CN113759527B

CN113759527B - Wide-angle lens

Info

Publication number: CN113759527B
Application number: CN202111317380.8A
Authority: CN
Inventors: 高博; 李伟娜; 鲍海江
Original assignee: Jiangxi Lianchuang Electronic Co Ltd
Current assignee: Jiangxi Lianchuang Electronic Co Ltd
Priority date: 2021-11-09
Filing date: 2021-11-09
Publication date: 2022-04-01
Anticipated expiration: 2041-11-09
Also published as: CN113759527A

Abstract

The invention provides a wide-angle lens, which comprises six lenses in total, and the wide-angle lens sequentially comprises the following components from an object side to an imaging surface: a first lens element having a negative optical power, an object-side surface of the first lens element being concave at a paraxial region thereof and an image-side surface of the first lens element being concave; a second lens with positive focal power, wherein the object side surface of the second lens is convex, and the image side surface of the second lens is concave; a third lens element having positive optical power, wherein the object-side surface and the image-side surface are convex at paraxial region; a fourth lens element having a negative optical power, an object-side surface being concave and an image-side surface being concave at a paraxial region; the image side surface of the fifth lens is a convex surface; a sixth lens element with negative optical power having a convex object-side surface at the paraxial region and a concave image-side surface at the paraxial region. The wide-angle lens has the advantages of uniform pixel distribution in the full field angle, large target surface, small volume, light weight, small distortion, high image quality and the like.

Description

Wide-angle lens

Technical Field

The invention relates to the technical field of optical lenses, in particular to a wide-angle lens.

Background

As the income level and living standard of people are continuously improved, the consumption demand for photography is also diversified. The traditional lens has a small field angle and can meet the pursuit of high-end photography people on details. However, most people are used for recording the life infusion, and with the development of the mobile internet, the photos and the images show the trend of network sharing, so that the wide-angle lens is favored by the people who like recording the life maca partially. Meanwhile, no matter the mobile phone camera shooting, the intelligent door lock or the Vlog application, a wider field angle is needed to record more information.

The current wide-angle lens generally has distortion problem, and because the focal length of the wide-angle lens is shorter, peripheral light rays have larger compression deformation after entering the lens, the wide-angle lens generally presents barrel-shaped distortion. Of course, wide-angle lenses have their unique viewing angle and surround, but do appear severely distorted to the planarized background. In order to overcome the distortion problem of the existing wide-angle lens, more aberration problems are often brought while the distortion is corrected, so that more lenses are often required to be added to correct the aberration. In addition, the development of chips also goes in two different directions: one is a large target surface chip, which has good light transmission amount and is very suitable for the image processing requirement with higher quality, and under the same light condition, the obtained light information is more, the image quality performance is better, the post-processing information amount is larger, but the product volume and the weight are larger. Secondly, the miniaturization of the chip can reduce the volume and the weight of the whole module greatly, so that the portability of the finished product is improved. Of course, how to combine the advantages of the two, which can not only obtain the effect of large target surface, but also reduce the weight of the module as much as possible to improve the portability, is a difficult point that needs to be solved urgently.

Disclosure of Invention

In view of the foregoing, it is an object of the present invention to provide a wide-angle lens that can at least overcome at least one of the above-mentioned drawbacks of the prior art, so as to meet the design requirements of the optical lens of the image-capturing electronic device.

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

the invention provides a wide-angle lens, which comprises six lenses in total, and the wide-angle lens sequentially comprises the following components from an object side to an imaging surface:

a first lens having a negative optical power, the first lens having a concave object-side surface at a paraxial region and a concave image-side surface;

the second lens has positive focal power, and the object side surface of the second lens is a convex surface and the image side surface of the second lens is a concave surface;

a third lens having a positive optical power, the third lens having a convex object-side surface and a convex image-side surface at a paraxial region;

a fourth lens having a negative optical power, the fourth lens having a concave object-side surface and a concave image-side surface at a paraxial region;

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

a sixth lens having a negative optical power, an object side surface of the sixth lens being convex at a paraxial region and an image side surface of the sixth lens being concave at a paraxial region;

the wide-angle lens meets the following conditional expression: IH/(f multiplied tan theta) is more than 0.97 and less than 1.03; wherein IH represents an actual image height of the wide-angle lens, f represents an effective focal length of the wide-angle lens, and θ represents a half field angle of the wide-angle lens;

and the diaphragm is arranged between the second lens and the third lens or between the third lens and the fourth lens.

