The stop ST is disposed at different positions to meet CRA (chief ray angle) requirements of different chips. The diaphragm ST is used to adjust the amount of light transmitted precisely, and a large light flux lens is required to capture a clear picture in a dark scene. The diaphragm ST is arranged at the position, so that the incident angle of the chief ray reaching the imaging surface IM can be controlled, the production and processing cost can be greatly reduced by arranging the diaphragm ST on the surface of the lens, the CRA is effectively controlled to be about 35 degrees, and the incident requirement of an imaging chip is better met.

In this embodiment, the wide-angle lens 100 may further include a filter G1 or a filter group (i.e., a combination formed by two or more filters), and the filter G1 is disposed between the eighth lens L8 and the image plane IM. The filter G1 may be a visible light filter. In the present embodiment, a filter with a thickness of 0.3mm is taken as an example, but it is understood that the thickness of the filter G1 or the filter group is not limited thereto. The light filter G1 is used for inhibiting the transmission of light in a non-working wave band, so that the chromatic aberration and stray light of an optical system are effectively reduced, and the imaging effect of the lens is improved.

The parameters related to each lens of the wide-angle lens 100 provided in the present embodiment are shown in table 1.

TABLE 1

The aspherical surface related parameters of each lens of the wide-angle lens 100 provided in this embodiment are shown in table 2.

TABLE 2

Surface number

K

B

C

D

E

F

S3

1.53E+01

1.70E-02

-3.33E-03

2.47E-04

-6.57E-06

-2.08E-09

S4

-1.14E+00

2.26E-02

-8.66E-04

-7.08E-04

7.88E-05

1.45E-07

S5

-1.01E+00

-2.90E-03

1.08E-03

-5.65E-04

5.27E-05

-1.24E-06

S6

-1.33E+02

-6.18E-03

-1.55E-03

6.57E-05

4.14E-05

5.01E-06

S7

-4.43E+00

-1.87E-03

-4.78E-03

2.65E-03

-3.93E-04

8.93E-06

S8

6.94E+00

1.19E-02

1.09E-02

-3.26E-03

1.44E-03

1.29E-04

S9

-7.62E+01

1.77E-02

-4.06E-02

2.43E-02

-1.07E-02

5.23E-04

S10

-9.82E+01

-5.55E-02

2.06E-03

1.03E-03

-1.34E-03

-3.07E-04

S11

-3.72E+02

-1.17E-02

3.14E-03

-1.79E-03

4.75E-04

-2.18E-05

S12

-3.15E+01

2.34E-02

-6.27E-03

1.06E-03

-1.27E-04

-9.22E-06

S13

-6.30E+01

1.02E-02

3.80E-03

-1.10E-03

1.60E-04

-2.86E-06

S14

-3.15E+01

-3.02E-02

1.16E-02

-2.96E-03

5.46E-04

-1.01E-05

S15

-2.87E+02

-6.92E-02

5.56E-03

-3.79E-04

2.87E-05

2.48E-06

S16

-1.29E+01

-3.19E-02

4.35E-03

-5.61E-04

3.49E-05

-6.94E-07

The field curvature graph and the F- θ distortion graph of the wide-angle lens 100 provided in the present embodiment are shown in fig. 2 and 3, respectively, and it can be seen that both the field curvature and the distortion of the wide-angle lens 100 are well corrected. Fig. 4 is an MTF curve of the wide-angle lens 100, which shows that the wide-angle lens 100 has good resolution and resolution.

Second embodiment

Fig. 5 is a schematic structural diagram of a wide-angle lens 200 according to the present embodiment. The structure of the wide-angle lens 200 in the present embodiment is largely the same as that of the wide-angle lens 100 in the first embodiment, except that: in the wide-angle lens 200 of this embodiment, the object-side surface S3 of the second lens element is concave at the paraxial region, the image-side surface S4 of the second lens element is convex at the paraxial region, and the overall shape of the second lens element L2 is M-shaped; the object side surface S5 of the third lens is concave, and the stop ST is made of light-shielding paper and is disposed between the fourth lens L4 and the fifth lens L5.

The present embodiment provides wide-angle lens 200 in which the relevant parameters of the respective lenses are shown in table 3.

TABLE 3

The aspherical surface related parameters of each lens in the wide-angle lens 200 provided in the present embodiment are shown in table 4.