In some embodiments, the wide-angle lens satisfies the following conditional expression: TTL/(f multiplied tan theta) is more than 2.1 and less than 2.8; wherein, TTL represents the total optical length of the wide-angle lens.

In some embodiments, the wide-angle lens satisfies the following conditional expression: -0.4 < phi 12/phi < -0.1; where φ 12 represents the combined optical power of the first lens and the second lens, and φ represents the optical power of the wide-angle lens.

In some embodiments, the wide-angle lens satisfies the following conditional expression: -1.2 < φ 3/φ 6 < -0.7; where φ 3 represents the optical power of the third lens and φ 6 represents the optical power of the sixth lens.

In some embodiments, the wide-angle lens satisfies the following conditional expression: phi 56/phi is more than 0.7 and less than 1.1; where phi 56 denotes a combined power of the fifth lens and the sixth lens, and phi denotes a power of the wide-angle lens.

In some embodiments, the wide-angle lens satisfies the following conditional expression: DT3/DT6 of 0.25 < 0.35; DT3 represents an effective aperture of the third lens, and DT6 represents an effective aperture of the sixth lens.

In some embodiments, the wide-angle lens satisfies the following conditional expression: 30 < | Vd3-Vd4| < 40, 30 < | Vd5-Vd6| < 40; wherein Vd3 denotes an abbe number of the third lens, Vd4 denotes an abbe number of the fourth lens, Vd5 denotes an abbe number of the fifth lens, and Vd6 denotes an abbe number of the sixth lens.

In some embodiments, the wide-angle lens satisfies the following conditional expression: 0.4 < CT4/CT6 < 0.6; wherein CT4 represents the center thickness of the fourth lens and CT6 represents the center thickness of the sixth lens.

In some embodiments, the wide-angle lens satisfies the following conditional expression: d/f is more than 2.3 and less than 2.7; wherein D represents an image plane size of the wide-angle lens.

In some embodiments, the wide-angle lens satisfies the following conditional expression: CRA < 20 °; the CRA represents an incident angle at which a principal ray of the wide-angle lens is incident on an imaging plane at a maximum field angle.

Compared with the prior art, the invention has the beneficial effects that: through the collocation among the lenses and the limitation of parameters, the wide-angle lens has the advantages that the distortion of the wide-angle lens is small, the image quality is high, and meanwhile, the weight and the size of the wide-angle lens are effectively reduced; meanwhile, the imaging surface of the wide-angle lens is large, and the requirement of inscribed circle imaging of a CMOS chip with a large target surface of more than 1 inch can be met. In other words, the wide-angle lens provided by the invention meets the use requirements of the market on a large-target-surface chip and a high-definition imaging lens.

Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

Drawings

The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

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 vertical axis chromatic aberration diagram of a wide-angle lens according to a first embodiment of the present invention;

fig. 3 is a field curvature diagram of a wide-angle lens according to a first embodiment of the invention;

fig. 4 is a distortion diagram of a wide-angle lens according to a first embodiment of the present invention;

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

FIG. 6 is a vertical axis chromatic aberration diagram of a wide-angle lens according to a second embodiment of the present invention;

fig. 7 is a field curvature diagram of a wide-angle lens according to a second embodiment of the invention;

fig. 8 is a distortion diagram of a wide-angle lens according to a second embodiment of the present invention;

fig. 9 is a schematic structural diagram of a wide-angle lens according to a third embodiment of the present invention;

fig. 10 is a vertical axis chromatic aberration diagram of a wide-angle lens according to a third embodiment of the present invention;

fig. 11 is a field curvature diagram of a wide-angle lens according to a third embodiment of the present invention;

fig. 12 is a distortion diagram of a wide-angle lens according to a third embodiment of the present invention.

Description of the main element symbols:

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

Detailed Description

In order to make the objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below. Several embodiments of the invention are presented in the drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. 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. Like reference numerals refer to like elements throughout the specification.

The invention provides a wide-angle lens, which comprises six lenses, wherein the wide-angle lens sequentially comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens and a sixth lens from an object side to an imaging surface, and the optical centers of the lenses are positioned on the same straight line.

The first lens element has a negative power, and has a concave object-side surface and a concave image-side surface at a paraxial region. The object side surface is set to be a concave surface at a position close to the optical axis, so that the effective radius of the first lens can be reduced, and the volume of the wide-angle lens is further reduced;

the second lens has positive focal power, and the object side surface of the second lens is a convex surface, and the image side surface of the second lens is a concave surface;

the third lens element has positive focal power, and has a convex object-side surface and a convex image-side surface at a paraxial region;

the fourth lens element has a negative power, and has a concave object-side surface and a concave image-side surface at a paraxial region;

the fifth lens has positive focal power, and the image side surface of the fifth lens is a convex surface, so that aberration can be eliminated;

the sixth lens element has negative focal power, and has a convex object-side surface at a paraxial region and a concave image-side surface at a paraxial region, thereby further eliminating aberration and correcting distortion;

wherein a diaphragm is disposed between the second lens and the third lens, or between the third lens and the fourth lens.

The diaphragm can be made of shading paper with a light through hole in the center, and the light through caliber of the diaphragm is smaller than that of the space ring, so that the light through quantity of the lens is determined by the light through hole diameter of the diaphragm, the requirement of the light through hole of the lens barrel can be reduced, the forming difficulty of the light through hole of the lens barrel is reduced, the production efficiency is improved, and the production cost is reduced. Meanwhile, the diaphragm is arranged between the second lens and the third lens or between the third lens and the fourth lens, so that the light flux can be accurately adjusted to shoot clear pictures in a dark scene, and the incidence angle of the chief ray reaching an imaging surface can be controlled to meet the requirement of the incidence angle of the chip.

An infrared light cut-off filter is arranged behind the sixth lens, and the filter can effectively cut off infrared light from passing through, increase the effect of visible light, reduce chromatic aberration and stray light and improve the imaging effect.

In addition, in the wide-angle lens, the first lens element, the fourth lens element, the fifth lens element and the sixth lens element all adopt plastic aspheric lens elements, and the second lens element and the third lens element all adopt plastic aspheric lens elements or glass aspheric lens elements, so as to reduce the weight of the wide-angle lens and the production cost thereof, and simultaneously improve the resolving power of the wide-angle lens, reduce the vertical chromatic aberration thereof, correct the aberration thereof and improve the imaging pixels thereof.

Further, the surface shape of the aspherical lens in the wide-angle lens satisfies the following equation:

wherein z represents the distance between the curved surface and the vertex of the curved surface in the optical axis direction, c is the curvature corresponding to the radius, h is the radial coordinate (the unit of the radial coordinate is the same as the unit of the lens length), and K is the coefficient of the conic section. When K is less than-1, the curve is hyperbolic, parabolic when equal to-1, elliptic when between-1 and 0, circular when equal to 0, and oblate when greater than 0. B. C, D, E, F, G respectively represent coefficients corresponding to fourth, sixth, eighth, tenth, twelfth, and fourteenth radial coordinates. The surface shape and size of the front and back aspheric surfaces of the lens can be accurately set through the parameters. The aspheric surface shape meets an even-order aspheric surface equation, and different aspheric surface coefficients are utilized, so that the aspheric surface plays the most role in the system, and more perfect resolving power is obtained.

In order to satisfy imaging deformation-free, the wide-angle lens satisfies the following conditional expression: IH/(f multiplied tan theta) is more than 0.97 and less than 1.03; where IH denotes an actual image height of the wide-angle lens, f denotes an effective focal length of the wide-angle lens, and θ denotes a half field angle of the wide-angle lens.

If the IH/(f × tan θ) exceeds 1.03 or is less than 0.97, visible image distortion may occur, which may require image quality adjustment at the module or product side, increase the host image quality processing load, and may have a certain effect on the image quality of the entire image plane after additional distortion correction by means of an algorithm or the like.

To limit the overall length of the optical system and to ensure a sufficiently good imaging quality of the system, the wide-angle lens satisfies the conditional expression: TTL/(f multiplied tan theta) is more than 2.1 and less than 2.8; wherein, TTL represents the optical total length of the wide-angle lens, f represents the effective focal length of the wide-angle lens, and theta represents the half field angle of the wide-angle lens.