TABLE 4

Surface number

K

B

C

D

E

F

S3

-2.86E+00

3.65E-02

-4.61E-03

2.88E-04

-7.04E-06

0.00E+00

S4

-8.93E-01

4.91E-02

-3.99E-03

3.12E-05

1.25E-05

0.00E+00

S5

1.50E+02

6.99E-04

-8.71E-04

-6.48E-05

2.05E-05

-1.22E-06

S6

-2.08E+00

3.66E-05

-7.67E-04

8.21E-05

-4.01E-06

0.00E+00

S7

-9.31E+01

-1.51E-02

1.56E-03

5.63E-04

-3.11E-04

0.00E+00

S8

-1.12E+01

-2.11E-02

7.50E-03

-1.17E-03

-1.61E-04

5.26E-06

S9

1.39E+00

-2.68E-02

-2.60E-03

4.21E-03

-3.11E-03

0.00E+00

S10

-7.20E+00

-2.79E-02

-6.35E-04

1.08E-03

-1.47E-03

0.00E+00

S11

1.43E+02

9.47E-03

-1.01E-02

2.24E-03

-1.09E-04

0.00E+00

S12

-1.46E+01

3.02E-02

-1.42E-02

3.92E-03

-4.60E-04

0.00E+00

S13

-3.74E+01

7.69E-03

1.82E-03

-2.60E-04

9.66E-06

0.00E+00

S14

-1.01E+01

-2.26E-02

4.65E-03

-3.74E-04

8.43E-05

0.00E+00

S15

1.31E+01

-5.00E-02

7.27E-04

5.98E-04

-7.72E-05

-1.22E-08

S16

-3.29E-01

-4.56E-02

5.28E-03

-5.13E-04

2.63E-05

-6.99E-07

The field curvature graph and the F- θ distortion graph of the wide-angle lens 200 provided in the present embodiment are shown in fig. 6 and 7, respectively, and it can be seen that both the field curvature and the distortion of the wide-angle lens 200 are well corrected. Fig. 8 is an MTF curve of wide-angle lens 200, which shows that wide-angle lens 200 has good resolution and resolution.

Table 5 shows the corresponding optical characteristics of the two embodiments, mainly including the focal length F, F #, the total optical length TL and the field angle 2 θ, and the values corresponding to each conditional expression.

TABLE 5

In summary, the wide-angle lens provided by the embodiment has at least the following advantages:

(1) the spherical lens and the aspheric lens are used in a mixed mode, and the aspheric lens comprises the plastic lens and the glass lens, so that the overall length of the lens is short, and meanwhile good resolution quality can be guaranteed.

(2) The wide-angle lens has the advantages of over 150 degrees of field angle, small distortion, large target surface and the like, for example, the diagonal length of the target surface is more than 8.0mm, and the wide-angle lens can be matched with a large target surface imaging chip of 1/2 inches.

(3) Through the special arrangement of the surface shapes of the second lens and the eighth lens, the lens has the advantages of adjustable compression ratio of the center field of view and the edge field of view, good chip compatibility and the like.

(4) The first lens and the fifth lens of wide-angle lens are glass lenses, the second lens, the third lens, the fourth lens, the sixth lens, the seventh lens and the eighth lens are plastic lenses, the reasonable collocation through glass, plastic lenses makes wide-angle lens reach high resolution, when with low costs, can also make wide-angle lens have the advantage that the volume of producing the focus drift is little in the high low temperature environment, can adapt to different temperature occasions, temperature control is better, and has higher life and stability.

Third embodiment

An imaging device 300 is further provided in the present embodiment, and as shown in fig. 9, the imaging device 300 includes an imaging element 310 and a wide-angle lens (e.g., wide-angle lens 100) in any of the embodiments described above. The imaging element 310 may be a CMOS (Complementary Metal Oxide Semiconductor) image sensor, and may also be a CCD (Charge coupled device) image sensor.

The imaging device 300 may be a moving camera, a drone, or any other electronic device loaded with the wide-angle lens 100.

The imaging device 300 provided by the embodiment of the present application includes the wide-angle lens in any of the above embodiments, and since the wide-angle lens has the advantages of a large wide angle, a small volume, and a high pixel, the imaging device 300 having the wide-angle lens also has the advantages of a large wide angle, a small volume, and a high pixel.