When the value of TTL/(f multiplied by tan theta) exceeds the upper limit, the total length of the whole lens is too long, the requirement of miniaturization is difficult to meet, and meanwhile, the requirement of automatic core adjustment by driving the lens through a lightweight motor is difficult to meet; or the target surface is too small under the condition that the total length is small enough, so that the larger chip is difficult to match; when the value of TTL/(f × tan θ) exceeds the lower limit, the lens aberration is difficult to correct because the power of each lens is too large, and the resolving power significantly decreases.

To provide a suitable lens size while correcting aberrations well, the wide-angle lens satisfies the following relation: -0.4 < phi 12/phi < -0.1; where φ 12 represents the combined optical power of the first and second lenses, φ represents the optical power of the wide-angle lens.

When the value of phi 12/phi exceeds the upper limit, the optical focuses of the first lens and the second lens are too strong, although the purpose of quickly converging light rays can be achieved, the total length of the system can be reduced, various aberrations generated by the lenses are too large and difficult to correct, and meanwhile, the curvature of the lenses is increased, the processing difficulty is improved, and the system error is increased; when the value of phi 12/phi exceeds the lower limit, the combined power of the first lens and the second lens decreases, the various aberrations described above relatively decrease, but the reduction in refractive power results in an increase in the overall length of the system.

In order to reasonably distribute the focal power of the lens and reduce the aberration of the optical lens, the wide-angle lens meets the following conditional expression: -1.2 < φ 3/φ 6 < -0.7; where φ 3 represents the optical power of the third lens and φ 6 represents the optical power of the sixth lens.

When the value of phi 3/phi 6 exceeds the upper limit or is lower than the lower limit, the power ratio of the third lens or the sixth lens is too large, so that the generated aberration is too large, and the re-correction difficulty of other lenses is increased.

In order to ensure that the aberration of the whole lens can be corrected finally, the wide-angle lens meets the following conditional expression: phi 56/phi is more than 0.7 and less than 1.1; where phi 56 denotes a combined power of the fifth lens and the sixth lens, and phi denotes a power of the wide-angle lens.

When the value of phi 56/phi exceeds the upper limit, the optical focuses of the fifth lens and the sixth lens are too strong, which is not beneficial to correcting the aberration generated by the first four lenses, so that new aberration is increased, the curvature of the lenses is increased, the processing difficulty is improved, and the system error is increased; when the value of φ 56/φ exceeds the lower limit, the combined power of the fifth lens and the sixth lens decreases, reducing their ability to correct aberrations, which may lead to system growth.

Further, the wide-angle lens satisfies the following conditional expression: DT3/DT6 of 0.25 < 0.35; DT3 represents an effective aperture of the third lens, and DT6 represents an effective aperture of the sixth lens.

When DT3 is too large, it is not favorable for correction of spherical aberration and curvature of field, and when it is too small, it is not favorable for processing and assembling; when DT6 is too large, it is not favorable for correcting system aberration, and when DT6 is too small, the system back focus is too large, and the incident angle CRA at which the principal ray of the wide-angle lens enters the image plane at the maximum angle of view is too large.

In order to better correct chromatic aberration, the wide-angle lens satisfies the following conditional expression: 30 < | Vd3-Vd4| < 40, 30 < | Vd5-Vd6| < 40; wherein Vd3 denotes an abbe number of the third lens, Vd4 denotes an abbe number of the fourth lens, Vd5 denotes an abbe number of the fifth lens, and Vd6 denotes an abbe number of the sixth lens.

The abbe number is an index indicating the dispersive power of the transparent medium. Generally, the smaller the abbe number of the lens, the more severe the dispersion; conversely, the larger the abbe number of the lens, the more slight the dispersion. In general, the chromatic aberration generated by the positive and negative lenses can compensate each other, but the abbe number difference is selected to be proper. When the value of the | Vd3-Vd4| or the | Vd5-Vd6| exceeds the lower limit, the chromatic aberration of the system is insufficiently corrected; when the values of | Vd3-Vd4| and | Vd5-Vd6| exceed the upper limit, the local chromatic aberration correction is too large, and material selection difficulty may occur.