Claims

1. A wide-angle lens comprising eight lenses having optical powers, comprising, in order from an object side to an image plane along an optical axis:

the lens comprises a first lens with negative focal power, a second lens and a third lens, wherein the object side surface of the first lens is a convex surface, and the image side surface of the first lens is a concave surface;

a second lens having a negative optical power;

the image side surface of the third lens is a convex surface;

the fourth lens is provided with positive focal power, the object side surface of the fourth lens is a concave surface, and the image side surface of the fourth lens is a convex surface;

a diaphragm;

the lens comprises a fifth lens with positive focal power, wherein both the object-side surface and the image-side surface of the fifth lens are convex surfaces;

a sixth lens element having a negative optical power, the sixth lens element having a concave object-side surface and a concave image-side surface;

a seventh lens having a positive optical power, the seventh lens having convex object and image side surfaces;

An eighth lens having a negative optical power, an object-side surface of the eighth lens being convex at a paraxial region, an image-side surface of the eighth lens being concave at a paraxial region, and both the object-side surface and the image-side surface of the eighth lens having at least one inflection point;

the first lens is a glass spherical lens, the fifth lens is a glass aspheric lens, and the second lens, the third lens, the fourth lens, the sixth lens, the seventh lens and the eighth lens are plastic aspheric lenses;

the wide-angle lens satisfies the conditional expression:

wherein the content of the first and second substances,

representing a combined optical power of the first lens, the second lens, the third lens, and the fourth lens,

represents a combined power of the fifth lens, the sixth lens, the seventh lens, and the eighth lens,

represents the power of the wide-angle lens.

2. The wide-angle lens of claim 1, wherein the wide-angle lens satisfies the conditional expression:

B2>0，C2<0，B8<0，C8>0；

wherein B2 represents a sum of fourth order surface coefficients of an object-side surface of the second lens and an image-side surface of the second lens, C2 represents a sum of sixth order surface coefficients of an object-side surface of the second lens and an image-side surface of the second lens, B8 represents a sum of fourth order surface coefficients of an object-side surface of the eighth lens and an image-side surface of the eighth lens, and C8 represents a sum of sixth order surface coefficients of an object-side surface of the eighth lens and an image-side surface of the eighth lens.

3. The wide-angle lens of claim 1, wherein the wide-angle lens satisfies the conditional expression:

13mm<TL<17mm，4mm<OL<7mm；

0.3<OL/TL<0.6；

wherein TL denotes an optical total length of the wide-angle lens, and OL denotes a sum of thicknesses of the first lens to the eighth lens on an optical axis.

4. The wide-angle lens of claim 1, wherein the wide-angle lens satisfies the conditional expression:

2mm<f<4mm，4mm<h≤4.1mm，155°<2θ≤156°；

1.3mm≤BL≤1.4mm；

wherein f represents a focal length of the wide-angle lens, 2 θ represents a full field angle of the wide-angle lens, h represents an actual half-image height of the wide-angle lens, and BL represents an optical back focus of the wide-angle lens.

5. The wide-angle lens of claim 1, wherein the wide-angle lens satisfies the conditional expression:

0.4mm ^-1 <1/R11-1/R12<0.6mm ^-1 ；

wherein R11 denotes a radius of curvature of an object-side surface of the fifth lens, and R12 denotes a radius of curvature of an image-side surface of the fifth lens.

6. The wide-angle lens of claim 1, wherein the wide-angle lens satisfies the conditional expression:

6.285mm≤Sd1<7.5mm；1.5<Sd1/h<2；1.2mm<GT1≤1.5mm；

where Sd1 denotes an effective half aperture of the first lens, GT1 denotes a center thickness of the first lens, and h denotes an actual half image height of the wide-angle lens.

7. The wide-angle lens of claim 1, wherein the wide-angle lens satisfies the conditional expression:

0.8mm<GT5≤0.989mm；

50<V5-V6<70；

Wherein GT5 denotes a center thickness of the fifth lens, V5 denotes an abbe number of the fifth lens, and V6 denotes an abbe number of the sixth lens.

8. The wide-angle lens of claim 1, wherein the wide-angle lens satisfies the conditional expression:

(dn/dt)5>-10×10 ^-6 /℃；

wherein (dn/dt)5 represents a material temperature refractive index coefficient of the fifth lens.

9. The wide-angle lens of claim 1, wherein the stop is a light-shielding paper, or a light-shielding material is provided along an outer circumference of an optical effective diameter of the object-side surface of the fifth lens.

10. An imaging apparatus comprising the wide-angle lens according to any one of claims 1 to 9, and an imaging element for converting an optical image formed by the wide-angle lens into an electrical signal.