For better correction of chromatic aberration, the wide-angle lens satisfies the following conditional expression: 0.4 < CT4/CT6 < 0.6; wherein CT4 represents the center thickness of the fourth lens and CT6 represents the center thickness of the sixth lens.

When the value of CT4/CT6 exceeds the lower limit, the chromatic aberration influence is too large, so that the selection of other lenses is difficult and the chromatic aberration correction of the whole system is difficult; when the value of CT4/CT6 exceeds the upper limit, the fourth lens and the sixth lens are difficult to process.

Further, the wide-angle lens satisfies the following conditional expression: d/f is more than 2.3 and less than 2.7; wherein D represents an image plane size of the wide-angle lens. The condition formula is satisfied, so that the lens has a larger visual angle and smaller distortion.

In order to match a conventional high-pixel chip on the market, the wide-angle lens satisfies the following conditional expression: CRA < 20 °; the CRA represents an incident angle at which a principal ray of the wide-angle lens is incident on an imaging plane at a maximum field angle. CRA control is within the above range and can better match the imaging requirements of conventional large CRA chips on the market.

The invention is further illustrated below in the following examples. In various embodiments, the thickness, the curvature radius, and the material selection of each lens in the wide-angle lens are different, and the specific differences can be referred to in the parameter tables of the various embodiments. The following examples are only preferred embodiments of the present invention, but the embodiments of the present invention are not limited only by the following examples, and any other changes, substitutions, combinations or simplifications which do not depart from the innovative points of the present invention should be construed as being equivalent substitutions and shall be included within the scope of the present invention.

First embodiment

Fig. 1 is a schematic structural diagram of a wide-angle lens 100 according to a first embodiment of the present invention, where the wide-angle lens 100 sequentially includes, from an object side to an image plane along an optical axis: the lens comprises a first lens L1, a second lens L2, a diaphragm ST, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, a filter G1 and an image plane S15, wherein the optical centers of the lenses are positioned on the same straight line.

A first lens L1 having a negative optical power, the first lens L1 having an object-side surface S1 that is concave at the paraxial region and an image-side surface S2 that is concave;

a second lens L2 having positive optical power, the second lens L2 having a convex object-side surface S3 and a concave image-side surface S4;

a third lens L3 having positive optical power, the third lens L3 having an object-side surface S5 that is convex and an image-side surface S6 that is convex at the paraxial region;

a fourth lens L4 having a negative optical power, the fourth lens L4 having an object-side surface S7 that is concave and an image-side surface S8 that is concave at the paraxial region;

a fifth lens L5 having positive optical power, the fifth lens L5 having a concave object-side surface S9 and a convex image-side surface S10;

a sixth lens L6 having a negative optical power, the sixth lens L6 having an object side S11 that is convex at a paraxial region and an image side S12 that is concave at a paraxial region;

please refer to table 1, which shows the related parameters of each lens of the wide-angle lens 100 in this embodiment.

TABLE 1

Please refer to table 2, which shows the aspheric parameters of the wide-angle lens 100 in this embodiment.

TABLE 2

In the present embodiment, the vertical axis chromatic aberration diagram, the curvature of field diagram, and the distortion diagram of the wide-angle lens 100 are shown in fig. 2, 3, and 4, respectively.

In fig. 2, the vertical axis chromatic aberration represents the chromatic aberration at different image heights on the image forming plane for each wavelength with respect to the center wavelength (0.55 μm), the horizontal axis represents the vertical axis chromatic aberration value (unit: μm) for each wavelength with respect to the center wavelength, and the vertical axis represents the normalized angle of view. As can be seen from FIG. 2, the vertical axis chromatic aberration of the longest wavelength and the shortest wavelength are controlled within + -7 μm, which shows that the optical lens can effectively correct the aberration of the fringe field and the secondary spectrum of the whole image plane.

The field curvature curve of fig. 3 indicates the degree of curvature of the meridional image plane and the sagittal image plane, the horizontal axis indicates the offset amount (unit: mm), and the vertical axis indicates the half field angle (unit: °). As can be seen from fig. 3, the field curvature of the meridional image plane and the sagittal image plane is controlled within ± 0.2mm, which indicates that the field curvature of the optical lens is better corrected.

The distortion curve in fig. 4 shows f-tan θ distortion at different image heights on the image forming plane, the abscissa shows f-tan θ distortion (unit:%), and the ordinate shows half field angle (unit:%). As can be seen from fig. 4, the optical distortion at different image heights on the image plane is controlled within ± 3%, which indicates that the distortion of the optical lens is well corrected.

Second embodiment

Fig. 5 is a schematic structural diagram of a wide-angle lens 200 according to a second embodiment. The wide-angle lens 200 in the present embodiment is substantially the same as the wide-angle lens 100 in the first embodiment, except that the parameters related to the respective lenses are different from those of the wide-angle lens 100 in the first embodiment, and the stop ST in the present embodiment is between the third lens L3 and the fourth lens L4, where the object-side surface S9 of the fifth lens is a convex surface.

Please refer to table 3, which shows the related parameters of each lens of the wide-angle lens 200 in this embodiment.

TABLE 3

Please refer to table 4, which shows the aspheric parameters of the wide-angle lens 200 of the present embodiment.

TABLE 4

In the present embodiment, the vertical axis chromatic aberration diagram, the curvature of field diagram, and the distortion diagram of wide-angle lens 200 are shown in fig. 6, 7, and 8, respectively.

The vertical axis chromatic aberration in fig. 6 indicates a chromatic aberration at different image heights on the image forming plane for each wavelength with respect to the center wavelength (0.55 μm), the horizontal axis indicates a vertical axis chromatic aberration value (unit: μm) for each wavelength with respect to the center wavelength, and the vertical axis indicates a normalized angle of view. As can be seen from FIG. 6, the vertical axis chromatic aberration of the longest wavelength and the shortest wavelength are controlled within + -7 μm, which shows that the optical lens can effectively correct the aberration of the fringe field and the secondary spectrum of the whole image plane.

The field curvature curve of fig. 7 indicates the degree of curvature of the meridional image plane and the sagittal image plane, the horizontal axis indicates the offset amount (unit: mm), and the vertical axis indicates the half field angle (unit: °). As can be seen from fig. 7, the field curvature of the meridional image plane and the sagittal image plane is controlled within ± 0.2mm, which indicates that the field curvature of the optical lens is better corrected.

The distortion curve in fig. 8 shows f-tan θ distortion at different image heights on the image forming plane, the abscissa shows f-tan θ distortion (unit:%), and the ordinate shows half field angle (unit:%). As can be seen from fig. 8, the optical distortion at different image heights on the image plane is controlled within ± 3%, which indicates that the distortion of the optical lens is well corrected.

Third embodiment

Fig. 9 is a schematic structural diagram of a wide-angle lens 300 according to a third embodiment. The wide-angle lens 300 in the present embodiment is substantially the same as the wide-angle lens 100 in the first embodiment, except that the parameters related to each lens are different from the parameters related to each lens of the wide-angle lens 100 in the first embodiment, and the third lens L3 is a glass aspheric surface.

Please refer to table 5, which shows the relevant parameters of each lens of the wide-angle lens 300 in this embodiment.

TABLE 5

Please refer to table 6, which shows the aspheric parameters of the wide-angle lens 300 of the present embodiment.

TABLE 6

In the present embodiment, the vertical axis chromatic aberration diagram, the curvature of field diagram, and the distortion diagram of wide-angle lens 300 are shown in fig. 10, fig. 11, and fig. 12, respectively.

In fig. 10, the vertical axis chromatic aberration represents the chromatic aberration at different image heights on the image forming plane for each wavelength with respect to the center wavelength (0.55 μm), the horizontal axis represents the vertical axis chromatic aberration value (unit: μm) for each wavelength with respect to the center wavelength, and the vertical axis represents the normalized angle of view. As can be seen from FIG. 10, the vertical axis chromatic aberration of the longest wavelength and the shortest wavelength are controlled within + -7 μm, which shows that the optical lens can effectively correct the aberration of the fringe field and the secondary spectrum of the whole image plane.

The field curvature curve of fig. 11 indicates the degree of curvature of the meridional image plane and the sagittal image plane, the horizontal axis indicates the offset amount (unit: mm), and the vertical axis indicates the half field angle (unit: °). As can be seen from fig. 11, the field curvature of the meridional image plane and the sagittal image plane is controlled within ± 0.2mm, which indicates that the field curvature of the optical lens is better corrected.

The distortion curve in fig. 12 indicates f-tan θ distortion at different image heights on the image forming plane, the abscissa indicates f-tan θ distortion (unit:%), and the ordinate indicates half field angle (unit:%). As can be seen from fig. 12, the optical distortion at different image heights on the image plane is controlled within ± 3%, indicating that the distortion of the optical lens is well corrected.

Please refer to table 7, which shows the optical characteristics corresponding to the wide-angle lens provided in each of the three embodiments, including the effective focal length F, F # and total optical length TTL of the wide-angle lens, and further including the related values corresponding to each of the conditional expressions.

TABLE 7

Compared with the prior art, the wide-angle lens provided by the invention at least has the following advantages:

1. the wide-angle lens adopts six plastic aspheric lenses or two glass aspheric lenses and four plastic aspheric lenses, so that the weight of the lens is reduced, and the light weight of the lens is realized.

2. The wide-angle lens structure is ingenious in design, the total length of the lens is greatly reduced through reasonable matching of the lenses, and the applicability and the overall size of the lens are improved.

3. The wide-angle lens has balanced focal power distribution of each lens, can still keep higher resolution level at a large angle, can be matched with an imaging chip with more than 1000 thousands of pixels, and realizes high-definition imaging.

4. The wide-angle lens has a large field angle which can reach more than 103 degrees, has small distortion, can reduce the influence of camera software on the image quality deterioration after the image stretching processing, and can be quickly matched with other chips and modules.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for those skilled in the art, various changes and modifications can be made without departing from the spirit of the invention, and these changes and modifications are all within the scope of the invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims

1. A wide-angle lens, comprising six lenses, the wide-angle lens comprising, in order from an object side to an image plane:

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

the diaphragm is arranged between the second lens and the third lens or between the third lens and the fourth lens;

the wide-angle lens meets the following conditional expression: TTL/(f multiplied tan theta) is more than 2.1 and less than 2.8; wherein, TTL represents the total optical length of the wide-angle lens.

2. The wide-angle lens of claim 1, wherein the wide-angle lens satisfies the following conditional expression: -0.4 < phi 12/phi < -0.1; where φ 12 represents the combined optical power of the first lens and the second lens, and φ represents the optical power of the wide-angle lens.

3. The wide-angle lens of claim 1, wherein the wide-angle lens satisfies the following conditional expression: -1.2 < φ 3/φ 6 < -0.7; where φ 3 represents the optical power of the third lens and φ 6 represents the optical power of the sixth lens.

4. The wide-angle lens of claim 1, wherein the wide-angle lens satisfies the following conditional expression: phi 56/phi is more than 0.7 and less than 1.1; where phi 56 denotes a combined power of the fifth lens and the sixth lens, and phi denotes a power of the wide-angle lens.

5. The wide-angle lens of claim 1, wherein the wide-angle lens satisfies the following conditional expression: DT3/DT6 of 0.25 < 0.35; DT3 represents an effective aperture of the third lens, and DT6 represents an effective aperture of the sixth lens.

6. The wide-angle lens of claim 1, wherein the wide-angle lens satisfies the following conditional expression: 30 < | Vd3-Vd4| < 40, 30 < | Vd5-Vd6| < 40; wherein Vd3 denotes an abbe number of the third lens, Vd4 denotes an abbe number of the fourth lens, Vd5 denotes an abbe number of the fifth lens, and Vd6 denotes an abbe number of the sixth lens.

7. The wide-angle lens of claim 1, wherein the wide-angle lens satisfies the following conditional expression: 0.4 < CT4/CT6 < 0.6; wherein CT4 represents the center thickness of the fourth lens and CT6 represents the center thickness of the sixth lens.

8. The wide-angle lens of claim 1, wherein the wide-angle lens satisfies the following conditional expression: d/f is more than 2.3 and less than 2.7; wherein D represents an image plane size of the wide-angle lens.

9. The wide-angle lens of claim 1, wherein the wide-angle lens satisfies the following conditional expression: CRA < 20 °; the CRA represents an incident angle at which a principal ray of the wide-angle lens is incident on an imaging plane at a maximum field angle.